Adding libwebp: Adding clean copy of libwebp 0.4.0

This commit imports libwebp 0.4.0, including AUTHORS, COPYING, ChangeLog,
NEWS, PATENTS, README and src directories. In src, only includes header
and source files.

The patches required to build it in Qt will follow in separate
commit(s).

Task-number: QTBUG-14205
Change-Id: I747918fe2a07716f66cffb795129f7aa5e067759
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

16 files changed, 7067 insertions, 0 deletions

diff --git a/src/3rdparty/libwebp/src/dec/alpha.c b/src/3rdparty/libwebp/src/dec/alpha.c
new file mode 100644
index 0000000..93729a0
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/alpha.c
@@ -0,0 +1,161 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Alpha-plane decompression.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <stdlib.h>
+#include "./alphai.h"
+#include "./vp8i.h"
+#include "./vp8li.h"
+#include "../utils/quant_levels_dec.h"
+#include "../webp/format_constants.h"
+
+//------------------------------------------------------------------------------
+// ALPHDecoder object.
+
+ALPHDecoder* ALPHNew(void) {
+  ALPHDecoder* const dec = (ALPHDecoder*)calloc(1, sizeof(*dec));
+  return dec;
+}
+
+void ALPHDelete(ALPHDecoder* const dec) {
+  if (dec != NULL) {
+    VP8LDelete(dec->vp8l_dec_);
+    dec->vp8l_dec_ = NULL;
+    free(dec);
+  }
+}
+
+//------------------------------------------------------------------------------
+// Decoding.
+
+// Initialize alpha decoding by parsing the alpha header and decoding the image
+// header for alpha data stored using lossless compression.
+// Returns false in case of error in alpha header (data too short, invalid
+// compression method or filter, error in lossless header data etc).
+static int ALPHInit(ALPHDecoder* const dec, const uint8_t* data,
+                    size_t data_size, int width, int height, uint8_t* output) {
+  int ok = 0;
+  const uint8_t* const alpha_data = data + ALPHA_HEADER_LEN;
+  const size_t alpha_data_size = data_size - ALPHA_HEADER_LEN;
+  int rsrv;
+
+  assert(width > 0 && height > 0);
+  assert(data != NULL && output != NULL);
+
+  dec->width_ = width;
+  dec->height_ = height;
+
+  if (data_size <= ALPHA_HEADER_LEN) {
+    return 0;
+  }
+
+  dec->method_ = (data[0] >> 0) & 0x03;
+  dec->filter_ = (data[0] >> 2) & 0x03;
+  dec->pre_processing_ = (data[0] >> 4) & 0x03;
+  rsrv = (data[0] >> 6) & 0x03;
+  if (dec->method_ < ALPHA_NO_COMPRESSION ||
+      dec->method_ > ALPHA_LOSSLESS_COMPRESSION ||
+      dec->filter_ >= WEBP_FILTER_LAST ||
+      dec->pre_processing_ > ALPHA_PREPROCESSED_LEVELS ||
+      rsrv != 0) {
+    return 0;
+  }
+
+  if (dec->method_ == ALPHA_NO_COMPRESSION) {
+    const size_t alpha_decoded_size = dec->width_ * dec->height_;
+    ok = (alpha_data_size >= alpha_decoded_size);
+  } else {
+    assert(dec->method_ == ALPHA_LOSSLESS_COMPRESSION);
+    ok = VP8LDecodeAlphaHeader(dec, alpha_data, alpha_data_size, output);
+  }
+  return ok;
+}
+
+// Decodes, unfilters and dequantizes *at least* 'num_rows' rows of alpha
+// starting from row number 'row'. It assumes that rows up to (row - 1) have
+// already been decoded.
+// Returns false in case of bitstream error.
+static int ALPHDecode(VP8Decoder* const dec, int row, int num_rows) {
+  ALPHDecoder* const alph_dec = dec->alph_dec_;
+  const int width = alph_dec->width_;
+  const int height = alph_dec->height_;
+  WebPUnfilterFunc unfilter_func = WebPUnfilters[alph_dec->filter_];
+  uint8_t* const output = dec->alpha_plane_;
+  if (alph_dec->method_ == ALPHA_NO_COMPRESSION) {
+    const size_t offset = row * width;
+    const size_t num_pixels = num_rows * width;
+    assert(dec->alpha_data_size_ >= ALPHA_HEADER_LEN + offset + num_pixels);
+    memcpy(dec->alpha_plane_ + offset,
+           dec->alpha_data_ + ALPHA_HEADER_LEN + offset, num_pixels);
+  } else {  // alph_dec->method_ == ALPHA_LOSSLESS_COMPRESSION
+    assert(alph_dec->vp8l_dec_ != NULL);
+    if (!VP8LDecodeAlphaImageStream(alph_dec, row + num_rows)) {
+      return 0;
+    }
+  }
+
+  if (unfilter_func != NULL) {
+    unfilter_func(width, height, width, row, num_rows, output);
+  }
+
+  if (alph_dec->pre_processing_ == ALPHA_PREPROCESSED_LEVELS) {
+    if (!DequantizeLevels(output, width, height, row, num_rows)) {
+      return 0;
+    }
+  }
+
+  if (row + num_rows == dec->pic_hdr_.height_) {
+    dec->is_alpha_decoded_ = 1;
+  }
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+// Main entry point.
+
+const uint8_t* VP8DecompressAlphaRows(VP8Decoder* const dec,
+                                      int row, int num_rows) {
+  const int width = dec->pic_hdr_.width_;
+  const int height = dec->pic_hdr_.height_;
+
+  if (row < 0 || num_rows <= 0 || row + num_rows > height) {
+    return NULL;    // sanity check.
+  }
+
+  if (row == 0) {
+    // Initialize decoding.
+    assert(dec->alpha_plane_ != NULL);
+    dec->alph_dec_ = ALPHNew();
+    if (dec->alph_dec_ == NULL) return NULL;
+    if (!ALPHInit(dec->alph_dec_, dec->alpha_data_, dec->alpha_data_size_,
+                  width, height, dec->alpha_plane_)) {
+      ALPHDelete(dec->alph_dec_);
+      dec->alph_dec_ = NULL;
+      return NULL;
+    }
+  }
+
+  if (!dec->is_alpha_decoded_) {
+    int ok = 0;
+    assert(dec->alph_dec_ != NULL);
+    ok = ALPHDecode(dec, row, num_rows);
+    if (!ok || dec->is_alpha_decoded_) {
+      ALPHDelete(dec->alph_dec_);
+      dec->alph_dec_ = NULL;
+    }
+    if (!ok) return NULL;  // Error.
+  }
+
+  // Return a pointer to the current decoded row.
+  return dec->alpha_plane_ + row * width;
+}
+
diff --git a/src/3rdparty/libwebp/src/dec/alphai.h b/src/3rdparty/libwebp/src/dec/alphai.h
new file mode 100644
index 0000000..5fa230c
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/alphai.h
@@ -0,0 +1,55 @@
+// Copyright 2013 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Alpha decoder: internal header.
+//
+// Author: Urvang (urvang@google.com)
+
+#ifndef WEBP_DEC_ALPHAI_H_
+#define WEBP_DEC_ALPHAI_H_
+
+#include "./webpi.h"
+#include "../utils/filters.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct VP8LDecoder;  // Defined in dec/vp8li.h.
+
+typedef struct ALPHDecoder ALPHDecoder;
+struct ALPHDecoder {
+  int width_;
+  int height_;
+  int method_;
+  WEBP_FILTER_TYPE filter_;
+  int pre_processing_;
+  struct VP8LDecoder* vp8l_dec_;
+  VP8Io io_;
+  int use_8b_decode;  // Although alpha channel requires only 1 byte per
+                      // pixel, sometimes VP8LDecoder may need to allocate
+                      // 4 bytes per pixel internally during decode.
+};
+
+//------------------------------------------------------------------------------
+// internal functions. Not public.
+
+// Allocates a new alpha decoder instance.
+ALPHDecoder* ALPHNew(void);
+
+// Clears and deallocates an alpha decoder instance.
+void ALPHDelete(ALPHDecoder* const dec);
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_DEC_ALPHAI_H_ */
diff --git a/src/3rdparty/libwebp/src/dec/buffer.c b/src/3rdparty/libwebp/src/dec/buffer.c
new file mode 100644
index 0000000..1e852ef
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/buffer.c
@@ -0,0 +1,210 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Everything about WebPDecBuffer
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <stdlib.h>
+
+#include "./vp8i.h"
+#include "./webpi.h"
+#include "../utils/utils.h"
+
+//------------------------------------------------------------------------------
+// WebPDecBuffer
+
+// Number of bytes per pixel for the different color-spaces.
+static const int kModeBpp[MODE_LAST] = {
+  3, 4, 3, 4, 4, 2, 2,
+  4, 4, 4, 2,    // pre-multiplied modes
+  1, 1 };
+
+// Check that webp_csp_mode is within the bounds of WEBP_CSP_MODE.
+// Convert to an integer to handle both the unsigned/signed enum cases
+// without the need for casting to remove type limit warnings.
+static int IsValidColorspace(int webp_csp_mode) {
+  return (webp_csp_mode >= MODE_RGB && webp_csp_mode < MODE_LAST);
+}
+
+static VP8StatusCode CheckDecBuffer(const WebPDecBuffer* const buffer) {
+  int ok = 1;
+  const WEBP_CSP_MODE mode = buffer->colorspace;
+  const int width = buffer->width;
+  const int height = buffer->height;
+  if (!IsValidColorspace(mode)) {
+    ok = 0;
+  } else if (!WebPIsRGBMode(mode)) {   // YUV checks
+    const WebPYUVABuffer* const buf = &buffer->u.YUVA;
+    const uint64_t y_size = (uint64_t)buf->y_stride * height;
+    const uint64_t u_size = (uint64_t)buf->u_stride * ((height + 1) / 2);
+    const uint64_t v_size = (uint64_t)buf->v_stride * ((height + 1) / 2);
+    const uint64_t a_size = (uint64_t)buf->a_stride * height;
+    ok &= (y_size <= buf->y_size);
+    ok &= (u_size <= buf->u_size);
+    ok &= (v_size <= buf->v_size);
+    ok &= (buf->y_stride >= width);
+    ok &= (buf->u_stride >= (width + 1) / 2);
+    ok &= (buf->v_stride >= (width + 1) / 2);
+    ok &= (buf->y != NULL);
+    ok &= (buf->u != NULL);
+    ok &= (buf->v != NULL);
+    if (mode == MODE_YUVA) {
+      ok &= (buf->a_stride >= width);
+      ok &= (a_size <= buf->a_size);
+      ok &= (buf->a != NULL);
+    }
+  } else {    // RGB checks
+    const WebPRGBABuffer* const buf = &buffer->u.RGBA;
+    const uint64_t size = (uint64_t)buf->stride * height;
+    ok &= (size <= buf->size);
+    ok &= (buf->stride >= width * kModeBpp[mode]);
+    ok &= (buf->rgba != NULL);
+  }
+  return ok ? VP8_STATUS_OK : VP8_STATUS_INVALID_PARAM;
+}
+
+static VP8StatusCode AllocateBuffer(WebPDecBuffer* const buffer) {
+  const int w = buffer->width;
+  const int h = buffer->height;
+  const WEBP_CSP_MODE mode = buffer->colorspace;
+
+  if (w <= 0 || h <= 0 || !IsValidColorspace(mode)) {
+    return VP8_STATUS_INVALID_PARAM;
+  }
+
+  if (!buffer->is_external_memory && buffer->private_memory == NULL) {
+    uint8_t* output;
+    int uv_stride = 0, a_stride = 0;
+    uint64_t uv_size = 0, a_size = 0, total_size;
+    // We need memory and it hasn't been allocated yet.
+    // => initialize output buffer, now that dimensions are known.
+    const int stride = w * kModeBpp[mode];
+    const uint64_t size = (uint64_t)stride * h;
+
+    if (!WebPIsRGBMode(mode)) {
+      uv_stride = (w + 1) / 2;
+      uv_size = (uint64_t)uv_stride * ((h + 1) / 2);
+      if (mode == MODE_YUVA) {
+        a_stride = w;
+        a_size = (uint64_t)a_stride * h;
+      }
+    }
+    total_size = size + 2 * uv_size + a_size;
+
+    // Security/sanity checks
+    output = (uint8_t*)WebPSafeMalloc(total_size, sizeof(*output));
+    if (output == NULL) {
+      return VP8_STATUS_OUT_OF_MEMORY;
+    }
+    buffer->private_memory = output;
+
+    if (!WebPIsRGBMode(mode)) {   // YUVA initialization
+      WebPYUVABuffer* const buf = &buffer->u.YUVA;
+      buf->y = output;
+      buf->y_stride = stride;
+      buf->y_size = (size_t)size;
+      buf->u = output + size;
+      buf->u_stride = uv_stride;
+      buf->u_size = (size_t)uv_size;
+      buf->v = output + size + uv_size;
+      buf->v_stride = uv_stride;
+      buf->v_size = (size_t)uv_size;
+      if (mode == MODE_YUVA) {
+        buf->a = output + size + 2 * uv_size;
+      }
+      buf->a_size = (size_t)a_size;
+      buf->a_stride = a_stride;
+    } else {  // RGBA initialization
+      WebPRGBABuffer* const buf = &buffer->u.RGBA;
+      buf->rgba = output;
+      buf->stride = stride;
+      buf->size = (size_t)size;
+    }
+  }
+  return CheckDecBuffer(buffer);
+}
+
+VP8StatusCode WebPAllocateDecBuffer(int w, int h,
+                                    const WebPDecoderOptions* const options,
+                                    WebPDecBuffer* const out) {
+  if (out == NULL || w <= 0 || h <= 0) {
+    return VP8_STATUS_INVALID_PARAM;
+  }
+  if (options != NULL) {    // First, apply options if there is any.
+    if (options->use_cropping) {
+      const int cw = options->crop_width;
+      const int ch = options->crop_height;
+      const int x = options->crop_left & ~1;
+      const int y = options->crop_top & ~1;
+      if (x < 0 || y < 0 || cw <= 0 || ch <= 0 || x + cw > w || y + ch > h) {
+        return VP8_STATUS_INVALID_PARAM;   // out of frame boundary.
+      }
+      w = cw;
+      h = ch;
+    }
+    if (options->use_scaling) {
+      if (options->scaled_width <= 0 || options->scaled_height <= 0) {
+        return VP8_STATUS_INVALID_PARAM;
+      }
+      w = options->scaled_width;
+      h = options->scaled_height;
+    }
+  }
+  out->width = w;
+  out->height = h;
+
+  // Then, allocate buffer for real
+  return AllocateBuffer(out);
+}
+
+//------------------------------------------------------------------------------
+// constructors / destructors
+
+int WebPInitDecBufferInternal(WebPDecBuffer* buffer, int version) {
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
+    return 0;  // version mismatch
+  }
+  if (buffer == NULL) return 0;
+  memset(buffer, 0, sizeof(*buffer));
+  return 1;
+}
+
+void WebPFreeDecBuffer(WebPDecBuffer* buffer) {
+  if (buffer != NULL) {
+    if (!buffer->is_external_memory)
+      free(buffer->private_memory);
+    buffer->private_memory = NULL;
+  }
+}
+
+void WebPCopyDecBuffer(const WebPDecBuffer* const src,
+                       WebPDecBuffer* const dst) {
+  if (src != NULL && dst != NULL) {
+    *dst = *src;
+    if (src->private_memory != NULL) {
+      dst->is_external_memory = 1;   // dst buffer doesn't own the memory.
+      dst->private_memory = NULL;
+    }
+  }
+}
+
+// Copy and transfer ownership from src to dst (beware of parameter order!)
+void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst) {
+  if (src != NULL && dst != NULL) {
+    *dst = *src;
+    if (src->private_memory != NULL) {
+      src->is_external_memory = 1;   // src relinquishes ownership
+      src->private_memory = NULL;
+    }
+  }
+}
+
+//------------------------------------------------------------------------------
+
diff --git a/src/3rdparty/libwebp/src/dec/decode_vp8.h b/src/3rdparty/libwebp/src/dec/decode_vp8.h
new file mode 100644
index 0000000..b9337bb
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/decode_vp8.h
@@ -0,0 +1,185 @@
+// Copyright 2010 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+//  Low-level API for VP8 decoder
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifndef WEBP_WEBP_DECODE_VP8_H_
+#define WEBP_WEBP_DECODE_VP8_H_
+
+#include "../webp/decode.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//------------------------------------------------------------------------------
+// Lower-level API
+//
+// These functions provide fine-grained control of the decoding process.
+// The call flow should resemble:
+//
+//   VP8Io io;
+//   VP8InitIo(&io);
+//   io.data = data;
+//   io.data_size = size;
+//   /* customize io's functions (setup()/put()/teardown()) if needed. */
+//
+//   VP8Decoder* dec = VP8New();
+//   bool ok = VP8Decode(dec);
+//   if (!ok) printf("Error: %s\n", VP8StatusMessage(dec));
+//   VP8Delete(dec);
+//   return ok;
+
+// Input / Output
+typedef struct VP8Io VP8Io;
+typedef int (*VP8IoPutHook)(const VP8Io* io);
+typedef int (*VP8IoSetupHook)(VP8Io* io);
+typedef void (*VP8IoTeardownHook)(const VP8Io* io);
+
+struct VP8Io {
+  // set by VP8GetHeaders()
+  int width, height;         // picture dimensions, in pixels (invariable).
+                             // These are the original, uncropped dimensions.
+                             // The actual area passed to put() is stored
+                             // in mb_w / mb_h fields.
+
+  // set before calling put()
+  int mb_y;                  // position of the current rows (in pixels)
+  int mb_w;                  // number of columns in the sample
+  int mb_h;                  // number of rows in the sample
+  const uint8_t* y, *u, *v;  // rows to copy (in yuv420 format)
+  int y_stride;              // row stride for luma
+  int uv_stride;             // row stride for chroma
+
+  void* opaque;              // user data
+
+  // called when fresh samples are available. Currently, samples are in
+  // YUV420 format, and can be up to width x 24 in size (depending on the
+  // in-loop filtering level, e.g.). Should return false in case of error
+  // or abort request. The actual size of the area to update is mb_w x mb_h
+  // in size, taking cropping into account.
+  VP8IoPutHook put;
+
+  // called just before starting to decode the blocks.
+  // Must return false in case of setup error, true otherwise. If false is
+  // returned, teardown() will NOT be called. But if the setup succeeded
+  // and true is returned, then teardown() will always be called afterward.
+  VP8IoSetupHook setup;
+
+  // Called just after block decoding is finished (or when an error occurred
+  // during put()). Is NOT called if setup() failed.
+  VP8IoTeardownHook teardown;
+
+  // this is a recommendation for the user-side yuv->rgb converter. This flag
+  // is set when calling setup() hook and can be overwritten by it. It then
+  // can be taken into consideration during the put() method.
+  int fancy_upsampling;
+
+  // Input buffer.
+  size_t data_size;
+  const uint8_t* data;
+
+  // If true, in-loop filtering will not be performed even if present in the
+  // bitstream. Switching off filtering may speed up decoding at the expense
+  // of more visible blocking. Note that output will also be non-compliant
+  // with the VP8 specifications.
+  int bypass_filtering;
+
+  // Cropping parameters.
+  int use_cropping;
+  int crop_left, crop_right, crop_top, crop_bottom;
+
+  // Scaling parameters.
+  int use_scaling;
+  int scaled_width, scaled_height;
+
+  // If non NULL, pointer to the alpha data (if present) corresponding to the
+  // start of the current row (That is: it is pre-offset by mb_y and takes
+  // cropping into account).
+  const uint8_t* a;
+};
+
+// Internal, version-checked, entry point
+int VP8InitIoInternal(VP8Io* const, int);
+
+// Set the custom IO function pointers and user-data. The setter for IO hooks
+// should be called before initiating incremental decoding. Returns true if
+// WebPIDecoder object is successfully modified, false otherwise.
+int WebPISetIOHooks(WebPIDecoder* const idec,
+                    VP8IoPutHook put,
+                    VP8IoSetupHook setup,
+                    VP8IoTeardownHook teardown,
+                    void* user_data);
+
+// Main decoding object. This is an opaque structure.
+typedef struct VP8Decoder VP8Decoder;
+
+// Create a new decoder object.
+VP8Decoder* VP8New(void);
+
+// Must be called to make sure 'io' is initialized properly.
+// Returns false in case of version mismatch. Upon such failure, no other
+// decoding function should be called (VP8Decode, VP8GetHeaders, ...)
+static WEBP_INLINE int VP8InitIo(VP8Io* const io) {
+  return VP8InitIoInternal(io, WEBP_DECODER_ABI_VERSION);
+}
+
+// Decode the VP8 frame header. Returns true if ok.
+// Note: 'io->data' must be pointing to the start of the VP8 frame header.
+int VP8GetHeaders(VP8Decoder* const dec, VP8Io* const io);
+
+// Decode a picture. Will call VP8GetHeaders() if it wasn't done already.
+// Returns false in case of error.
+int VP8Decode(VP8Decoder* const dec, VP8Io* const io);
+
+// Return current status of the decoder:
+VP8StatusCode VP8Status(VP8Decoder* const dec);
+
+// return readable string corresponding to the last status.
+const char* VP8StatusMessage(VP8Decoder* const dec);
+
+// Resets the decoder in its initial state, reclaiming memory.
+// Not a mandatory call between calls to VP8Decode().
+void VP8Clear(VP8Decoder* const dec);
+
+// Destroy the decoder object.
+void VP8Delete(VP8Decoder* const dec);
+
+//------------------------------------------------------------------------------
+// Miscellaneous VP8/VP8L bitstream probing functions.
+
+// Returns true if the next 3 bytes in data contain the VP8 signature.
+WEBP_EXTERN(int) VP8CheckSignature(const uint8_t* const data, size_t data_size);
+
+// Validates the VP8 data-header and retrieves basic header information viz
+// width and height. Returns 0 in case of formatting error. *width/*height
+// can be passed NULL.
+WEBP_EXTERN(int) VP8GetInfo(
+    const uint8_t* data,
+    size_t data_size,    // data available so far
+    size_t chunk_size,   // total data size expected in the chunk
+    int* const width, int* const height);
+
+// Returns true if the next byte(s) in data is a VP8L signature.
+WEBP_EXTERN(int) VP8LCheckSignature(const uint8_t* const data, size_t size);
+
+// Validates the VP8L data-header and retrieves basic header information viz
+// width, height and alpha. Returns 0 in case of formatting error.
+// width/height/has_alpha can be passed NULL.
+WEBP_EXTERN(int) VP8LGetInfo(
+    const uint8_t* data, size_t data_size,  // data available so far
+    int* const width, int* const height, int* const has_alpha);
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_WEBP_DECODE_VP8_H_ */
diff --git a/src/3rdparty/libwebp/src/dec/frame.c b/src/3rdparty/libwebp/src/dec/frame.c
new file mode 100644
index 0000000..e1eea94
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/frame.c
@@ -0,0 +1,818 @@
+// Copyright 2010 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Frame-reconstruction function. Memory allocation.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <stdlib.h>
+#include "./vp8i.h"
+#include "../utils/utils.h"
+
+#define ALIGN_MASK (32 - 1)
+
+static void ReconstructRow(const VP8Decoder* const dec,
+                           const VP8ThreadContext* ctx);  // TODO(skal): remove
+
+//------------------------------------------------------------------------------
+// Filtering
+
+// kFilterExtraRows[] = How many extra lines are needed on the MB boundary
+// for caching, given a filtering level.
+// Simple filter:  up to 2 luma samples are read and 1 is written.
+// Complex filter: up to 4 luma samples are read and 3 are written. Same for
+//                 U/V, so it's 8 samples total (because of the 2x upsampling).
+static const uint8_t kFilterExtraRows[3] = { 0, 2, 8 };
+
+static void DoFilter(const VP8Decoder* const dec, int mb_x, int mb_y) {
+  const VP8ThreadContext* const ctx = &dec->thread_ctx_;
+  const int cache_id = ctx->id_;
+  const int y_bps = dec->cache_y_stride_;
+  const VP8FInfo* const f_info = ctx->f_info_ + mb_x;
+  uint8_t* const y_dst = dec->cache_y_ + cache_id * 16 * y_bps + mb_x * 16;
+  const int ilevel = f_info->f_ilevel_;
+  const int limit = f_info->f_limit_;
+  if (limit == 0) {
+    return;
+  }
+  assert(limit >= 3);
+  if (dec->filter_type_ == 1) {   // simple
+    if (mb_x > 0) {
+      VP8SimpleHFilter16(y_dst, y_bps, limit + 4);
+    }
+    if (f_info->f_inner_) {
+      VP8SimpleHFilter16i(y_dst, y_bps, limit);
+    }
+    if (mb_y > 0) {
+      VP8SimpleVFilter16(y_dst, y_bps, limit + 4);
+    }
+    if (f_info->f_inner_) {
+      VP8SimpleVFilter16i(y_dst, y_bps, limit);
+    }
+  } else {    // complex
+    const int uv_bps = dec->cache_uv_stride_;
+    uint8_t* const u_dst = dec->cache_u_ + cache_id * 8 * uv_bps + mb_x * 8;
+    uint8_t* const v_dst = dec->cache_v_ + cache_id * 8 * uv_bps + mb_x * 8;
+    const int hev_thresh = f_info->hev_thresh_;
+    if (mb_x > 0) {
+      VP8HFilter16(y_dst, y_bps, limit + 4, ilevel, hev_thresh);
+      VP8HFilter8(u_dst, v_dst, uv_bps, limit + 4, ilevel, hev_thresh);
+    }
+    if (f_info->f_inner_) {
+      VP8HFilter16i(y_dst, y_bps, limit, ilevel, hev_thresh);
+      VP8HFilter8i(u_dst, v_dst, uv_bps, limit, ilevel, hev_thresh);
+    }
+    if (mb_y > 0) {
+      VP8VFilter16(y_dst, y_bps, limit + 4, ilevel, hev_thresh);
+      VP8VFilter8(u_dst, v_dst, uv_bps, limit + 4, ilevel, hev_thresh);
+    }
+    if (f_info->f_inner_) {
+      VP8VFilter16i(y_dst, y_bps, limit, ilevel, hev_thresh);
+      VP8VFilter8i(u_dst, v_dst, uv_bps, limit, ilevel, hev_thresh);
+    }
+  }
+}
+
+// Filter the decoded macroblock row (if needed)
+static void FilterRow(const VP8Decoder* const dec) {
+  int mb_x;
+  const int mb_y = dec->thread_ctx_.mb_y_;
+  assert(dec->thread_ctx_.filter_row_);
+  for (mb_x = dec->tl_mb_x_; mb_x < dec->br_mb_x_; ++mb_x) {
+    DoFilter(dec, mb_x, mb_y);
+  }
+}
+
+//------------------------------------------------------------------------------
+// Precompute the filtering strength for each segment and each i4x4/i16x16 mode.
+
+static void PrecomputeFilterStrengths(VP8Decoder* const dec) {
+  if (dec->filter_type_ > 0) {
+    int s;
+    const VP8FilterHeader* const hdr = &dec->filter_hdr_;
+    for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
+      int i4x4;
+      // First, compute the initial level
+      int base_level;
+      if (dec->segment_hdr_.use_segment_) {
+        base_level = dec->segment_hdr_.filter_strength_[s];
+        if (!dec->segment_hdr_.absolute_delta_) {
+          base_level += hdr->level_;
+        }
+      } else {
+        base_level = hdr->level_;
+      }
+      for (i4x4 = 0; i4x4 <= 1; ++i4x4) {
+        VP8FInfo* const info = &dec->fstrengths_[s][i4x4];
+        int level = base_level;
+        if (hdr->use_lf_delta_) {
+          // TODO(skal): only CURRENT is handled for now.
+          level += hdr->ref_lf_delta_[0];
+          if (i4x4) {
+            level += hdr->mode_lf_delta_[0];
+          }
+        }
+        level = (level < 0) ? 0 : (level > 63) ? 63 : level;
+        if (level > 0) {
+          int ilevel = level;
+          if (hdr->sharpness_ > 0) {
+            if (hdr->sharpness_ > 4) {
+              ilevel >>= 2;
+            } else {
+              ilevel >>= 1;
+            }
+            if (ilevel > 9 - hdr->sharpness_) {
+              ilevel = 9 - hdr->sharpness_;
+            }
+          }
+          if (ilevel < 1) ilevel = 1;
+          info->f_ilevel_ = ilevel;
+          info->f_limit_ = 2 * level + ilevel;
+          info->hev_thresh_ = (level >= 40) ? 2 : (level >= 15) ? 1 : 0;
+        } else {
+          info->f_limit_ = 0;  // no filtering
+        }
+        info->f_inner_ = i4x4;
+      }
+    }
+  }
+}
+
+//------------------------------------------------------------------------------
+// Dithering
+
+#define DITHER_AMP_TAB_SIZE 12
+static const int kQuantToDitherAmp[DITHER_AMP_TAB_SIZE] = {
+  // roughly, it's dqm->uv_mat_[1]
+  8, 7, 6, 4, 4, 2, 2, 2, 1, 1, 1, 1
+};
+
+void VP8InitDithering(const WebPDecoderOptions* const options,
+                      VP8Decoder* const dec) {
+  assert(dec != NULL);
+  if (options != NULL) {
+    const int d = options->dithering_strength;
+    const int max_amp = (1 << VP8_RANDOM_DITHER_FIX) - 1;
+    const int f = (d < 0) ? 0 : (d > 100) ? max_amp : (d * max_amp / 100);
+    if (f > 0) {
+      int s;
+      int all_amp = 0;
+      for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
+        VP8QuantMatrix* const dqm = &dec->dqm_[s];
+        if (dqm->uv_quant_ < DITHER_AMP_TAB_SIZE) {
+          // TODO(skal): should we specially dither more for uv_quant_ < 0?
+          const int idx = (dqm->uv_quant_ < 0) ? 0 : dqm->uv_quant_;
+          dqm->dither_ = (f * kQuantToDitherAmp[idx]) >> 3;
+        }
+        all_amp |= dqm->dither_;
+      }
+      if (all_amp != 0) {
+        VP8InitRandom(&dec->dithering_rg_, 1.0f);
+        dec->dither_ = 1;
+      }
+    }
+  }
+}
+
+// minimal amp that will provide a non-zero dithering effect
+#define MIN_DITHER_AMP 4
+#define DITHER_DESCALE 4
+#define DITHER_DESCALE_ROUNDER (1 << (DITHER_DESCALE - 1))
+#define DITHER_AMP_BITS 8
+#define DITHER_AMP_CENTER (1 << DITHER_AMP_BITS)
+
+static void Dither8x8(VP8Random* const rg, uint8_t* dst, int bps, int amp) {
+  int i, j;
+  for (j = 0; j < 8; ++j) {
+    for (i = 0; i < 8; ++i) {
+      // TODO: could be made faster with SSE2
+      const int bits =
+          VP8RandomBits2(rg, DITHER_AMP_BITS + 1, amp) - DITHER_AMP_CENTER;
+      // Convert to range: [-2,2] for dither=50, [-4,4] for dither=100
+      const int delta = (bits + DITHER_DESCALE_ROUNDER) >> DITHER_DESCALE;
+      const int v = (int)dst[i] + delta;
+      dst[i] = (v < 0) ? 0 : (v > 255) ? 255u : (uint8_t)v;
+    }
+    dst += bps;
+  }
+}
+
+static void DitherRow(VP8Decoder* const dec) {
+  int mb_x;
+  assert(dec->dither_);
+  for (mb_x = dec->tl_mb_x_; mb_x < dec->br_mb_x_; ++mb_x) {
+    const VP8ThreadContext* const ctx = &dec->thread_ctx_;
+    const VP8MBData* const data = ctx->mb_data_ + mb_x;
+    const int cache_id = ctx->id_;
+    const int uv_bps = dec->cache_uv_stride_;
+    if (data->dither_ >= MIN_DITHER_AMP) {
+      uint8_t* const u_dst = dec->cache_u_ + cache_id * 8 * uv_bps + mb_x * 8;
+      uint8_t* const v_dst = dec->cache_v_ + cache_id * 8 * uv_bps + mb_x * 8;
+      Dither8x8(&dec->dithering_rg_, u_dst, uv_bps, data->dither_);
+      Dither8x8(&dec->dithering_rg_, v_dst, uv_bps, data->dither_);
+    }
+  }
+}
+
+//------------------------------------------------------------------------------
+// This function is called after a row of macroblocks is finished decoding.
+// It also takes into account the following restrictions:
+//  * In case of in-loop filtering, we must hold off sending some of the bottom
+//    pixels as they are yet unfiltered. They will be when the next macroblock
+//    row is decoded. Meanwhile, we must preserve them by rotating them in the
+//    cache area. This doesn't hold for the very bottom row of the uncropped
+//    picture of course.
+//  * we must clip the remaining pixels against the cropping area. The VP8Io
+//    struct must have the following fields set correctly before calling put():
+
+#define MACROBLOCK_VPOS(mb_y)  ((mb_y) * 16)    // vertical position of a MB
+
+// Finalize and transmit a complete row. Return false in case of user-abort.
+static int FinishRow(VP8Decoder* const dec, VP8Io* const io) {
+  int ok = 1;
+  const VP8ThreadContext* const ctx = &dec->thread_ctx_;
+  const int cache_id = ctx->id_;
+  const int extra_y_rows = kFilterExtraRows[dec->filter_type_];
+  const int ysize = extra_y_rows * dec->cache_y_stride_;
+  const int uvsize = (extra_y_rows / 2) * dec->cache_uv_stride_;
+  const int y_offset = cache_id * 16 * dec->cache_y_stride_;
+  const int uv_offset = cache_id * 8 * dec->cache_uv_stride_;
+  uint8_t* const ydst = dec->cache_y_ - ysize + y_offset;
+  uint8_t* const udst = dec->cache_u_ - uvsize + uv_offset;
+  uint8_t* const vdst = dec->cache_v_ - uvsize + uv_offset;
+  const int mb_y = ctx->mb_y_;
+  const int is_first_row = (mb_y == 0);
+  const int is_last_row = (mb_y >= dec->br_mb_y_ - 1);
+
+  if (dec->mt_method_ == 2) {
+    ReconstructRow(dec, ctx);
+  }
+
+  if (ctx->filter_row_) {
+    FilterRow(dec);
+  }
+
+  if (dec->dither_) {
+    DitherRow(dec);
+  }
+
+  if (io->put != NULL) {
+    int y_start = MACROBLOCK_VPOS(mb_y);
+    int y_end = MACROBLOCK_VPOS(mb_y + 1);
+    if (!is_first_row) {
+      y_start -= extra_y_rows;
+      io->y = ydst;
+      io->u = udst;
+      io->v = vdst;
+    } else {
+      io->y = dec->cache_y_ + y_offset;
+      io->u = dec->cache_u_ + uv_offset;
+      io->v = dec->cache_v_ + uv_offset;
+    }
+
+    if (!is_last_row) {
+      y_end -= extra_y_rows;
+    }
+    if (y_end > io->crop_bottom) {
+      y_end = io->crop_bottom;    // make sure we don't overflow on last row.
+    }
+    io->a = NULL;
+    if (dec->alpha_data_ != NULL && y_start < y_end) {
+      // TODO(skal): testing presence of alpha with dec->alpha_data_ is not a
+      // good idea.
+      io->a = VP8DecompressAlphaRows(dec, y_start, y_end - y_start);
+      if (io->a == NULL) {
+        return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
+                           "Could not decode alpha data.");
+      }
+    }
+    if (y_start < io->crop_top) {
+      const int delta_y = io->crop_top - y_start;
+      y_start = io->crop_top;
+      assert(!(delta_y & 1));
+      io->y += dec->cache_y_stride_ * delta_y;
+      io->u += dec->cache_uv_stride_ * (delta_y >> 1);
+      io->v += dec->cache_uv_stride_ * (delta_y >> 1);
+      if (io->a != NULL) {
+        io->a += io->width * delta_y;
+      }
+    }
+    if (y_start < y_end) {
+      io->y += io->crop_left;
+      io->u += io->crop_left >> 1;
+      io->v += io->crop_left >> 1;
+      if (io->a != NULL) {
+        io->a += io->crop_left;
+      }
+      io->mb_y = y_start - io->crop_top;
+      io->mb_w = io->crop_right - io->crop_left;
+      io->mb_h = y_end - y_start;
+      ok = io->put(io);
+    }
+  }
+  // rotate top samples if needed
+  if (cache_id + 1 == dec->num_caches_) {
+    if (!is_last_row) {
+      memcpy(dec->cache_y_ - ysize, ydst + 16 * dec->cache_y_stride_, ysize);
+      memcpy(dec->cache_u_ - uvsize, udst + 8 * dec->cache_uv_stride_, uvsize);
+      memcpy(dec->cache_v_ - uvsize, vdst + 8 * dec->cache_uv_stride_, uvsize);
+    }
+  }
+
+  return ok;
+}
+
+#undef MACROBLOCK_VPOS
+
+//------------------------------------------------------------------------------
+
+int VP8ProcessRow(VP8Decoder* const dec, VP8Io* const io) {
+  int ok = 1;
+  VP8ThreadContext* const ctx = &dec->thread_ctx_;
+  const int filter_row =
+      (dec->filter_type_ > 0) &&
+      (dec->mb_y_ >= dec->tl_mb_y_) && (dec->mb_y_ <= dec->br_mb_y_);
+  if (dec->mt_method_ == 0) {
+    // ctx->id_ and ctx->f_info_ are already set
+    ctx->mb_y_ = dec->mb_y_;
+    ctx->filter_row_ = filter_row;
+    ReconstructRow(dec, ctx);
+    ok = FinishRow(dec, io);
+  } else {
+    WebPWorker* const worker = &dec->worker_;
+    // Finish previous job *before* updating context
+    ok &= WebPWorkerSync(worker);
+    assert(worker->status_ == OK);
+    if (ok) {   // spawn a new deblocking/output job
+      ctx->io_ = *io;
+      ctx->id_ = dec->cache_id_;
+      ctx->mb_y_ = dec->mb_y_;
+      ctx->filter_row_ = filter_row;
+      if (dec->mt_method_ == 2) {  // swap macroblock data
+        VP8MBData* const tmp = ctx->mb_data_;
+        ctx->mb_data_ = dec->mb_data_;
+        dec->mb_data_ = tmp;
+      } else {
+        // perform reconstruction directly in main thread
+        ReconstructRow(dec, ctx);
+      }
+      if (filter_row) {            // swap filter info
+        VP8FInfo* const tmp = ctx->f_info_;
+        ctx->f_info_ = dec->f_info_;
+        dec->f_info_ = tmp;
+      }
+      WebPWorkerLaunch(worker);    // (reconstruct)+filter in parallel
+      if (++dec->cache_id_ == dec->num_caches_) {
+        dec->cache_id_ = 0;
+      }
+    }
+  }
+  return ok;
+}
+
+//------------------------------------------------------------------------------
+// Finish setting up the decoding parameter once user's setup() is called.
+
+VP8StatusCode VP8EnterCritical(VP8Decoder* const dec, VP8Io* const io) {
+  // Call setup() first. This may trigger additional decoding features on 'io'.
+  // Note: Afterward, we must call teardown() no matter what.
+  if (io->setup != NULL && !io->setup(io)) {
+    VP8SetError(dec, VP8_STATUS_USER_ABORT, "Frame setup failed");
+    return dec->status_;
+  }
+
+  // Disable filtering per user request
+  if (io->bypass_filtering) {
+    dec->filter_type_ = 0;
+  }
+  // TODO(skal): filter type / strength / sharpness forcing
+
+  // Define the area where we can skip in-loop filtering, in case of cropping.
+  //
+  // 'Simple' filter reads two luma samples outside of the macroblock
+  // and filters one. It doesn't filter the chroma samples. Hence, we can
+  // avoid doing the in-loop filtering before crop_top/crop_left position.
+  // For the 'Complex' filter, 3 samples are read and up to 3 are filtered.
+  // Means: there's a dependency chain that goes all the way up to the
+  // top-left corner of the picture (MB #0). We must filter all the previous
+  // macroblocks.
+  // TODO(skal): add an 'approximate_decoding' option, that won't produce
+  // a 1:1 bit-exactness for complex filtering?
+  {
+    const int extra_pixels = kFilterExtraRows[dec->filter_type_];
+    if (dec->filter_type_ == 2) {
+      // For complex filter, we need to preserve the dependency chain.
+      dec->tl_mb_x_ = 0;
+      dec->tl_mb_y_ = 0;
+    } else {
+      // For simple filter, we can filter only the cropped region.
+      // We include 'extra_pixels' on the other side of the boundary, since
+      // vertical or horizontal filtering of the previous macroblock can
+      // modify some abutting pixels.
+      dec->tl_mb_x_ = (io->crop_left - extra_pixels) >> 4;
+      dec->tl_mb_y_ = (io->crop_top - extra_pixels) >> 4;
+      if (dec->tl_mb_x_ < 0) dec->tl_mb_x_ = 0;
+      if (dec->tl_mb_y_ < 0) dec->tl_mb_y_ = 0;
+    }
+    // We need some 'extra' pixels on the right/bottom.
+    dec->br_mb_y_ = (io->crop_bottom + 15 + extra_pixels) >> 4;
+    dec->br_mb_x_ = (io->crop_right + 15 + extra_pixels) >> 4;
+    if (dec->br_mb_x_ > dec->mb_w_) {
+      dec->br_mb_x_ = dec->mb_w_;
+    }
+    if (dec->br_mb_y_ > dec->mb_h_) {
+      dec->br_mb_y_ = dec->mb_h_;
+    }
+  }
+  PrecomputeFilterStrengths(dec);
+  return VP8_STATUS_OK;
+}
+
+int VP8ExitCritical(VP8Decoder* const dec, VP8Io* const io) {
+  int ok = 1;
+  if (dec->mt_method_ > 0) {
+    ok = WebPWorkerSync(&dec->worker_);
+  }
+
+  if (io->teardown != NULL) {
+    io->teardown(io);
+  }
+  return ok;
+}
+
+//------------------------------------------------------------------------------
+// For multi-threaded decoding we need to use 3 rows of 16 pixels as delay line.
+//
+// Reason is: the deblocking filter cannot deblock the bottom horizontal edges
+// immediately, and needs to wait for first few rows of the next macroblock to
+// be decoded. Hence, deblocking is lagging behind by 4 or 8 pixels (depending
+// on strength).
+// With two threads, the vertical positions of the rows being decoded are:
+// Decode:  [ 0..15][16..31][32..47][48..63][64..79][...
+// Deblock:         [ 0..11][12..27][28..43][44..59][...
+// If we use two threads and two caches of 16 pixels, the sequence would be:
+// Decode:  [ 0..15][16..31][ 0..15!!][16..31][ 0..15][...
+// Deblock:         [ 0..11][12..27!!][-4..11][12..27][...
+// The problem occurs during row [12..15!!] that both the decoding and
+// deblocking threads are writing simultaneously.
+// With 3 cache lines, one get a safe write pattern:
+// Decode:  [ 0..15][16..31][32..47][ 0..15][16..31][32..47][0..
+// Deblock:         [ 0..11][12..27][28..43][-4..11][12..27][28...
+// Note that multi-threaded output _without_ deblocking can make use of two
+// cache lines of 16 pixels only, since there's no lagging behind. The decoding
+// and output process have non-concurrent writing:
+// Decode:  [ 0..15][16..31][ 0..15][16..31][...
+// io->put:         [ 0..15][16..31][ 0..15][...
+
+#define MT_CACHE_LINES 3
+#define ST_CACHE_LINES 1   // 1 cache row only for single-threaded case
+
+// Initialize multi/single-thread worker
+static int InitThreadContext(VP8Decoder* const dec) {
+  dec->cache_id_ = 0;
+  if (dec->mt_method_ > 0) {
+    WebPWorker* const worker = &dec->worker_;
+    if (!WebPWorkerReset(worker)) {
+      return VP8SetError(dec, VP8_STATUS_OUT_OF_MEMORY,
+                         "thread initialization failed.");
+    }
+    worker->data1 = dec;
+    worker->data2 = (void*)&dec->thread_ctx_.io_;
+    worker->hook = (WebPWorkerHook)FinishRow;
+    dec->num_caches_ =
+      (dec->filter_type_ > 0) ? MT_CACHE_LINES : MT_CACHE_LINES - 1;
+  } else {
+    dec->num_caches_ = ST_CACHE_LINES;
+  }
+  return 1;
+}
+
+int VP8GetThreadMethod(const WebPDecoderOptions* const options,
+                       const WebPHeaderStructure* const headers,
+                       int width, int height) {
+  if (options == NULL || options->use_threads == 0) {
+    return 0;
+  }
+  (void)headers;
+  (void)width;
+  (void)height;
+  assert(!headers->is_lossless);
+#if defined(WEBP_USE_THREAD)
+  if (width < MIN_WIDTH_FOR_THREADS) return 0;
+  // TODO(skal): tune the heuristic further
+#if 0
+  if (height < 2 * width) return 2;
+#endif
+  return 2;
+#else   // !WEBP_USE_THREAD
+  return 0;
+#endif
+}
+
+#undef MT_CACHE_LINES
+#undef ST_CACHE_LINES
+
+//------------------------------------------------------------------------------
+// Memory setup
+
+static int AllocateMemory(VP8Decoder* const dec) {
+  const int num_caches = dec->num_caches_;
+  const int mb_w = dec->mb_w_;
+  // Note: we use 'size_t' when there's no overflow risk, uint64_t otherwise.
+  const size_t intra_pred_mode_size = 4 * mb_w * sizeof(uint8_t);
+  const size_t top_size = sizeof(VP8TopSamples) * mb_w;
+  const size_t mb_info_size = (mb_w + 1) * sizeof(VP8MB);
+  const size_t f_info_size =
+      (dec->filter_type_ > 0) ?
+          mb_w * (dec->mt_method_ > 0 ? 2 : 1) * sizeof(VP8FInfo)
+        : 0;
+  const size_t yuv_size = YUV_SIZE * sizeof(*dec->yuv_b_);
+  const size_t mb_data_size =
+      (dec->mt_method_ == 2 ? 2 : 1) * mb_w * sizeof(*dec->mb_data_);
+  const size_t cache_height = (16 * num_caches
+                            + kFilterExtraRows[dec->filter_type_]) * 3 / 2;
+  const size_t cache_size = top_size * cache_height;
+  // alpha_size is the only one that scales as width x height.
+  const uint64_t alpha_size = (dec->alpha_data_ != NULL) ?
+      (uint64_t)dec->pic_hdr_.width_ * dec->pic_hdr_.height_ : 0ULL;
+  const uint64_t needed = (uint64_t)intra_pred_mode_size
+                        + top_size + mb_info_size + f_info_size
+                        + yuv_size + mb_data_size
+                        + cache_size + alpha_size + ALIGN_MASK;
+  uint8_t* mem;
+
+  if (needed != (size_t)needed) return 0;  // check for overflow
+  if (needed > dec->mem_size_) {
+    free(dec->mem_);
+    dec->mem_size_ = 0;
+    dec->mem_ = WebPSafeMalloc(needed, sizeof(uint8_t));
+    if (dec->mem_ == NULL) {
+      return VP8SetError(dec, VP8_STATUS_OUT_OF_MEMORY,
+                         "no memory during frame initialization.");
+    }
+    // down-cast is ok, thanks to WebPSafeAlloc() above.
+    dec->mem_size_ = (size_t)needed;
+  }
+
+  mem = (uint8_t*)dec->mem_;
+  dec->intra_t_ = (uint8_t*)mem;
+  mem += intra_pred_mode_size;
+
+  dec->yuv_t_ = (VP8TopSamples*)mem;
+  mem += top_size;
+
+  dec->mb_info_ = ((VP8MB*)mem) + 1;
+  mem += mb_info_size;
+
+  dec->f_info_ = f_info_size ? (VP8FInfo*)mem : NULL;
+  mem += f_info_size;
+  dec->thread_ctx_.id_ = 0;
+  dec->thread_ctx_.f_info_ = dec->f_info_;
+  if (dec->mt_method_ > 0) {
+    // secondary cache line. The deblocking process need to make use of the
+    // filtering strength from previous macroblock row, while the new ones
+    // are being decoded in parallel. We'll just swap the pointers.
+    dec->thread_ctx_.f_info_ += mb_w;
+  }
+
+  mem = (uint8_t*)((uintptr_t)(mem + ALIGN_MASK) & ~ALIGN_MASK);
+  assert((yuv_size & ALIGN_MASK) == 0);
+  dec->yuv_b_ = (uint8_t*)mem;
+  mem += yuv_size;
+
+  dec->mb_data_ = (VP8MBData*)mem;
+  dec->thread_ctx_.mb_data_ = (VP8MBData*)mem;
+  if (dec->mt_method_ == 2) {
+    dec->thread_ctx_.mb_data_ += mb_w;
+  }
+  mem += mb_data_size;
+
+  dec->cache_y_stride_ = 16 * mb_w;
+  dec->cache_uv_stride_ = 8 * mb_w;
+  {
+    const int extra_rows = kFilterExtraRows[dec->filter_type_];
+    const int extra_y = extra_rows * dec->cache_y_stride_;
+    const int extra_uv = (extra_rows / 2) * dec->cache_uv_stride_;
+    dec->cache_y_ = ((uint8_t*)mem) + extra_y;
+    dec->cache_u_ = dec->cache_y_
+                  + 16 * num_caches * dec->cache_y_stride_ + extra_uv;
+    dec->cache_v_ = dec->cache_u_
+                  + 8 * num_caches * dec->cache_uv_stride_ + extra_uv;
+    dec->cache_id_ = 0;
+  }
+  mem += cache_size;
+
+  // alpha plane
+  dec->alpha_plane_ = alpha_size ? (uint8_t*)mem : NULL;
+  mem += alpha_size;
+  assert(mem <= (uint8_t*)dec->mem_ + dec->mem_size_);
+
+  // note: left/top-info is initialized once for all.
+  memset(dec->mb_info_ - 1, 0, mb_info_size);
+  VP8InitScanline(dec);   // initialize left too.
+
+  // initialize top
+  memset(dec->intra_t_, B_DC_PRED, intra_pred_mode_size);
+
+  return 1;
+}
+
+static void InitIo(VP8Decoder* const dec, VP8Io* io) {
+  // prepare 'io'
+  io->mb_y = 0;
+  io->y = dec->cache_y_;
+  io->u = dec->cache_u_;
+  io->v = dec->cache_v_;
+  io->y_stride = dec->cache_y_stride_;
+  io->uv_stride = dec->cache_uv_stride_;
+  io->a = NULL;
+}
+
+int VP8InitFrame(VP8Decoder* const dec, VP8Io* io) {
+  if (!InitThreadContext(dec)) return 0;  // call first. Sets dec->num_caches_.
+  if (!AllocateMemory(dec)) return 0;
+  InitIo(dec, io);
+  VP8DspInit();  // Init critical function pointers and look-up tables.
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+// Main reconstruction function.
+
+static const int kScan[16] = {
+  0 +  0 * BPS,  4 +  0 * BPS, 8 +  0 * BPS, 12 +  0 * BPS,
+  0 +  4 * BPS,  4 +  4 * BPS, 8 +  4 * BPS, 12 +  4 * BPS,
+  0 +  8 * BPS,  4 +  8 * BPS, 8 +  8 * BPS, 12 +  8 * BPS,
+  0 + 12 * BPS,  4 + 12 * BPS, 8 + 12 * BPS, 12 + 12 * BPS
+};
+
+static int CheckMode(int mb_x, int mb_y, int mode) {
+  if (mode == B_DC_PRED) {
+    if (mb_x == 0) {
+      return (mb_y == 0) ? B_DC_PRED_NOTOPLEFT : B_DC_PRED_NOLEFT;
+    } else {
+      return (mb_y == 0) ? B_DC_PRED_NOTOP : B_DC_PRED;
+    }
+  }
+  return mode;
+}
+
+static void Copy32b(uint8_t* dst, uint8_t* src) {
+  memcpy(dst, src, 4);
+}
+
+static WEBP_INLINE void DoTransform(uint32_t bits, const int16_t* const src,
+                                    uint8_t* const dst) {
+  switch (bits >> 30) {
+    case 3:
+      VP8Transform(src, dst, 0);
+      break;
+    case 2:
+      VP8TransformAC3(src, dst);
+      break;
+    case 1:
+      VP8TransformDC(src, dst);
+      break;
+    default:
+      break;
+  }
+}
+
+static void DoUVTransform(uint32_t bits, const int16_t* const src,
+                          uint8_t* const dst) {
+  if (bits & 0xff) {    // any non-zero coeff at all?
+    if (bits & 0xaa) {  // any non-zero AC coefficient?
+      VP8TransformUV(src, dst);   // note we don't use the AC3 variant for U/V
+    } else {
+      VP8TransformDCUV(src, dst);
+    }
+  }
+}
+
+static void ReconstructRow(const VP8Decoder* const dec,
+                           const VP8ThreadContext* ctx) {
+  int j;
+  int mb_x;
+  const int mb_y = ctx->mb_y_;
+  const int cache_id = ctx->id_;
+  uint8_t* const y_dst = dec->yuv_b_ + Y_OFF;
+  uint8_t* const u_dst = dec->yuv_b_ + U_OFF;
+  uint8_t* const v_dst = dec->yuv_b_ + V_OFF;
+  for (mb_x = 0; mb_x < dec->mb_w_; ++mb_x) {
+    const VP8MBData* const block = ctx->mb_data_ + mb_x;
+
+    // Rotate in the left samples from previously decoded block. We move four
+    // pixels at a time for alignment reason, and because of in-loop filter.
+    if (mb_x > 0) {
+      for (j = -1; j < 16; ++j) {
+        Copy32b(&y_dst[j * BPS - 4], &y_dst[j * BPS + 12]);
+      }
+      for (j = -1; j < 8; ++j) {
+        Copy32b(&u_dst[j * BPS - 4], &u_dst[j * BPS + 4]);
+        Copy32b(&v_dst[j * BPS - 4], &v_dst[j * BPS + 4]);
+      }
+    } else {
+      for (j = 0; j < 16; ++j) {
+        y_dst[j * BPS - 1] = 129;
+      }
+      for (j = 0; j < 8; ++j) {
+        u_dst[j * BPS - 1] = 129;
+        v_dst[j * BPS - 1] = 129;
+      }
+      // Init top-left sample on left column too
+      if (mb_y > 0) {
+        y_dst[-1 - BPS] = u_dst[-1 - BPS] = v_dst[-1 - BPS] = 129;
+      }
+    }
+    {
+      // bring top samples into the cache
+      VP8TopSamples* const top_yuv = dec->yuv_t_ + mb_x;
+      const int16_t* const coeffs = block->coeffs_;
+      uint32_t bits = block->non_zero_y_;
+      int n;
+
+      if (mb_y > 0) {
+        memcpy(y_dst - BPS, top_yuv[0].y, 16);
+        memcpy(u_dst - BPS, top_yuv[0].u, 8);
+        memcpy(v_dst - BPS, top_yuv[0].v, 8);
+      } else if (mb_x == 0) {
+        // we only need to do this init once at block (0,0).
+        // Afterward, it remains valid for the whole topmost row.
+        memset(y_dst - BPS - 1, 127, 16 + 4 + 1);
+        memset(u_dst - BPS - 1, 127, 8 + 1);
+        memset(v_dst - BPS - 1, 127, 8 + 1);
+      }
+
+      // predict and add residuals
+      if (block->is_i4x4_) {   // 4x4
+        uint32_t* const top_right = (uint32_t*)(y_dst - BPS + 16);
+
+        if (mb_y > 0) {
+          if (mb_x >= dec->mb_w_ - 1) {    // on rightmost border
+            memset(top_right, top_yuv[0].y[15], sizeof(*top_right));
+          } else {
+            memcpy(top_right, top_yuv[1].y, sizeof(*top_right));
+          }
+        }
+        // replicate the top-right pixels below
+        top_right[BPS] = top_right[2 * BPS] = top_right[3 * BPS] = top_right[0];
+
+        // predict and add residuals for all 4x4 blocks in turn.
+        for (n = 0; n < 16; ++n, bits <<= 2) {
+          uint8_t* const dst = y_dst + kScan[n];
+          VP8PredLuma4[block->imodes_[n]](dst);
+          DoTransform(bits, coeffs + n * 16, dst);
+        }
+      } else {    // 16x16
+        const int pred_func = CheckMode(mb_x, mb_y,
+                                        block->imodes_[0]);
+        VP8PredLuma16[pred_func](y_dst);
+        if (bits != 0) {
+          for (n = 0; n < 16; ++n, bits <<= 2) {
+            DoTransform(bits, coeffs + n * 16, y_dst + kScan[n]);
+          }
+        }
+      }
+      {
+        // Chroma
+        const uint32_t bits_uv = block->non_zero_uv_;
+        const int pred_func = CheckMode(mb_x, mb_y, block->uvmode_);
+        VP8PredChroma8[pred_func](u_dst);
+        VP8PredChroma8[pred_func](v_dst);
+        DoUVTransform(bits_uv >> 0, coeffs + 16 * 16, u_dst);
+        DoUVTransform(bits_uv >> 8, coeffs + 20 * 16, v_dst);
+      }
+
+      // stash away top samples for next block
+      if (mb_y < dec->mb_h_ - 1) {
+        memcpy(top_yuv[0].y, y_dst + 15 * BPS, 16);
+        memcpy(top_yuv[0].u, u_dst +  7 * BPS,  8);
+        memcpy(top_yuv[0].v, v_dst +  7 * BPS,  8);
+      }
+    }
+    // Transfer reconstructed samples from yuv_b_ cache to final destination.
+    {
+      const int y_offset = cache_id * 16 * dec->cache_y_stride_;
+      const int uv_offset = cache_id * 8 * dec->cache_uv_stride_;
+      uint8_t* const y_out = dec->cache_y_ + mb_x * 16 + y_offset;
+      uint8_t* const u_out = dec->cache_u_ + mb_x * 8 + uv_offset;
+      uint8_t* const v_out = dec->cache_v_ + mb_x * 8 + uv_offset;
+      for (j = 0; j < 16; ++j) {
+        memcpy(y_out + j * dec->cache_y_stride_, y_dst + j * BPS, 16);
+      }
+      for (j = 0; j < 8; ++j) {
+        memcpy(u_out + j * dec->cache_uv_stride_, u_dst + j * BPS, 8);
+        memcpy(v_out + j * dec->cache_uv_stride_, v_dst + j * BPS, 8);
+      }
+    }
+  }
+}
+
+//------------------------------------------------------------------------------
+
diff --git a/src/3rdparty/libwebp/src/dec/idec.c b/src/3rdparty/libwebp/src/dec/idec.c
new file mode 100644
index 0000000..40d5ff6
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/idec.c
@@ -0,0 +1,849 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Incremental decoding
+//
+// Author: somnath@google.com (Somnath Banerjee)
+
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include "./alphai.h"
+#include "./webpi.h"
+#include "./vp8i.h"
+#include "../utils/utils.h"
+
+// In append mode, buffer allocations increase as multiples of this value.
+// Needs to be a power of 2.
+#define CHUNK_SIZE 4096
+#define MAX_MB_SIZE 4096
+
+//------------------------------------------------------------------------------
+// Data structures for memory and states
+
+// Decoding states. State normally flows as:
+// WEBP_HEADER->VP8_HEADER->VP8_PARTS0->VP8_DATA->DONE for a lossy image, and
+// WEBP_HEADER->VP8L_HEADER->VP8L_DATA->DONE for a lossless image.
+// If there is any error the decoder goes into state ERROR.
+typedef enum {
+  STATE_WEBP_HEADER,  // All the data before that of the VP8/VP8L chunk.
+  STATE_VP8_HEADER,   // The VP8 Frame header (within the VP8 chunk).
+  STATE_VP8_PARTS0,
+  STATE_VP8_DATA,
+  STATE_VP8L_HEADER,
+  STATE_VP8L_DATA,
+  STATE_DONE,
+  STATE_ERROR
+} DecState;
+
+// Operating state for the MemBuffer
+typedef enum {
+  MEM_MODE_NONE = 0,
+  MEM_MODE_APPEND,
+  MEM_MODE_MAP
+} MemBufferMode;
+
+// storage for partition #0 and partial data (in a rolling fashion)
+typedef struct {
+  MemBufferMode mode_;  // Operation mode
+  size_t start_;        // start location of the data to be decoded
+  size_t end_;          // end location
+  size_t buf_size_;     // size of the allocated buffer
+  uint8_t* buf_;        // We don't own this buffer in case WebPIUpdate()
+
+  size_t part0_size_;         // size of partition #0
+  const uint8_t* part0_buf_;  // buffer to store partition #0
+} MemBuffer;
+
+struct WebPIDecoder {
+  DecState state_;         // current decoding state
+  WebPDecParams params_;   // Params to store output info
+  int is_lossless_;        // for down-casting 'dec_'.
+  void* dec_;              // either a VP8Decoder or a VP8LDecoder instance
+  VP8Io io_;
+
+  MemBuffer mem_;          // input memory buffer.
+  WebPDecBuffer output_;   // output buffer (when no external one is supplied)
+  size_t chunk_size_;      // Compressed VP8/VP8L size extracted from Header.
+};
+
+// MB context to restore in case VP8DecodeMB() fails
+typedef struct {
+  VP8MB left_;
+  VP8MB info_;
+  uint8_t intra_t_[4];
+  uint8_t intra_l_[4];
+  VP8BitReader br_;
+  VP8BitReader token_br_;
+} MBContext;
+
+//------------------------------------------------------------------------------
+// MemBuffer: incoming data handling
+
+static void RemapBitReader(VP8BitReader* const br, ptrdiff_t offset) {
+  if (br->buf_ != NULL) {
+    br->buf_ += offset;
+    br->buf_end_ += offset;
+  }
+}
+
+static WEBP_INLINE size_t MemDataSize(const MemBuffer* mem) {
+  return (mem->end_ - mem->start_);
+}
+
+// Check if we need to preserve the compressed alpha data, as it may not have
+// been decoded yet.
+static int NeedCompressedAlpha(const WebPIDecoder* const idec) {
+  if (idec->state_ == STATE_WEBP_HEADER) {
+    // We haven't parsed the headers yet, so we don't know whether the image is
+    // lossy or lossless. This also means that we haven't parsed the ALPH chunk.
+    return 0;
+  }
+  if (idec->is_lossless_) {
+    return 0;  // ALPH chunk is not present for lossless images.
+  } else {
+    const VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
+    assert(dec != NULL);  // Must be true as idec->state_ != STATE_WEBP_HEADER.
+    return (dec->alpha_data_ != NULL) && !dec->is_alpha_decoded_;
+  }
+}
+
+static void DoRemap(WebPIDecoder* const idec, ptrdiff_t offset) {
+  MemBuffer* const mem = &idec->mem_;
+  const uint8_t* const new_base = mem->buf_ + mem->start_;
+  // note: for VP8, setting up idec->io_ is only really needed at the beginning
+  // of the decoding, till partition #0 is complete.
+  idec->io_.data = new_base;
+  idec->io_.data_size = MemDataSize(mem);
+
+  if (idec->dec_ != NULL) {
+    if (!idec->is_lossless_) {
+      VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
+      const int last_part = dec->num_parts_ - 1;
+      if (offset != 0) {
+        int p;
+        for (p = 0; p <= last_part; ++p) {
+          RemapBitReader(dec->parts_ + p, offset);
+        }
+        // Remap partition #0 data pointer to new offset, but only in MAP
+        // mode (in APPEND mode, partition #0 is copied into a fixed memory).
+        if (mem->mode_ == MEM_MODE_MAP) {
+          RemapBitReader(&dec->br_, offset);
+        }
+      }
+      assert(last_part >= 0);
+      dec->parts_[last_part].buf_end_ = mem->buf_ + mem->end_;
+      if (NeedCompressedAlpha(idec)) {
+        ALPHDecoder* const alph_dec = dec->alph_dec_;
+        dec->alpha_data_ += offset;
+        if (alph_dec != NULL) {
+          if (alph_dec->method_ == ALPHA_LOSSLESS_COMPRESSION) {
+            VP8LDecoder* const alph_vp8l_dec = alph_dec->vp8l_dec_;
+            assert(alph_vp8l_dec != NULL);
+            assert(dec->alpha_data_size_ >= ALPHA_HEADER_LEN);
+            VP8LBitReaderSetBuffer(&alph_vp8l_dec->br_,
+                                   dec->alpha_data_ + ALPHA_HEADER_LEN,
+                                   dec->alpha_data_size_ - ALPHA_HEADER_LEN);
+          } else {  // alph_dec->method_ == ALPHA_NO_COMPRESSION
+            // Nothing special to do in this case.
+          }
+        }
+      }
+    } else {    // Resize lossless bitreader
+      VP8LDecoder* const dec = (VP8LDecoder*)idec->dec_;
+      VP8LBitReaderSetBuffer(&dec->br_, new_base, MemDataSize(mem));
+    }
+  }
+}
+
+// Appends data to the end of MemBuffer->buf_. It expands the allocated memory
+// size if required and also updates VP8BitReader's if new memory is allocated.
+static int AppendToMemBuffer(WebPIDecoder* const idec,
+                             const uint8_t* const data, size_t data_size) {
+  VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
+  MemBuffer* const mem = &idec->mem_;
+  const int need_compressed_alpha = NeedCompressedAlpha(idec);
+  const uint8_t* const old_start = mem->buf_ + mem->start_;
+  const uint8_t* const old_base =
+      need_compressed_alpha ? dec->alpha_data_ : old_start;
+  assert(mem->mode_ == MEM_MODE_APPEND);
+  if (data_size > MAX_CHUNK_PAYLOAD) {
+    // security safeguard: trying to allocate more than what the format
+    // allows for a chunk should be considered a smoke smell.
+    return 0;
+  }
+
+  if (mem->end_ + data_size > mem->buf_size_) {  // Need some free memory
+    const size_t new_mem_start = old_start - old_base;
+    const size_t current_size = MemDataSize(mem) + new_mem_start;
+    const uint64_t new_size = (uint64_t)current_size + data_size;
+    const uint64_t extra_size = (new_size + CHUNK_SIZE - 1) & ~(CHUNK_SIZE - 1);
+    uint8_t* const new_buf =
+        (uint8_t*)WebPSafeMalloc(extra_size, sizeof(*new_buf));
+    if (new_buf == NULL) return 0;
+    memcpy(new_buf, old_base, current_size);
+    free(mem->buf_);
+    mem->buf_ = new_buf;
+    mem->buf_size_ = (size_t)extra_size;
+    mem->start_ = new_mem_start;
+    mem->end_ = current_size;
+  }
+
+  memcpy(mem->buf_ + mem->end_, data, data_size);
+  mem->end_ += data_size;
+  assert(mem->end_ <= mem->buf_size_);
+
+  DoRemap(idec, mem->buf_ + mem->start_ - old_start);
+  return 1;
+}
+
+static int RemapMemBuffer(WebPIDecoder* const idec,
+                          const uint8_t* const data, size_t data_size) {
+  MemBuffer* const mem = &idec->mem_;
+  const uint8_t* const old_buf = mem->buf_;
+  const uint8_t* const old_start = old_buf + mem->start_;
+  assert(mem->mode_ == MEM_MODE_MAP);
+
+  if (data_size < mem->buf_size_) return 0;  // can't remap to a shorter buffer!
+
+  mem->buf_ = (uint8_t*)data;
+  mem->end_ = mem->buf_size_ = data_size;
+
+  DoRemap(idec, mem->buf_ + mem->start_ - old_start);
+  return 1;
+}
+
+static void InitMemBuffer(MemBuffer* const mem) {
+  mem->mode_       = MEM_MODE_NONE;
+  mem->buf_        = NULL;
+  mem->buf_size_   = 0;
+  mem->part0_buf_  = NULL;
+  mem->part0_size_ = 0;
+}
+
+static void ClearMemBuffer(MemBuffer* const mem) {
+  assert(mem);
+  if (mem->mode_ == MEM_MODE_APPEND) {
+    free(mem->buf_);
+    free((void*)mem->part0_buf_);
+  }
+}
+
+static int CheckMemBufferMode(MemBuffer* const mem, MemBufferMode expected) {
+  if (mem->mode_ == MEM_MODE_NONE) {
+    mem->mode_ = expected;    // switch to the expected mode
+  } else if (mem->mode_ != expected) {
+    return 0;         // we mixed the modes => error
+  }
+  assert(mem->mode_ == expected);   // mode is ok
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+// Macroblock-decoding contexts
+
+static void SaveContext(const VP8Decoder* dec, const VP8BitReader* token_br,
+                        MBContext* const context) {
+  const VP8BitReader* const br = &dec->br_;
+  const VP8MB* const left = dec->mb_info_ - 1;
+  const VP8MB* const info = dec->mb_info_ + dec->mb_x_;
+
+  context->left_ = *left;
+  context->info_ = *info;
+  context->br_ = *br;
+  context->token_br_ = *token_br;
+  memcpy(context->intra_t_, dec->intra_t_ + 4 * dec->mb_x_, 4);
+  memcpy(context->intra_l_, dec->intra_l_, 4);
+}
+
+static void RestoreContext(const MBContext* context, VP8Decoder* const dec,
+                           VP8BitReader* const token_br) {
+  VP8BitReader* const br = &dec->br_;
+  VP8MB* const left = dec->mb_info_ - 1;
+  VP8MB* const info = dec->mb_info_ + dec->mb_x_;
+
+  *left = context->left_;
+  *info = context->info_;
+  *br = context->br_;
+  *token_br = context->token_br_;
+  memcpy(dec->intra_t_ + 4 * dec->mb_x_, context->intra_t_, 4);
+  memcpy(dec->intra_l_, context->intra_l_, 4);
+}
+
+//------------------------------------------------------------------------------
+
+static VP8StatusCode IDecError(WebPIDecoder* const idec, VP8StatusCode error) {
+  if (idec->state_ == STATE_VP8_DATA) {
+    VP8Io* const io = &idec->io_;
+    if (io->teardown != NULL) {
+      io->teardown(io);
+    }
+  }
+  idec->state_ = STATE_ERROR;
+  return error;
+}
+
+static void ChangeState(WebPIDecoder* const idec, DecState new_state,
+                        size_t consumed_bytes) {
+  MemBuffer* const mem = &idec->mem_;
+  idec->state_ = new_state;
+  mem->start_ += consumed_bytes;
+  assert(mem->start_ <= mem->end_);
+  idec->io_.data = mem->buf_ + mem->start_;
+  idec->io_.data_size = MemDataSize(mem);
+}
+
+// Headers
+static VP8StatusCode DecodeWebPHeaders(WebPIDecoder* const idec) {
+  MemBuffer* const mem = &idec->mem_;
+  const uint8_t* data = mem->buf_ + mem->start_;
+  size_t curr_size = MemDataSize(mem);
+  VP8StatusCode status;
+  WebPHeaderStructure headers;
+
+  headers.data = data;
+  headers.data_size = curr_size;
+  status = WebPParseHeaders(&headers);
+  if (status == VP8_STATUS_NOT_ENOUGH_DATA) {
+    return VP8_STATUS_SUSPENDED;  // We haven't found a VP8 chunk yet.
+  } else if (status != VP8_STATUS_OK) {
+    return IDecError(idec, status);
+  }
+
+  idec->chunk_size_ = headers.compressed_size;
+  idec->is_lossless_ = headers.is_lossless;
+  if (!idec->is_lossless_) {
+    VP8Decoder* const dec = VP8New();
+    if (dec == NULL) {
+      return VP8_STATUS_OUT_OF_MEMORY;
+    }
+    idec->dec_ = dec;
+    dec->alpha_data_ = headers.alpha_data;
+    dec->alpha_data_size_ = headers.alpha_data_size;
+    ChangeState(idec, STATE_VP8_HEADER, headers.offset);
+  } else {
+    VP8LDecoder* const dec = VP8LNew();
+    if (dec == NULL) {
+      return VP8_STATUS_OUT_OF_MEMORY;
+    }
+    idec->dec_ = dec;
+    ChangeState(idec, STATE_VP8L_HEADER, headers.offset);
+  }
+  return VP8_STATUS_OK;
+}
+
+static VP8StatusCode DecodeVP8FrameHeader(WebPIDecoder* const idec) {
+  const uint8_t* data = idec->mem_.buf_ + idec->mem_.start_;
+  const size_t curr_size = MemDataSize(&idec->mem_);
+  int width, height;
+  uint32_t bits;
+
+  if (curr_size < VP8_FRAME_HEADER_SIZE) {
+    // Not enough data bytes to extract VP8 Frame Header.
+    return VP8_STATUS_SUSPENDED;
+  }
+  if (!VP8GetInfo(data, curr_size, idec->chunk_size_, &width, &height)) {
+    return IDecError(idec, VP8_STATUS_BITSTREAM_ERROR);
+  }
+
+  bits = data[0] | (data[1] << 8) | (data[2] << 16);
+  idec->mem_.part0_size_ = (bits >> 5) + VP8_FRAME_HEADER_SIZE;
+
+  idec->io_.data = data;
+  idec->io_.data_size = curr_size;
+  idec->state_ = STATE_VP8_PARTS0;
+  return VP8_STATUS_OK;
+}
+
+// Partition #0
+static int CopyParts0Data(WebPIDecoder* const idec) {
+  VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
+  VP8BitReader* const br = &dec->br_;
+  const size_t psize = br->buf_end_ - br->buf_;
+  MemBuffer* const mem = &idec->mem_;
+  assert(!idec->is_lossless_);
+  assert(mem->part0_buf_ == NULL);
+  assert(psize > 0);
+  assert(psize <= mem->part0_size_);  // Format limit: no need for runtime check
+  if (mem->mode_ == MEM_MODE_APPEND) {
+    // We copy and grab ownership of the partition #0 data.
+    uint8_t* const part0_buf = (uint8_t*)malloc(psize);
+    if (part0_buf == NULL) {
+      return 0;
+    }
+    memcpy(part0_buf, br->buf_, psize);
+    mem->part0_buf_ = part0_buf;
+    br->buf_ = part0_buf;
+    br->buf_end_ = part0_buf + psize;
+  } else {
+    // Else: just keep pointers to the partition #0's data in dec_->br_.
+  }
+  mem->start_ += psize;
+  return 1;
+}
+
+static VP8StatusCode DecodePartition0(WebPIDecoder* const idec) {
+  VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
+  VP8Io* const io = &idec->io_;
+  const WebPDecParams* const params = &idec->params_;
+  WebPDecBuffer* const output = params->output;
+
+  // Wait till we have enough data for the whole partition #0
+  if (MemDataSize(&idec->mem_) < idec->mem_.part0_size_) {
+    return VP8_STATUS_SUSPENDED;
+  }
+
+  if (!VP8GetHeaders(dec, io)) {
+    const VP8StatusCode status = dec->status_;
+    if (status == VP8_STATUS_SUSPENDED ||
+        status == VP8_STATUS_NOT_ENOUGH_DATA) {
+      // treating NOT_ENOUGH_DATA as SUSPENDED state
+      return VP8_STATUS_SUSPENDED;
+    }
+    return IDecError(idec, status);
+  }
+
+  // Allocate/Verify output buffer now
+  dec->status_ = WebPAllocateDecBuffer(io->width, io->height, params->options,
+                                       output);
+  if (dec->status_ != VP8_STATUS_OK) {
+    return IDecError(idec, dec->status_);
+  }
+  // This change must be done before calling VP8InitFrame()
+  dec->mt_method_ = VP8GetThreadMethod(params->options, NULL,
+                                       io->width, io->height);
+  VP8InitDithering(params->options, dec);
+  if (!CopyParts0Data(idec)) {
+    return IDecError(idec, VP8_STATUS_OUT_OF_MEMORY);
+  }
+
+  // Finish setting up the decoding parameters. Will call io->setup().
+  if (VP8EnterCritical(dec, io) != VP8_STATUS_OK) {
+    return IDecError(idec, dec->status_);
+  }
+
+  // Note: past this point, teardown() must always be called
+  // in case of error.
+  idec->state_ = STATE_VP8_DATA;
+  // Allocate memory and prepare everything.
+  if (!VP8InitFrame(dec, io)) {
+    return IDecError(idec, dec->status_);
+  }
+  return VP8_STATUS_OK;
+}
+
+// Remaining partitions
+static VP8StatusCode DecodeRemaining(WebPIDecoder* const idec) {
+  VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
+  VP8Io* const io = &idec->io_;
+
+  assert(dec->ready_);
+  for (; dec->mb_y_ < dec->mb_h_; ++dec->mb_y_) {
+    VP8BitReader* token_br = &dec->parts_[dec->mb_y_ & (dec->num_parts_ - 1)];
+    for (; dec->mb_x_ < dec->mb_w_; ++dec->mb_x_) {
+      MBContext context;
+      SaveContext(dec, token_br, &context);
+      if (!VP8DecodeMB(dec, token_br)) {
+        RestoreContext(&context, dec, token_br);
+        // We shouldn't fail when MAX_MB data was available
+        if (dec->num_parts_ == 1 && MemDataSize(&idec->mem_) > MAX_MB_SIZE) {
+          return IDecError(idec, VP8_STATUS_BITSTREAM_ERROR);
+        }
+        return VP8_STATUS_SUSPENDED;
+      }
+      // Release buffer only if there is only one partition
+      if (dec->num_parts_ == 1) {
+        idec->mem_.start_ = token_br->buf_ - idec->mem_.buf_;
+        assert(idec->mem_.start_ <= idec->mem_.end_);
+      }
+    }
+    VP8InitScanline(dec);   // Prepare for next scanline
+
+    // Reconstruct, filter and emit the row.
+    if (!VP8ProcessRow(dec, io)) {
+      return IDecError(idec, VP8_STATUS_USER_ABORT);
+    }
+  }
+  // Synchronize the thread and check for errors.
+  if (!VP8ExitCritical(dec, io)) {
+    return IDecError(idec, VP8_STATUS_USER_ABORT);
+  }
+  dec->ready_ = 0;
+  idec->state_ = STATE_DONE;
+
+  return VP8_STATUS_OK;
+}
+
+static VP8StatusCode ErrorStatusLossless(WebPIDecoder* const idec,
+                                         VP8StatusCode status) {
+  if (status == VP8_STATUS_SUSPENDED || status == VP8_STATUS_NOT_ENOUGH_DATA) {
+    return VP8_STATUS_SUSPENDED;
+  }
+  return IDecError(idec, status);
+}
+
+static VP8StatusCode DecodeVP8LHeader(WebPIDecoder* const idec) {
+  VP8Io* const io = &idec->io_;
+  VP8LDecoder* const dec = (VP8LDecoder*)idec->dec_;
+  const WebPDecParams* const params = &idec->params_;
+  WebPDecBuffer* const output = params->output;
+  size_t curr_size = MemDataSize(&idec->mem_);
+  assert(idec->is_lossless_);
+
+  // Wait until there's enough data for decoding header.
+  if (curr_size < (idec->chunk_size_ >> 3)) {
+    return VP8_STATUS_SUSPENDED;
+  }
+  if (!VP8LDecodeHeader(dec, io)) {
+    return ErrorStatusLossless(idec, dec->status_);
+  }
+  // Allocate/verify output buffer now.
+  dec->status_ = WebPAllocateDecBuffer(io->width, io->height, params->options,
+                                       output);
+  if (dec->status_ != VP8_STATUS_OK) {
+    return IDecError(idec, dec->status_);
+  }
+
+  idec->state_ = STATE_VP8L_DATA;
+  return VP8_STATUS_OK;
+}
+
+static VP8StatusCode DecodeVP8LData(WebPIDecoder* const idec) {
+  VP8LDecoder* const dec = (VP8LDecoder*)idec->dec_;
+  const size_t curr_size = MemDataSize(&idec->mem_);
+  assert(idec->is_lossless_);
+
+  // At present Lossless decoder can't decode image incrementally. So wait till
+  // all the image data is aggregated before image can be decoded.
+  if (curr_size < idec->chunk_size_) {
+    return VP8_STATUS_SUSPENDED;
+  }
+
+  if (!VP8LDecodeImage(dec)) {
+    return ErrorStatusLossless(idec, dec->status_);
+  }
+
+  idec->state_ = STATE_DONE;
+
+  return VP8_STATUS_OK;
+}
+
+  // Main decoding loop
+static VP8StatusCode IDecode(WebPIDecoder* idec) {
+  VP8StatusCode status = VP8_STATUS_SUSPENDED;
+
+  if (idec->state_ == STATE_WEBP_HEADER) {
+    status = DecodeWebPHeaders(idec);
+  } else {
+    if (idec->dec_ == NULL) {
+      return VP8_STATUS_SUSPENDED;    // can't continue if we have no decoder.
+    }
+  }
+  if (idec->state_ == STATE_VP8_HEADER) {
+    status = DecodeVP8FrameHeader(idec);
+  }
+  if (idec->state_ == STATE_VP8_PARTS0) {
+    status = DecodePartition0(idec);
+  }
+  if (idec->state_ == STATE_VP8_DATA) {
+    status = DecodeRemaining(idec);
+  }
+  if (idec->state_ == STATE_VP8L_HEADER) {
+    status = DecodeVP8LHeader(idec);
+  }
+  if (idec->state_ == STATE_VP8L_DATA) {
+    status = DecodeVP8LData(idec);
+  }
+  return status;
+}
+
+//------------------------------------------------------------------------------
+// Public functions
+
+WebPIDecoder* WebPINewDecoder(WebPDecBuffer* output_buffer) {
+  WebPIDecoder* idec = (WebPIDecoder*)calloc(1, sizeof(*idec));
+  if (idec == NULL) {
+    return NULL;
+  }
+
+  idec->state_ = STATE_WEBP_HEADER;
+  idec->chunk_size_ = 0;
+
+  InitMemBuffer(&idec->mem_);
+  WebPInitDecBuffer(&idec->output_);
+  VP8InitIo(&idec->io_);
+
+  WebPResetDecParams(&idec->params_);
+  idec->params_.output = (output_buffer != NULL) ? output_buffer
+                                                 : &idec->output_;
+  WebPInitCustomIo(&idec->params_, &idec->io_);  // Plug the I/O functions.
+
+  return idec;
+}
+
+WebPIDecoder* WebPIDecode(const uint8_t* data, size_t data_size,
+                          WebPDecoderConfig* config) {
+  WebPIDecoder* idec;
+
+  // Parse the bitstream's features, if requested:
+  if (data != NULL && data_size > 0 && config != NULL) {
+    if (WebPGetFeatures(data, data_size, &config->input) != VP8_STATUS_OK) {
+      return NULL;
+    }
+  }
+  // Create an instance of the incremental decoder
+  idec = WebPINewDecoder(config ? &config->output : NULL);
+  if (idec == NULL) {
+    return NULL;
+  }
+  // Finish initialization
+  if (config != NULL) {
+    idec->params_.options = &config->options;
+  }
+  return idec;
+}
+
+void WebPIDelete(WebPIDecoder* idec) {
+  if (idec == NULL) return;
+  if (idec->dec_ != NULL) {
+    if (!idec->is_lossless_) {
+      if (idec->state_ == STATE_VP8_DATA) {
+        // Synchronize the thread, clean-up and check for errors.
+        VP8ExitCritical((VP8Decoder*)idec->dec_, &idec->io_);
+      }
+      VP8Delete((VP8Decoder*)idec->dec_);
+    } else {
+      VP8LDelete((VP8LDecoder*)idec->dec_);
+    }
+  }
+  ClearMemBuffer(&idec->mem_);
+  WebPFreeDecBuffer(&idec->output_);
+  free(idec);
+}
+
+//------------------------------------------------------------------------------
+// Wrapper toward WebPINewDecoder
+
+WebPIDecoder* WebPINewRGB(WEBP_CSP_MODE mode, uint8_t* output_buffer,
+                          size_t output_buffer_size, int output_stride) {
+  const int is_external_memory = (output_buffer != NULL);
+  WebPIDecoder* idec;
+
+  if (mode >= MODE_YUV) return NULL;
+  if (!is_external_memory) {    // Overwrite parameters to sane values.
+    output_buffer_size = 0;
+    output_stride = 0;
+  } else {  // A buffer was passed. Validate the other params.
+    if (output_stride == 0 || output_buffer_size == 0) {
+      return NULL;   // invalid parameter.
+    }
+  }
+  idec = WebPINewDecoder(NULL);
+  if (idec == NULL) return NULL;
+  idec->output_.colorspace = mode;
+  idec->output_.is_external_memory = is_external_memory;
+  idec->output_.u.RGBA.rgba = output_buffer;
+  idec->output_.u.RGBA.stride = output_stride;
+  idec->output_.u.RGBA.size = output_buffer_size;
+  return idec;
+}
+
+WebPIDecoder* WebPINewYUVA(uint8_t* luma, size_t luma_size, int luma_stride,
+                           uint8_t* u, size_t u_size, int u_stride,
+                           uint8_t* v, size_t v_size, int v_stride,
+                           uint8_t* a, size_t a_size, int a_stride) {
+  const int is_external_memory = (luma != NULL);
+  WebPIDecoder* idec;
+  WEBP_CSP_MODE colorspace;
+
+  if (!is_external_memory) {    // Overwrite parameters to sane values.
+    luma_size = u_size = v_size = a_size = 0;
+    luma_stride = u_stride = v_stride = a_stride = 0;
+    u = v = a = NULL;
+    colorspace = MODE_YUVA;
+  } else {  // A luma buffer was passed. Validate the other parameters.
+    if (u == NULL || v == NULL) return NULL;
+    if (luma_size == 0 || u_size == 0 || v_size == 0) return NULL;
+    if (luma_stride == 0 || u_stride == 0 || v_stride == 0) return NULL;
+    if (a != NULL) {
+      if (a_size == 0 || a_stride == 0) return NULL;
+    }
+    colorspace = (a == NULL) ? MODE_YUV : MODE_YUVA;
+  }
+
+  idec = WebPINewDecoder(NULL);
+  if (idec == NULL) return NULL;
+
+  idec->output_.colorspace = colorspace;
+  idec->output_.is_external_memory = is_external_memory;
+  idec->output_.u.YUVA.y = luma;
+  idec->output_.u.YUVA.y_stride = luma_stride;
+  idec->output_.u.YUVA.y_size = luma_size;
+  idec->output_.u.YUVA.u = u;
+  idec->output_.u.YUVA.u_stride = u_stride;
+  idec->output_.u.YUVA.u_size = u_size;
+  idec->output_.u.YUVA.v = v;
+  idec->output_.u.YUVA.v_stride = v_stride;
+  idec->output_.u.YUVA.v_size = v_size;
+  idec->output_.u.YUVA.a = a;
+  idec->output_.u.YUVA.a_stride = a_stride;
+  idec->output_.u.YUVA.a_size = a_size;
+  return idec;
+}
+
+WebPIDecoder* WebPINewYUV(uint8_t* luma, size_t luma_size, int luma_stride,
+                          uint8_t* u, size_t u_size, int u_stride,
+                          uint8_t* v, size_t v_size, int v_stride) {
+  return WebPINewYUVA(luma, luma_size, luma_stride,
+                      u, u_size, u_stride,
+                      v, v_size, v_stride,
+                      NULL, 0, 0);
+}
+
+//------------------------------------------------------------------------------
+
+static VP8StatusCode IDecCheckStatus(const WebPIDecoder* const idec) {
+  assert(idec);
+  if (idec->state_ == STATE_ERROR) {
+    return VP8_STATUS_BITSTREAM_ERROR;
+  }
+  if (idec->state_ == STATE_DONE) {
+    return VP8_STATUS_OK;
+  }
+  return VP8_STATUS_SUSPENDED;
+}
+
+VP8StatusCode WebPIAppend(WebPIDecoder* idec,
+                          const uint8_t* data, size_t data_size) {
+  VP8StatusCode status;
+  if (idec == NULL || data == NULL) {
+    return VP8_STATUS_INVALID_PARAM;
+  }
+  status = IDecCheckStatus(idec);
+  if (status != VP8_STATUS_SUSPENDED) {
+    return status;
+  }
+  // Check mixed calls between RemapMemBuffer and AppendToMemBuffer.
+  if (!CheckMemBufferMode(&idec->mem_, MEM_MODE_APPEND)) {
+    return VP8_STATUS_INVALID_PARAM;
+  }
+  // Append data to memory buffer
+  if (!AppendToMemBuffer(idec, data, data_size)) {
+    return VP8_STATUS_OUT_OF_MEMORY;
+  }
+  return IDecode(idec);
+}
+
+VP8StatusCode WebPIUpdate(WebPIDecoder* idec,
+                          const uint8_t* data, size_t data_size) {
+  VP8StatusCode status;
+  if (idec == NULL || data == NULL) {
+    return VP8_STATUS_INVALID_PARAM;
+  }
+  status = IDecCheckStatus(idec);
+  if (status != VP8_STATUS_SUSPENDED) {
+    return status;
+  }
+  // Check mixed calls between RemapMemBuffer and AppendToMemBuffer.
+  if (!CheckMemBufferMode(&idec->mem_, MEM_MODE_MAP)) {
+    return VP8_STATUS_INVALID_PARAM;
+  }
+  // Make the memory buffer point to the new buffer
+  if (!RemapMemBuffer(idec, data, data_size)) {
+    return VP8_STATUS_INVALID_PARAM;
+  }
+  return IDecode(idec);
+}
+
+//------------------------------------------------------------------------------
+
+static const WebPDecBuffer* GetOutputBuffer(const WebPIDecoder* const idec) {
+  if (idec == NULL || idec->dec_ == NULL) {
+    return NULL;
+  }
+  if (idec->state_ <= STATE_VP8_PARTS0) {
+    return NULL;
+  }
+  return idec->params_.output;
+}
+
+const WebPDecBuffer* WebPIDecodedArea(const WebPIDecoder* idec,
+                                      int* left, int* top,
+                                      int* width, int* height) {
+  const WebPDecBuffer* const src = GetOutputBuffer(idec);
+  if (left != NULL) *left = 0;
+  if (top != NULL) *top = 0;
+  // TODO(skal): later include handling of rotations.
+  if (src) {
+    if (width != NULL) *width = src->width;
+    if (height != NULL) *height = idec->params_.last_y;
+  } else {
+    if (width != NULL) *width = 0;
+    if (height != NULL) *height = 0;
+  }
+  return src;
+}
+
+uint8_t* WebPIDecGetRGB(const WebPIDecoder* idec, int* last_y,
+                        int* width, int* height, int* stride) {
+  const WebPDecBuffer* const src = GetOutputBuffer(idec);
+  if (src == NULL) return NULL;
+  if (src->colorspace >= MODE_YUV) {
+    return NULL;
+  }
+
+  if (last_y != NULL) *last_y = idec->params_.last_y;
+  if (width != NULL) *width = src->width;
+  if (height != NULL) *height = src->height;
+  if (stride != NULL) *stride = src->u.RGBA.stride;
+
+  return src->u.RGBA.rgba;
+}
+
+uint8_t* WebPIDecGetYUVA(const WebPIDecoder* idec, int* last_y,
+                         uint8_t** u, uint8_t** v, uint8_t** a,
+                         int* width, int* height,
+                         int* stride, int* uv_stride, int* a_stride) {
+  const WebPDecBuffer* const src = GetOutputBuffer(idec);
+  if (src == NULL) return NULL;
+  if (src->colorspace < MODE_YUV) {
+    return NULL;
+  }
+
+  if (last_y != NULL) *last_y = idec->params_.last_y;
+  if (u != NULL) *u = src->u.YUVA.u;
+  if (v != NULL) *v = src->u.YUVA.v;
+  if (a != NULL) *a = src->u.YUVA.a;
+  if (width != NULL) *width = src->width;
+  if (height != NULL) *height = src->height;
+  if (stride != NULL) *stride = src->u.YUVA.y_stride;
+  if (uv_stride != NULL) *uv_stride = src->u.YUVA.u_stride;
+  if (a_stride != NULL) *a_stride = src->u.YUVA.a_stride;
+
+  return src->u.YUVA.y;
+}
+
+int WebPISetIOHooks(WebPIDecoder* const idec,
+                    VP8IoPutHook put,
+                    VP8IoSetupHook setup,
+                    VP8IoTeardownHook teardown,
+                    void* user_data) {
+  if (idec == NULL || idec->state_ > STATE_WEBP_HEADER) {
+    return 0;
+  }
+
+  idec->io_.put = put;
+  idec->io_.setup = setup;
+  idec->io_.teardown = teardown;
+  idec->io_.opaque = user_data;
+
+  return 1;
+}
+
diff --git a/src/3rdparty/libwebp/src/dec/io.c b/src/3rdparty/libwebp/src/dec/io.c
new file mode 100644
index 0000000..1ba376e
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/io.c
@@ -0,0 +1,628 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// functions for sample output.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <assert.h>
+#include <stdlib.h>
+#include "../dec/vp8i.h"
+#include "./webpi.h"
+#include "../dsp/dsp.h"
+#include "../dsp/yuv.h"
+
+//------------------------------------------------------------------------------
+// Main YUV<->RGB conversion functions
+
+static int EmitYUV(const VP8Io* const io, WebPDecParams* const p) {
+  WebPDecBuffer* output = p->output;
+  const WebPYUVABuffer* const buf = &output->u.YUVA;
+  uint8_t* const y_dst = buf->y + io->mb_y * buf->y_stride;
+  uint8_t* const u_dst = buf->u + (io->mb_y >> 1) * buf->u_stride;
+  uint8_t* const v_dst = buf->v + (io->mb_y >> 1) * buf->v_stride;
+  const int mb_w = io->mb_w;
+  const int mb_h = io->mb_h;
+  const int uv_w = (mb_w + 1) / 2;
+  const int uv_h = (mb_h + 1) / 2;
+  int j;
+  for (j = 0; j < mb_h; ++j) {
+    memcpy(y_dst + j * buf->y_stride, io->y + j * io->y_stride, mb_w);
+  }
+  for (j = 0; j < uv_h; ++j) {
+    memcpy(u_dst + j * buf->u_stride, io->u + j * io->uv_stride, uv_w);
+    memcpy(v_dst + j * buf->v_stride, io->v + j * io->uv_stride, uv_w);
+  }
+  return io->mb_h;
+}
+
+// Point-sampling U/V sampler.
+static int EmitSampledRGB(const VP8Io* const io, WebPDecParams* const p) {
+  WebPDecBuffer* output = p->output;
+  const WebPRGBABuffer* const buf = &output->u.RGBA;
+  uint8_t* dst = buf->rgba + io->mb_y * buf->stride;
+  const uint8_t* y_src = io->y;
+  const uint8_t* u_src = io->u;
+  const uint8_t* v_src = io->v;
+  const WebPSampleLinePairFunc sample = WebPSamplers[output->colorspace];
+  const int mb_w = io->mb_w;
+  const int last = io->mb_h - 1;
+  int j;
+  for (j = 0; j < last; j += 2) {
+    sample(y_src, y_src + io->y_stride, u_src, v_src,
+           dst, dst + buf->stride, mb_w);
+    y_src += 2 * io->y_stride;
+    u_src += io->uv_stride;
+    v_src += io->uv_stride;
+    dst += 2 * buf->stride;
+  }
+  if (j == last) {  // Just do the last line twice
+    sample(y_src, y_src, u_src, v_src, dst, dst, mb_w);
+  }
+  return io->mb_h;
+}
+
+//------------------------------------------------------------------------------
+// YUV444 -> RGB conversion
+
+#if 0   // TODO(skal): this is for future rescaling.
+static int EmitRGB(const VP8Io* const io, WebPDecParams* const p) {
+  WebPDecBuffer* output = p->output;
+  const WebPRGBABuffer* const buf = &output->u.RGBA;
+  uint8_t* dst = buf->rgba + io->mb_y * buf->stride;
+  const uint8_t* y_src = io->y;
+  const uint8_t* u_src = io->u;
+  const uint8_t* v_src = io->v;
+  const WebPYUV444Converter convert = WebPYUV444Converters[output->colorspace];
+  const int mb_w = io->mb_w;
+  const int last = io->mb_h;
+  int j;
+  for (j = 0; j < last; ++j) {
+    convert(y_src, u_src, v_src, dst, mb_w);
+    y_src += io->y_stride;
+    u_src += io->uv_stride;
+    v_src += io->uv_stride;
+    dst += buf->stride;
+  }
+  return io->mb_h;
+}
+#endif
+
+//------------------------------------------------------------------------------
+// Fancy upsampling
+
+#ifdef FANCY_UPSAMPLING
+static int EmitFancyRGB(const VP8Io* const io, WebPDecParams* const p) {
+  int num_lines_out = io->mb_h;   // a priori guess
+  const WebPRGBABuffer* const buf = &p->output->u.RGBA;
+  uint8_t* dst = buf->rgba + io->mb_y * buf->stride;
+  WebPUpsampleLinePairFunc upsample = WebPUpsamplers[p->output->colorspace];
+  const uint8_t* cur_y = io->y;
+  const uint8_t* cur_u = io->u;
+  const uint8_t* cur_v = io->v;
+  const uint8_t* top_u = p->tmp_u;
+  const uint8_t* top_v = p->tmp_v;
+  int y = io->mb_y;
+  const int y_end = io->mb_y + io->mb_h;
+  const int mb_w = io->mb_w;
+  const int uv_w = (mb_w + 1) / 2;
+
+  if (y == 0) {
+    // First line is special cased. We mirror the u/v samples at boundary.
+    upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v, dst, NULL, mb_w);
+  } else {
+    // We can finish the left-over line from previous call.
+    upsample(p->tmp_y, cur_y, top_u, top_v, cur_u, cur_v,
+             dst - buf->stride, dst, mb_w);
+    ++num_lines_out;
+  }
+  // Loop over each output pairs of row.
+  for (; y + 2 < y_end; y += 2) {
+    top_u = cur_u;
+    top_v = cur_v;
+    cur_u += io->uv_stride;
+    cur_v += io->uv_stride;
+    dst += 2 * buf->stride;
+    cur_y += 2 * io->y_stride;
+    upsample(cur_y - io->y_stride, cur_y,
+             top_u, top_v, cur_u, cur_v,
+             dst - buf->stride, dst, mb_w);
+  }
+  // move to last row
+  cur_y += io->y_stride;
+  if (io->crop_top + y_end < io->crop_bottom) {
+    // Save the unfinished samples for next call (as we're not done yet).
+    memcpy(p->tmp_y, cur_y, mb_w * sizeof(*p->tmp_y));
+    memcpy(p->tmp_u, cur_u, uv_w * sizeof(*p->tmp_u));
+    memcpy(p->tmp_v, cur_v, uv_w * sizeof(*p->tmp_v));
+    // The fancy upsampler leaves a row unfinished behind
+    // (except for the very last row)
+    num_lines_out--;
+  } else {
+    // Process the very last row of even-sized picture
+    if (!(y_end & 1)) {
+      upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v,
+               dst + buf->stride, NULL, mb_w);
+    }
+  }
+  return num_lines_out;
+}
+
+#endif    /* FANCY_UPSAMPLING */
+
+//------------------------------------------------------------------------------
+
+static int EmitAlphaYUV(const VP8Io* const io, WebPDecParams* const p) {
+  const uint8_t* alpha = io->a;
+  const WebPYUVABuffer* const buf = &p->output->u.YUVA;
+  const int mb_w = io->mb_w;
+  const int mb_h = io->mb_h;
+  uint8_t* dst = buf->a + io->mb_y * buf->a_stride;
+  int j;
+
+  if (alpha != NULL) {
+    for (j = 0; j < mb_h; ++j) {
+      memcpy(dst, alpha, mb_w * sizeof(*dst));
+      alpha += io->width;
+      dst += buf->a_stride;
+    }
+  } else if (buf->a != NULL) {
+    // the user requested alpha, but there is none, set it to opaque.
+    for (j = 0; j < mb_h; ++j) {
+      memset(dst, 0xff, mb_w * sizeof(*dst));
+      dst += buf->a_stride;
+    }
+  }
+  return 0;
+}
+
+static int GetAlphaSourceRow(const VP8Io* const io,
+                             const uint8_t** alpha, int* const num_rows) {
+  int start_y = io->mb_y;
+  *num_rows = io->mb_h;
+
+  // Compensate for the 1-line delay of the fancy upscaler.
+  // This is similar to EmitFancyRGB().
+  if (io->fancy_upsampling) {
+    if (start_y == 0) {
+      // We don't process the last row yet. It'll be done during the next call.
+      --*num_rows;
+    } else {
+      --start_y;
+      // Fortunately, *alpha data is persistent, so we can go back
+      // one row and finish alpha blending, now that the fancy upscaler
+      // completed the YUV->RGB interpolation.
+      *alpha -= io->width;
+    }
+    if (io->crop_top + io->mb_y + io->mb_h == io->crop_bottom) {
+      // If it's the very last call, we process all the remaining rows!
+      *num_rows = io->crop_bottom - io->crop_top - start_y;
+    }
+  }
+  return start_y;
+}
+
+static int EmitAlphaRGB(const VP8Io* const io, WebPDecParams* const p) {
+  const uint8_t* alpha = io->a;
+  if (alpha != NULL) {
+    const int mb_w = io->mb_w;
+    const WEBP_CSP_MODE colorspace = p->output->colorspace;
+    const int alpha_first =
+        (colorspace == MODE_ARGB || colorspace == MODE_Argb);
+    const WebPRGBABuffer* const buf = &p->output->u.RGBA;
+    int num_rows;
+    const int start_y = GetAlphaSourceRow(io, &alpha, &num_rows);
+    uint8_t* const base_rgba = buf->rgba + start_y * buf->stride;
+    uint8_t* dst = base_rgba + (alpha_first ? 0 : 3);
+    uint32_t alpha_mask = 0xff;
+    int i, j;
+
+    for (j = 0; j < num_rows; ++j) {
+      for (i = 0; i < mb_w; ++i) {
+        const uint32_t alpha_value = alpha[i];
+        dst[4 * i] = alpha_value;
+        alpha_mask &= alpha_value;
+      }
+      alpha += io->width;
+      dst += buf->stride;
+    }
+    // alpha_mask is < 0xff if there's non-trivial alpha to premultiply with.
+    if (alpha_mask != 0xff && WebPIsPremultipliedMode(colorspace)) {
+      WebPApplyAlphaMultiply(base_rgba, alpha_first,
+                             mb_w, num_rows, buf->stride);
+    }
+  }
+  return 0;
+}
+
+static int EmitAlphaRGBA4444(const VP8Io* const io, WebPDecParams* const p) {
+  const uint8_t* alpha = io->a;
+  if (alpha != NULL) {
+    const int mb_w = io->mb_w;
+    const WEBP_CSP_MODE colorspace = p->output->colorspace;
+    const WebPRGBABuffer* const buf = &p->output->u.RGBA;
+    int num_rows;
+    const int start_y = GetAlphaSourceRow(io, &alpha, &num_rows);
+    uint8_t* const base_rgba = buf->rgba + start_y * buf->stride;
+    uint8_t* alpha_dst = base_rgba + 1;
+    uint32_t alpha_mask = 0x0f;
+    int i, j;
+
+    for (j = 0; j < num_rows; ++j) {
+      for (i = 0; i < mb_w; ++i) {
+        // Fill in the alpha value (converted to 4 bits).
+        const uint32_t alpha_value = alpha[i] >> 4;
+        alpha_dst[2 * i] = (alpha_dst[2 * i] & 0xf0) | alpha_value;
+        alpha_mask &= alpha_value;
+      }
+      alpha += io->width;
+      alpha_dst += buf->stride;
+    }
+    if (alpha_mask != 0x0f && WebPIsPremultipliedMode(colorspace)) {
+      WebPApplyAlphaMultiply4444(base_rgba, mb_w, num_rows, buf->stride);
+    }
+  }
+  return 0;
+}
+
+//------------------------------------------------------------------------------
+// YUV rescaling (no final RGB conversion needed)
+
+static int Rescale(const uint8_t* src, int src_stride,
+                   int new_lines, WebPRescaler* const wrk) {
+  int num_lines_out = 0;
+  while (new_lines > 0) {    // import new contributions of source rows.
+    const int lines_in = WebPRescalerImport(wrk, new_lines, src, src_stride);
+    src += lines_in * src_stride;
+    new_lines -= lines_in;
+    num_lines_out += WebPRescalerExport(wrk);    // emit output row(s)
+  }
+  return num_lines_out;
+}
+
+static int EmitRescaledYUV(const VP8Io* const io, WebPDecParams* const p) {
+  const int mb_h = io->mb_h;
+  const int uv_mb_h = (mb_h + 1) >> 1;
+  const int num_lines_out = Rescale(io->y, io->y_stride, mb_h, &p->scaler_y);
+  Rescale(io->u, io->uv_stride, uv_mb_h, &p->scaler_u);
+  Rescale(io->v, io->uv_stride, uv_mb_h, &p->scaler_v);
+  return num_lines_out;
+}
+
+static int EmitRescaledAlphaYUV(const VP8Io* const io, WebPDecParams* const p) {
+  if (io->a != NULL) {
+    Rescale(io->a, io->width, io->mb_h, &p->scaler_a);
+  }
+  return 0;
+}
+
+static int InitYUVRescaler(const VP8Io* const io, WebPDecParams* const p) {
+  const int has_alpha = WebPIsAlphaMode(p->output->colorspace);
+  const WebPYUVABuffer* const buf = &p->output->u.YUVA;
+  const int out_width  = io->scaled_width;
+  const int out_height = io->scaled_height;
+  const int uv_out_width  = (out_width + 1) >> 1;
+  const int uv_out_height = (out_height + 1) >> 1;
+  const int uv_in_width  = (io->mb_w + 1) >> 1;
+  const int uv_in_height = (io->mb_h + 1) >> 1;
+  const size_t work_size = 2 * out_width;   // scratch memory for luma rescaler
+  const size_t uv_work_size = 2 * uv_out_width;  // and for each u/v ones
+  size_t tmp_size;
+  int32_t* work;
+
+  tmp_size = work_size + 2 * uv_work_size;
+  if (has_alpha) {
+    tmp_size += work_size;
+  }
+  p->memory = calloc(1, tmp_size * sizeof(*work));
+  if (p->memory == NULL) {
+    return 0;   // memory error
+  }
+  work = (int32_t*)p->memory;
+  WebPRescalerInit(&p->scaler_y, io->mb_w, io->mb_h,
+                   buf->y, out_width, out_height, buf->y_stride, 1,
+                   io->mb_w, out_width, io->mb_h, out_height,
+                   work);
+  WebPRescalerInit(&p->scaler_u, uv_in_width, uv_in_height,
+                   buf->u, uv_out_width, uv_out_height, buf->u_stride, 1,
+                   uv_in_width, uv_out_width,
+                   uv_in_height, uv_out_height,
+                   work + work_size);
+  WebPRescalerInit(&p->scaler_v, uv_in_width, uv_in_height,
+                   buf->v, uv_out_width, uv_out_height, buf->v_stride, 1,
+                   uv_in_width, uv_out_width,
+                   uv_in_height, uv_out_height,
+                   work + work_size + uv_work_size);
+  p->emit = EmitRescaledYUV;
+
+  if (has_alpha) {
+    WebPRescalerInit(&p->scaler_a, io->mb_w, io->mb_h,
+                     buf->a, out_width, out_height, buf->a_stride, 1,
+                     io->mb_w, out_width, io->mb_h, out_height,
+                     work + work_size + 2 * uv_work_size);
+    p->emit_alpha = EmitRescaledAlphaYUV;
+  }
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+// RGBA rescaling
+
+static int ExportRGB(WebPDecParams* const p, int y_pos) {
+  const WebPYUV444Converter convert =
+      WebPYUV444Converters[p->output->colorspace];
+  const WebPRGBABuffer* const buf = &p->output->u.RGBA;
+  uint8_t* dst = buf->rgba + (p->last_y + y_pos) * buf->stride;
+  int num_lines_out = 0;
+  // For RGB rescaling, because of the YUV420, current scan position
+  // U/V can be +1/-1 line from the Y one.  Hence the double test.
+  while (WebPRescalerHasPendingOutput(&p->scaler_y) &&
+         WebPRescalerHasPendingOutput(&p->scaler_u)) {
+    assert(p->last_y + y_pos + num_lines_out < p->output->height);
+    assert(p->scaler_u.y_accum == p->scaler_v.y_accum);
+    WebPRescalerExportRow(&p->scaler_y);
+    WebPRescalerExportRow(&p->scaler_u);
+    WebPRescalerExportRow(&p->scaler_v);
+    convert(p->scaler_y.dst, p->scaler_u.dst, p->scaler_v.dst,
+            dst, p->scaler_y.dst_width);
+    dst += buf->stride;
+    ++num_lines_out;
+  }
+  return num_lines_out;
+}
+
+static int EmitRescaledRGB(const VP8Io* const io, WebPDecParams* const p) {
+  const int mb_h = io->mb_h;
+  const int uv_mb_h = (mb_h + 1) >> 1;
+  int j = 0, uv_j = 0;
+  int num_lines_out = 0;
+  while (j < mb_h) {
+    const int y_lines_in =
+        WebPRescalerImport(&p->scaler_y, mb_h - j,
+                           io->y + j * io->y_stride, io->y_stride);
+    const int u_lines_in =
+        WebPRescalerImport(&p->scaler_u, uv_mb_h - uv_j,
+                           io->u + uv_j * io->uv_stride, io->uv_stride);
+    const int v_lines_in =
+        WebPRescalerImport(&p->scaler_v, uv_mb_h - uv_j,
+                           io->v + uv_j * io->uv_stride, io->uv_stride);
+    (void)v_lines_in;   // remove a gcc warning
+    assert(u_lines_in == v_lines_in);
+    j += y_lines_in;
+    uv_j += u_lines_in;
+    num_lines_out += ExportRGB(p, num_lines_out);
+  }
+  return num_lines_out;
+}
+
+static int ExportAlpha(WebPDecParams* const p, int y_pos) {
+  const WebPRGBABuffer* const buf = &p->output->u.RGBA;
+  uint8_t* const base_rgba = buf->rgba + (p->last_y + y_pos) * buf->stride;
+  const WEBP_CSP_MODE colorspace = p->output->colorspace;
+  const int alpha_first =
+      (colorspace == MODE_ARGB || colorspace == MODE_Argb);
+  uint8_t* dst = base_rgba + (alpha_first ? 0 : 3);
+  int num_lines_out = 0;
+  const int is_premult_alpha = WebPIsPremultipliedMode(colorspace);
+  uint32_t alpha_mask = 0xff;
+  const int width = p->scaler_a.dst_width;
+
+  while (WebPRescalerHasPendingOutput(&p->scaler_a)) {
+    int i;
+    assert(p->last_y + y_pos + num_lines_out < p->output->height);
+    WebPRescalerExportRow(&p->scaler_a);
+    for (i = 0; i < width; ++i) {
+      const uint32_t alpha_value = p->scaler_a.dst[i];
+      dst[4 * i] = alpha_value;
+      alpha_mask &= alpha_value;
+    }
+    dst += buf->stride;
+    ++num_lines_out;
+  }
+  if (is_premult_alpha && alpha_mask != 0xff) {
+    WebPApplyAlphaMultiply(base_rgba, alpha_first,
+                           width, num_lines_out, buf->stride);
+  }
+  return num_lines_out;
+}
+
+static int ExportAlphaRGBA4444(WebPDecParams* const p, int y_pos) {
+  const WebPRGBABuffer* const buf = &p->output->u.RGBA;
+  uint8_t* const base_rgba = buf->rgba + (p->last_y + y_pos) * buf->stride;
+  uint8_t* alpha_dst = base_rgba + 1;
+  int num_lines_out = 0;
+  const WEBP_CSP_MODE colorspace = p->output->colorspace;
+  const int width = p->scaler_a.dst_width;
+  const int is_premult_alpha = WebPIsPremultipliedMode(colorspace);
+  uint32_t alpha_mask = 0x0f;
+
+  while (WebPRescalerHasPendingOutput(&p->scaler_a)) {
+    int i;
+    assert(p->last_y + y_pos + num_lines_out < p->output->height);
+    WebPRescalerExportRow(&p->scaler_a);
+    for (i = 0; i < width; ++i) {
+      // Fill in the alpha value (converted to 4 bits).
+      const uint32_t alpha_value = p->scaler_a.dst[i] >> 4;
+      alpha_dst[2 * i] = (alpha_dst[2 * i] & 0xf0) | alpha_value;
+      alpha_mask &= alpha_value;
+    }
+    alpha_dst += buf->stride;
+    ++num_lines_out;
+  }
+  if (is_premult_alpha && alpha_mask != 0x0f) {
+    WebPApplyAlphaMultiply4444(base_rgba, width, num_lines_out, buf->stride);
+  }
+  return num_lines_out;
+}
+
+static int EmitRescaledAlphaRGB(const VP8Io* const io, WebPDecParams* const p) {
+  if (io->a != NULL) {
+    WebPRescaler* const scaler = &p->scaler_a;
+    int j = 0;
+    int pos = 0;
+    while (j < io->mb_h) {
+      j += WebPRescalerImport(scaler, io->mb_h - j,
+                              io->a + j * io->width, io->width);
+      pos += p->emit_alpha_row(p, pos);
+    }
+  }
+  return 0;
+}
+
+static int InitRGBRescaler(const VP8Io* const io, WebPDecParams* const p) {
+  const int has_alpha = WebPIsAlphaMode(p->output->colorspace);
+  const int out_width  = io->scaled_width;
+  const int out_height = io->scaled_height;
+  const int uv_in_width  = (io->mb_w + 1) >> 1;
+  const int uv_in_height = (io->mb_h + 1) >> 1;
+  const size_t work_size = 2 * out_width;   // scratch memory for one rescaler
+  int32_t* work;  // rescalers work area
+  uint8_t* tmp;   // tmp storage for scaled YUV444 samples before RGB conversion
+  size_t tmp_size1, tmp_size2;
+
+  tmp_size1 = 3 * work_size;
+  tmp_size2 = 3 * out_width;
+  if (has_alpha) {
+    tmp_size1 += work_size;
+    tmp_size2 += out_width;
+  }
+  p->memory = calloc(1, tmp_size1 * sizeof(*work) + tmp_size2 * sizeof(*tmp));
+  if (p->memory == NULL) {
+    return 0;   // memory error
+  }
+  work = (int32_t*)p->memory;
+  tmp = (uint8_t*)(work + tmp_size1);
+  WebPRescalerInit(&p->scaler_y, io->mb_w, io->mb_h,
+                   tmp + 0 * out_width, out_width, out_height, 0, 1,
+                   io->mb_w, out_width, io->mb_h, out_height,
+                   work + 0 * work_size);
+  WebPRescalerInit(&p->scaler_u, uv_in_width, uv_in_height,
+                   tmp + 1 * out_width, out_width, out_height, 0, 1,
+                   io->mb_w, 2 * out_width, io->mb_h, 2 * out_height,
+                   work + 1 * work_size);
+  WebPRescalerInit(&p->scaler_v, uv_in_width, uv_in_height,
+                   tmp + 2 * out_width, out_width, out_height, 0, 1,
+                   io->mb_w, 2 * out_width, io->mb_h, 2 * out_height,
+                   work + 2 * work_size);
+  p->emit = EmitRescaledRGB;
+
+  if (has_alpha) {
+    WebPRescalerInit(&p->scaler_a, io->mb_w, io->mb_h,
+                     tmp + 3 * out_width, out_width, out_height, 0, 1,
+                     io->mb_w, out_width, io->mb_h, out_height,
+                     work + 3 * work_size);
+    p->emit_alpha = EmitRescaledAlphaRGB;
+    if (p->output->colorspace == MODE_RGBA_4444 ||
+        p->output->colorspace == MODE_rgbA_4444) {
+      p->emit_alpha_row = ExportAlphaRGBA4444;
+    } else {
+      p->emit_alpha_row = ExportAlpha;
+    }
+  }
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+// Default custom functions
+
+static int CustomSetup(VP8Io* io) {
+  WebPDecParams* const p = (WebPDecParams*)io->opaque;
+  const WEBP_CSP_MODE colorspace = p->output->colorspace;
+  const int is_rgb = WebPIsRGBMode(colorspace);
+  const int is_alpha = WebPIsAlphaMode(colorspace);
+
+  p->memory = NULL;
+  p->emit = NULL;
+  p->emit_alpha = NULL;
+  p->emit_alpha_row = NULL;
+  if (!WebPIoInitFromOptions(p->options, io, is_alpha ? MODE_YUV : MODE_YUVA)) {
+    return 0;
+  }
+
+  if (io->use_scaling) {
+    const int ok = is_rgb ? InitRGBRescaler(io, p) : InitYUVRescaler(io, p);
+    if (!ok) {
+      return 0;    // memory error
+    }
+  } else {
+    if (is_rgb) {
+      p->emit = EmitSampledRGB;   // default
+#ifdef FANCY_UPSAMPLING
+      if (io->fancy_upsampling) {
+        const int uv_width = (io->mb_w + 1) >> 1;
+        p->memory = malloc(io->mb_w + 2 * uv_width);
+        if (p->memory == NULL) {
+          return 0;   // memory error.
+        }
+        p->tmp_y = (uint8_t*)p->memory;
+        p->tmp_u = p->tmp_y + io->mb_w;
+        p->tmp_v = p->tmp_u + uv_width;
+        p->emit = EmitFancyRGB;
+        WebPInitUpsamplers();
+      }
+#endif
+    } else {
+      p->emit = EmitYUV;
+    }
+    if (is_alpha) {  // need transparency output
+      if (WebPIsPremultipliedMode(colorspace)) WebPInitPremultiply();
+      p->emit_alpha =
+          (colorspace == MODE_RGBA_4444 || colorspace == MODE_rgbA_4444) ?
+              EmitAlphaRGBA4444
+          : is_rgb ? EmitAlphaRGB
+          : EmitAlphaYUV;
+    }
+  }
+
+  if (is_rgb) {
+    VP8YUVInit();
+  }
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+
+static int CustomPut(const VP8Io* io) {
+  WebPDecParams* const p = (WebPDecParams*)io->opaque;
+  const int mb_w = io->mb_w;
+  const int mb_h = io->mb_h;
+  int num_lines_out;
+  assert(!(io->mb_y & 1));
+
+  if (mb_w <= 0 || mb_h <= 0) {
+    return 0;
+  }
+  num_lines_out = p->emit(io, p);
+  if (p->emit_alpha != NULL) {
+    p->emit_alpha(io, p);
+  }
+  p->last_y += num_lines_out;
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+
+static void CustomTeardown(const VP8Io* io) {
+  WebPDecParams* const p = (WebPDecParams*)io->opaque;
+  free(p->memory);
+  p->memory = NULL;
+}
+
+//------------------------------------------------------------------------------
+// Main entry point
+
+void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io) {
+  io->put      = CustomPut;
+  io->setup    = CustomSetup;
+  io->teardown = CustomTeardown;
+  io->opaque   = params;
+}
+
+//------------------------------------------------------------------------------
+
diff --git a/src/3rdparty/libwebp/src/dec/layer.c b/src/3rdparty/libwebp/src/dec/layer.c
new file mode 100644
index 0000000..dacb9e2
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/layer.c
@@ -0,0 +1,30 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Enhancement layer (for YUV444/422)
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include "./vp8i.h"
+
+//------------------------------------------------------------------------------
+
+int VP8DecodeLayer(VP8Decoder* const dec) {
+  assert(dec);
+  assert(dec->layer_data_size_ > 0);
+  (void)dec;
+
+  // TODO: handle enhancement layer here.
+
+  return 1;
+}
+
diff --git a/src/3rdparty/libwebp/src/dec/quant.c b/src/3rdparty/libwebp/src/dec/quant.c
new file mode 100644
index 0000000..5b648f9
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/quant.c
@@ -0,0 +1,110 @@
+// Copyright 2010 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Quantizer initialization
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include "./vp8i.h"
+
+static WEBP_INLINE int clip(int v, int M) {
+  return v < 0 ? 0 : v > M ? M : v;
+}
+
+// Paragraph 14.1
+static const uint8_t kDcTable[128] = {
+  4,     5,   6,   7,   8,   9,  10,  10,
+  11,   12,  13,  14,  15,  16,  17,  17,
+  18,   19,  20,  20,  21,  21,  22,  22,
+  23,   23,  24,  25,  25,  26,  27,  28,
+  29,   30,  31,  32,  33,  34,  35,  36,
+  37,   37,  38,  39,  40,  41,  42,  43,
+  44,   45,  46,  46,  47,  48,  49,  50,
+  51,   52,  53,  54,  55,  56,  57,  58,
+  59,   60,  61,  62,  63,  64,  65,  66,
+  67,   68,  69,  70,  71,  72,  73,  74,
+  75,   76,  76,  77,  78,  79,  80,  81,
+  82,   83,  84,  85,  86,  87,  88,  89,
+  91,   93,  95,  96,  98, 100, 101, 102,
+  104, 106, 108, 110, 112, 114, 116, 118,
+  122, 124, 126, 128, 130, 132, 134, 136,
+  138, 140, 143, 145, 148, 151, 154, 157
+};
+
+static const uint16_t kAcTable[128] = {
+  4,     5,   6,   7,   8,   9,  10,  11,
+  12,   13,  14,  15,  16,  17,  18,  19,
+  20,   21,  22,  23,  24,  25,  26,  27,
+  28,   29,  30,  31,  32,  33,  34,  35,
+  36,   37,  38,  39,  40,  41,  42,  43,
+  44,   45,  46,  47,  48,  49,  50,  51,
+  52,   53,  54,  55,  56,  57,  58,  60,
+  62,   64,  66,  68,  70,  72,  74,  76,
+  78,   80,  82,  84,  86,  88,  90,  92,
+  94,   96,  98, 100, 102, 104, 106, 108,
+  110, 112, 114, 116, 119, 122, 125, 128,
+  131, 134, 137, 140, 143, 146, 149, 152,
+  155, 158, 161, 164, 167, 170, 173, 177,
+  181, 185, 189, 193, 197, 201, 205, 209,
+  213, 217, 221, 225, 229, 234, 239, 245,
+  249, 254, 259, 264, 269, 274, 279, 284
+};
+
+//------------------------------------------------------------------------------
+// Paragraph 9.6
+
+void VP8ParseQuant(VP8Decoder* const dec) {
+  VP8BitReader* const br = &dec->br_;
+  const int base_q0 = VP8GetValue(br, 7);
+  const int dqy1_dc = VP8Get(br) ? VP8GetSignedValue(br, 4) : 0;
+  const int dqy2_dc = VP8Get(br) ? VP8GetSignedValue(br, 4) : 0;
+  const int dqy2_ac = VP8Get(br) ? VP8GetSignedValue(br, 4) : 0;
+  const int dquv_dc = VP8Get(br) ? VP8GetSignedValue(br, 4) : 0;
+  const int dquv_ac = VP8Get(br) ? VP8GetSignedValue(br, 4) : 0;
+
+  const VP8SegmentHeader* const hdr = &dec->segment_hdr_;
+  int i;
+
+  for (i = 0; i < NUM_MB_SEGMENTS; ++i) {
+    int q;
+    if (hdr->use_segment_) {
+      q = hdr->quantizer_[i];
+      if (!hdr->absolute_delta_) {
+        q += base_q0;
+      }
+    } else {
+      if (i > 0) {
+        dec->dqm_[i] = dec->dqm_[0];
+        continue;
+      } else {
+        q = base_q0;
+      }
+    }
+    {
+      VP8QuantMatrix* const m = &dec->dqm_[i];
+      m->y1_mat_[0] = kDcTable[clip(q + dqy1_dc, 127)];
+      m->y1_mat_[1] = kAcTable[clip(q + 0,       127)];
+
+      m->y2_mat_[0] = kDcTable[clip(q + dqy2_dc, 127)] * 2;
+      // For all x in [0..284], x*155/100 is bitwise equal to (x*101581) >> 16.
+      // The smallest precision for that is '(x*6349) >> 12' but 16 is a good
+      // word size.
+      m->y2_mat_[1] = (kAcTable[clip(q + dqy2_ac, 127)] * 101581) >> 16;
+      if (m->y2_mat_[1] < 8) m->y2_mat_[1] = 8;
+
+      m->uv_mat_[0] = kDcTable[clip(q + dquv_dc, 117)];
+      m->uv_mat_[1] = kAcTable[clip(q + dquv_ac, 127)];
+
+      m->uv_quant_ = q + dquv_ac;   // for dithering strength evaluation
+    }
+  }
+}
+
+//------------------------------------------------------------------------------
+
diff --git a/src/3rdparty/libwebp/src/dec/tree.c b/src/3rdparty/libwebp/src/dec/tree.c
new file mode 100644
index 0000000..bf9b7c5
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/tree.c
@@ -0,0 +1,494 @@
+// Copyright 2010 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Coding trees and probas
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include "vp8i.h"
+
+#define USE_GENERIC_TREE
+
+#ifdef USE_GENERIC_TREE
+static const int8_t kYModesIntra4[18] = {
+  -B_DC_PRED, 1,
+    -B_TM_PRED, 2,
+      -B_VE_PRED, 3,
+        4, 6,
+          -B_HE_PRED, 5,
+            -B_RD_PRED, -B_VR_PRED,
+        -B_LD_PRED, 7,
+          -B_VL_PRED, 8,
+            -B_HD_PRED, -B_HU_PRED
+};
+#endif
+
+//------------------------------------------------------------------------------
+// Default probabilities
+
+// Paragraph 13.5
+static const uint8_t
+  CoeffsProba0[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS] = {
+  { { { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
+      { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
+      { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
+    },
+    { { 253, 136, 254, 255, 228, 219, 128, 128, 128, 128, 128 },
+      { 189, 129, 242, 255, 227, 213, 255, 219, 128, 128, 128 },
+      { 106, 126, 227, 252, 214, 209, 255, 255, 128, 128, 128 }
+    },
+    { { 1, 98, 248, 255, 236, 226, 255, 255, 128, 128, 128 },
+      { 181, 133, 238, 254, 221, 234, 255, 154, 128, 128, 128 },
+      { 78, 134, 202, 247, 198, 180, 255, 219, 128, 128, 128 },
+    },
+    { { 1, 185, 249, 255, 243, 255, 128, 128, 128, 128, 128 },
+      { 184, 150, 247, 255, 236, 224, 128, 128, 128, 128, 128 },
+      { 77, 110, 216, 255, 236, 230, 128, 128, 128, 128, 128 },
+    },
+    { { 1, 101, 251, 255, 241, 255, 128, 128, 128, 128, 128 },
+      { 170, 139, 241, 252, 236, 209, 255, 255, 128, 128, 128 },
+      { 37, 116, 196, 243, 228, 255, 255, 255, 128, 128, 128 }
+    },
+    { { 1, 204, 254, 255, 245, 255, 128, 128, 128, 128, 128 },
+      { 207, 160, 250, 255, 238, 128, 128, 128, 128, 128, 128 },
+      { 102, 103, 231, 255, 211, 171, 128, 128, 128, 128, 128 }
+    },
+    { { 1, 152, 252, 255, 240, 255, 128, 128, 128, 128, 128 },
+      { 177, 135, 243, 255, 234, 225, 128, 128, 128, 128, 128 },
+      { 80, 129, 211, 255, 194, 224, 128, 128, 128, 128, 128 }
+    },
+    { { 1, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
+      { 246, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
+      { 255, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
+    }
+  },
+  { { { 198, 35, 237, 223, 193, 187, 162, 160, 145, 155, 62 },
+      { 131, 45, 198, 221, 172, 176, 220, 157, 252, 221, 1 },
+      { 68, 47, 146, 208, 149, 167, 221, 162, 255, 223, 128 }
+    },
+    { { 1, 149, 241, 255, 221, 224, 255, 255, 128, 128, 128 },
+      { 184, 141, 234, 253, 222, 220, 255, 199, 128, 128, 128 },
+      { 81, 99, 181, 242, 176, 190, 249, 202, 255, 255, 128 }
+    },
+    { { 1, 129, 232, 253, 214, 197, 242, 196, 255, 255, 128 },
+      { 99, 121, 210, 250, 201, 198, 255, 202, 128, 128, 128 },
+      { 23, 91, 163, 242, 170, 187, 247, 210, 255, 255, 128 }
+    },
+    { { 1, 200, 246, 255, 234, 255, 128, 128, 128, 128, 128 },
+      { 109, 178, 241, 255, 231, 245, 255, 255, 128, 128, 128 },
+      { 44, 130, 201, 253, 205, 192, 255, 255, 128, 128, 128 }
+    },
+    { { 1, 132, 239, 251, 219, 209, 255, 165, 128, 128, 128 },
+      { 94, 136, 225, 251, 218, 190, 255, 255, 128, 128, 128 },
+      { 22, 100, 174, 245, 186, 161, 255, 199, 128, 128, 128 }
+    },
+    { { 1, 182, 249, 255, 232, 235, 128, 128, 128, 128, 128 },
+      { 124, 143, 241, 255, 227, 234, 128, 128, 128, 128, 128 },
+      { 35, 77, 181, 251, 193, 211, 255, 205, 128, 128, 128 }
+    },
+    { { 1, 157, 247, 255, 236, 231, 255, 255, 128, 128, 128 },
+      { 121, 141, 235, 255, 225, 227, 255, 255, 128, 128, 128 },
+      { 45, 99, 188, 251, 195, 217, 255, 224, 128, 128, 128 }
+    },
+    { { 1, 1, 251, 255, 213, 255, 128, 128, 128, 128, 128 },
+      { 203, 1, 248, 255, 255, 128, 128, 128, 128, 128, 128 },
+      { 137, 1, 177, 255, 224, 255, 128, 128, 128, 128, 128 }
+    }
+  },
+  { { { 253, 9, 248, 251, 207, 208, 255, 192, 128, 128, 128 },
+      { 175, 13, 224, 243, 193, 185, 249, 198, 255, 255, 128 },
+      { 73, 17, 171, 221, 161, 179, 236, 167, 255, 234, 128 }
+    },
+    { { 1, 95, 247, 253, 212, 183, 255, 255, 128, 128, 128 },
+      { 239, 90, 244, 250, 211, 209, 255, 255, 128, 128, 128 },
+      { 155, 77, 195, 248, 188, 195, 255, 255, 128, 128, 128 }
+    },
+    { { 1, 24, 239, 251, 218, 219, 255, 205, 128, 128, 128 },
+      { 201, 51, 219, 255, 196, 186, 128, 128, 128, 128, 128 },
+      { 69, 46, 190, 239, 201, 218, 255, 228, 128, 128, 128 }
+    },
+    { { 1, 191, 251, 255, 255, 128, 128, 128, 128, 128, 128 },
+      { 223, 165, 249, 255, 213, 255, 128, 128, 128, 128, 128 },
+      { 141, 124, 248, 255, 255, 128, 128, 128, 128, 128, 128 }
+    },
+    { { 1, 16, 248, 255, 255, 128, 128, 128, 128, 128, 128 },
+      { 190, 36, 230, 255, 236, 255, 128, 128, 128, 128, 128 },
+      { 149, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
+    },
+    { { 1, 226, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
+      { 247, 192, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
+      { 240, 128, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
+    },
+    { { 1, 134, 252, 255, 255, 128, 128, 128, 128, 128, 128 },
+      { 213, 62, 250, 255, 255, 128, 128, 128, 128, 128, 128 },
+      { 55, 93, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
+    },
+    { { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
+      { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
+      { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
+    }
+  },
+  { { { 202, 24, 213, 235, 186, 191, 220, 160, 240, 175, 255 },
+      { 126, 38, 182, 232, 169, 184, 228, 174, 255, 187, 128 },
+      { 61, 46, 138, 219, 151, 178, 240, 170, 255, 216, 128 }
+    },
+    { { 1, 112, 230, 250, 199, 191, 247, 159, 255, 255, 128 },
+      { 166, 109, 228, 252, 211, 215, 255, 174, 128, 128, 128 },
+      { 39, 77, 162, 232, 172, 180, 245, 178, 255, 255, 128 }
+    },
+    { { 1, 52, 220, 246, 198, 199, 249, 220, 255, 255, 128 },
+      { 124, 74, 191, 243, 183, 193, 250, 221, 255, 255, 128 },
+      { 24, 71, 130, 219, 154, 170, 243, 182, 255, 255, 128 }
+    },
+    { { 1, 182, 225, 249, 219, 240, 255, 224, 128, 128, 128 },
+      { 149, 150, 226, 252, 216, 205, 255, 171, 128, 128, 128 },
+      { 28, 108, 170, 242, 183, 194, 254, 223, 255, 255, 128 }
+    },
+    { { 1, 81, 230, 252, 204, 203, 255, 192, 128, 128, 128 },
+      { 123, 102, 209, 247, 188, 196, 255, 233, 128, 128, 128 },
+      { 20, 95, 153, 243, 164, 173, 255, 203, 128, 128, 128 }
+    },
+    { { 1, 222, 248, 255, 216, 213, 128, 128, 128, 128, 128 },
+      { 168, 175, 246, 252, 235, 205, 255, 255, 128, 128, 128 },
+      { 47, 116, 215, 255, 211, 212, 255, 255, 128, 128, 128 }
+    },
+    { { 1, 121, 236, 253, 212, 214, 255, 255, 128, 128, 128 },
+      { 141, 84, 213, 252, 201, 202, 255, 219, 128, 128, 128 },
+      { 42, 80, 160, 240, 162, 185, 255, 205, 128, 128, 128 }
+    },
+    { { 1, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
+      { 244, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
+      { 238, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
+    }
+  }
+};
+
+// Paragraph 11.5
+static const uint8_t kBModesProba[NUM_BMODES][NUM_BMODES][NUM_BMODES - 1] = {
+  { { 231, 120, 48, 89, 115, 113, 120, 152, 112 },
+    { 152, 179, 64, 126, 170, 118, 46, 70, 95 },
+    { 175, 69, 143, 80, 85, 82, 72, 155, 103 },
+    { 56, 58, 10, 171, 218, 189, 17, 13, 152 },
+    { 114, 26, 17, 163, 44, 195, 21, 10, 173 },
+    { 121, 24, 80, 195, 26, 62, 44, 64, 85 },
+    { 144, 71, 10, 38, 171, 213, 144, 34, 26 },
+    { 170, 46, 55, 19, 136, 160, 33, 206, 71 },
+    { 63, 20, 8, 114, 114, 208, 12, 9, 226 },
+    { 81, 40, 11, 96, 182, 84, 29, 16, 36 } },
+  { { 134, 183, 89, 137, 98, 101, 106, 165, 148 },
+    { 72, 187, 100, 130, 157, 111, 32, 75, 80 },
+    { 66, 102, 167, 99, 74, 62, 40, 234, 128 },
+    { 41, 53, 9, 178, 241, 141, 26, 8, 107 },
+    { 74, 43, 26, 146, 73, 166, 49, 23, 157 },
+    { 65, 38, 105, 160, 51, 52, 31, 115, 128 },
+    { 104, 79, 12, 27, 217, 255, 87, 17, 7 },
+    { 87, 68, 71, 44, 114, 51, 15, 186, 23 },
+    { 47, 41, 14, 110, 182, 183, 21, 17, 194 },
+    { 66, 45, 25, 102, 197, 189, 23, 18, 22 } },
+  { { 88, 88, 147, 150, 42, 46, 45, 196, 205 },
+    { 43, 97, 183, 117, 85, 38, 35, 179, 61 },
+    { 39, 53, 200, 87, 26, 21, 43, 232, 171 },
+    { 56, 34, 51, 104, 114, 102, 29, 93, 77 },
+    { 39, 28, 85, 171, 58, 165, 90, 98, 64 },
+    { 34, 22, 116, 206, 23, 34, 43, 166, 73 },
+    { 107, 54, 32, 26, 51, 1, 81, 43, 31 },
+    { 68, 25, 106, 22, 64, 171, 36, 225, 114 },
+    { 34, 19, 21, 102, 132, 188, 16, 76, 124 },
+    { 62, 18, 78, 95, 85, 57, 50, 48, 51 } },
+  { { 193, 101, 35, 159, 215, 111, 89, 46, 111 },
+    { 60, 148, 31, 172, 219, 228, 21, 18, 111 },
+    { 112, 113, 77, 85, 179, 255, 38, 120, 114 },
+    { 40, 42, 1, 196, 245, 209, 10, 25, 109 },
+    { 88, 43, 29, 140, 166, 213, 37, 43, 154 },
+    { 61, 63, 30, 155, 67, 45, 68, 1, 209 },
+    { 100, 80, 8, 43, 154, 1, 51, 26, 71 },
+    { 142, 78, 78, 16, 255, 128, 34, 197, 171 },
+    { 41, 40, 5, 102, 211, 183, 4, 1, 221 },
+    { 51, 50, 17, 168, 209, 192, 23, 25, 82 } },
+  { { 138, 31, 36, 171, 27, 166, 38, 44, 229 },
+    { 67, 87, 58, 169, 82, 115, 26, 59, 179 },
+    { 63, 59, 90, 180, 59, 166, 93, 73, 154 },
+    { 40, 40, 21, 116, 143, 209, 34, 39, 175 },
+    { 47, 15, 16, 183, 34, 223, 49, 45, 183 },
+    { 46, 17, 33, 183, 6, 98, 15, 32, 183 },
+    { 57, 46, 22, 24, 128, 1, 54, 17, 37 },
+    { 65, 32, 73, 115, 28, 128, 23, 128, 205 },
+    { 40, 3, 9, 115, 51, 192, 18, 6, 223 },
+    { 87, 37, 9, 115, 59, 77, 64, 21, 47 } },
+  { { 104, 55, 44, 218, 9, 54, 53, 130, 226 },
+    { 64, 90, 70, 205, 40, 41, 23, 26, 57 },
+    { 54, 57, 112, 184, 5, 41, 38, 166, 213 },
+    { 30, 34, 26, 133, 152, 116, 10, 32, 134 },
+    { 39, 19, 53, 221, 26, 114, 32, 73, 255 },
+    { 31, 9, 65, 234, 2, 15, 1, 118, 73 },
+    { 75, 32, 12, 51, 192, 255, 160, 43, 51 },
+    { 88, 31, 35, 67, 102, 85, 55, 186, 85 },
+    { 56, 21, 23, 111, 59, 205, 45, 37, 192 },
+    { 55, 38, 70, 124, 73, 102, 1, 34, 98 } },
+  { { 125, 98, 42, 88, 104, 85, 117, 175, 82 },
+    { 95, 84, 53, 89, 128, 100, 113, 101, 45 },
+    { 75, 79, 123, 47, 51, 128, 81, 171, 1 },
+    { 57, 17, 5, 71, 102, 57, 53, 41, 49 },
+    { 38, 33, 13, 121, 57, 73, 26, 1, 85 },
+    { 41, 10, 67, 138, 77, 110, 90, 47, 114 },
+    { 115, 21, 2, 10, 102, 255, 166, 23, 6 },
+    { 101, 29, 16, 10, 85, 128, 101, 196, 26 },
+    { 57, 18, 10, 102, 102, 213, 34, 20, 43 },
+    { 117, 20, 15, 36, 163, 128, 68, 1, 26 } },
+  { { 102, 61, 71, 37, 34, 53, 31, 243, 192 },
+    { 69, 60, 71, 38, 73, 119, 28, 222, 37 },
+    { 68, 45, 128, 34, 1, 47, 11, 245, 171 },
+    { 62, 17, 19, 70, 146, 85, 55, 62, 70 },
+    { 37, 43, 37, 154, 100, 163, 85, 160, 1 },
+    { 63, 9, 92, 136, 28, 64, 32, 201, 85 },
+    { 75, 15, 9, 9, 64, 255, 184, 119, 16 },
+    { 86, 6, 28, 5, 64, 255, 25, 248, 1 },
+    { 56, 8, 17, 132, 137, 255, 55, 116, 128 },
+    { 58, 15, 20, 82, 135, 57, 26, 121, 40 } },
+  { { 164, 50, 31, 137, 154, 133, 25, 35, 218 },
+    { 51, 103, 44, 131, 131, 123, 31, 6, 158 },
+    { 86, 40, 64, 135, 148, 224, 45, 183, 128 },
+    { 22, 26, 17, 131, 240, 154, 14, 1, 209 },
+    { 45, 16, 21, 91, 64, 222, 7, 1, 197 },
+    { 56, 21, 39, 155, 60, 138, 23, 102, 213 },
+    { 83, 12, 13, 54, 192, 255, 68, 47, 28 },
+    { 85, 26, 85, 85, 128, 128, 32, 146, 171 },
+    { 18, 11, 7, 63, 144, 171, 4, 4, 246 },
+    { 35, 27, 10, 146, 174, 171, 12, 26, 128 } },
+  { { 190, 80, 35, 99, 180, 80, 126, 54, 45 },
+    { 85, 126, 47, 87, 176, 51, 41, 20, 32 },
+    { 101, 75, 128, 139, 118, 146, 116, 128, 85 },
+    { 56, 41, 15, 176, 236, 85, 37, 9, 62 },
+    { 71, 30, 17, 119, 118, 255, 17, 18, 138 },
+    { 101, 38, 60, 138, 55, 70, 43, 26, 142 },
+    { 146, 36, 19, 30, 171, 255, 97, 27, 20 },
+    { 138, 45, 61, 62, 219, 1, 81, 188, 64 },
+    { 32, 41, 20, 117, 151, 142, 20, 21, 163 },
+    { 112, 19, 12, 61, 195, 128, 48, 4, 24 } }
+};
+
+void VP8ResetProba(VP8Proba* const proba) {
+  memset(proba->segments_, 255u, sizeof(proba->segments_));
+  // proba->bands_[][] is initialized later
+}
+
+void VP8ParseIntraMode(VP8BitReader* const br, VP8Decoder* const dec) {
+  uint8_t* const top = dec->intra_t_ + 4 * dec->mb_x_;
+  uint8_t* const left = dec->intra_l_;
+  VP8MBData* const block = dec->mb_data_ + dec->mb_x_;
+
+  block->is_i4x4_ = !VP8GetBit(br, 145);   // decide for B_PRED first
+  if (!block->is_i4x4_) {
+    // Hardcoded 16x16 intra-mode decision tree.
+    const int ymode =
+        VP8GetBit(br, 156) ? (VP8GetBit(br, 128) ? TM_PRED : H_PRED)
+                           : (VP8GetBit(br, 163) ? V_PRED : DC_PRED);
+    block->imodes_[0] = ymode;
+    memset(top, ymode, 4 * sizeof(*top));
+    memset(left, ymode, 4 * sizeof(*left));
+  } else {
+    uint8_t* modes = block->imodes_;
+    int y;
+    for (y = 0; y < 4; ++y) {
+      int ymode = left[y];
+      int x;
+      for (x = 0; x < 4; ++x) {
+        const uint8_t* const prob = kBModesProba[top[x]][ymode];
+#ifdef USE_GENERIC_TREE
+        // Generic tree-parsing
+        int i = kYModesIntra4[VP8GetBit(br, prob[0])];
+        while (i > 0) {
+          i = kYModesIntra4[2 * i + VP8GetBit(br, prob[i])];
+        }
+        ymode = -i;
+#else
+        // Hardcoded tree parsing
+        ymode = !VP8GetBit(br, prob[0]) ? B_DC_PRED :
+                  !VP8GetBit(br, prob[1]) ? B_TM_PRED :
+                    !VP8GetBit(br, prob[2]) ? B_VE_PRED :
+                      !VP8GetBit(br, prob[3]) ?
+                        (!VP8GetBit(br, prob[4]) ? B_HE_PRED :
+                          (!VP8GetBit(br, prob[5]) ? B_RD_PRED : B_VR_PRED)) :
+                        (!VP8GetBit(br, prob[6]) ? B_LD_PRED :
+                          (!VP8GetBit(br, prob[7]) ? B_VL_PRED :
+                            (!VP8GetBit(br, prob[8]) ? B_HD_PRED : B_HU_PRED)));
+#endif    // USE_GENERIC_TREE
+        top[x] = ymode;
+      }
+      memcpy(modes, top, 4 * sizeof(*top));
+      modes += 4;
+      left[y] = ymode;
+    }
+  }
+  // Hardcoded UVMode decision tree
+  block->uvmode_ = !VP8GetBit(br, 142) ? DC_PRED
+                 : !VP8GetBit(br, 114) ? V_PRED
+                 : VP8GetBit(br, 183) ? TM_PRED : H_PRED;
+}
+
+//------------------------------------------------------------------------------
+// Paragraph 13
+
+static const uint8_t
+    CoeffsUpdateProba[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS] = {
+  { { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 176, 246, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 223, 241, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 249, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 244, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 234, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 246, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 239, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 254, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 248, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 251, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 251, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 254, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 254, 253, 255, 254, 255, 255, 255, 255, 255, 255 },
+      { 250, 255, 254, 255, 254, 255, 255, 255, 255, 255, 255 },
+      { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    }
+  },
+  { { { 217, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 225, 252, 241, 253, 255, 255, 254, 255, 255, 255, 255 },
+      { 234, 250, 241, 250, 253, 255, 253, 254, 255, 255, 255 }
+    },
+    { { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 223, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 238, 253, 254, 254, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 248, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 249, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 253, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 247, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 252, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 254, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 250, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    }
+  },
+  { { { 186, 251, 250, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 234, 251, 244, 254, 255, 255, 255, 255, 255, 255, 255 },
+      { 251, 251, 243, 253, 254, 255, 254, 255, 255, 255, 255 }
+    },
+    { { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 236, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 251, 253, 253, 254, 254, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 254, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    }
+  },
+  { { { 248, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 250, 254, 252, 254, 255, 255, 255, 255, 255, 255, 255 },
+      { 248, 254, 249, 253, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 246, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 252, 254, 251, 254, 254, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 254, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 248, 254, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 253, 255, 254, 254, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 251, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 245, 251, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 253, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 251, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 252, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 252, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 249, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 255, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 250, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    },
+    { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
+      { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
+    }
+  }
+};
+
+// Paragraph 9.9
+void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec) {
+  VP8Proba* const proba = &dec->proba_;
+  int t, b, c, p;
+  for (t = 0; t < NUM_TYPES; ++t) {
+    for (b = 0; b < NUM_BANDS; ++b) {
+      for (c = 0; c < NUM_CTX; ++c) {
+        for (p = 0; p < NUM_PROBAS; ++p) {
+          const int v = VP8GetBit(br, CoeffsUpdateProba[t][b][c][p]) ?
+                        VP8GetValue(br, 8) : CoeffsProba0[t][b][c][p];
+          proba->bands_[t][b].probas_[c][p] = v;
+        }
+      }
+    }
+  }
+  dec->use_skip_proba_ = VP8Get(br);
+  if (dec->use_skip_proba_) {
+    dec->skip_p_ = VP8GetValue(br, 8);
+  }
+}
+
diff --git a/src/3rdparty/libwebp/src/dec/vp8.c b/src/3rdparty/libwebp/src/dec/vp8.c
new file mode 100644
index 0000000..bfd0e8f
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/vp8.c
@@ -0,0 +1,713 @@
+// Copyright 2010 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// main entry for the decoder
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <stdlib.h>
+
+#include "./alphai.h"
+#include "./vp8i.h"
+#include "./vp8li.h"
+#include "./webpi.h"
+#include "../utils/bit_reader.h"
+
+//------------------------------------------------------------------------------
+
+int WebPGetDecoderVersion(void) {
+  return (DEC_MAJ_VERSION << 16) | (DEC_MIN_VERSION << 8) | DEC_REV_VERSION;
+}
+
+//------------------------------------------------------------------------------
+// VP8Decoder
+
+static void SetOk(VP8Decoder* const dec) {
+  dec->status_ = VP8_STATUS_OK;
+  dec->error_msg_ = "OK";
+}
+
+int VP8InitIoInternal(VP8Io* const io, int version) {
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
+    return 0;  // mismatch error
+  }
+  if (io != NULL) {
+    memset(io, 0, sizeof(*io));
+  }
+  return 1;
+}
+
+VP8Decoder* VP8New(void) {
+  VP8Decoder* const dec = (VP8Decoder*)calloc(1, sizeof(*dec));
+  if (dec != NULL) {
+    SetOk(dec);
+    WebPWorkerInit(&dec->worker_);
+    dec->ready_ = 0;
+    dec->num_parts_ = 1;
+  }
+  return dec;
+}
+
+VP8StatusCode VP8Status(VP8Decoder* const dec) {
+  if (!dec) return VP8_STATUS_INVALID_PARAM;
+  return dec->status_;
+}
+
+const char* VP8StatusMessage(VP8Decoder* const dec) {
+  if (dec == NULL) return "no object";
+  if (!dec->error_msg_) return "OK";
+  return dec->error_msg_;
+}
+
+void VP8Delete(VP8Decoder* const dec) {
+  if (dec != NULL) {
+    VP8Clear(dec);
+    free(dec);
+  }
+}
+
+int VP8SetError(VP8Decoder* const dec,
+                VP8StatusCode error, const char* const msg) {
+  // TODO This check would be unnecessary if alpha decompression was separated
+  // from VP8ProcessRow/FinishRow. This avoids setting 'dec->status_' to
+  // something other than VP8_STATUS_BITSTREAM_ERROR on alpha decompression
+  // failure.
+  if (dec->status_ == VP8_STATUS_OK) {
+    dec->status_ = error;
+    dec->error_msg_ = msg;
+    dec->ready_ = 0;
+  }
+  return 0;
+}
+
+//------------------------------------------------------------------------------
+
+int VP8CheckSignature(const uint8_t* const data, size_t data_size) {
+  return (data_size >= 3 &&
+          data[0] == 0x9d && data[1] == 0x01 && data[2] == 0x2a);
+}
+
+int VP8GetInfo(const uint8_t* data, size_t data_size, size_t chunk_size,
+               int* const width, int* const height) {
+  if (data == NULL || data_size < VP8_FRAME_HEADER_SIZE) {
+    return 0;         // not enough data
+  }
+  // check signature
+  if (!VP8CheckSignature(data + 3, data_size - 3)) {
+    return 0;         // Wrong signature.
+  } else {
+    const uint32_t bits = data[0] | (data[1] << 8) | (data[2] << 16);
+    const int key_frame = !(bits & 1);
+    const int w = ((data[7] << 8) | data[6]) & 0x3fff;
+    const int h = ((data[9] << 8) | data[8]) & 0x3fff;
+
+    if (!key_frame) {   // Not a keyframe.
+      return 0;
+    }
+
+    if (((bits >> 1) & 7) > 3) {
+      return 0;         // unknown profile
+    }
+    if (!((bits >> 4) & 1)) {
+      return 0;         // first frame is invisible!
+    }
+    if (((bits >> 5)) >= chunk_size) {  // partition_length
+      return 0;         // inconsistent size information.
+    }
+    if (w == 0 || h == 0) {
+      return 0;         // We don't support both width and height to be zero.
+    }
+
+    if (width) {
+      *width = w;
+    }
+    if (height) {
+      *height = h;
+    }
+
+    return 1;
+  }
+}
+
+//------------------------------------------------------------------------------
+// Header parsing
+
+static void ResetSegmentHeader(VP8SegmentHeader* const hdr) {
+  assert(hdr != NULL);
+  hdr->use_segment_ = 0;
+  hdr->update_map_ = 0;
+  hdr->absolute_delta_ = 1;
+  memset(hdr->quantizer_, 0, sizeof(hdr->quantizer_));
+  memset(hdr->filter_strength_, 0, sizeof(hdr->filter_strength_));
+}
+
+// Paragraph 9.3
+static int ParseSegmentHeader(VP8BitReader* br,
+                              VP8SegmentHeader* hdr, VP8Proba* proba) {
+  assert(br != NULL);
+  assert(hdr != NULL);
+  hdr->use_segment_ = VP8Get(br);
+  if (hdr->use_segment_) {
+    hdr->update_map_ = VP8Get(br);
+    if (VP8Get(br)) {   // update data
+      int s;
+      hdr->absolute_delta_ = VP8Get(br);
+      for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
+        hdr->quantizer_[s] = VP8Get(br) ? VP8GetSignedValue(br, 7) : 0;
+      }
+      for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
+        hdr->filter_strength_[s] = VP8Get(br) ? VP8GetSignedValue(br, 6) : 0;
+      }
+    }
+    if (hdr->update_map_) {
+      int s;
+      for (s = 0; s < MB_FEATURE_TREE_PROBS; ++s) {
+        proba->segments_[s] = VP8Get(br) ? VP8GetValue(br, 8) : 255u;
+      }
+    }
+  } else {
+    hdr->update_map_ = 0;
+  }
+  return !br->eof_;
+}
+
+// Paragraph 9.5
+// This function returns VP8_STATUS_SUSPENDED if we don't have all the
+// necessary data in 'buf'.
+// This case is not necessarily an error (for incremental decoding).
+// Still, no bitreader is ever initialized to make it possible to read
+// unavailable memory.
+// If we don't even have the partitions' sizes, than VP8_STATUS_NOT_ENOUGH_DATA
+// is returned, and this is an unrecoverable error.
+// If the partitions were positioned ok, VP8_STATUS_OK is returned.
+static VP8StatusCode ParsePartitions(VP8Decoder* const dec,
+                                     const uint8_t* buf, size_t size) {
+  VP8BitReader* const br = &dec->br_;
+  const uint8_t* sz = buf;
+  const uint8_t* buf_end = buf + size;
+  const uint8_t* part_start;
+  int last_part;
+  int p;
+
+  dec->num_parts_ = 1 << VP8GetValue(br, 2);
+  last_part = dec->num_parts_ - 1;
+  part_start = buf + last_part * 3;
+  if (buf_end < part_start) {
+    // we can't even read the sizes with sz[]! That's a failure.
+    return VP8_STATUS_NOT_ENOUGH_DATA;
+  }
+  for (p = 0; p < last_part; ++p) {
+    const uint32_t psize = sz[0] | (sz[1] << 8) | (sz[2] << 16);
+    const uint8_t* part_end = part_start + psize;
+    if (part_end > buf_end) part_end = buf_end;
+    VP8InitBitReader(dec->parts_ + p, part_start, part_end);
+    part_start = part_end;
+    sz += 3;
+  }
+  VP8InitBitReader(dec->parts_ + last_part, part_start, buf_end);
+  return (part_start < buf_end) ? VP8_STATUS_OK :
+           VP8_STATUS_SUSPENDED;   // Init is ok, but there's not enough data
+}
+
+// Paragraph 9.4
+static int ParseFilterHeader(VP8BitReader* br, VP8Decoder* const dec) {
+  VP8FilterHeader* const hdr = &dec->filter_hdr_;
+  hdr->simple_    = VP8Get(br);
+  hdr->level_     = VP8GetValue(br, 6);
+  hdr->sharpness_ = VP8GetValue(br, 3);
+  hdr->use_lf_delta_ = VP8Get(br);
+  if (hdr->use_lf_delta_) {
+    if (VP8Get(br)) {   // update lf-delta?
+      int i;
+      for (i = 0; i < NUM_REF_LF_DELTAS; ++i) {
+        if (VP8Get(br)) {
+          hdr->ref_lf_delta_[i] = VP8GetSignedValue(br, 6);
+        }
+      }
+      for (i = 0; i < NUM_MODE_LF_DELTAS; ++i) {
+        if (VP8Get(br)) {
+          hdr->mode_lf_delta_[i] = VP8GetSignedValue(br, 6);
+        }
+      }
+    }
+  }
+  dec->filter_type_ = (hdr->level_ == 0) ? 0 : hdr->simple_ ? 1 : 2;
+  return !br->eof_;
+}
+
+// Topmost call
+int VP8GetHeaders(VP8Decoder* const dec, VP8Io* const io) {
+  const uint8_t* buf;
+  size_t buf_size;
+  VP8FrameHeader* frm_hdr;
+  VP8PictureHeader* pic_hdr;
+  VP8BitReader* br;
+  VP8StatusCode status;
+
+  if (dec == NULL) {
+    return 0;
+  }
+  SetOk(dec);
+  if (io == NULL) {
+    return VP8SetError(dec, VP8_STATUS_INVALID_PARAM,
+                       "null VP8Io passed to VP8GetHeaders()");
+  }
+  buf = io->data;
+  buf_size = io->data_size;
+  if (buf_size < 4) {
+    return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
+                       "Truncated header.");
+  }
+
+  // Paragraph 9.1
+  {
+    const uint32_t bits = buf[0] | (buf[1] << 8) | (buf[2] << 16);
+    frm_hdr = &dec->frm_hdr_;
+    frm_hdr->key_frame_ = !(bits & 1);
+    frm_hdr->profile_ = (bits >> 1) & 7;
+    frm_hdr->show_ = (bits >> 4) & 1;
+    frm_hdr->partition_length_ = (bits >> 5);
+    if (frm_hdr->profile_ > 3)
+      return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
+                         "Incorrect keyframe parameters.");
+    if (!frm_hdr->show_)
+      return VP8SetError(dec, VP8_STATUS_UNSUPPORTED_FEATURE,
+                         "Frame not displayable.");
+    buf += 3;
+    buf_size -= 3;
+  }
+
+  pic_hdr = &dec->pic_hdr_;
+  if (frm_hdr->key_frame_) {
+    // Paragraph 9.2
+    if (buf_size < 7) {
+      return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
+                         "cannot parse picture header");
+    }
+    if (!VP8CheckSignature(buf, buf_size)) {
+      return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
+                         "Bad code word");
+    }
+    pic_hdr->width_ = ((buf[4] << 8) | buf[3]) & 0x3fff;
+    pic_hdr->xscale_ = buf[4] >> 6;   // ratio: 1, 5/4 5/3 or 2
+    pic_hdr->height_ = ((buf[6] << 8) | buf[5]) & 0x3fff;
+    pic_hdr->yscale_ = buf[6] >> 6;
+    buf += 7;
+    buf_size -= 7;
+
+    dec->mb_w_ = (pic_hdr->width_ + 15) >> 4;
+    dec->mb_h_ = (pic_hdr->height_ + 15) >> 4;
+    // Setup default output area (can be later modified during io->setup())
+    io->width = pic_hdr->width_;
+    io->height = pic_hdr->height_;
+    io->use_scaling  = 0;
+    io->use_cropping = 0;
+    io->crop_top  = 0;
+    io->crop_left = 0;
+    io->crop_right  = io->width;
+    io->crop_bottom = io->height;
+    io->mb_w = io->width;   // sanity check
+    io->mb_h = io->height;  // ditto
+
+    VP8ResetProba(&dec->proba_);
+    ResetSegmentHeader(&dec->segment_hdr_);
+    dec->segment_ = 0;    // default for intra
+  }
+
+  // Check if we have all the partition #0 available, and initialize dec->br_
+  // to read this partition (and this partition only).
+  if (frm_hdr->partition_length_ > buf_size) {
+    return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
+                       "bad partition length");
+  }
+
+  br = &dec->br_;
+  VP8InitBitReader(br, buf, buf + frm_hdr->partition_length_);
+  buf += frm_hdr->partition_length_;
+  buf_size -= frm_hdr->partition_length_;
+
+  if (frm_hdr->key_frame_) {
+    pic_hdr->colorspace_ = VP8Get(br);
+    pic_hdr->clamp_type_ = VP8Get(br);
+  }
+  if (!ParseSegmentHeader(br, &dec->segment_hdr_, &dec->proba_)) {
+    return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
+                       "cannot parse segment header");
+  }
+  // Filter specs
+  if (!ParseFilterHeader(br, dec)) {
+    return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
+                       "cannot parse filter header");
+  }
+  status = ParsePartitions(dec, buf, buf_size);
+  if (status != VP8_STATUS_OK) {
+    return VP8SetError(dec, status, "cannot parse partitions");
+  }
+
+  // quantizer change
+  VP8ParseQuant(dec);
+
+  // Frame buffer marking
+  if (!frm_hdr->key_frame_) {
+    return VP8SetError(dec, VP8_STATUS_UNSUPPORTED_FEATURE,
+                       "Not a key frame.");
+  }
+
+  VP8Get(br);   // ignore the value of update_proba_
+
+  VP8ParseProba(br, dec);
+
+#ifdef WEBP_EXPERIMENTAL_FEATURES
+  // Extensions
+  if (dec->pic_hdr_.colorspace_) {
+    const size_t kTrailerSize = 8;
+    const uint8_t kTrailerMarker = 0x01;
+    const uint8_t* ext_buf = buf - kTrailerSize;
+    size_t size;
+
+    if (frm_hdr->partition_length_ < kTrailerSize ||
+        ext_buf[kTrailerSize - 1] != kTrailerMarker) {
+      return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
+                         "RIFF: Inconsistent extra information.");
+    }
+
+    // Layer
+    size = (ext_buf[0] << 0) | (ext_buf[1] << 8) | (ext_buf[2] << 16);
+    dec->layer_data_size_ = size;
+    dec->layer_data_ = NULL;  // will be set later
+    dec->layer_colorspace_ = ext_buf[3];
+  }
+#endif
+
+  // sanitized state
+  dec->ready_ = 1;
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+// Residual decoding (Paragraph 13.2 / 13.3)
+
+static const int kBands[16 + 1] = {
+  0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
+  0  // extra entry as sentinel
+};
+
+static const uint8_t kCat3[] = { 173, 148, 140, 0 };
+static const uint8_t kCat4[] = { 176, 155, 140, 135, 0 };
+static const uint8_t kCat5[] = { 180, 157, 141, 134, 130, 0 };
+static const uint8_t kCat6[] =
+  { 254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129, 0 };
+static const uint8_t* const kCat3456[] = { kCat3, kCat4, kCat5, kCat6 };
+static const uint8_t kZigzag[16] = {
+  0, 1, 4, 8,  5, 2, 3, 6,  9, 12, 13, 10,  7, 11, 14, 15
+};
+
+// See section 13-2: http://tools.ietf.org/html/rfc6386#section-13.2
+static int GetLargeValue(VP8BitReader* const br, const uint8_t* const p) {
+  int v;
+  if (!VP8GetBit(br, p[3])) {
+    if (!VP8GetBit(br, p[4])) {
+      v = 2;
+    } else {
+      v = 3 + VP8GetBit(br, p[5]);
+    }
+  } else {
+    if (!VP8GetBit(br, p[6])) {
+      if (!VP8GetBit(br, p[7])) {
+        v = 5 + VP8GetBit(br, 159);
+      } else {
+        v = 7 + 2 * VP8GetBit(br, 165);
+        v += VP8GetBit(br, 145);
+      }
+    } else {
+      const uint8_t* tab;
+      const int bit1 = VP8GetBit(br, p[8]);
+      const int bit0 = VP8GetBit(br, p[9 + bit1]);
+      const int cat = 2 * bit1 + bit0;
+      v = 0;
+      for (tab = kCat3456[cat]; *tab; ++tab) {
+        v += v + VP8GetBit(br, *tab);
+      }
+      v += 3 + (8 << cat);
+    }
+  }
+  return v;
+}
+
+// Returns the position of the last non-zero coeff plus one
+static int GetCoeffs(VP8BitReader* const br, const VP8BandProbas* const prob,
+                     int ctx, const quant_t dq, int n, int16_t* out) {
+  // n is either 0 or 1 here. kBands[n] is not necessary for extracting '*p'.
+  const uint8_t* p = prob[n].probas_[ctx];
+  for (; n < 16; ++n) {
+    if (!VP8GetBit(br, p[0])) {
+      return n;  // previous coeff was last non-zero coeff
+    }
+    while (!VP8GetBit(br, p[1])) {       // sequence of zero coeffs
+      p = prob[kBands[++n]].probas_[0];
+      if (n == 16) return 16;
+    }
+    {        // non zero coeff
+      const VP8ProbaArray* const p_ctx = &prob[kBands[n + 1]].probas_[0];
+      int v;
+      if (!VP8GetBit(br, p[2])) {
+        v = 1;
+        p = p_ctx[1];
+      } else {
+        v = GetLargeValue(br, p);
+        p = p_ctx[2];
+      }
+      out[kZigzag[n]] = VP8GetSigned(br, v) * dq[n > 0];
+    }
+  }
+  return 16;
+}
+
+static WEBP_INLINE uint32_t NzCodeBits(uint32_t nz_coeffs, int nz, int dc_nz) {
+  nz_coeffs <<= 2;
+  nz_coeffs |= (nz > 3) ? 3 : (nz > 1) ? 2 : dc_nz;
+  return nz_coeffs;
+}
+
+static int ParseResiduals(VP8Decoder* const dec,
+                          VP8MB* const mb, VP8BitReader* const token_br) {
+  VP8BandProbas (* const bands)[NUM_BANDS] = dec->proba_.bands_;
+  const VP8BandProbas* ac_proba;
+  const VP8QuantMatrix* const q = &dec->dqm_[dec->segment_];
+  VP8MBData* const block = dec->mb_data_ + dec->mb_x_;
+  int16_t* dst = block->coeffs_;
+  VP8MB* const left_mb = dec->mb_info_ - 1;
+  uint8_t tnz, lnz;
+  uint32_t non_zero_y = 0;
+  uint32_t non_zero_uv = 0;
+  int x, y, ch;
+  uint32_t out_t_nz, out_l_nz;
+  int first;
+
+  memset(dst, 0, 384 * sizeof(*dst));
+  if (!block->is_i4x4_) {    // parse DC
+    int16_t dc[16] = { 0 };
+    const int ctx = mb->nz_dc_ + left_mb->nz_dc_;
+    const int nz = GetCoeffs(token_br, bands[1], ctx, q->y2_mat_, 0, dc);
+    mb->nz_dc_ = left_mb->nz_dc_ = (nz > 0);
+    if (nz > 1) {   // more than just the DC -> perform the full transform
+      VP8TransformWHT(dc, dst);
+    } else {        // only DC is non-zero -> inlined simplified transform
+      int i;
+      const int dc0 = (dc[0] + 3) >> 3;
+      for (i = 0; i < 16 * 16; i += 16) dst[i] = dc0;
+    }
+    first = 1;
+    ac_proba = bands[0];
+  } else {
+    first = 0;
+    ac_proba = bands[3];
+  }
+
+  tnz = mb->nz_ & 0x0f;
+  lnz = left_mb->nz_ & 0x0f;
+  for (y = 0; y < 4; ++y) {
+    int l = lnz & 1;
+    uint32_t nz_coeffs = 0;
+    for (x = 0; x < 4; ++x) {
+      const int ctx = l + (tnz & 1);
+      const int nz = GetCoeffs(token_br, ac_proba, ctx, q->y1_mat_, first, dst);
+      l = (nz > first);
+      tnz = (tnz >> 1) | (l << 7);
+      nz_coeffs = NzCodeBits(nz_coeffs, nz, dst[0] != 0);
+      dst += 16;
+    }
+    tnz >>= 4;
+    lnz = (lnz >> 1) | (l << 7);
+    non_zero_y = (non_zero_y << 8) | nz_coeffs;
+  }
+  out_t_nz = tnz;
+  out_l_nz = lnz >> 4;
+
+  for (ch = 0; ch < 4; ch += 2) {
+    uint32_t nz_coeffs = 0;
+    tnz = mb->nz_ >> (4 + ch);
+    lnz = left_mb->nz_ >> (4 + ch);
+    for (y = 0; y < 2; ++y) {
+      int l = lnz & 1;
+      for (x = 0; x < 2; ++x) {
+        const int ctx = l + (tnz & 1);
+        const int nz = GetCoeffs(token_br, bands[2], ctx, q->uv_mat_, 0, dst);
+        l = (nz > 0);
+        tnz = (tnz >> 1) | (l << 3);
+        nz_coeffs = NzCodeBits(nz_coeffs, nz, dst[0] != 0);
+        dst += 16;
+      }
+      tnz >>= 2;
+      lnz = (lnz >> 1) | (l << 5);
+    }
+    // Note: we don't really need the per-4x4 details for U/V blocks.
+    non_zero_uv |= nz_coeffs << (4 * ch);
+    out_t_nz |= (tnz << 4) << ch;
+    out_l_nz |= (lnz & 0xf0) << ch;
+  }
+  mb->nz_ = out_t_nz;
+  left_mb->nz_ = out_l_nz;
+
+  block->non_zero_y_ = non_zero_y;
+  block->non_zero_uv_ = non_zero_uv;
+
+  // We look at the mode-code of each block and check if some blocks have less
+  // than three non-zero coeffs (code < 2). This is to avoid dithering flat and
+  // empty blocks.
+  block->dither_ = (non_zero_uv & 0xaaaa) ? 0 : q->dither_;
+
+  return !(non_zero_y | non_zero_uv);  // will be used for further optimization
+}
+
+//------------------------------------------------------------------------------
+// Main loop
+
+int VP8DecodeMB(VP8Decoder* const dec, VP8BitReader* const token_br) {
+  VP8BitReader* const br = &dec->br_;
+  VP8MB* const left = dec->mb_info_ - 1;
+  VP8MB* const mb = dec->mb_info_ + dec->mb_x_;
+  VP8MBData* const block = dec->mb_data_ + dec->mb_x_;
+  int skip;
+
+  // Note: we don't save segment map (yet), as we don't expect
+  // to decode more than 1 keyframe.
+  if (dec->segment_hdr_.update_map_) {
+    // Hardcoded tree parsing
+    dec->segment_ = !VP8GetBit(br, dec->proba_.segments_[0]) ?
+        VP8GetBit(br, dec->proba_.segments_[1]) :
+        2 + VP8GetBit(br, dec->proba_.segments_[2]);
+  }
+  skip = dec->use_skip_proba_ ? VP8GetBit(br, dec->skip_p_) : 0;
+
+  VP8ParseIntraMode(br, dec);
+  if (br->eof_) {
+    return 0;
+  }
+
+  if (!skip) {
+    skip = ParseResiduals(dec, mb, token_br);
+  } else {
+    left->nz_ = mb->nz_ = 0;
+    if (!block->is_i4x4_) {
+      left->nz_dc_ = mb->nz_dc_ = 0;
+    }
+    block->non_zero_y_ = 0;
+    block->non_zero_uv_ = 0;
+  }
+
+  if (dec->filter_type_ > 0) {  // store filter info
+    VP8FInfo* const finfo = dec->f_info_ + dec->mb_x_;
+    *finfo = dec->fstrengths_[dec->segment_][block->is_i4x4_];
+    finfo->f_inner_ |= !skip;
+  }
+
+  return !token_br->eof_;
+}
+
+void VP8InitScanline(VP8Decoder* const dec) {
+  VP8MB* const left = dec->mb_info_ - 1;
+  left->nz_ = 0;
+  left->nz_dc_ = 0;
+  memset(dec->intra_l_, B_DC_PRED, sizeof(dec->intra_l_));
+  dec->mb_x_ = 0;
+}
+
+static int ParseFrame(VP8Decoder* const dec, VP8Io* io) {
+  for (dec->mb_y_ = 0; dec->mb_y_ < dec->br_mb_y_; ++dec->mb_y_) {
+    // Parse bitstream for this row.
+    VP8BitReader* const token_br =
+        &dec->parts_[dec->mb_y_ & (dec->num_parts_ - 1)];
+    for (; dec->mb_x_ < dec->mb_w_; ++dec->mb_x_) {
+      if (!VP8DecodeMB(dec, token_br)) {
+        return VP8SetError(dec, VP8_STATUS_NOT_ENOUGH_DATA,
+                           "Premature end-of-file encountered.");
+      }
+    }
+    VP8InitScanline(dec);   // Prepare for next scanline
+
+    // Reconstruct, filter and emit the row.
+    if (!VP8ProcessRow(dec, io)) {
+      return VP8SetError(dec, VP8_STATUS_USER_ABORT, "Output aborted.");
+    }
+  }
+  if (dec->mt_method_ > 0) {
+    if (!WebPWorkerSync(&dec->worker_)) return 0;
+  }
+
+  // Finish
+#ifdef WEBP_EXPERIMENTAL_FEATURES
+  if (dec->layer_data_size_ > 0) {
+    if (!VP8DecodeLayer(dec)) {
+      return 0;
+    }
+  }
+#endif
+
+  return 1;
+}
+
+// Main entry point
+int VP8Decode(VP8Decoder* const dec, VP8Io* const io) {
+  int ok = 0;
+  if (dec == NULL) {
+    return 0;
+  }
+  if (io == NULL) {
+    return VP8SetError(dec, VP8_STATUS_INVALID_PARAM,
+                       "NULL VP8Io parameter in VP8Decode().");
+  }
+
+  if (!dec->ready_) {
+    if (!VP8GetHeaders(dec, io)) {
+      return 0;
+    }
+  }
+  assert(dec->ready_);
+
+  // Finish setting up the decoding parameter. Will call io->setup().
+  ok = (VP8EnterCritical(dec, io) == VP8_STATUS_OK);
+  if (ok) {   // good to go.
+    // Will allocate memory and prepare everything.
+    if (ok) ok = VP8InitFrame(dec, io);
+
+    // Main decoding loop
+    if (ok) ok = ParseFrame(dec, io);
+
+    // Exit.
+    ok &= VP8ExitCritical(dec, io);
+  }
+
+  if (!ok) {
+    VP8Clear(dec);
+    return 0;
+  }
+
+  dec->ready_ = 0;
+  return ok;
+}
+
+void VP8Clear(VP8Decoder* const dec) {
+  if (dec == NULL) {
+    return;
+  }
+  if (dec->mt_method_ > 0) {
+    WebPWorkerEnd(&dec->worker_);
+  }
+  ALPHDelete(dec->alph_dec_);
+  dec->alph_dec_ = NULL;
+  free(dec->mem_);
+  dec->mem_ = NULL;
+  dec->mem_size_ = 0;
+  memset(&dec->br_, 0, sizeof(dec->br_));
+  dec->ready_ = 0;
+}
+
+//------------------------------------------------------------------------------
+
diff --git a/src/3rdparty/libwebp/src/dec/vp8i.h b/src/3rdparty/libwebp/src/dec/vp8i.h
new file mode 100644
index 0000000..3f4cf29
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/vp8i.h
@@ -0,0 +1,359 @@
+// Copyright 2010 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// VP8 decoder: internal header.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifndef WEBP_DEC_VP8I_H_
+#define WEBP_DEC_VP8I_H_
+
+#include <string.h>     // for memcpy()
+#include "./vp8li.h"
+#include "../utils/bit_reader.h"
+#include "../utils/random.h"
+#include "../utils/thread.h"
+#include "../dsp/dsp.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//------------------------------------------------------------------------------
+// Various defines and enums
+
+// version numbers
+#define DEC_MAJ_VERSION 0
+#define DEC_MIN_VERSION 4
+#define DEC_REV_VERSION 0
+
+// intra prediction modes
+enum { B_DC_PRED = 0,   // 4x4 modes
+       B_TM_PRED,
+       B_VE_PRED,
+       B_HE_PRED,
+       B_RD_PRED,
+       B_VR_PRED,
+       B_LD_PRED,
+       B_VL_PRED,
+       B_HD_PRED,
+       B_HU_PRED,
+       NUM_BMODES = B_HU_PRED + 1 - B_DC_PRED,  // = 10
+
+       // Luma16 or UV modes
+       DC_PRED = B_DC_PRED, V_PRED = B_VE_PRED,
+       H_PRED = B_HE_PRED, TM_PRED = B_TM_PRED,
+       B_PRED = NUM_BMODES,   // refined I4x4 mode
+
+       // special modes
+       B_DC_PRED_NOTOP = 4,
+       B_DC_PRED_NOLEFT = 5,
+       B_DC_PRED_NOTOPLEFT = 6,
+       NUM_B_DC_MODES = 7 };
+
+enum { MB_FEATURE_TREE_PROBS = 3,
+       NUM_MB_SEGMENTS = 4,
+       NUM_REF_LF_DELTAS = 4,
+       NUM_MODE_LF_DELTAS = 4,    // I4x4, ZERO, *, SPLIT
+       MAX_NUM_PARTITIONS = 8,
+       // Probabilities
+       NUM_TYPES = 4,
+       NUM_BANDS = 8,
+       NUM_CTX = 3,
+       NUM_PROBAS = 11,
+       NUM_MV_PROBAS = 19 };
+
+// YUV-cache parameters.
+// Constraints are: We need to store one 16x16 block of luma samples (y),
+// and two 8x8 chroma blocks (u/v). These are better be 16-bytes aligned,
+// in order to be SIMD-friendly. We also need to store the top, left and
+// top-left samples (from previously decoded blocks), along with four
+// extra top-right samples for luma (intra4x4 prediction only).
+// One possible layout is, using 32 * (17 + 9) bytes:
+//
+//   .+------   <- only 1 pixel high
+//   .|yyyyt.
+//   .|yyyyt.
+//   .|yyyyt.
+//   .|yyyy..
+//   .+--.+--   <- only 1 pixel high
+//   .|uu.|vv
+//   .|uu.|vv
+//
+// Every character is a 4x4 block, with legend:
+//  '.' = unused
+//  'y' = y-samples   'u' = u-samples     'v' = u-samples
+//  '|' = left sample,   '-' = top sample,    '+' = top-left sample
+//  't' = extra top-right sample for 4x4 modes
+// With this layout, BPS (=Bytes Per Scan-line) is one cacheline size.
+#define BPS       32    // this is the common stride used by yuv[]
+#define YUV_SIZE (BPS * 17 + BPS * 9)
+#define Y_SIZE   (BPS * 17)
+#define Y_OFF    (BPS * 1 + 8)
+#define U_OFF    (Y_OFF + BPS * 16 + BPS)
+#define V_OFF    (U_OFF + 16)
+
+// minimal width under which lossy multi-threading is always disabled
+#define MIN_WIDTH_FOR_THREADS 512
+
+//------------------------------------------------------------------------------
+// Headers
+
+typedef struct {
+  uint8_t key_frame_;
+  uint8_t profile_;
+  uint8_t show_;
+  uint32_t partition_length_;
+} VP8FrameHeader;
+
+typedef struct {
+  uint16_t width_;
+  uint16_t height_;
+  uint8_t xscale_;
+  uint8_t yscale_;
+  uint8_t colorspace_;   // 0 = YCbCr
+  uint8_t clamp_type_;
+} VP8PictureHeader;
+
+// segment features
+typedef struct {
+  int use_segment_;
+  int update_map_;        // whether to update the segment map or not
+  int absolute_delta_;    // absolute or delta values for quantizer and filter
+  int8_t quantizer_[NUM_MB_SEGMENTS];        // quantization changes
+  int8_t filter_strength_[NUM_MB_SEGMENTS];  // filter strength for segments
+} VP8SegmentHeader;
+
+
+// probas associated to one of the contexts
+typedef uint8_t VP8ProbaArray[NUM_PROBAS];
+
+typedef struct {   // all the probas associated to one band
+  VP8ProbaArray probas_[NUM_CTX];
+} VP8BandProbas;
+
+// Struct collecting all frame-persistent probabilities.
+typedef struct {
+  uint8_t segments_[MB_FEATURE_TREE_PROBS];
+  // Type: 0:Intra16-AC  1:Intra16-DC   2:Chroma   3:Intra4
+  VP8BandProbas bands_[NUM_TYPES][NUM_BANDS];
+} VP8Proba;
+
+// Filter parameters
+typedef struct {
+  int simple_;                  // 0=complex, 1=simple
+  int level_;                   // [0..63]
+  int sharpness_;               // [0..7]
+  int use_lf_delta_;
+  int ref_lf_delta_[NUM_REF_LF_DELTAS];
+  int mode_lf_delta_[NUM_MODE_LF_DELTAS];
+} VP8FilterHeader;
+
+//------------------------------------------------------------------------------
+// Informations about the macroblocks.
+
+typedef struct {  // filter specs
+  uint8_t f_limit_;      // filter limit in [3..189], or 0 if no filtering
+  uint8_t f_ilevel_;     // inner limit in [1..63]
+  uint8_t f_inner_;      // do inner filtering?
+  uint8_t hev_thresh_;   // high edge variance threshold in [0..2]
+} VP8FInfo;
+
+typedef struct {  // Top/Left Contexts used for syntax-parsing
+  uint8_t nz_;        // non-zero AC/DC coeffs (4bit for luma + 4bit for chroma)
+  uint8_t nz_dc_;     // non-zero DC coeff (1bit)
+} VP8MB;
+
+// Dequantization matrices
+typedef int quant_t[2];      // [DC / AC].  Can be 'uint16_t[2]' too (~slower).
+typedef struct {
+  quant_t y1_mat_, y2_mat_, uv_mat_;
+
+  int uv_quant_;   // U/V quantizer value
+  int dither_;     // dithering amplitude (0 = off, max=255)
+} VP8QuantMatrix;
+
+// Data needed to reconstruct a macroblock
+typedef struct {
+  int16_t coeffs_[384];   // 384 coeffs = (16+4+4) * 4*4
+  uint8_t is_i4x4_;       // true if intra4x4
+  uint8_t imodes_[16];    // one 16x16 mode (#0) or sixteen 4x4 modes
+  uint8_t uvmode_;        // chroma prediction mode
+  // bit-wise info about the content of each sub-4x4 blocks (in decoding order).
+  // Each of the 4x4 blocks for y/u/v is associated with a 2b code according to:
+  //   code=0 -> no coefficient
+  //   code=1 -> only DC
+  //   code=2 -> first three coefficients are non-zero
+  //   code=3 -> more than three coefficients are non-zero
+  // This allows to call specialized transform functions.
+  uint32_t non_zero_y_;
+  uint32_t non_zero_uv_;
+  uint8_t dither_;      // local dithering strength (deduced from non_zero_*)
+} VP8MBData;
+
+// Persistent information needed by the parallel processing
+typedef struct {
+  int id_;              // cache row to process (in [0..2])
+  int mb_y_;            // macroblock position of the row
+  int filter_row_;      // true if row-filtering is needed
+  VP8FInfo* f_info_;    // filter strengths (swapped with dec->f_info_)
+  VP8MBData* mb_data_;  // reconstruction data (swapped with dec->mb_data_)
+  VP8Io io_;            // copy of the VP8Io to pass to put()
+} VP8ThreadContext;
+
+// Saved top samples, per macroblock. Fits into a cache-line.
+typedef struct {
+  uint8_t y[16], u[8], v[8];
+} VP8TopSamples;
+
+//------------------------------------------------------------------------------
+// VP8Decoder: the main opaque structure handed over to user
+
+struct VP8Decoder {
+  VP8StatusCode status_;
+  int ready_;     // true if ready to decode a picture with VP8Decode()
+  const char* error_msg_;  // set when status_ is not OK.
+
+  // Main data source
+  VP8BitReader br_;
+
+  // headers
+  VP8FrameHeader   frm_hdr_;
+  VP8PictureHeader pic_hdr_;
+  VP8FilterHeader  filter_hdr_;
+  VP8SegmentHeader segment_hdr_;
+
+  // Worker
+  WebPWorker worker_;
+  int mt_method_;      // multi-thread method: 0=off, 1=[parse+recon][filter]
+                       // 2=[parse][recon+filter]
+  int cache_id_;       // current cache row
+  int num_caches_;     // number of cached rows of 16 pixels (1, 2 or 3)
+  VP8ThreadContext thread_ctx_;  // Thread context
+
+  // dimension, in macroblock units.
+  int mb_w_, mb_h_;
+
+  // Macroblock to process/filter, depending on cropping and filter_type.
+  int tl_mb_x_, tl_mb_y_;  // top-left MB that must be in-loop filtered
+  int br_mb_x_, br_mb_y_;  // last bottom-right MB that must be decoded
+
+  // number of partitions.
+  int num_parts_;
+  // per-partition boolean decoders.
+  VP8BitReader parts_[MAX_NUM_PARTITIONS];
+
+  // Dithering strength, deduced from decoding options
+  int dither_;                // whether to use dithering or not
+  VP8Random dithering_rg_;    // random generator for dithering
+
+  // dequantization (one set of DC/AC dequant factor per segment)
+  VP8QuantMatrix dqm_[NUM_MB_SEGMENTS];
+
+  // probabilities
+  VP8Proba proba_;
+  int use_skip_proba_;
+  uint8_t skip_p_;
+
+  // Boundary data cache and persistent buffers.
+  uint8_t* intra_t_;      // top intra modes values: 4 * mb_w_
+  uint8_t  intra_l_[4];   // left intra modes values
+
+  uint8_t segment_;       // segment of the currently parsed block
+  VP8TopSamples* yuv_t_;  // top y/u/v samples
+
+  VP8MB* mb_info_;        // contextual macroblock info (mb_w_ + 1)
+  VP8FInfo* f_info_;      // filter strength info
+  uint8_t* yuv_b_;        // main block for Y/U/V (size = YUV_SIZE)
+
+  uint8_t* cache_y_;      // macroblock row for storing unfiltered samples
+  uint8_t* cache_u_;
+  uint8_t* cache_v_;
+  int cache_y_stride_;
+  int cache_uv_stride_;
+
+  // main memory chunk for the above data. Persistent.
+  void* mem_;
+  size_t mem_size_;
+
+  // Per macroblock non-persistent infos.
+  int mb_x_, mb_y_;       // current position, in macroblock units
+  VP8MBData* mb_data_;    // parsed reconstruction data
+
+  // Filtering side-info
+  int filter_type_;                          // 0=off, 1=simple, 2=complex
+  VP8FInfo fstrengths_[NUM_MB_SEGMENTS][2];  // precalculated per-segment/type
+
+  // Alpha
+  struct ALPHDecoder* alph_dec_;  // alpha-plane decoder object
+  const uint8_t* alpha_data_;     // compressed alpha data (if present)
+  size_t alpha_data_size_;
+  int is_alpha_decoded_;  // true if alpha_data_ is decoded in alpha_plane_
+  uint8_t* alpha_plane_;        // output. Persistent, contains the whole data.
+
+  // extensions
+  int layer_colorspace_;
+  const uint8_t* layer_data_;   // compressed layer data (if present)
+  size_t layer_data_size_;
+};
+
+//------------------------------------------------------------------------------
+// internal functions. Not public.
+
+// in vp8.c
+int VP8SetError(VP8Decoder* const dec,
+                VP8StatusCode error, const char* const msg);
+
+// in tree.c
+void VP8ResetProba(VP8Proba* const proba);
+void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec);
+void VP8ParseIntraMode(VP8BitReader* const br,  VP8Decoder* const dec);
+
+// in quant.c
+void VP8ParseQuant(VP8Decoder* const dec);
+
+// in frame.c
+int VP8InitFrame(VP8Decoder* const dec, VP8Io* io);
+// Call io->setup() and finish setting up scan parameters.
+// After this call returns, one must always call VP8ExitCritical() with the
+// same parameters. Both functions should be used in pair. Returns VP8_STATUS_OK
+// if ok, otherwise sets and returns the error status on *dec.
+VP8StatusCode VP8EnterCritical(VP8Decoder* const dec, VP8Io* const io);
+// Must always be called in pair with VP8EnterCritical().
+// Returns false in case of error.
+int VP8ExitCritical(VP8Decoder* const dec, VP8Io* const io);
+// Return the multi-threading method to use (0=off), depending
+// on options and bitstream size. Only for lossy decoding.
+int VP8GetThreadMethod(const WebPDecoderOptions* const options,
+                       const WebPHeaderStructure* const headers,
+                       int width, int height);
+// Initialize dithering post-process if needed.
+void VP8InitDithering(const WebPDecoderOptions* const options,
+                      VP8Decoder* const dec);
+// Process the last decoded row (filtering + output).
+int VP8ProcessRow(VP8Decoder* const dec, VP8Io* const io);
+// To be called at the start of a new scanline, to initialize predictors.
+void VP8InitScanline(VP8Decoder* const dec);
+// Decode one macroblock. Returns false if there is not enough data.
+int VP8DecodeMB(VP8Decoder* const dec, VP8BitReader* const token_br);
+
+// in alpha.c
+const uint8_t* VP8DecompressAlphaRows(VP8Decoder* const dec,
+                                      int row, int num_rows);
+
+// in layer.c
+int VP8DecodeLayer(VP8Decoder* const dec);
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_DEC_VP8I_H_ */
diff --git a/src/3rdparty/libwebp/src/dec/vp8l.c b/src/3rdparty/libwebp/src/dec/vp8l.c
new file mode 100644
index 0000000..ea0254d
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/vp8l.c
@@ -0,0 +1,1380 @@
+// Copyright 2012 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// main entry for the decoder
+//
+// Authors: Vikas Arora (vikaas.arora@gmail.com)
+//          Jyrki Alakuijala (jyrki@google.com)
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "./alphai.h"
+#include "./vp8li.h"
+#include "../dsp/lossless.h"
+#include "../dsp/yuv.h"
+#include "../utils/alpha_processing.h"
+#include "../utils/huffman.h"
+#include "../utils/utils.h"
+
+#define NUM_ARGB_CACHE_ROWS          16
+
+static const int kCodeLengthLiterals = 16;
+static const int kCodeLengthRepeatCode = 16;
+static const int kCodeLengthExtraBits[3] = { 2, 3, 7 };
+static const int kCodeLengthRepeatOffsets[3] = { 3, 3, 11 };
+
+// -----------------------------------------------------------------------------
+//  Five Huffman codes are used at each meta code:
+//  1. green + length prefix codes + color cache codes,
+//  2. alpha,
+//  3. red,
+//  4. blue, and,
+//  5. distance prefix codes.
+typedef enum {
+  GREEN = 0,
+  RED   = 1,
+  BLUE  = 2,
+  ALPHA = 3,
+  DIST  = 4
+} HuffIndex;
+
+static const uint16_t kAlphabetSize[HUFFMAN_CODES_PER_META_CODE] = {
+  NUM_LITERAL_CODES + NUM_LENGTH_CODES,
+  NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES,
+  NUM_DISTANCE_CODES
+};
+
+
+#define NUM_CODE_LENGTH_CODES       19
+static const uint8_t kCodeLengthCodeOrder[NUM_CODE_LENGTH_CODES] = {
+  17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
+};
+
+#define CODE_TO_PLANE_CODES        120
+static const uint8_t kCodeToPlane[CODE_TO_PLANE_CODES] = {
+  0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a,
+  0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a,
+  0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b,
+  0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03,
+  0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c,
+  0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e,
+  0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b,
+  0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f,
+  0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b,
+  0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41,
+  0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f,
+  0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70
+};
+
+static int DecodeImageStream(int xsize, int ysize,
+                             int is_level0,
+                             VP8LDecoder* const dec,
+                             uint32_t** const decoded_data);
+
+//------------------------------------------------------------------------------
+
+int VP8LCheckSignature(const uint8_t* const data, size_t size) {
+  return (size >= VP8L_FRAME_HEADER_SIZE &&
+          data[0] == VP8L_MAGIC_BYTE &&
+          (data[4] >> 5) == 0);  // version
+}
+
+static int ReadImageInfo(VP8LBitReader* const br,
+                         int* const width, int* const height,
+                         int* const has_alpha) {
+  if (VP8LReadBits(br, 8) != VP8L_MAGIC_BYTE) return 0;
+  *width = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1;
+  *height = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1;
+  *has_alpha = VP8LReadBits(br, 1);
+  if (VP8LReadBits(br, VP8L_VERSION_BITS) != 0) return 0;
+  return 1;
+}
+
+int VP8LGetInfo(const uint8_t* data, size_t data_size,
+                int* const width, int* const height, int* const has_alpha) {
+  if (data == NULL || data_size < VP8L_FRAME_HEADER_SIZE) {
+    return 0;         // not enough data
+  } else if (!VP8LCheckSignature(data, data_size)) {
+    return 0;         // bad signature
+  } else {
+    int w, h, a;
+    VP8LBitReader br;
+    VP8LInitBitReader(&br, data, data_size);
+    if (!ReadImageInfo(&br, &w, &h, &a)) {
+      return 0;
+    }
+    if (width != NULL) *width = w;
+    if (height != NULL) *height = h;
+    if (has_alpha != NULL) *has_alpha = a;
+    return 1;
+  }
+}
+
+//------------------------------------------------------------------------------
+
+static WEBP_INLINE int GetCopyDistance(int distance_symbol,
+                                       VP8LBitReader* const br) {
+  int extra_bits, offset;
+  if (distance_symbol < 4) {
+    return distance_symbol + 1;
+  }
+  extra_bits = (distance_symbol - 2) >> 1;
+  offset = (2 + (distance_symbol & 1)) << extra_bits;
+  return offset + VP8LReadBits(br, extra_bits) + 1;
+}
+
+static WEBP_INLINE int GetCopyLength(int length_symbol,
+                                     VP8LBitReader* const br) {
+  // Length and distance prefixes are encoded the same way.
+  return GetCopyDistance(length_symbol, br);
+}
+
+static WEBP_INLINE int PlaneCodeToDistance(int xsize, int plane_code) {
+  if (plane_code > CODE_TO_PLANE_CODES) {
+    return plane_code - CODE_TO_PLANE_CODES;
+  } else {
+    const int dist_code = kCodeToPlane[plane_code - 1];
+    const int yoffset = dist_code >> 4;
+    const int xoffset = 8 - (dist_code & 0xf);
+    const int dist = yoffset * xsize + xoffset;
+    return (dist >= 1) ? dist : 1;  // dist<1 can happen if xsize is very small
+  }
+}
+
+//------------------------------------------------------------------------------
+// Decodes the next Huffman code from bit-stream.
+// FillBitWindow(br) needs to be called at minimum every second call
+// to ReadSymbol, in order to pre-fetch enough bits.
+static WEBP_INLINE int ReadSymbol(const HuffmanTree* tree,
+                                  VP8LBitReader* const br) {
+  const HuffmanTreeNode* node = tree->root_;
+  uint32_t bits = VP8LPrefetchBits(br);
+  int bitpos = br->bit_pos_;
+  // Check if we find the bit combination from the Huffman lookup table.
+  const int lut_ix = bits & (HUFF_LUT - 1);
+  const int lut_bits = tree->lut_bits_[lut_ix];
+  if (lut_bits <= HUFF_LUT_BITS) {
+    VP8LSetBitPos(br, bitpos + lut_bits);
+    return tree->lut_symbol_[lut_ix];
+  }
+  node += tree->lut_jump_[lut_ix];
+  bitpos += HUFF_LUT_BITS;
+  bits >>= HUFF_LUT_BITS;
+
+  // Decode the value from a binary tree.
+  assert(node != NULL);
+  do {
+    node = HuffmanTreeNextNode(node, bits & 1);
+    bits >>= 1;
+    ++bitpos;
+  } while (HuffmanTreeNodeIsNotLeaf(node));
+  VP8LSetBitPos(br, bitpos);
+  return node->symbol_;
+}
+
+static int ReadHuffmanCodeLengths(
+    VP8LDecoder* const dec, const int* const code_length_code_lengths,
+    int num_symbols, int* const code_lengths) {
+  int ok = 0;
+  VP8LBitReader* const br = &dec->br_;
+  int symbol;
+  int max_symbol;
+  int prev_code_len = DEFAULT_CODE_LENGTH;
+  HuffmanTree tree;
+
+  if (!HuffmanTreeBuildImplicit(&tree, code_length_code_lengths,
+                                NUM_CODE_LENGTH_CODES)) {
+    dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
+    return 0;
+  }
+
+  if (VP8LReadBits(br, 1)) {    // use length
+    const int length_nbits = 2 + 2 * VP8LReadBits(br, 3);
+    max_symbol = 2 + VP8LReadBits(br, length_nbits);
+    if (max_symbol > num_symbols) {
+      dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
+      goto End;
+    }
+  } else {
+    max_symbol = num_symbols;
+  }
+
+  symbol = 0;
+  while (symbol < num_symbols) {
+    int code_len;
+    if (max_symbol-- == 0) break;
+    VP8LFillBitWindow(br);
+    code_len = ReadSymbol(&tree, br);
+    if (code_len < kCodeLengthLiterals) {
+      code_lengths[symbol++] = code_len;
+      if (code_len != 0) prev_code_len = code_len;
+    } else {
+      const int use_prev = (code_len == kCodeLengthRepeatCode);
+      const int slot = code_len - kCodeLengthLiterals;
+      const int extra_bits = kCodeLengthExtraBits[slot];
+      const int repeat_offset = kCodeLengthRepeatOffsets[slot];
+      int repeat = VP8LReadBits(br, extra_bits) + repeat_offset;
+      if (symbol + repeat > num_symbols) {
+        dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
+        goto End;
+      } else {
+        const int length = use_prev ? prev_code_len : 0;
+        while (repeat-- > 0) code_lengths[symbol++] = length;
+      }
+    }
+  }
+  ok = 1;
+
+ End:
+  HuffmanTreeRelease(&tree);
+  return ok;
+}
+
+static int ReadHuffmanCode(int alphabet_size, VP8LDecoder* const dec,
+                           HuffmanTree* const tree) {
+  int ok = 0;
+  VP8LBitReader* const br = &dec->br_;
+  const int simple_code = VP8LReadBits(br, 1);
+
+  if (simple_code) {  // Read symbols, codes & code lengths directly.
+    int symbols[2];
+    int codes[2];
+    int code_lengths[2];
+    const int num_symbols = VP8LReadBits(br, 1) + 1;
+    const int first_symbol_len_code = VP8LReadBits(br, 1);
+    // The first code is either 1 bit or 8 bit code.
+    symbols[0] = VP8LReadBits(br, (first_symbol_len_code == 0) ? 1 : 8);
+    codes[0] = 0;
+    code_lengths[0] = num_symbols - 1;
+    // The second code (if present), is always 8 bit long.
+    if (num_symbols == 2) {
+      symbols[1] = VP8LReadBits(br, 8);
+      codes[1] = 1;
+      code_lengths[1] = num_symbols - 1;
+    }
+    ok = HuffmanTreeBuildExplicit(tree, code_lengths, codes, symbols,
+                                  alphabet_size, num_symbols);
+  } else {  // Decode Huffman-coded code lengths.
+    int* code_lengths = NULL;
+    int i;
+    int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 };
+    const int num_codes = VP8LReadBits(br, 4) + 4;
+    if (num_codes > NUM_CODE_LENGTH_CODES) {
+      dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
+      return 0;
+    }
+
+    code_lengths =
+        (int*)WebPSafeCalloc((uint64_t)alphabet_size, sizeof(*code_lengths));
+    if (code_lengths == NULL) {
+      dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
+      return 0;
+    }
+
+    for (i = 0; i < num_codes; ++i) {
+      code_length_code_lengths[kCodeLengthCodeOrder[i]] = VP8LReadBits(br, 3);
+    }
+    ok = ReadHuffmanCodeLengths(dec, code_length_code_lengths, alphabet_size,
+                                code_lengths);
+    if (ok) {
+      ok = HuffmanTreeBuildImplicit(tree, code_lengths, alphabet_size);
+    }
+    free(code_lengths);
+  }
+  ok = ok && !br->error_;
+  if (!ok) {
+    dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
+    return 0;
+  }
+  return 1;
+}
+
+static void DeleteHtreeGroups(HTreeGroup* htree_groups, int num_htree_groups) {
+  if (htree_groups != NULL) {
+    int i, j;
+    for (i = 0; i < num_htree_groups; ++i) {
+      HuffmanTree* const htrees = htree_groups[i].htrees_;
+      for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) {
+        HuffmanTreeRelease(&htrees[j]);
+      }
+    }
+    free(htree_groups);
+  }
+}
+
+static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
+                            int color_cache_bits, int allow_recursion) {
+  int i, j;
+  VP8LBitReader* const br = &dec->br_;
+  VP8LMetadata* const hdr = &dec->hdr_;
+  uint32_t* huffman_image = NULL;
+  HTreeGroup* htree_groups = NULL;
+  int num_htree_groups = 1;
+
+  if (allow_recursion && VP8LReadBits(br, 1)) {
+    // use meta Huffman codes.
+    const int huffman_precision = VP8LReadBits(br, 3) + 2;
+    const int huffman_xsize = VP8LSubSampleSize(xsize, huffman_precision);
+    const int huffman_ysize = VP8LSubSampleSize(ysize, huffman_precision);
+    const int huffman_pixs = huffman_xsize * huffman_ysize;
+    if (!DecodeImageStream(huffman_xsize, huffman_ysize, 0, dec,
+                           &huffman_image)) {
+      dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
+      goto Error;
+    }
+    hdr->huffman_subsample_bits_ = huffman_precision;
+    for (i = 0; i < huffman_pixs; ++i) {
+      // The huffman data is stored in red and green bytes.
+      const int group = (huffman_image[i] >> 8) & 0xffff;
+      huffman_image[i] = group;
+      if (group >= num_htree_groups) {
+        num_htree_groups = group + 1;
+      }
+    }
+  }
+
+  if (br->error_) goto Error;
+
+  assert(num_htree_groups <= 0x10000);
+  htree_groups =
+      (HTreeGroup*)WebPSafeCalloc((uint64_t)num_htree_groups,
+                                  sizeof(*htree_groups));
+  if (htree_groups == NULL) {
+    dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
+    goto Error;
+  }
+
+  for (i = 0; i < num_htree_groups; ++i) {
+    HuffmanTree* const htrees = htree_groups[i].htrees_;
+    for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) {
+      int alphabet_size = kAlphabetSize[j];
+      if (j == 0 && color_cache_bits > 0) {
+        alphabet_size += 1 << color_cache_bits;
+      }
+      if (!ReadHuffmanCode(alphabet_size, dec, htrees + j)) goto Error;
+    }
+  }
+
+  // All OK. Finalize pointers and return.
+  hdr->huffman_image_ = huffman_image;
+  hdr->num_htree_groups_ = num_htree_groups;
+  hdr->htree_groups_ = htree_groups;
+  return 1;
+
+ Error:
+  free(huffman_image);
+  DeleteHtreeGroups(htree_groups, num_htree_groups);
+  return 0;
+}
+
+//------------------------------------------------------------------------------
+// Scaling.
+
+static int AllocateAndInitRescaler(VP8LDecoder* const dec, VP8Io* const io) {
+  const int num_channels = 4;
+  const int in_width = io->mb_w;
+  const int out_width = io->scaled_width;
+  const int in_height = io->mb_h;
+  const int out_height = io->scaled_height;
+  const uint64_t work_size = 2 * num_channels * (uint64_t)out_width;
+  int32_t* work;        // Rescaler work area.
+  const uint64_t scaled_data_size = num_channels * (uint64_t)out_width;
+  uint32_t* scaled_data;  // Temporary storage for scaled BGRA data.
+  const uint64_t memory_size = sizeof(*dec->rescaler) +
+                               work_size * sizeof(*work) +
+                               scaled_data_size * sizeof(*scaled_data);
+  uint8_t* memory = (uint8_t*)WebPSafeCalloc(memory_size, sizeof(*memory));
+  if (memory == NULL) {
+    dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
+    return 0;
+  }
+  assert(dec->rescaler_memory == NULL);
+  dec->rescaler_memory = memory;
+
+  dec->rescaler = (WebPRescaler*)memory;
+  memory += sizeof(*dec->rescaler);
+  work = (int32_t*)memory;
+  memory += work_size * sizeof(*work);
+  scaled_data = (uint32_t*)memory;
+
+  WebPRescalerInit(dec->rescaler, in_width, in_height, (uint8_t*)scaled_data,
+                   out_width, out_height, 0, num_channels,
+                   in_width, out_width, in_height, out_height, work);
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+// Export to ARGB
+
+// We have special "export" function since we need to convert from BGRA
+static int Export(WebPRescaler* const rescaler, WEBP_CSP_MODE colorspace,
+                  int rgba_stride, uint8_t* const rgba) {
+  uint32_t* const src = (uint32_t*)rescaler->dst;
+  const int dst_width = rescaler->dst_width;
+  int num_lines_out = 0;
+  while (WebPRescalerHasPendingOutput(rescaler)) {
+    uint8_t* const dst = rgba + num_lines_out * rgba_stride;
+    WebPRescalerExportRow(rescaler);
+    WebPMultARGBRow(src, dst_width, 1);
+    VP8LConvertFromBGRA(src, dst_width, colorspace, dst);
+    ++num_lines_out;
+  }
+  return num_lines_out;
+}
+
+// Emit scaled rows.
+static int EmitRescaledRowsRGBA(const VP8LDecoder* const dec,
+                                uint8_t* in, int in_stride, int mb_h,
+                                uint8_t* const out, int out_stride) {
+  const WEBP_CSP_MODE colorspace = dec->output_->colorspace;
+  int num_lines_in = 0;
+  int num_lines_out = 0;
+  while (num_lines_in < mb_h) {
+    uint8_t* const row_in = in + num_lines_in * in_stride;
+    uint8_t* const row_out = out + num_lines_out * out_stride;
+    const int lines_left = mb_h - num_lines_in;
+    const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left);
+    assert(needed_lines > 0 && needed_lines <= lines_left);
+    WebPMultARGBRows(row_in, in_stride,
+                     dec->rescaler->src_width, needed_lines, 0);
+    WebPRescalerImport(dec->rescaler, lines_left, row_in, in_stride);
+    num_lines_in += needed_lines;
+    num_lines_out += Export(dec->rescaler, colorspace, out_stride, row_out);
+  }
+  return num_lines_out;
+}
+
+// Emit rows without any scaling.
+static int EmitRows(WEBP_CSP_MODE colorspace,
+                    const uint8_t* row_in, int in_stride,
+                    int mb_w, int mb_h,
+                    uint8_t* const out, int out_stride) {
+  int lines = mb_h;
+  uint8_t* row_out = out;
+  while (lines-- > 0) {
+    VP8LConvertFromBGRA((const uint32_t*)row_in, mb_w, colorspace, row_out);
+    row_in += in_stride;
+    row_out += out_stride;
+  }
+  return mb_h;  // Num rows out == num rows in.
+}
+
+//------------------------------------------------------------------------------
+// Export to YUVA
+
+static void ConvertToYUVA(const uint32_t* const src, int width, int y_pos,
+                          const WebPDecBuffer* const output) {
+  const WebPYUVABuffer* const buf = &output->u.YUVA;
+  // first, the luma plane
+  {
+    int i;
+    uint8_t* const y = buf->y + y_pos * buf->y_stride;
+    for (i = 0; i < width; ++i) {
+      const uint32_t p = src[i];
+      y[i] = VP8RGBToY((p >> 16) & 0xff, (p >> 8) & 0xff, (p >> 0) & 0xff,
+                       YUV_HALF);
+    }
+  }
+
+  // then U/V planes
+  {
+    uint8_t* const u = buf->u + (y_pos >> 1) * buf->u_stride;
+    uint8_t* const v = buf->v + (y_pos >> 1) * buf->v_stride;
+    const int uv_width = width >> 1;
+    int i;
+    for (i = 0; i < uv_width; ++i) {
+      const uint32_t v0 = src[2 * i + 0];
+      const uint32_t v1 = src[2 * i + 1];
+      // VP8RGBToU/V expects four accumulated pixels. Hence we need to
+      // scale r/g/b value by a factor 2. We just shift v0/v1 one bit less.
+      const int r = ((v0 >> 15) & 0x1fe) + ((v1 >> 15) & 0x1fe);
+      const int g = ((v0 >>  7) & 0x1fe) + ((v1 >>  7) & 0x1fe);
+      const int b = ((v0 <<  1) & 0x1fe) + ((v1 <<  1) & 0x1fe);
+      if (!(y_pos & 1)) {  // even lines: store values
+        u[i] = VP8RGBToU(r, g, b, YUV_HALF << 2);
+        v[i] = VP8RGBToV(r, g, b, YUV_HALF << 2);
+      } else {             // odd lines: average with previous values
+        const int tmp_u = VP8RGBToU(r, g, b, YUV_HALF << 2);
+        const int tmp_v = VP8RGBToV(r, g, b, YUV_HALF << 2);
+        // Approximated average-of-four. But it's an acceptable diff.
+        u[i] = (u[i] + tmp_u + 1) >> 1;
+        v[i] = (v[i] + tmp_v + 1) >> 1;
+      }
+    }
+    if (width & 1) {       // last pixel
+      const uint32_t v0 = src[2 * i + 0];
+      const int r = (v0 >> 14) & 0x3fc;
+      const int g = (v0 >>  6) & 0x3fc;
+      const int b = (v0 <<  2) & 0x3fc;
+      if (!(y_pos & 1)) {  // even lines
+        u[i] = VP8RGBToU(r, g, b, YUV_HALF << 2);
+        v[i] = VP8RGBToV(r, g, b, YUV_HALF << 2);
+      } else {             // odd lines (note: we could just skip this)
+        const int tmp_u = VP8RGBToU(r, g, b, YUV_HALF << 2);
+        const int tmp_v = VP8RGBToV(r, g, b, YUV_HALF << 2);
+        u[i] = (u[i] + tmp_u + 1) >> 1;
+        v[i] = (v[i] + tmp_v + 1) >> 1;
+      }
+    }
+  }
+  // Lastly, store alpha if needed.
+  if (buf->a != NULL) {
+    int i;
+    uint8_t* const a = buf->a + y_pos * buf->a_stride;
+    for (i = 0; i < width; ++i) a[i] = (src[i] >> 24);
+  }
+}
+
+static int ExportYUVA(const VP8LDecoder* const dec, int y_pos) {
+  WebPRescaler* const rescaler = dec->rescaler;
+  uint32_t* const src = (uint32_t*)rescaler->dst;
+  const int dst_width = rescaler->dst_width;
+  int num_lines_out = 0;
+  while (WebPRescalerHasPendingOutput(rescaler)) {
+    WebPRescalerExportRow(rescaler);
+    WebPMultARGBRow(src, dst_width, 1);
+    ConvertToYUVA(src, dst_width, y_pos, dec->output_);
+    ++y_pos;
+    ++num_lines_out;
+  }
+  return num_lines_out;
+}
+
+static int EmitRescaledRowsYUVA(const VP8LDecoder* const dec,
+                                uint8_t* in, int in_stride, int mb_h) {
+  int num_lines_in = 0;
+  int y_pos = dec->last_out_row_;
+  while (num_lines_in < mb_h) {
+    const int lines_left = mb_h - num_lines_in;
+    const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left);
+    WebPMultARGBRows(in, in_stride, dec->rescaler->src_width, needed_lines, 0);
+    WebPRescalerImport(dec->rescaler, lines_left, in, in_stride);
+    num_lines_in += needed_lines;
+    in += needed_lines * in_stride;
+    y_pos += ExportYUVA(dec, y_pos);
+  }
+  return y_pos;
+}
+
+static int EmitRowsYUVA(const VP8LDecoder* const dec,
+                        const uint8_t* in, int in_stride,
+                        int mb_w, int num_rows) {
+  int y_pos = dec->last_out_row_;
+  while (num_rows-- > 0) {
+    ConvertToYUVA((const uint32_t*)in, mb_w, y_pos, dec->output_);
+    in += in_stride;
+    ++y_pos;
+  }
+  return y_pos;
+}
+
+//------------------------------------------------------------------------------
+// Cropping.
+
+// Sets io->mb_y, io->mb_h & io->mb_w according to start row, end row and
+// crop options. Also updates the input data pointer, so that it points to the
+// start of the cropped window. Note that pixels are in ARGB format even if
+// 'in_data' is uint8_t*.
+// Returns true if the crop window is not empty.
+static int SetCropWindow(VP8Io* const io, int y_start, int y_end,
+                         uint8_t** const in_data, int pixel_stride) {
+  assert(y_start < y_end);
+  assert(io->crop_left < io->crop_right);
+  if (y_end > io->crop_bottom) {
+    y_end = io->crop_bottom;  // make sure we don't overflow on last row.
+  }
+  if (y_start < io->crop_top) {
+    const int delta = io->crop_top - y_start;
+    y_start = io->crop_top;
+    *in_data += delta * pixel_stride;
+  }
+  if (y_start >= y_end) return 0;  // Crop window is empty.
+
+  *in_data += io->crop_left * sizeof(uint32_t);
+
+  io->mb_y = y_start - io->crop_top;
+  io->mb_w = io->crop_right - io->crop_left;
+  io->mb_h = y_end - y_start;
+  return 1;  // Non-empty crop window.
+}
+
+//------------------------------------------------------------------------------
+
+static WEBP_INLINE int GetMetaIndex(
+    const uint32_t* const image, int xsize, int bits, int x, int y) {
+  if (bits == 0) return 0;
+  return image[xsize * (y >> bits) + (x >> bits)];
+}
+
+static WEBP_INLINE HTreeGroup* GetHtreeGroupForPos(VP8LMetadata* const hdr,
+                                                   int x, int y) {
+  const int meta_index = GetMetaIndex(hdr->huffman_image_, hdr->huffman_xsize_,
+                                      hdr->huffman_subsample_bits_, x, y);
+  assert(meta_index < hdr->num_htree_groups_);
+  return hdr->htree_groups_ + meta_index;
+}
+
+//------------------------------------------------------------------------------
+// Main loop, with custom row-processing function
+
+typedef void (*ProcessRowsFunc)(VP8LDecoder* const dec, int row);
+
+static void ApplyInverseTransforms(VP8LDecoder* const dec, int num_rows,
+                                   const uint32_t* const rows) {
+  int n = dec->next_transform_;
+  const int cache_pixs = dec->width_ * num_rows;
+  const int start_row = dec->last_row_;
+  const int end_row = start_row + num_rows;
+  const uint32_t* rows_in = rows;
+  uint32_t* const rows_out = dec->argb_cache_;
+
+  // Inverse transforms.
+  // TODO: most transforms only need to operate on the cropped region only.
+  memcpy(rows_out, rows_in, cache_pixs * sizeof(*rows_out));
+  while (n-- > 0) {
+    VP8LTransform* const transform = &dec->transforms_[n];
+    VP8LInverseTransform(transform, start_row, end_row, rows_in, rows_out);
+    rows_in = rows_out;
+  }
+}
+
+// Special method for paletted alpha data.
+static void ApplyInverseTransformsAlpha(VP8LDecoder* const dec, int num_rows,
+                                        const uint8_t* const rows) {
+  const int start_row = dec->last_row_;
+  const int end_row = start_row + num_rows;
+  const uint8_t* rows_in = rows;
+  uint8_t* rows_out = (uint8_t*)dec->io_->opaque + dec->io_->width * start_row;
+  VP8LTransform* const transform = &dec->transforms_[0];
+  assert(dec->next_transform_ == 1);
+  assert(transform->type_ == COLOR_INDEXING_TRANSFORM);
+  VP8LColorIndexInverseTransformAlpha(transform, start_row, end_row, rows_in,
+                                      rows_out);
+}
+
+// Processes (transforms, scales & color-converts) the rows decoded after the
+// last call.
+static void ProcessRows(VP8LDecoder* const dec, int row) {
+  const uint32_t* const rows = dec->pixels_ + dec->width_ * dec->last_row_;
+  const int num_rows = row - dec->last_row_;
+
+  if (num_rows <= 0) return;  // Nothing to be done.
+  ApplyInverseTransforms(dec, num_rows, rows);
+
+  // Emit output.
+  {
+    VP8Io* const io = dec->io_;
+    uint8_t* rows_data = (uint8_t*)dec->argb_cache_;
+    const int in_stride = io->width * sizeof(uint32_t);  // in unit of RGBA
+    if (!SetCropWindow(io, dec->last_row_, row, &rows_data, in_stride)) {
+      // Nothing to output (this time).
+    } else {
+      const WebPDecBuffer* const output = dec->output_;
+      if (output->colorspace < MODE_YUV) {  // convert to RGBA
+        const WebPRGBABuffer* const buf = &output->u.RGBA;
+        uint8_t* const rgba = buf->rgba + dec->last_out_row_ * buf->stride;
+        const int num_rows_out = io->use_scaling ?
+            EmitRescaledRowsRGBA(dec, rows_data, in_stride, io->mb_h,
+                                 rgba, buf->stride) :
+            EmitRows(output->colorspace, rows_data, in_stride,
+                     io->mb_w, io->mb_h, rgba, buf->stride);
+        // Update 'last_out_row_'.
+        dec->last_out_row_ += num_rows_out;
+      } else {                              // convert to YUVA
+        dec->last_out_row_ = io->use_scaling ?
+            EmitRescaledRowsYUVA(dec, rows_data, in_stride, io->mb_h) :
+            EmitRowsYUVA(dec, rows_data, in_stride, io->mb_w, io->mb_h);
+      }
+      assert(dec->last_out_row_ <= output->height);
+    }
+  }
+
+  // Update 'last_row_'.
+  dec->last_row_ = row;
+  assert(dec->last_row_ <= dec->height_);
+}
+
+// Row-processing for the special case when alpha data contains only one
+// transform (color indexing), and trivial non-green literals.
+static int Is8bOptimizable(const VP8LMetadata* const hdr) {
+  int i;
+  if (hdr->color_cache_size_ > 0) return 0;
+  // When the Huffman tree contains only one symbol, we can skip the
+  // call to ReadSymbol() for red/blue/alpha channels.
+  for (i = 0; i < hdr->num_htree_groups_; ++i) {
+    const HuffmanTree* const htrees = hdr->htree_groups_[i].htrees_;
+    if (htrees[RED].num_nodes_ > 1) return 0;
+    if (htrees[BLUE].num_nodes_ > 1) return 0;
+    if (htrees[ALPHA].num_nodes_ > 1) return 0;
+  }
+  return 1;
+}
+
+static void ExtractPalettedAlphaRows(VP8LDecoder* const dec, int row) {
+  const int num_rows = row - dec->last_row_;
+  const uint8_t* const in =
+      (uint8_t*)dec->pixels_ + dec->width_ * dec->last_row_;
+  if (num_rows > 0) {
+    ApplyInverseTransformsAlpha(dec, num_rows, in);
+  }
+  dec->last_row_ = dec->last_out_row_ = row;
+}
+
+static int DecodeAlphaData(VP8LDecoder* const dec, uint8_t* const data,
+                           int width, int height, int last_row) {
+  int ok = 1;
+  int row = dec->last_pixel_ / width;
+  int col = dec->last_pixel_ % width;
+  VP8LBitReader* const br = &dec->br_;
+  VP8LMetadata* const hdr = &dec->hdr_;
+  const HTreeGroup* htree_group = GetHtreeGroupForPos(hdr, col, row);
+  int pos = dec->last_pixel_;         // current position
+  const int end = width * height;     // End of data
+  const int last = width * last_row;  // Last pixel to decode
+  const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES;
+  const int mask = hdr->huffman_mask_;
+  assert(htree_group != NULL);
+  assert(last_row <= height);
+  assert(Is8bOptimizable(hdr));
+
+  while (!br->eos_ && pos < last) {
+    int code;
+    // Only update when changing tile.
+    if ((col & mask) == 0) {
+      htree_group = GetHtreeGroupForPos(hdr, col, row);
+    }
+    VP8LFillBitWindow(br);
+    code = ReadSymbol(&htree_group->htrees_[GREEN], br);
+    if (code < NUM_LITERAL_CODES) {  // Literal
+      data[pos] = code;
+      ++pos;
+      ++col;
+      if (col >= width) {
+        col = 0;
+        ++row;
+        if (row % NUM_ARGB_CACHE_ROWS == 0) {
+          ExtractPalettedAlphaRows(dec, row);
+        }
+      }
+    } else if (code < len_code_limit) {  // Backward reference
+      int dist_code, dist;
+      const int length_sym = code - NUM_LITERAL_CODES;
+      const int length = GetCopyLength(length_sym, br);
+      const int dist_symbol = ReadSymbol(&htree_group->htrees_[DIST], br);
+      VP8LFillBitWindow(br);
+      dist_code = GetCopyDistance(dist_symbol, br);
+      dist = PlaneCodeToDistance(width, dist_code);
+      if (pos >= dist && end - pos >= length) {
+        int i;
+        for (i = 0; i < length; ++i) data[pos + i] = data[pos + i - dist];
+      } else {
+        ok = 0;
+        goto End;
+      }
+      pos += length;
+      col += length;
+      while (col >= width) {
+        col -= width;
+        ++row;
+        if (row % NUM_ARGB_CACHE_ROWS == 0) {
+          ExtractPalettedAlphaRows(dec, row);
+        }
+      }
+      if (pos < last && (col & mask)) {
+        htree_group = GetHtreeGroupForPos(hdr, col, row);
+      }
+    } else {  // Not reached
+      ok = 0;
+      goto End;
+    }
+    ok = !br->error_;
+    if (!ok) goto End;
+  }
+  // Process the remaining rows corresponding to last row-block.
+  ExtractPalettedAlphaRows(dec, row);
+
+ End:
+  if (br->error_ || !ok || (br->eos_ && pos < end)) {
+    ok = 0;
+    dec->status_ = br->eos_ ? VP8_STATUS_SUSPENDED
+                            : VP8_STATUS_BITSTREAM_ERROR;
+  } else {
+    dec->last_pixel_ = (int)pos;
+    if (pos == end) dec->state_ = READ_DATA;
+  }
+  return ok;
+}
+
+static int DecodeImageData(VP8LDecoder* const dec, uint32_t* const data,
+                           int width, int height, int last_row,
+                           ProcessRowsFunc process_func) {
+  int ok = 1;
+  int row = dec->last_pixel_ / width;
+  int col = dec->last_pixel_ % width;
+  VP8LBitReader* const br = &dec->br_;
+  VP8LMetadata* const hdr = &dec->hdr_;
+  HTreeGroup* htree_group = GetHtreeGroupForPos(hdr, col, row);
+  uint32_t* src = data + dec->last_pixel_;
+  uint32_t* last_cached = src;
+  uint32_t* const src_end = data + width * height;     // End of data
+  uint32_t* const src_last = data + width * last_row;  // Last pixel to decode
+  const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES;
+  const int color_cache_limit = len_code_limit + hdr->color_cache_size_;
+  VP8LColorCache* const color_cache =
+      (hdr->color_cache_size_ > 0) ? &hdr->color_cache_ : NULL;
+  const int mask = hdr->huffman_mask_;
+  assert(htree_group != NULL);
+  assert(src_last <= src_end);
+
+  while (!br->eos_ && src < src_last) {
+    int code;
+    // Only update when changing tile. Note we could use this test:
+    // if "((((prev_col ^ col) | prev_row ^ row)) > mask)" -> tile changed
+    // but that's actually slower and needs storing the previous col/row.
+    if ((col & mask) == 0) {
+      htree_group = GetHtreeGroupForPos(hdr, col, row);
+    }
+    VP8LFillBitWindow(br);
+    code = ReadSymbol(&htree_group->htrees_[GREEN], br);
+    if (code < NUM_LITERAL_CODES) {  // Literal
+      int red, green, blue, alpha;
+      red = ReadSymbol(&htree_group->htrees_[RED], br);
+      green = code;
+      VP8LFillBitWindow(br);
+      blue = ReadSymbol(&htree_group->htrees_[BLUE], br);
+      alpha = ReadSymbol(&htree_group->htrees_[ALPHA], br);
+      *src = (alpha << 24) | (red << 16) | (green << 8) | blue;
+    AdvanceByOne:
+      ++src;
+      ++col;
+      if (col >= width) {
+        col = 0;
+        ++row;
+        if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) {
+          process_func(dec, row);
+        }
+        if (color_cache != NULL) {
+          while (last_cached < src) {
+            VP8LColorCacheInsert(color_cache, *last_cached++);
+          }
+        }
+      }
+    } else if (code < len_code_limit) {  // Backward reference
+      int dist_code, dist;
+      const int length_sym = code - NUM_LITERAL_CODES;
+      const int length = GetCopyLength(length_sym, br);
+      const int dist_symbol = ReadSymbol(&htree_group->htrees_[DIST], br);
+      VP8LFillBitWindow(br);
+      dist_code = GetCopyDistance(dist_symbol, br);
+      dist = PlaneCodeToDistance(width, dist_code);
+      if (src - data < (ptrdiff_t)dist || src_end - src < (ptrdiff_t)length) {
+        ok = 0;
+        goto End;
+      } else {
+        int i;
+        for (i = 0; i < length; ++i) src[i] = src[i - dist];
+        src += length;
+      }
+      col += length;
+      while (col >= width) {
+        col -= width;
+        ++row;
+        if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) {
+          process_func(dec, row);
+        }
+      }
+      if (src < src_last) {
+        if (col & mask) htree_group = GetHtreeGroupForPos(hdr, col, row);
+        if (color_cache != NULL) {
+          while (last_cached < src) {
+            VP8LColorCacheInsert(color_cache, *last_cached++);
+          }
+        }
+      }
+    } else if (code < color_cache_limit) {  // Color cache
+      const int key = code - len_code_limit;
+      assert(color_cache != NULL);
+      while (last_cached < src) {
+        VP8LColorCacheInsert(color_cache, *last_cached++);
+      }
+      *src = VP8LColorCacheLookup(color_cache, key);
+      goto AdvanceByOne;
+    } else {  // Not reached
+      ok = 0;
+      goto End;
+    }
+    ok = !br->error_;
+    if (!ok) goto End;
+  }
+  // Process the remaining rows corresponding to last row-block.
+  if (process_func != NULL) process_func(dec, row);
+
+ End:
+  if (br->error_ || !ok || (br->eos_ && src < src_end)) {
+    ok = 0;
+    dec->status_ = br->eos_ ? VP8_STATUS_SUSPENDED
+                            : VP8_STATUS_BITSTREAM_ERROR;
+  } else {
+    dec->last_pixel_ = (int)(src - data);
+    if (src == src_end) dec->state_ = READ_DATA;
+  }
+  return ok;
+}
+
+// -----------------------------------------------------------------------------
+// VP8LTransform
+
+static void ClearTransform(VP8LTransform* const transform) {
+  free(transform->data_);
+  transform->data_ = NULL;
+}
+
+// For security reason, we need to remap the color map to span
+// the total possible bundled values, and not just the num_colors.
+static int ExpandColorMap(int num_colors, VP8LTransform* const transform) {
+  int i;
+  const int final_num_colors = 1 << (8 >> transform->bits_);
+  uint32_t* const new_color_map =
+      (uint32_t*)WebPSafeMalloc((uint64_t)final_num_colors,
+                                sizeof(*new_color_map));
+  if (new_color_map == NULL) {
+    return 0;
+  } else {
+    uint8_t* const data = (uint8_t*)transform->data_;
+    uint8_t* const new_data = (uint8_t*)new_color_map;
+    new_color_map[0] = transform->data_[0];
+    for (i = 4; i < 4 * num_colors; ++i) {
+      // Equivalent to AddPixelEq(), on a byte-basis.
+      new_data[i] = (data[i] + new_data[i - 4]) & 0xff;
+    }
+    for (; i < 4 * final_num_colors; ++i)
+      new_data[i] = 0;  // black tail.
+    free(transform->data_);
+    transform->data_ = new_color_map;
+  }
+  return 1;
+}
+
+static int ReadTransform(int* const xsize, int const* ysize,
+                         VP8LDecoder* const dec) {
+  int ok = 1;
+  VP8LBitReader* const br = &dec->br_;
+  VP8LTransform* transform = &dec->transforms_[dec->next_transform_];
+  const VP8LImageTransformType type =
+      (VP8LImageTransformType)VP8LReadBits(br, 2);
+
+  // Each transform type can only be present once in the stream.
+  if (dec->transforms_seen_ & (1U << type)) {
+    return 0;  // Already there, let's not accept the second same transform.
+  }
+  dec->transforms_seen_ |= (1U << type);
+
+  transform->type_ = type;
+  transform->xsize_ = *xsize;
+  transform->ysize_ = *ysize;
+  transform->data_ = NULL;
+  ++dec->next_transform_;
+  assert(dec->next_transform_ <= NUM_TRANSFORMS);
+
+  switch (type) {
+    case PREDICTOR_TRANSFORM:
+    case CROSS_COLOR_TRANSFORM:
+      transform->bits_ = VP8LReadBits(br, 3) + 2;
+      ok = DecodeImageStream(VP8LSubSampleSize(transform->xsize_,
+                                               transform->bits_),
+                             VP8LSubSampleSize(transform->ysize_,
+                                               transform->bits_),
+                             0, dec, &transform->data_);
+      break;
+    case COLOR_INDEXING_TRANSFORM: {
+       const int num_colors = VP8LReadBits(br, 8) + 1;
+       const int bits = (num_colors > 16) ? 0
+                      : (num_colors > 4) ? 1
+                      : (num_colors > 2) ? 2
+                      : 3;
+       *xsize = VP8LSubSampleSize(transform->xsize_, bits);
+       transform->bits_ = bits;
+       ok = DecodeImageStream(num_colors, 1, 0, dec, &transform->data_);
+       ok = ok && ExpandColorMap(num_colors, transform);
+      break;
+    }
+    case SUBTRACT_GREEN:
+      break;
+    default:
+      assert(0);    // can't happen
+      break;
+  }
+
+  return ok;
+}
+
+// -----------------------------------------------------------------------------
+// VP8LMetadata
+
+static void InitMetadata(VP8LMetadata* const hdr) {
+  assert(hdr);
+  memset(hdr, 0, sizeof(*hdr));
+}
+
+static void ClearMetadata(VP8LMetadata* const hdr) {
+  assert(hdr);
+
+  free(hdr->huffman_image_);
+  DeleteHtreeGroups(hdr->htree_groups_, hdr->num_htree_groups_);
+  VP8LColorCacheClear(&hdr->color_cache_);
+  InitMetadata(hdr);
+}
+
+// -----------------------------------------------------------------------------
+// VP8LDecoder
+
+VP8LDecoder* VP8LNew(void) {
+  VP8LDecoder* const dec = (VP8LDecoder*)calloc(1, sizeof(*dec));
+  if (dec == NULL) return NULL;
+  dec->status_ = VP8_STATUS_OK;
+  dec->action_ = READ_DIM;
+  dec->state_ = READ_DIM;
+
+  VP8LDspInit();  // Init critical function pointers.
+
+  return dec;
+}
+
+void VP8LClear(VP8LDecoder* const dec) {
+  int i;
+  if (dec == NULL) return;
+  ClearMetadata(&dec->hdr_);
+
+  free(dec->pixels_);
+  dec->pixels_ = NULL;
+  for (i = 0; i < dec->next_transform_; ++i) {
+    ClearTransform(&dec->transforms_[i]);
+  }
+  dec->next_transform_ = 0;
+  dec->transforms_seen_ = 0;
+
+  free(dec->rescaler_memory);
+  dec->rescaler_memory = NULL;
+
+  dec->output_ = NULL;   // leave no trace behind
+}
+
+void VP8LDelete(VP8LDecoder* const dec) {
+  if (dec != NULL) {
+    VP8LClear(dec);
+    free(dec);
+  }
+}
+
+static void UpdateDecoder(VP8LDecoder* const dec, int width, int height) {
+  VP8LMetadata* const hdr = &dec->hdr_;
+  const int num_bits = hdr->huffman_subsample_bits_;
+  dec->width_ = width;
+  dec->height_ = height;
+
+  hdr->huffman_xsize_ = VP8LSubSampleSize(width, num_bits);
+  hdr->huffman_mask_ = (num_bits == 0) ? ~0 : (1 << num_bits) - 1;
+}
+
+static int DecodeImageStream(int xsize, int ysize,
+                             int is_level0,
+                             VP8LDecoder* const dec,
+                             uint32_t** const decoded_data) {
+  int ok = 1;
+  int transform_xsize = xsize;
+  int transform_ysize = ysize;
+  VP8LBitReader* const br = &dec->br_;
+  VP8LMetadata* const hdr = &dec->hdr_;
+  uint32_t* data = NULL;
+  int color_cache_bits = 0;
+
+  // Read the transforms (may recurse).
+  if (is_level0) {
+    while (ok && VP8LReadBits(br, 1)) {
+      ok = ReadTransform(&transform_xsize, &transform_ysize, dec);
+    }
+  }
+
+  // Color cache
+  if (ok && VP8LReadBits(br, 1)) {
+    color_cache_bits = VP8LReadBits(br, 4);
+    ok = (color_cache_bits >= 1 && color_cache_bits <= MAX_CACHE_BITS);
+    if (!ok) {
+      dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
+      goto End;
+    }
+  }
+
+  // Read the Huffman codes (may recurse).
+  ok = ok && ReadHuffmanCodes(dec, transform_xsize, transform_ysize,
+                              color_cache_bits, is_level0);
+  if (!ok) {
+    dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
+    goto End;
+  }
+
+  // Finish setting up the color-cache
+  if (color_cache_bits > 0) {
+    hdr->color_cache_size_ = 1 << color_cache_bits;
+    if (!VP8LColorCacheInit(&hdr->color_cache_, color_cache_bits)) {
+      dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
+      ok = 0;
+      goto End;
+    }
+  } else {
+    hdr->color_cache_size_ = 0;
+  }
+  UpdateDecoder(dec, transform_xsize, transform_ysize);
+
+  if (is_level0) {   // level 0 complete
+    dec->state_ = READ_HDR;
+    goto End;
+  }
+
+  {
+    const uint64_t total_size = (uint64_t)transform_xsize * transform_ysize;
+    data = (uint32_t*)WebPSafeMalloc(total_size, sizeof(*data));
+    if (data == NULL) {
+      dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
+      ok = 0;
+      goto End;
+    }
+  }
+
+  // Use the Huffman trees to decode the LZ77 encoded data.
+  ok = DecodeImageData(dec, data, transform_xsize, transform_ysize,
+                       transform_ysize, NULL);
+  ok = ok && !br->error_;
+
+ End:
+
+  if (!ok) {
+    free(data);
+    ClearMetadata(hdr);
+    // If not enough data (br.eos_) resulted in BIT_STREAM_ERROR, update the
+    // status appropriately.
+    if (dec->status_ == VP8_STATUS_BITSTREAM_ERROR && dec->br_.eos_) {
+      dec->status_ = VP8_STATUS_SUSPENDED;
+    }
+  } else {
+    if (decoded_data != NULL) {
+      *decoded_data = data;
+    } else {
+      // We allocate image data in this function only for transforms. At level 0
+      // (that is: not the transforms), we shouldn't have allocated anything.
+      assert(data == NULL);
+      assert(is_level0);
+    }
+    dec->last_pixel_ = 0;  // Reset for future DECODE_DATA_FUNC() calls.
+    if (!is_level0) ClearMetadata(hdr);  // Clean up temporary data behind.
+  }
+  return ok;
+}
+
+//------------------------------------------------------------------------------
+// Allocate internal buffers dec->pixels_ and dec->argb_cache_.
+static int AllocateInternalBuffers32b(VP8LDecoder* const dec, int final_width) {
+  const uint64_t num_pixels = (uint64_t)dec->width_ * dec->height_;
+  // Scratch buffer corresponding to top-prediction row for transforming the
+  // first row in the row-blocks. Not needed for paletted alpha.
+  const uint64_t cache_top_pixels = (uint16_t)final_width;
+  // Scratch buffer for temporary BGRA storage. Not needed for paletted alpha.
+  const uint64_t cache_pixels = (uint64_t)final_width * NUM_ARGB_CACHE_ROWS;
+  const uint64_t total_num_pixels =
+      num_pixels + cache_top_pixels + cache_pixels;
+
+  assert(dec->width_ <= final_width);
+  dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(uint32_t));
+  if (dec->pixels_ == NULL) {
+    dec->argb_cache_ = NULL;    // for sanity check
+    dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
+    return 0;
+  }
+  dec->argb_cache_ = dec->pixels_ + num_pixels + cache_top_pixels;
+  return 1;
+}
+
+static int AllocateInternalBuffers8b(VP8LDecoder* const dec) {
+  const uint64_t total_num_pixels = (uint64_t)dec->width_ * dec->height_;
+  dec->argb_cache_ = NULL;    // for sanity check
+  dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(uint8_t));
+  if (dec->pixels_ == NULL) {
+    dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
+    return 0;
+  }
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+
+// Special row-processing that only stores the alpha data.
+static void ExtractAlphaRows(VP8LDecoder* const dec, int row) {
+  const int num_rows = row - dec->last_row_;
+  const uint32_t* const in = dec->pixels_ + dec->width_ * dec->last_row_;
+
+  if (num_rows <= 0) return;  // Nothing to be done.
+  ApplyInverseTransforms(dec, num_rows, in);
+
+  // Extract alpha (which is stored in the green plane).
+  {
+    const int width = dec->io_->width;      // the final width (!= dec->width_)
+    const int cache_pixs = width * num_rows;
+    uint8_t* const dst = (uint8_t*)dec->io_->opaque + width * dec->last_row_;
+    const uint32_t* const src = dec->argb_cache_;
+    int i;
+    for (i = 0; i < cache_pixs; ++i) dst[i] = (src[i] >> 8) & 0xff;
+  }
+  dec->last_row_ = dec->last_out_row_ = row;
+}
+
+int VP8LDecodeAlphaHeader(ALPHDecoder* const alph_dec,
+                          const uint8_t* const data, size_t data_size,
+                          uint8_t* const output) {
+  int ok = 0;
+  VP8LDecoder* dec;
+  VP8Io* io;
+  assert(alph_dec != NULL);
+  alph_dec->vp8l_dec_ = VP8LNew();
+  if (alph_dec->vp8l_dec_ == NULL) return 0;
+  dec = alph_dec->vp8l_dec_;
+
+  dec->width_ = alph_dec->width_;
+  dec->height_ = alph_dec->height_;
+  dec->io_ = &alph_dec->io_;
+  io = dec->io_;
+
+  VP8InitIo(io);
+  WebPInitCustomIo(NULL, io);  // Just a sanity Init. io won't be used.
+  io->opaque = output;
+  io->width = alph_dec->width_;
+  io->height = alph_dec->height_;
+
+  dec->status_ = VP8_STATUS_OK;
+  VP8LInitBitReader(&dec->br_, data, data_size);
+
+  dec->action_ = READ_HDR;
+  if (!DecodeImageStream(alph_dec->width_, alph_dec->height_, 1, dec, NULL)) {
+    goto Err;
+  }
+
+  // Special case: if alpha data uses only the color indexing transform and
+  // doesn't use color cache (a frequent case), we will use DecodeAlphaData()
+  // method that only needs allocation of 1 byte per pixel (alpha channel).
+  if (dec->next_transform_ == 1 &&
+      dec->transforms_[0].type_ == COLOR_INDEXING_TRANSFORM &&
+      Is8bOptimizable(&dec->hdr_)) {
+    alph_dec->use_8b_decode = 1;
+    ok = AllocateInternalBuffers8b(dec);
+  } else {
+    // Allocate internal buffers (note that dec->width_ may have changed here).
+    alph_dec->use_8b_decode = 0;
+    ok = AllocateInternalBuffers32b(dec, alph_dec->width_);
+  }
+
+  if (!ok) goto Err;
+
+  dec->action_ = READ_DATA;
+  return 1;
+
+ Err:
+  VP8LDelete(alph_dec->vp8l_dec_);
+  alph_dec->vp8l_dec_ = NULL;
+  return 0;
+}
+
+int VP8LDecodeAlphaImageStream(ALPHDecoder* const alph_dec, int last_row) {
+  VP8LDecoder* const dec = alph_dec->vp8l_dec_;
+  assert(dec != NULL);
+  assert(dec->action_ == READ_DATA);
+  assert(last_row <= dec->height_);
+
+  // Decode (with special row processing).
+  return alph_dec->use_8b_decode ?
+      DecodeAlphaData(dec, (uint8_t*)dec->pixels_, dec->width_, dec->height_,
+                      last_row) :
+      DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_,
+                      last_row, ExtractAlphaRows);
+}
+
+//------------------------------------------------------------------------------
+
+int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io) {
+  int width, height, has_alpha;
+
+  if (dec == NULL) return 0;
+  if (io == NULL) {
+    dec->status_ = VP8_STATUS_INVALID_PARAM;
+    return 0;
+  }
+
+  dec->io_ = io;
+  dec->status_ = VP8_STATUS_OK;
+  VP8LInitBitReader(&dec->br_, io->data, io->data_size);
+  if (!ReadImageInfo(&dec->br_, &width, &height, &has_alpha)) {
+    dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
+    goto Error;
+  }
+  dec->state_ = READ_DIM;
+  io->width = width;
+  io->height = height;
+
+  dec->action_ = READ_HDR;
+  if (!DecodeImageStream(width, height, 1, dec, NULL)) goto Error;
+  return 1;
+
+ Error:
+  VP8LClear(dec);
+  assert(dec->status_ != VP8_STATUS_OK);
+  return 0;
+}
+
+int VP8LDecodeImage(VP8LDecoder* const dec) {
+  VP8Io* io = NULL;
+  WebPDecParams* params = NULL;
+
+  // Sanity checks.
+  if (dec == NULL) return 0;
+
+  io = dec->io_;
+  assert(io != NULL);
+  params = (WebPDecParams*)io->opaque;
+  assert(params != NULL);
+  dec->output_ = params->output;
+  assert(dec->output_ != NULL);
+
+  // Initialization.
+  if (!WebPIoInitFromOptions(params->options, io, MODE_BGRA)) {
+    dec->status_ = VP8_STATUS_INVALID_PARAM;
+    goto Err;
+  }
+
+  if (!AllocateInternalBuffers32b(dec, io->width)) goto Err;
+
+  if (io->use_scaling && !AllocateAndInitRescaler(dec, io)) goto Err;
+
+  // Decode.
+  dec->action_ = READ_DATA;
+  if (!DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_,
+                       dec->height_, ProcessRows)) {
+    goto Err;
+  }
+
+  // Cleanup.
+  params->last_y = dec->last_out_row_;
+  VP8LClear(dec);
+  return 1;
+
+ Err:
+  VP8LClear(dec);
+  assert(dec->status_ != VP8_STATUS_OK);
+  return 0;
+}
+
+//------------------------------------------------------------------------------
+
diff --git a/src/3rdparty/libwebp/src/dec/vp8li.h b/src/3rdparty/libwebp/src/dec/vp8li.h
new file mode 100644
index 0000000..afa294d
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/vp8li.h
@@ -0,0 +1,137 @@
+// Copyright 2012 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Lossless decoder: internal header.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+//         Vikas Arora(vikaas.arora@gmail.com)
+
+#ifndef WEBP_DEC_VP8LI_H_
+#define WEBP_DEC_VP8LI_H_
+
+#include <string.h>     // for memcpy()
+#include "./webpi.h"
+#include "../utils/bit_reader.h"
+#include "../utils/color_cache.h"
+#include "../utils/huffman.h"
+#include "../webp/format_constants.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum {
+  READ_DATA = 0,
+  READ_HDR = 1,
+  READ_DIM = 2
+} VP8LDecodeState;
+
+typedef struct VP8LTransform VP8LTransform;
+struct VP8LTransform {
+  VP8LImageTransformType type_;   // transform type.
+  int                    bits_;   // subsampling bits defining transform window.
+  int                    xsize_;  // transform window X index.
+  int                    ysize_;  // transform window Y index.
+  uint32_t              *data_;   // transform data.
+};
+
+typedef struct {
+  HuffmanTree htrees_[HUFFMAN_CODES_PER_META_CODE];
+} HTreeGroup;
+
+typedef struct {
+  int             color_cache_size_;
+  VP8LColorCache  color_cache_;
+
+  int             huffman_mask_;
+  int             huffman_subsample_bits_;
+  int             huffman_xsize_;
+  uint32_t       *huffman_image_;
+  int             num_htree_groups_;
+  HTreeGroup     *htree_groups_;
+} VP8LMetadata;
+
+typedef struct VP8LDecoder VP8LDecoder;
+struct VP8LDecoder {
+  VP8StatusCode    status_;
+  VP8LDecodeState  action_;
+  VP8LDecodeState  state_;
+  VP8Io           *io_;
+
+  const WebPDecBuffer *output_;    // shortcut to io->opaque->output
+
+  uint32_t        *pixels_;        // Internal data: either uint8_t* for alpha
+                                   // or uint32_t* for BGRA.
+  uint32_t        *argb_cache_;    // Scratch buffer for temporary BGRA storage.
+
+  VP8LBitReader    br_;
+
+  int              width_;
+  int              height_;
+  int              last_row_;      // last input row decoded so far.
+  int              last_pixel_;    // last pixel decoded so far. However, it may
+                                   // not be transformed, scaled and
+                                   // color-converted yet.
+  int              last_out_row_;  // last row output so far.
+
+  VP8LMetadata     hdr_;
+
+  int              next_transform_;
+  VP8LTransform    transforms_[NUM_TRANSFORMS];
+  // or'd bitset storing the transforms types.
+  uint32_t         transforms_seen_;
+
+  uint8_t         *rescaler_memory;  // Working memory for rescaling work.
+  WebPRescaler    *rescaler;         // Common rescaler for all channels.
+};
+
+//------------------------------------------------------------------------------
+// internal functions. Not public.
+
+struct ALPHDecoder;  // Defined in dec/alphai.h.
+
+// in vp8l.c
+
+// Decodes image header for alpha data stored using lossless compression.
+// Returns false in case of error.
+int VP8LDecodeAlphaHeader(struct ALPHDecoder* const alph_dec,
+                          const uint8_t* const data, size_t data_size,
+                          uint8_t* const output);
+
+// Decodes *at least* 'last_row' rows of alpha. If some of the initial rows are
+// already decoded in previous call(s), it will resume decoding from where it
+// was paused.
+// Returns false in case of bitstream error.
+int VP8LDecodeAlphaImageStream(struct ALPHDecoder* const alph_dec,
+                               int last_row);
+
+// Allocates and initialize a new lossless decoder instance.
+VP8LDecoder* VP8LNew(void);
+
+// Decodes the image header. Returns false in case of error.
+int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io);
+
+// Decodes an image. It's required to decode the lossless header before calling
+// this function. Returns false in case of error, with updated dec->status_.
+int VP8LDecodeImage(VP8LDecoder* const dec);
+
+// Resets the decoder in its initial state, reclaiming memory.
+// Preserves the dec->status_ value.
+void VP8LClear(VP8LDecoder* const dec);
+
+// Clears and deallocate a lossless decoder instance.
+void VP8LDelete(VP8LDecoder* const dec);
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_DEC_VP8LI_H_ */
diff --git a/src/3rdparty/libwebp/src/dec/webp.c b/src/3rdparty/libwebp/src/dec/webp.c
new file mode 100644
index 0000000..fda88bd
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/webp.c
@@ -0,0 +1,822 @@
+// Copyright 2010 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Main decoding functions for WEBP images.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <stdlib.h>
+
+#include "./vp8i.h"
+#include "./vp8li.h"
+#include "./webpi.h"
+#include "../webp/mux_types.h"  // ALPHA_FLAG
+
+//------------------------------------------------------------------------------
+// RIFF layout is:
+//   Offset  tag
+//   0...3   "RIFF" 4-byte tag
+//   4...7   size of image data (including metadata) starting at offset 8
+//   8...11  "WEBP"   our form-type signature
+// The RIFF container (12 bytes) is followed by appropriate chunks:
+//   12..15  "VP8 ": 4-bytes tags, signaling the use of VP8 video format
+//   16..19  size of the raw VP8 image data, starting at offset 20
+//   20....  the VP8 bytes
+// Or,
+//   12..15  "VP8L": 4-bytes tags, signaling the use of VP8L lossless format
+//   16..19  size of the raw VP8L image data, starting at offset 20
+//   20....  the VP8L bytes
+// Or,
+//   12..15  "VP8X": 4-bytes tags, describing the extended-VP8 chunk.
+//   16..19  size of the VP8X chunk starting at offset 20.
+//   20..23  VP8X flags bit-map corresponding to the chunk-types present.
+//   24..26  Width of the Canvas Image.
+//   27..29  Height of the Canvas Image.
+// There can be extra chunks after the "VP8X" chunk (ICCP, FRGM, ANMF, VP8,
+// VP8L, XMP, EXIF  ...)
+// All sizes are in little-endian order.
+// Note: chunk data size must be padded to multiple of 2 when written.
+
+static WEBP_INLINE uint32_t get_le24(const uint8_t* const data) {
+  return data[0] | (data[1] << 8) | (data[2] << 16);
+}
+
+static WEBP_INLINE uint32_t get_le32(const uint8_t* const data) {
+  return (uint32_t)get_le24(data) | (data[3] << 24);
+}
+
+// Validates the RIFF container (if detected) and skips over it.
+// If a RIFF container is detected,
+// Returns VP8_STATUS_BITSTREAM_ERROR for invalid header, and
+//         VP8_STATUS_OK otherwise.
+// In case there are not enough bytes (partial RIFF container), return 0 for
+// *riff_size. Else return the RIFF size extracted from the header.
+static VP8StatusCode ParseRIFF(const uint8_t** const data,
+                               size_t* const data_size,
+                               size_t* const riff_size) {
+  assert(data != NULL);
+  assert(data_size != NULL);
+  assert(riff_size != NULL);
+
+  *riff_size = 0;  // Default: no RIFF present.
+  if (*data_size >= RIFF_HEADER_SIZE && !memcmp(*data, "RIFF", TAG_SIZE)) {
+    if (memcmp(*data + 8, "WEBP", TAG_SIZE)) {
+      return VP8_STATUS_BITSTREAM_ERROR;  // Wrong image file signature.
+    } else {
+      const uint32_t size = get_le32(*data + TAG_SIZE);
+      // Check that we have at least one chunk (i.e "WEBP" + "VP8?nnnn").
+      if (size < TAG_SIZE + CHUNK_HEADER_SIZE) {
+        return VP8_STATUS_BITSTREAM_ERROR;
+      }
+      if (size > MAX_CHUNK_PAYLOAD) {
+        return VP8_STATUS_BITSTREAM_ERROR;
+      }
+      // We have a RIFF container. Skip it.
+      *riff_size = size;
+      *data += RIFF_HEADER_SIZE;
+      *data_size -= RIFF_HEADER_SIZE;
+    }
+  }
+  return VP8_STATUS_OK;
+}
+
+// Validates the VP8X header and skips over it.
+// Returns VP8_STATUS_BITSTREAM_ERROR for invalid VP8X header,
+//         VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
+//         VP8_STATUS_OK otherwise.
+// If a VP8X chunk is found, found_vp8x is set to true and *width_ptr,
+// *height_ptr and *flags_ptr are set to the corresponding values extracted
+// from the VP8X chunk.
+static VP8StatusCode ParseVP8X(const uint8_t** const data,
+                               size_t* const data_size,
+                               int* const found_vp8x,
+                               int* const width_ptr, int* const height_ptr,
+                               uint32_t* const flags_ptr) {
+  const uint32_t vp8x_size = CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE;
+  assert(data != NULL);
+  assert(data_size != NULL);
+  assert(found_vp8x != NULL);
+
+  *found_vp8x = 0;
+
+  if (*data_size < CHUNK_HEADER_SIZE) {
+    return VP8_STATUS_NOT_ENOUGH_DATA;  // Insufficient data.
+  }
+
+  if (!memcmp(*data, "VP8X", TAG_SIZE)) {
+    int width, height;
+    uint32_t flags;
+    const uint32_t chunk_size = get_le32(*data + TAG_SIZE);
+    if (chunk_size != VP8X_CHUNK_SIZE) {
+      return VP8_STATUS_BITSTREAM_ERROR;  // Wrong chunk size.
+    }
+
+    // Verify if enough data is available to validate the VP8X chunk.
+    if (*data_size < vp8x_size) {
+      return VP8_STATUS_NOT_ENOUGH_DATA;  // Insufficient data.
+    }
+    flags = get_le32(*data + 8);
+    width = 1 + get_le24(*data + 12);
+    height = 1 + get_le24(*data + 15);
+    if (width * (uint64_t)height >= MAX_IMAGE_AREA) {
+      return VP8_STATUS_BITSTREAM_ERROR;  // image is too large
+    }
+
+    if (flags_ptr != NULL) *flags_ptr = flags;
+    if (width_ptr != NULL) *width_ptr = width;
+    if (height_ptr != NULL) *height_ptr = height;
+    // Skip over VP8X header bytes.
+    *data += vp8x_size;
+    *data_size -= vp8x_size;
+    *found_vp8x = 1;
+  }
+  return VP8_STATUS_OK;
+}
+
+// Skips to the next VP8/VP8L chunk header in the data given the size of the
+// RIFF chunk 'riff_size'.
+// Returns VP8_STATUS_BITSTREAM_ERROR if any invalid chunk size is encountered,
+//         VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
+//         VP8_STATUS_OK otherwise.
+// If an alpha chunk is found, *alpha_data and *alpha_size are set
+// appropriately.
+static VP8StatusCode ParseOptionalChunks(const uint8_t** const data,
+                                         size_t* const data_size,
+                                         size_t const riff_size,
+                                         const uint8_t** const alpha_data,
+                                         size_t* const alpha_size) {
+  const uint8_t* buf;
+  size_t buf_size;
+  uint32_t total_size = TAG_SIZE +           // "WEBP".
+                        CHUNK_HEADER_SIZE +  // "VP8Xnnnn".
+                        VP8X_CHUNK_SIZE;     // data.
+  assert(data != NULL);
+  assert(data_size != NULL);
+  buf = *data;
+  buf_size = *data_size;
+
+  assert(alpha_data != NULL);
+  assert(alpha_size != NULL);
+  *alpha_data = NULL;
+  *alpha_size = 0;
+
+  while (1) {
+    uint32_t chunk_size;
+    uint32_t disk_chunk_size;   // chunk_size with padding
+
+    *data = buf;
+    *data_size = buf_size;
+
+    if (buf_size < CHUNK_HEADER_SIZE) {  // Insufficient data.
+      return VP8_STATUS_NOT_ENOUGH_DATA;
+    }
+
+    chunk_size = get_le32(buf + TAG_SIZE);
+    if (chunk_size > MAX_CHUNK_PAYLOAD) {
+      return VP8_STATUS_BITSTREAM_ERROR;          // Not a valid chunk size.
+    }
+    // For odd-sized chunk-payload, there's one byte padding at the end.
+    disk_chunk_size = (CHUNK_HEADER_SIZE + chunk_size + 1) & ~1;
+    total_size += disk_chunk_size;
+
+    // Check that total bytes skipped so far does not exceed riff_size.
+    if (riff_size > 0 && (total_size > riff_size)) {
+      return VP8_STATUS_BITSTREAM_ERROR;          // Not a valid chunk size.
+    }
+
+    // Start of a (possibly incomplete) VP8/VP8L chunk implies that we have
+    // parsed all the optional chunks.
+    // Note: This check must occur before the check 'buf_size < disk_chunk_size'
+    // below to allow incomplete VP8/VP8L chunks.
+    if (!memcmp(buf, "VP8 ", TAG_SIZE) ||
+        !memcmp(buf, "VP8L", TAG_SIZE)) {
+      return VP8_STATUS_OK;
+    }
+
+    if (buf_size < disk_chunk_size) {             // Insufficient data.
+      return VP8_STATUS_NOT_ENOUGH_DATA;
+    }
+
+    if (!memcmp(buf, "ALPH", TAG_SIZE)) {         // A valid ALPH header.
+      *alpha_data = buf + CHUNK_HEADER_SIZE;
+      *alpha_size = chunk_size;
+    }
+
+    // We have a full and valid chunk; skip it.
+    buf += disk_chunk_size;
+    buf_size -= disk_chunk_size;
+  }
+}
+
+// Validates the VP8/VP8L Header ("VP8 nnnn" or "VP8L nnnn") and skips over it.
+// Returns VP8_STATUS_BITSTREAM_ERROR for invalid (chunk larger than
+//         riff_size) VP8/VP8L header,
+//         VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
+//         VP8_STATUS_OK otherwise.
+// If a VP8/VP8L chunk is found, *chunk_size is set to the total number of bytes
+// extracted from the VP8/VP8L chunk header.
+// The flag '*is_lossless' is set to 1 in case of VP8L chunk / raw VP8L data.
+static VP8StatusCode ParseVP8Header(const uint8_t** const data_ptr,
+                                    size_t* const data_size,
+                                    size_t riff_size,
+                                    size_t* const chunk_size,
+                                    int* const is_lossless) {
+  const uint8_t* const data = *data_ptr;
+  const int is_vp8 = !memcmp(data, "VP8 ", TAG_SIZE);
+  const int is_vp8l = !memcmp(data, "VP8L", TAG_SIZE);
+  const uint32_t minimal_size =
+      TAG_SIZE + CHUNK_HEADER_SIZE;  // "WEBP" + "VP8 nnnn" OR
+                                     // "WEBP" + "VP8Lnnnn"
+  assert(data != NULL);
+  assert(data_size != NULL);
+  assert(chunk_size != NULL);
+  assert(is_lossless != NULL);
+
+  if (*data_size < CHUNK_HEADER_SIZE) {
+    return VP8_STATUS_NOT_ENOUGH_DATA;  // Insufficient data.
+  }
+
+  if (is_vp8 || is_vp8l) {
+    // Bitstream contains VP8/VP8L header.
+    const uint32_t size = get_le32(data + TAG_SIZE);
+    if ((riff_size >= minimal_size) && (size > riff_size - minimal_size)) {
+      return VP8_STATUS_BITSTREAM_ERROR;  // Inconsistent size information.
+    }
+    // Skip over CHUNK_HEADER_SIZE bytes from VP8/VP8L Header.
+    *chunk_size = size;
+    *data_ptr += CHUNK_HEADER_SIZE;
+    *data_size -= CHUNK_HEADER_SIZE;
+    *is_lossless = is_vp8l;
+  } else {
+    // Raw VP8/VP8L bitstream (no header).
+    *is_lossless = VP8LCheckSignature(data, *data_size);
+    *chunk_size = *data_size;
+  }
+
+  return VP8_STATUS_OK;
+}
+
+//------------------------------------------------------------------------------
+
+// Fetch '*width', '*height', '*has_alpha' and fill out 'headers' based on
+// 'data'. All the output parameters may be NULL. If 'headers' is NULL only the
+// minimal amount will be read to fetch the remaining parameters.
+// If 'headers' is non-NULL this function will attempt to locate both alpha
+// data (with or without a VP8X chunk) and the bitstream chunk (VP8/VP8L).
+// Note: The following chunk sequences (before the raw VP8/VP8L data) are
+// considered valid by this function:
+// RIFF + VP8(L)
+// RIFF + VP8X + (optional chunks) + VP8(L)
+// ALPH + VP8 <-- Not a valid WebP format: only allowed for internal purpose.
+// VP8(L)     <-- Not a valid WebP format: only allowed for internal purpose.
+static VP8StatusCode ParseHeadersInternal(const uint8_t* data,
+                                          size_t data_size,
+                                          int* const width,
+                                          int* const height,
+                                          int* const has_alpha,
+                                          int* const has_animation,
+                                          int* const format,
+                                          WebPHeaderStructure* const headers) {
+  int canvas_width = 0;
+  int canvas_height = 0;
+  int image_width = 0;
+  int image_height = 0;
+  int found_riff = 0;
+  int found_vp8x = 0;
+  int animation_present = 0;
+  int fragments_present = 0;
+
+  VP8StatusCode status;
+  WebPHeaderStructure hdrs;
+
+  if (data == NULL || data_size < RIFF_HEADER_SIZE) {
+    return VP8_STATUS_NOT_ENOUGH_DATA;
+  }
+  memset(&hdrs, 0, sizeof(hdrs));
+  hdrs.data = data;
+  hdrs.data_size = data_size;
+
+  // Skip over RIFF header.
+  status = ParseRIFF(&data, &data_size, &hdrs.riff_size);
+  if (status != VP8_STATUS_OK) {
+    return status;   // Wrong RIFF header / insufficient data.
+  }
+  found_riff = (hdrs.riff_size > 0);
+
+  // Skip over VP8X.
+  {
+    uint32_t flags = 0;
+    status = ParseVP8X(&data, &data_size, &found_vp8x,
+                       &canvas_width, &canvas_height, &flags);
+    if (status != VP8_STATUS_OK) {
+      return status;  // Wrong VP8X / insufficient data.
+    }
+    animation_present = !!(flags & ANIMATION_FLAG);
+    fragments_present = !!(flags & FRAGMENTS_FLAG);
+    if (!found_riff && found_vp8x) {
+      // Note: This restriction may be removed in the future, if it becomes
+      // necessary to send VP8X chunk to the decoder.
+      return VP8_STATUS_BITSTREAM_ERROR;
+    }
+    if (has_alpha != NULL) *has_alpha = !!(flags & ALPHA_FLAG);
+    if (has_animation != NULL) *has_animation = animation_present;
+    if (format != NULL) *format = 0;   // default = undefined
+
+    image_width = canvas_width;
+    image_height = canvas_height;
+    if (found_vp8x && (animation_present || fragments_present) &&
+        headers == NULL) {
+      status = VP8_STATUS_OK;
+      goto ReturnWidthHeight;  // Just return features from VP8X header.
+    }
+  }
+
+  if (data_size < TAG_SIZE) {
+    status = VP8_STATUS_NOT_ENOUGH_DATA;
+    goto ReturnWidthHeight;
+  }
+
+  // Skip over optional chunks if data started with "RIFF + VP8X" or "ALPH".
+  if ((found_riff && found_vp8x) ||
+      (!found_riff && !found_vp8x && !memcmp(data, "ALPH", TAG_SIZE))) {
+    status = ParseOptionalChunks(&data, &data_size, hdrs.riff_size,
+                                 &hdrs.alpha_data, &hdrs.alpha_data_size);
+    if (status != VP8_STATUS_OK) {
+      goto ReturnWidthHeight;  // Invalid chunk size / insufficient data.
+    }
+  }
+
+  // Skip over VP8/VP8L header.
+  status = ParseVP8Header(&data, &data_size, hdrs.riff_size,
+                          &hdrs.compressed_size, &hdrs.is_lossless);
+  if (status != VP8_STATUS_OK) {
+    goto ReturnWidthHeight;  // Wrong VP8/VP8L chunk-header / insufficient data.
+  }
+  if (hdrs.compressed_size > MAX_CHUNK_PAYLOAD) {
+    return VP8_STATUS_BITSTREAM_ERROR;
+  }
+
+  if (format != NULL && !(animation_present || fragments_present)) {
+    *format = hdrs.is_lossless ? 2 : 1;
+  }
+
+  if (!hdrs.is_lossless) {
+    if (data_size < VP8_FRAME_HEADER_SIZE) {
+      status = VP8_STATUS_NOT_ENOUGH_DATA;
+      goto ReturnWidthHeight;
+    }
+    // Validates raw VP8 data.
+    if (!VP8GetInfo(data, data_size, (uint32_t)hdrs.compressed_size,
+                    &image_width, &image_height)) {
+      return VP8_STATUS_BITSTREAM_ERROR;
+    }
+  } else {
+    if (data_size < VP8L_FRAME_HEADER_SIZE) {
+      status = VP8_STATUS_NOT_ENOUGH_DATA;
+      goto ReturnWidthHeight;
+    }
+    // Validates raw VP8L data.
+    if (!VP8LGetInfo(data, data_size, &image_width, &image_height, has_alpha)) {
+      return VP8_STATUS_BITSTREAM_ERROR;
+    }
+  }
+  // Validates image size coherency.
+  if (found_vp8x) {
+    if (canvas_width != image_width || canvas_height != image_height) {
+      return VP8_STATUS_BITSTREAM_ERROR;
+    }
+  }
+  if (headers != NULL) {
+    *headers = hdrs;
+    headers->offset = data - headers->data;
+    assert((uint64_t)(data - headers->data) < MAX_CHUNK_PAYLOAD);
+    assert(headers->offset == headers->data_size - data_size);
+  }
+ ReturnWidthHeight:
+  if (status == VP8_STATUS_OK ||
+      (status == VP8_STATUS_NOT_ENOUGH_DATA && found_vp8x && headers == NULL)) {
+    if (has_alpha != NULL) {
+      // If the data did not contain a VP8X/VP8L chunk the only definitive way
+      // to set this is by looking for alpha data (from an ALPH chunk).
+      *has_alpha |= (hdrs.alpha_data != NULL);
+    }
+    if (width != NULL) *width = image_width;
+    if (height != NULL) *height = image_height;
+    return VP8_STATUS_OK;
+  } else {
+    return status;
+  }
+}
+
+VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers) {
+  VP8StatusCode status;
+  int has_animation = 0;
+  assert(headers != NULL);
+  // fill out headers, ignore width/height/has_alpha.
+  status = ParseHeadersInternal(headers->data, headers->data_size,
+                                NULL, NULL, NULL, &has_animation,
+                                NULL, headers);
+  if (status == VP8_STATUS_OK || status == VP8_STATUS_NOT_ENOUGH_DATA) {
+    // TODO(jzern): full support of animation frames will require API additions.
+    if (has_animation) {
+      status = VP8_STATUS_UNSUPPORTED_FEATURE;
+    }
+  }
+  return status;
+}
+
+//------------------------------------------------------------------------------
+// WebPDecParams
+
+void WebPResetDecParams(WebPDecParams* const params) {
+  if (params != NULL) {
+    memset(params, 0, sizeof(*params));
+  }
+}
+
+//------------------------------------------------------------------------------
+// "Into" decoding variants
+
+// Main flow
+static VP8StatusCode DecodeInto(const uint8_t* const data, size_t data_size,
+                                WebPDecParams* const params) {
+  VP8StatusCode status;
+  VP8Io io;
+  WebPHeaderStructure headers;
+
+  headers.data = data;
+  headers.data_size = data_size;
+  status = WebPParseHeaders(&headers);   // Process Pre-VP8 chunks.
+  if (status != VP8_STATUS_OK) {
+    return status;
+  }
+
+  assert(params != NULL);
+  VP8InitIo(&io);
+  io.data = headers.data + headers.offset;
+  io.data_size = headers.data_size - headers.offset;
+  WebPInitCustomIo(params, &io);  // Plug the I/O functions.
+
+  if (!headers.is_lossless) {
+    VP8Decoder* const dec = VP8New();
+    if (dec == NULL) {
+      return VP8_STATUS_OUT_OF_MEMORY;
+    }
+    dec->alpha_data_ = headers.alpha_data;
+    dec->alpha_data_size_ = headers.alpha_data_size;
+
+    // Decode bitstream header, update io->width/io->height.
+    if (!VP8GetHeaders(dec, &io)) {
+      status = dec->status_;   // An error occurred. Grab error status.
+    } else {
+      // Allocate/check output buffers.
+      status = WebPAllocateDecBuffer(io.width, io.height, params->options,
+                                     params->output);
+      if (status == VP8_STATUS_OK) {  // Decode
+        // This change must be done before calling VP8Decode()
+        dec->mt_method_ = VP8GetThreadMethod(params->options, &headers,
+                                             io.width, io.height);
+        VP8InitDithering(params->options, dec);
+        if (!VP8Decode(dec, &io)) {
+          status = dec->status_;
+        }
+      }
+    }
+    VP8Delete(dec);
+  } else {
+    VP8LDecoder* const dec = VP8LNew();
+    if (dec == NULL) {
+      return VP8_STATUS_OUT_OF_MEMORY;
+    }
+    if (!VP8LDecodeHeader(dec, &io)) {
+      status = dec->status_;   // An error occurred. Grab error status.
+    } else {
+      // Allocate/check output buffers.
+      status = WebPAllocateDecBuffer(io.width, io.height, params->options,
+                                     params->output);
+      if (status == VP8_STATUS_OK) {  // Decode
+        if (!VP8LDecodeImage(dec)) {
+          status = dec->status_;
+        }
+      }
+    }
+    VP8LDelete(dec);
+  }
+
+  if (status != VP8_STATUS_OK) {
+    WebPFreeDecBuffer(params->output);
+  }
+  return status;
+}
+
+// Helpers
+static uint8_t* DecodeIntoRGBABuffer(WEBP_CSP_MODE colorspace,
+                                     const uint8_t* const data,
+                                     size_t data_size,
+                                     uint8_t* const rgba,
+                                     int stride, size_t size) {
+  WebPDecParams params;
+  WebPDecBuffer buf;
+  if (rgba == NULL) {
+    return NULL;
+  }
+  WebPInitDecBuffer(&buf);
+  WebPResetDecParams(&params);
+  params.output = &buf;
+  buf.colorspace    = colorspace;
+  buf.u.RGBA.rgba   = rgba;
+  buf.u.RGBA.stride = stride;
+  buf.u.RGBA.size   = size;
+  buf.is_external_memory = 1;
+  if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
+    return NULL;
+  }
+  return rgba;
+}
+
+uint8_t* WebPDecodeRGBInto(const uint8_t* data, size_t data_size,
+                           uint8_t* output, size_t size, int stride) {
+  return DecodeIntoRGBABuffer(MODE_RGB, data, data_size, output, stride, size);
+}
+
+uint8_t* WebPDecodeRGBAInto(const uint8_t* data, size_t data_size,
+                            uint8_t* output, size_t size, int stride) {
+  return DecodeIntoRGBABuffer(MODE_RGBA, data, data_size, output, stride, size);
+}
+
+uint8_t* WebPDecodeARGBInto(const uint8_t* data, size_t data_size,
+                            uint8_t* output, size_t size, int stride) {
+  return DecodeIntoRGBABuffer(MODE_ARGB, data, data_size, output, stride, size);
+}
+
+uint8_t* WebPDecodeBGRInto(const uint8_t* data, size_t data_size,
+                           uint8_t* output, size_t size, int stride) {
+  return DecodeIntoRGBABuffer(MODE_BGR, data, data_size, output, stride, size);
+}
+
+uint8_t* WebPDecodeBGRAInto(const uint8_t* data, size_t data_size,
+                            uint8_t* output, size_t size, int stride) {
+  return DecodeIntoRGBABuffer(MODE_BGRA, data, data_size, output, stride, size);
+}
+
+uint8_t* WebPDecodeYUVInto(const uint8_t* data, size_t data_size,
+                           uint8_t* luma, size_t luma_size, int luma_stride,
+                           uint8_t* u, size_t u_size, int u_stride,
+                           uint8_t* v, size_t v_size, int v_stride) {
+  WebPDecParams params;
+  WebPDecBuffer output;
+  if (luma == NULL) return NULL;
+  WebPInitDecBuffer(&output);
+  WebPResetDecParams(&params);
+  params.output = &output;
+  output.colorspace      = MODE_YUV;
+  output.u.YUVA.y        = luma;
+  output.u.YUVA.y_stride = luma_stride;
+  output.u.YUVA.y_size   = luma_size;
+  output.u.YUVA.u        = u;
+  output.u.YUVA.u_stride = u_stride;
+  output.u.YUVA.u_size   = u_size;
+  output.u.YUVA.v        = v;
+  output.u.YUVA.v_stride = v_stride;
+  output.u.YUVA.v_size   = v_size;
+  output.is_external_memory = 1;
+  if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
+    return NULL;
+  }
+  return luma;
+}
+
+//------------------------------------------------------------------------------
+
+static uint8_t* Decode(WEBP_CSP_MODE mode, const uint8_t* const data,
+                       size_t data_size, int* const width, int* const height,
+                       WebPDecBuffer* const keep_info) {
+  WebPDecParams params;
+  WebPDecBuffer output;
+
+  WebPInitDecBuffer(&output);
+  WebPResetDecParams(&params);
+  params.output = &output;
+  output.colorspace = mode;
+
+  // Retrieve (and report back) the required dimensions from bitstream.
+  if (!WebPGetInfo(data, data_size, &output.width, &output.height)) {
+    return NULL;
+  }
+  if (width != NULL) *width = output.width;
+  if (height != NULL) *height = output.height;
+
+  // Decode
+  if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
+    return NULL;
+  }
+  if (keep_info != NULL) {    // keep track of the side-info
+    WebPCopyDecBuffer(&output, keep_info);
+  }
+  // return decoded samples (don't clear 'output'!)
+  return WebPIsRGBMode(mode) ? output.u.RGBA.rgba : output.u.YUVA.y;
+}
+
+uint8_t* WebPDecodeRGB(const uint8_t* data, size_t data_size,
+                       int* width, int* height) {
+  return Decode(MODE_RGB, data, data_size, width, height, NULL);
+}
+
+uint8_t* WebPDecodeRGBA(const uint8_t* data, size_t data_size,
+                        int* width, int* height) {
+  return Decode(MODE_RGBA, data, data_size, width, height, NULL);
+}
+
+uint8_t* WebPDecodeARGB(const uint8_t* data, size_t data_size,
+                        int* width, int* height) {
+  return Decode(MODE_ARGB, data, data_size, width, height, NULL);
+}
+
+uint8_t* WebPDecodeBGR(const uint8_t* data, size_t data_size,
+                       int* width, int* height) {
+  return Decode(MODE_BGR, data, data_size, width, height, NULL);
+}
+
+uint8_t* WebPDecodeBGRA(const uint8_t* data, size_t data_size,
+                        int* width, int* height) {
+  return Decode(MODE_BGRA, data, data_size, width, height, NULL);
+}
+
+uint8_t* WebPDecodeYUV(const uint8_t* data, size_t data_size,
+                       int* width, int* height, uint8_t** u, uint8_t** v,
+                       int* stride, int* uv_stride) {
+  WebPDecBuffer output;   // only to preserve the side-infos
+  uint8_t* const out = Decode(MODE_YUV, data, data_size,
+                              width, height, &output);
+
+  if (out != NULL) {
+    const WebPYUVABuffer* const buf = &output.u.YUVA;
+    *u = buf->u;
+    *v = buf->v;
+    *stride = buf->y_stride;
+    *uv_stride = buf->u_stride;
+    assert(buf->u_stride == buf->v_stride);
+  }
+  return out;
+}
+
+static void DefaultFeatures(WebPBitstreamFeatures* const features) {
+  assert(features != NULL);
+  memset(features, 0, sizeof(*features));
+}
+
+static VP8StatusCode GetFeatures(const uint8_t* const data, size_t data_size,
+                                 WebPBitstreamFeatures* const features) {
+  if (features == NULL || data == NULL) {
+    return VP8_STATUS_INVALID_PARAM;
+  }
+  DefaultFeatures(features);
+
+  // Only parse enough of the data to retrieve the features.
+  return ParseHeadersInternal(data, data_size,
+                              &features->width, &features->height,
+                              &features->has_alpha, &features->has_animation,
+                              &features->format, NULL);
+}
+
+//------------------------------------------------------------------------------
+// WebPGetInfo()
+
+int WebPGetInfo(const uint8_t* data, size_t data_size,
+                int* width, int* height) {
+  WebPBitstreamFeatures features;
+
+  if (GetFeatures(data, data_size, &features) != VP8_STATUS_OK) {
+    return 0;
+  }
+
+  if (width != NULL) {
+    *width  = features.width;
+  }
+  if (height != NULL) {
+    *height = features.height;
+  }
+
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+// Advance decoding API
+
+int WebPInitDecoderConfigInternal(WebPDecoderConfig* config,
+                                  int version) {
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
+    return 0;   // version mismatch
+  }
+  if (config == NULL) {
+    return 0;
+  }
+  memset(config, 0, sizeof(*config));
+  DefaultFeatures(&config->input);
+  WebPInitDecBuffer(&config->output);
+  return 1;
+}
+
+VP8StatusCode WebPGetFeaturesInternal(const uint8_t* data, size_t data_size,
+                                      WebPBitstreamFeatures* features,
+                                      int version) {
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
+    return VP8_STATUS_INVALID_PARAM;   // version mismatch
+  }
+  if (features == NULL) {
+    return VP8_STATUS_INVALID_PARAM;
+  }
+  return GetFeatures(data, data_size, features);
+}
+
+VP8StatusCode WebPDecode(const uint8_t* data, size_t data_size,
+                         WebPDecoderConfig* config) {
+  WebPDecParams params;
+  VP8StatusCode status;
+
+  if (config == NULL) {
+    return VP8_STATUS_INVALID_PARAM;
+  }
+
+  status = GetFeatures(data, data_size, &config->input);
+  if (status != VP8_STATUS_OK) {
+    if (status == VP8_STATUS_NOT_ENOUGH_DATA) {
+      return VP8_STATUS_BITSTREAM_ERROR;  // Not-enough-data treated as error.
+    }
+    return status;
+  }
+
+  WebPResetDecParams(&params);
+  params.output = &config->output;
+  params.options = &config->options;
+  status = DecodeInto(data, data_size, &params);
+
+  return status;
+}
+
+//------------------------------------------------------------------------------
+// Cropping and rescaling.
+
+int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
+                          VP8Io* const io, WEBP_CSP_MODE src_colorspace) {
+  const int W = io->width;
+  const int H = io->height;
+  int x = 0, y = 0, w = W, h = H;
+
+  // Cropping
+  io->use_cropping = (options != NULL) && (options->use_cropping > 0);
+  if (io->use_cropping) {
+    w = options->crop_width;
+    h = options->crop_height;
+    x = options->crop_left;
+    y = options->crop_top;
+    if (!WebPIsRGBMode(src_colorspace)) {   // only snap for YUV420 or YUV422
+      x &= ~1;
+      y &= ~1;    // TODO(later): only for YUV420, not YUV422.
+    }
+    if (x < 0 || y < 0 || w <= 0 || h <= 0 || x + w > W || y + h > H) {
+      return 0;  // out of frame boundary error
+    }
+  }
+  io->crop_left   = x;
+  io->crop_top    = y;
+  io->crop_right  = x + w;
+  io->crop_bottom = y + h;
+  io->mb_w = w;
+  io->mb_h = h;
+
+  // Scaling
+  io->use_scaling = (options != NULL) && (options->use_scaling > 0);
+  if (io->use_scaling) {
+    if (options->scaled_width <= 0 || options->scaled_height <= 0) {
+      return 0;
+    }
+    io->scaled_width = options->scaled_width;
+    io->scaled_height = options->scaled_height;
+  }
+
+  // Filter
+  io->bypass_filtering = options && options->bypass_filtering;
+
+  // Fancy upsampler
+#ifdef FANCY_UPSAMPLING
+  io->fancy_upsampling = (options == NULL) || (!options->no_fancy_upsampling);
+#endif
+
+  if (io->use_scaling) {
+    // disable filter (only for large downscaling ratio).
+    io->bypass_filtering = (io->scaled_width < W * 3 / 4) &&
+                           (io->scaled_height < H * 3 / 4);
+    io->fancy_upsampling = 0;
+  }
+  return 1;
+}
+
+//------------------------------------------------------------------------------
+
diff --git a/src/3rdparty/libwebp/src/dec/webpi.h b/src/3rdparty/libwebp/src/dec/webpi.h
new file mode 100644
index 0000000..d915f5e
--- /dev/null
+++ b/src/3rdparty/libwebp/src/dec/webpi.h
@@ -0,0 +1,116 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Internal header: WebP decoding parameters and custom IO on buffer
+//
+// Author: somnath@google.com (Somnath Banerjee)
+
+#ifndef WEBP_DEC_WEBPI_H_
+#define WEBP_DEC_WEBPI_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "../utils/rescaler.h"
+#include "./decode_vp8.h"
+
+//------------------------------------------------------------------------------
+// WebPDecParams: Decoding output parameters. Transient internal object.
+
+typedef struct WebPDecParams WebPDecParams;
+typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p);
+typedef int (*OutputRowFunc)(WebPDecParams* const p, int y_pos);
+
+struct WebPDecParams {
+  WebPDecBuffer* output;             // output buffer.
+  uint8_t* tmp_y, *tmp_u, *tmp_v;    // cache for the fancy upsampler
+                                     // or used for tmp rescaling
+
+  int last_y;                 // coordinate of the line that was last output
+  const WebPDecoderOptions* options;  // if not NULL, use alt decoding features
+  // rescalers
+  WebPRescaler scaler_y, scaler_u, scaler_v, scaler_a;
+  void* memory;                  // overall scratch memory for the output work.
+
+  OutputFunc emit;               // output RGB or YUV samples
+  OutputFunc emit_alpha;         // output alpha channel
+  OutputRowFunc emit_alpha_row;  // output one line of rescaled alpha values
+};
+
+// Should be called first, before any use of the WebPDecParams object.
+void WebPResetDecParams(WebPDecParams* const params);
+
+//------------------------------------------------------------------------------
+// Header parsing helpers
+
+// Structure storing a description of the RIFF headers.
+typedef struct {
+  const uint8_t* data;         // input buffer
+  size_t data_size;            // input buffer size
+  size_t offset;               // offset to main data chunk (VP8 or VP8L)
+  const uint8_t* alpha_data;   // points to alpha chunk (if present)
+  size_t alpha_data_size;      // alpha chunk size
+  size_t compressed_size;      // VP8/VP8L compressed data size
+  size_t riff_size;            // size of the riff payload (or 0 if absent)
+  int is_lossless;             // true if a VP8L chunk is present
+} WebPHeaderStructure;
+
+// Skips over all valid chunks prior to the first VP8/VP8L frame header.
+// Returns: VP8_STATUS_OK, VP8_STATUS_BITSTREAM_ERROR (invalid header/chunk),
+// VP8_STATUS_NOT_ENOUGH_DATA (partial input) or VP8_STATUS_UNSUPPORTED_FEATURE
+// in the case of non-decodable features (animation for instance).
+// In 'headers', compressed_size, offset, alpha_data, alpha_size, and lossless
+// fields are updated appropriately upon success.
+VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers);
+
+//------------------------------------------------------------------------------
+// Misc utils
+
+// Initializes VP8Io with custom setup, io and teardown functions. The default
+// hooks will use the supplied 'params' as io->opaque handle.
+void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io);
+
+// Setup crop_xxx fields, mb_w and mb_h in io. 'src_colorspace' refers
+// to the *compressed* format, not the output one.
+int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
+                          VP8Io* const io, WEBP_CSP_MODE src_colorspace);
+
+//------------------------------------------------------------------------------
+// Internal functions regarding WebPDecBuffer memory (in buffer.c).
+// Don't really need to be externally visible for now.
+
+// Prepare 'buffer' with the requested initial dimensions width/height.
+// If no external storage is supplied, initializes buffer by allocating output
+// memory and setting up the stride information. Validate the parameters. Return
+// an error code in case of problem (no memory, or invalid stride / size /
+// dimension / etc.). If *options is not NULL, also verify that the options'
+// parameters are valid and apply them to the width/height dimensions of the
+// output buffer. This takes cropping / scaling / rotation into account.
+VP8StatusCode WebPAllocateDecBuffer(int width, int height,
+                                    const WebPDecoderOptions* const options,
+                                    WebPDecBuffer* const buffer);
+
+// Copy 'src' into 'dst' buffer, making sure 'dst' is not marked as owner of the
+// memory (still held by 'src').
+void WebPCopyDecBuffer(const WebPDecBuffer* const src,
+                       WebPDecBuffer* const dst);
+
+// Copy and transfer ownership from src to dst (beware of parameter order!)
+void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst);
+
+
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_DEC_WEBPI_H_ */