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>

4 files changed, 1973 insertions, 0 deletions

diff --git a/src/3rdparty/libwebp/src/mux/muxedit.c b/src/3rdparty/libwebp/src/mux/muxedit.c
new file mode 100644
index 0000000..25770b3
--- /dev/null
+++ b/src/3rdparty/libwebp/src/mux/muxedit.c
@@ -0,0 +1,652 @@
+// 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.
+// -----------------------------------------------------------------------------
+//
+// Set and delete APIs for mux.
+//
+// Authors: Urvang (urvang@google.com)
+//          Vikas (vikasa@google.com)
+
+#include <assert.h>
+#include "./muxi.h"
+#include "../utils/utils.h"
+
+//------------------------------------------------------------------------------
+// Life of a mux object.
+
+static void MuxInit(WebPMux* const mux) {
+  if (mux == NULL) return;
+  memset(mux, 0, sizeof(*mux));
+}
+
+WebPMux* WebPNewInternal(int version) {
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_MUX_ABI_VERSION)) {
+    return NULL;
+  } else {
+    WebPMux* const mux = (WebPMux*)malloc(sizeof(WebPMux));
+    // If mux is NULL MuxInit is a noop.
+    MuxInit(mux);
+    return mux;
+  }
+}
+
+// Delete all images in 'wpi_list'.
+static void DeleteAllImages(WebPMuxImage** const wpi_list) {
+  while (*wpi_list != NULL) {
+    *wpi_list = MuxImageDelete(*wpi_list);
+  }
+}
+
+static void MuxRelease(WebPMux* const mux) {
+  if (mux == NULL) return;
+  DeleteAllImages(&mux->images_);
+  ChunkListDelete(&mux->vp8x_);
+  ChunkListDelete(&mux->iccp_);
+  ChunkListDelete(&mux->anim_);
+  ChunkListDelete(&mux->exif_);
+  ChunkListDelete(&mux->xmp_);
+  ChunkListDelete(&mux->unknown_);
+}
+
+void WebPMuxDelete(WebPMux* mux) {
+  // If mux is NULL MuxRelease is a noop.
+  MuxRelease(mux);
+  free(mux);
+}
+
+//------------------------------------------------------------------------------
+// Helper method(s).
+
+// Handy MACRO, makes MuxSet() very symmetric to MuxGet().
+#define SWITCH_ID_LIST(INDEX, LIST)                                            \
+  if (idx == (INDEX)) {                                                        \
+    err = ChunkAssignData(&chunk, data, copy_data, tag);                       \
+    if (err == WEBP_MUX_OK) {                                                  \
+      err = ChunkSetNth(&chunk, (LIST), nth);                                  \
+    }                                                                          \
+    return err;                                                                \
+  }
+
+static WebPMuxError MuxSet(WebPMux* const mux, uint32_t tag, uint32_t nth,
+                           const WebPData* const data, int copy_data) {
+  WebPChunk chunk;
+  WebPMuxError err = WEBP_MUX_NOT_FOUND;
+  const CHUNK_INDEX idx = ChunkGetIndexFromTag(tag);
+  assert(mux != NULL);
+  assert(!IsWPI(kChunks[idx].id));
+
+  ChunkInit(&chunk);
+  SWITCH_ID_LIST(IDX_VP8X,    &mux->vp8x_);
+  SWITCH_ID_LIST(IDX_ICCP,    &mux->iccp_);
+  SWITCH_ID_LIST(IDX_ANIM,    &mux->anim_);
+  SWITCH_ID_LIST(IDX_EXIF,    &mux->exif_);
+  SWITCH_ID_LIST(IDX_XMP,     &mux->xmp_);
+  SWITCH_ID_LIST(IDX_UNKNOWN, &mux->unknown_);
+  return err;
+}
+#undef SWITCH_ID_LIST
+
+// Create data for frame/fragment given image data, offsets and duration.
+static WebPMuxError CreateFrameFragmentData(
+    int width, int height, const WebPMuxFrameInfo* const info, int is_frame,
+    WebPData* const frame_frgm) {
+  uint8_t* frame_frgm_bytes;
+  const size_t frame_frgm_size = kChunks[is_frame ? IDX_ANMF : IDX_FRGM].size;
+
+  assert(width > 0 && height > 0 && info->duration >= 0);
+  assert(info->dispose_method == (info->dispose_method & 1));
+  // Note: assertion on upper bounds is done in PutLE24().
+
+  frame_frgm_bytes = (uint8_t*)malloc(frame_frgm_size);
+  if (frame_frgm_bytes == NULL) return WEBP_MUX_MEMORY_ERROR;
+
+  PutLE24(frame_frgm_bytes + 0, info->x_offset / 2);
+  PutLE24(frame_frgm_bytes + 3, info->y_offset / 2);
+
+  if (is_frame) {
+    PutLE24(frame_frgm_bytes + 6, width - 1);
+    PutLE24(frame_frgm_bytes + 9, height - 1);
+    PutLE24(frame_frgm_bytes + 12, info->duration);
+    frame_frgm_bytes[15] =
+        (info->blend_method == WEBP_MUX_NO_BLEND ? 2 : 0) |
+        (info->dispose_method == WEBP_MUX_DISPOSE_BACKGROUND ? 1 : 0);
+  }
+
+  frame_frgm->bytes = frame_frgm_bytes;
+  frame_frgm->size = frame_frgm_size;
+  return WEBP_MUX_OK;
+}
+
+// Outputs image data given a bitstream. The bitstream can either be a
+// single-image WebP file or raw VP8/VP8L data.
+// Also outputs 'is_lossless' to be true if the given bitstream is lossless.
+static WebPMuxError GetImageData(const WebPData* const bitstream,
+                                 WebPData* const image, WebPData* const alpha,
+                                 int* const is_lossless) {
+  WebPDataInit(alpha);  // Default: no alpha.
+  if (bitstream->size < TAG_SIZE ||
+      memcmp(bitstream->bytes, "RIFF", TAG_SIZE)) {
+    // It is NOT webp file data. Return input data as is.
+    *image = *bitstream;
+  } else {
+    // It is webp file data. Extract image data from it.
+    const WebPMuxImage* wpi;
+    WebPMux* const mux = WebPMuxCreate(bitstream, 0);
+    if (mux == NULL) return WEBP_MUX_BAD_DATA;
+    wpi = mux->images_;
+    assert(wpi != NULL && wpi->img_ != NULL);
+    *image = wpi->img_->data_;
+    if (wpi->alpha_ != NULL) {
+      *alpha = wpi->alpha_->data_;
+    }
+    WebPMuxDelete(mux);
+  }
+  *is_lossless = VP8LCheckSignature(image->bytes, image->size);
+  return WEBP_MUX_OK;
+}
+
+static WebPMuxError DeleteChunks(WebPChunk** chunk_list, uint32_t tag) {
+  WebPMuxError err = WEBP_MUX_NOT_FOUND;
+  assert(chunk_list);
+  while (*chunk_list) {
+    WebPChunk* const chunk = *chunk_list;
+    if (chunk->tag_ == tag) {
+      *chunk_list = ChunkDelete(chunk);
+      err = WEBP_MUX_OK;
+    } else {
+      chunk_list = &chunk->next_;
+    }
+  }
+  return err;
+}
+
+static WebPMuxError MuxDeleteAllNamedData(WebPMux* const mux, uint32_t tag) {
+  const WebPChunkId id = ChunkGetIdFromTag(tag);
+  assert(mux != NULL);
+  if (IsWPI(id)) return WEBP_MUX_INVALID_ARGUMENT;
+  return DeleteChunks(MuxGetChunkListFromId(mux, id), tag);
+}
+
+//------------------------------------------------------------------------------
+// Set API(s).
+
+WebPMuxError WebPMuxSetChunk(WebPMux* mux, const char fourcc[4],
+                             const WebPData* chunk_data, int copy_data) {
+  uint32_t tag;
+  WebPMuxError err;
+  if (mux == NULL || fourcc == NULL || chunk_data == NULL ||
+      chunk_data->bytes == NULL || chunk_data->size > MAX_CHUNK_PAYLOAD) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+  tag = ChunkGetTagFromFourCC(fourcc);
+
+  // Delete existing chunk(s) with the same 'fourcc'.
+  err = MuxDeleteAllNamedData(mux, tag);
+  if (err != WEBP_MUX_OK && err != WEBP_MUX_NOT_FOUND) return err;
+
+  // Add the given chunk.
+  return MuxSet(mux, tag, 1, chunk_data, copy_data);
+}
+
+// Creates a chunk from given 'data' and sets it as 1st chunk in 'chunk_list'.
+static WebPMuxError AddDataToChunkList(
+    const WebPData* const data, int copy_data, uint32_t tag,
+    WebPChunk** chunk_list) {
+  WebPChunk chunk;
+  WebPMuxError err;
+  ChunkInit(&chunk);
+  err = ChunkAssignData(&chunk, data, copy_data, tag);
+  if (err != WEBP_MUX_OK) goto Err;
+  err = ChunkSetNth(&chunk, chunk_list, 1);
+  if (err != WEBP_MUX_OK) goto Err;
+  return WEBP_MUX_OK;
+ Err:
+  ChunkRelease(&chunk);
+  return err;
+}
+
+// Extracts image & alpha data from the given bitstream and then sets wpi.alpha_
+// and wpi.img_ appropriately.
+static WebPMuxError SetAlphaAndImageChunks(
+    const WebPData* const bitstream, int copy_data, WebPMuxImage* const wpi) {
+  int is_lossless = 0;
+  WebPData image, alpha;
+  WebPMuxError err = GetImageData(bitstream, &image, &alpha, &is_lossless);
+  const int image_tag =
+      is_lossless ? kChunks[IDX_VP8L].tag : kChunks[IDX_VP8].tag;
+  if (err != WEBP_MUX_OK) return err;
+  if (alpha.bytes != NULL) {
+    err = AddDataToChunkList(&alpha, copy_data, kChunks[IDX_ALPHA].tag,
+                             &wpi->alpha_);
+    if (err != WEBP_MUX_OK) return err;
+  }
+  err = AddDataToChunkList(&image, copy_data, image_tag, &wpi->img_);
+  if (err != WEBP_MUX_OK) return err;
+  return MuxImageFinalize(wpi) ? WEBP_MUX_OK : WEBP_MUX_INVALID_ARGUMENT;
+}
+
+WebPMuxError WebPMuxSetImage(WebPMux* mux, const WebPData* bitstream,
+                             int copy_data) {
+  WebPMuxImage wpi;
+  WebPMuxError err;
+
+  // Sanity checks.
+  if (mux == NULL || bitstream == NULL || bitstream->bytes == NULL ||
+      bitstream->size > MAX_CHUNK_PAYLOAD) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+
+  if (mux->images_ != NULL) {
+    // Only one 'simple image' can be added in mux. So, remove present images.
+    DeleteAllImages(&mux->images_);
+  }
+
+  MuxImageInit(&wpi);
+  err = SetAlphaAndImageChunks(bitstream, copy_data, &wpi);
+  if (err != WEBP_MUX_OK) goto Err;
+
+  // Add this WebPMuxImage to mux.
+  err = MuxImagePush(&wpi, &mux->images_);
+  if (err != WEBP_MUX_OK) goto Err;
+
+  // All is well.
+  return WEBP_MUX_OK;
+
+ Err:  // Something bad happened.
+  MuxImageRelease(&wpi);
+  return err;
+}
+
+WebPMuxError WebPMuxPushFrame(WebPMux* mux, const WebPMuxFrameInfo* frame,
+                              int copy_data) {
+  WebPMuxImage wpi;
+  WebPMuxError err;
+  int is_frame;
+  const WebPData* const bitstream = &frame->bitstream;
+
+  // Sanity checks.
+  if (mux == NULL || frame == NULL) return WEBP_MUX_INVALID_ARGUMENT;
+
+  is_frame = (frame->id == WEBP_CHUNK_ANMF);
+  if (!(is_frame || (frame->id == WEBP_CHUNK_FRGM))) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+#ifndef WEBP_EXPERIMENTAL_FEATURES
+  if (frame->id == WEBP_CHUNK_FRGM) {     // disabled for now.
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+#endif
+
+  if (bitstream->bytes == NULL || bitstream->size > MAX_CHUNK_PAYLOAD) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+
+  if (mux->images_ != NULL) {
+    const WebPMuxImage* const image = mux->images_;
+    const uint32_t image_id = (image->header_ != NULL) ?
+        ChunkGetIdFromTag(image->header_->tag_) : WEBP_CHUNK_IMAGE;
+    if (image_id != frame->id) {
+      return WEBP_MUX_INVALID_ARGUMENT;  // Conflicting frame types.
+    }
+  }
+
+  MuxImageInit(&wpi);
+  err = SetAlphaAndImageChunks(bitstream, copy_data, &wpi);
+  if (err != WEBP_MUX_OK) goto Err;
+  assert(wpi.img_ != NULL);  // As SetAlphaAndImageChunks() was successful.
+
+  {
+    WebPData frame_frgm;
+    const uint32_t tag = kChunks[is_frame ? IDX_ANMF : IDX_FRGM].tag;
+    WebPMuxFrameInfo tmp = *frame;
+    tmp.x_offset &= ~1;  // Snap offsets to even.
+    tmp.y_offset &= ~1;
+    if (!is_frame) {  // Reset unused values.
+      tmp.duration = 1;
+      tmp.dispose_method = WEBP_MUX_DISPOSE_NONE;
+      tmp.blend_method = WEBP_MUX_BLEND;
+    }
+    if (tmp.x_offset < 0 || tmp.x_offset >= MAX_POSITION_OFFSET ||
+        tmp.y_offset < 0 || tmp.y_offset >= MAX_POSITION_OFFSET ||
+        (tmp.duration < 0 || tmp.duration >= MAX_DURATION) ||
+        tmp.dispose_method != (tmp.dispose_method & 1)) {
+      err = WEBP_MUX_INVALID_ARGUMENT;
+      goto Err;
+    }
+    err = CreateFrameFragmentData(wpi.width_, wpi.height_, &tmp, is_frame,
+                                  &frame_frgm);
+    if (err != WEBP_MUX_OK) goto Err;
+    // Add frame/fragment chunk (with copy_data = 1).
+    err = AddDataToChunkList(&frame_frgm, 1, tag, &wpi.header_);
+    WebPDataClear(&frame_frgm);  // frame_frgm owned by wpi.header_ now.
+    if (err != WEBP_MUX_OK) goto Err;
+  }
+
+  // Add this WebPMuxImage to mux.
+  err = MuxImagePush(&wpi, &mux->images_);
+  if (err != WEBP_MUX_OK) goto Err;
+
+  // All is well.
+  return WEBP_MUX_OK;
+
+ Err:  // Something bad happened.
+  MuxImageRelease(&wpi);
+  return err;
+}
+
+WebPMuxError WebPMuxSetAnimationParams(WebPMux* mux,
+                                       const WebPMuxAnimParams* params) {
+  WebPMuxError err;
+  uint8_t data[ANIM_CHUNK_SIZE];
+  const WebPData anim = { data, ANIM_CHUNK_SIZE };
+
+  if (mux == NULL || params == NULL) return WEBP_MUX_INVALID_ARGUMENT;
+  if (params->loop_count < 0 || params->loop_count >= MAX_LOOP_COUNT) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+
+  // Delete any existing ANIM chunk(s).
+  err = MuxDeleteAllNamedData(mux, kChunks[IDX_ANIM].tag);
+  if (err != WEBP_MUX_OK && err != WEBP_MUX_NOT_FOUND) return err;
+
+  // Set the animation parameters.
+  PutLE32(data, params->bgcolor);
+  PutLE16(data + 4, params->loop_count);
+  return MuxSet(mux, kChunks[IDX_ANIM].tag, 1, &anim, 1);
+}
+
+//------------------------------------------------------------------------------
+// Delete API(s).
+
+WebPMuxError WebPMuxDeleteChunk(WebPMux* mux, const char fourcc[4]) {
+  if (mux == NULL || fourcc == NULL) return WEBP_MUX_INVALID_ARGUMENT;
+  return MuxDeleteAllNamedData(mux, ChunkGetTagFromFourCC(fourcc));
+}
+
+WebPMuxError WebPMuxDeleteFrame(WebPMux* mux, uint32_t nth) {
+  if (mux == NULL) return WEBP_MUX_INVALID_ARGUMENT;
+  return MuxImageDeleteNth(&mux->images_, nth);
+}
+
+//------------------------------------------------------------------------------
+// Assembly of the WebP RIFF file.
+
+static WebPMuxError GetFrameFragmentInfo(
+    const WebPChunk* const frame_frgm_chunk,
+    int* const x_offset, int* const y_offset, int* const duration) {
+  const uint32_t tag = frame_frgm_chunk->tag_;
+  const int is_frame = (tag == kChunks[IDX_ANMF].tag);
+  const WebPData* const data = &frame_frgm_chunk->data_;
+  const size_t expected_data_size =
+      is_frame ? ANMF_CHUNK_SIZE : FRGM_CHUNK_SIZE;
+  assert(frame_frgm_chunk != NULL);
+  assert(tag == kChunks[IDX_ANMF].tag || tag ==  kChunks[IDX_FRGM].tag);
+  if (data->size != expected_data_size) return WEBP_MUX_INVALID_ARGUMENT;
+
+  *x_offset = 2 * GetLE24(data->bytes + 0);
+  *y_offset = 2 * GetLE24(data->bytes + 3);
+  if (is_frame) *duration = GetLE24(data->bytes + 12);
+  return WEBP_MUX_OK;
+}
+
+static WebPMuxError GetImageInfo(const WebPMuxImage* const wpi,
+                                 int* const x_offset, int* const y_offset,
+                                 int* const duration,
+                                 int* const width, int* const height) {
+  const WebPChunk* const frame_frgm_chunk = wpi->header_;
+  WebPMuxError err;
+  assert(wpi != NULL);
+  assert(frame_frgm_chunk != NULL);
+
+  // Get offsets and duration from ANMF/FRGM chunk.
+  err = GetFrameFragmentInfo(frame_frgm_chunk, x_offset, y_offset, duration);
+  if (err != WEBP_MUX_OK) return err;
+
+  // Get width and height from VP8/VP8L chunk.
+  if (width != NULL) *width = wpi->width_;
+  if (height != NULL) *height = wpi->height_;
+  return WEBP_MUX_OK;
+}
+
+static WebPMuxError GetImageCanvasWidthHeight(
+    const WebPMux* const mux, uint32_t flags,
+    int* const width, int* const height) {
+  WebPMuxImage* wpi = NULL;
+  assert(mux != NULL);
+  assert(width != NULL && height != NULL);
+
+  wpi = mux->images_;
+  assert(wpi != NULL);
+  assert(wpi->img_ != NULL);
+
+  if (wpi->next_ != NULL) {
+    int max_x = 0;
+    int max_y = 0;
+    int64_t image_area = 0;
+    // if we have a chain of wpi's, header_ is necessarily set
+    assert(wpi->header_ != NULL);
+    // Aggregate the bounding box for animation frames & fragmented images.
+    for (; wpi != NULL; wpi = wpi->next_) {
+      int x_offset = 0, y_offset = 0, duration = 0, w = 0, h = 0;
+      const WebPMuxError err = GetImageInfo(wpi, &x_offset, &y_offset,
+                                            &duration, &w, &h);
+      const int max_x_pos = x_offset + w;
+      const int max_y_pos = y_offset + h;
+      if (err != WEBP_MUX_OK) return err;
+      assert(x_offset < MAX_POSITION_OFFSET);
+      assert(y_offset < MAX_POSITION_OFFSET);
+
+      if (max_x_pos > max_x) max_x = max_x_pos;
+      if (max_y_pos > max_y) max_y = max_y_pos;
+      image_area += w * h;
+    }
+    *width = max_x;
+    *height = max_y;
+    // Crude check to validate that there are no image overlaps/holes for
+    // fragmented images. Check that the aggregated image area for individual
+    // fragments exactly matches the image area of the constructed canvas.
+    // However, the area-match is necessary but not sufficient condition.
+    if ((flags & FRAGMENTS_FLAG) && (image_area != (max_x * max_y))) {
+      *width = 0;
+      *height = 0;
+      return WEBP_MUX_INVALID_ARGUMENT;
+    }
+  } else {
+    // For a single image, canvas dimensions are same as image dimensions.
+    *width = wpi->width_;
+    *height = wpi->height_;
+  }
+  return WEBP_MUX_OK;
+}
+
+// VP8X format:
+// Total Size : 10,
+// Flags  : 4 bytes,
+// Width  : 3 bytes,
+// Height : 3 bytes.
+static WebPMuxError CreateVP8XChunk(WebPMux* const mux) {
+  WebPMuxError err = WEBP_MUX_OK;
+  uint32_t flags = 0;
+  int width = 0;
+  int height = 0;
+  uint8_t data[VP8X_CHUNK_SIZE];
+  const WebPData vp8x = { data, VP8X_CHUNK_SIZE };
+  const WebPMuxImage* images = NULL;
+
+  assert(mux != NULL);
+  images = mux->images_;  // First image.
+  if (images == NULL || images->img_ == NULL ||
+      images->img_->data_.bytes == NULL) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+
+  // If VP8X chunk(s) is(are) already present, remove them (and later add new
+  // VP8X chunk with updated flags).
+  err = MuxDeleteAllNamedData(mux, kChunks[IDX_VP8X].tag);
+  if (err != WEBP_MUX_OK && err != WEBP_MUX_NOT_FOUND) return err;
+
+  // Set flags.
+  if (mux->iccp_ != NULL && mux->iccp_->data_.bytes != NULL) {
+    flags |= ICCP_FLAG;
+  }
+  if (mux->exif_ != NULL && mux->exif_->data_.bytes != NULL) {
+    flags |= EXIF_FLAG;
+  }
+  if (mux->xmp_ != NULL && mux->xmp_->data_.bytes != NULL) {
+    flags |= XMP_FLAG;
+  }
+  if (images->header_ != NULL) {
+    if (images->header_->tag_ == kChunks[IDX_FRGM].tag) {
+      // This is a fragmented image.
+      flags |= FRAGMENTS_FLAG;
+    } else if (images->header_->tag_ == kChunks[IDX_ANMF].tag) {
+      // This is an image with animation.
+      flags |= ANIMATION_FLAG;
+    }
+  }
+  if (MuxImageCount(images, WEBP_CHUNK_ALPHA) > 0) {
+    flags |= ALPHA_FLAG;  // Some images have an alpha channel.
+  }
+
+  if (flags == 0) {
+    // For Simple Image, VP8X chunk should not be added.
+    return WEBP_MUX_OK;
+  }
+
+  err = GetImageCanvasWidthHeight(mux, flags, &width, &height);
+  if (err != WEBP_MUX_OK) return err;
+
+  if (width <= 0 || height <= 0) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+  if (width > MAX_CANVAS_SIZE || height > MAX_CANVAS_SIZE) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+
+  if (MuxHasAlpha(images)) {
+    // This means some frames explicitly/implicitly contain alpha.
+    // Note: This 'flags' update must NOT be done for a lossless image
+    // without a VP8X chunk!
+    flags |= ALPHA_FLAG;
+  }
+
+  PutLE32(data + 0, flags);   // VP8X chunk flags.
+  PutLE24(data + 4, width - 1);   // canvas width.
+  PutLE24(data + 7, height - 1);  // canvas height.
+
+  return MuxSet(mux, kChunks[IDX_VP8X].tag, 1, &vp8x, 1);
+}
+
+// Cleans up 'mux' by removing any unnecessary chunks.
+static WebPMuxError MuxCleanup(WebPMux* const mux) {
+  int num_frames;
+  int num_fragments;
+  int num_anim_chunks;
+
+  // If we have an image with single fragment or frame, convert it to a
+  // non-animated non-fragmented image (to avoid writing FRGM/ANMF chunk
+  // unnecessarily).
+  WebPMuxError err = WebPMuxNumChunks(mux, kChunks[IDX_ANMF].id, &num_frames);
+  if (err != WEBP_MUX_OK) return err;
+  err = WebPMuxNumChunks(mux, kChunks[IDX_FRGM].id, &num_fragments);
+  if (err != WEBP_MUX_OK) return err;
+  if (num_frames == 1 || num_fragments == 1) {
+    WebPMuxImage* frame_frag;
+    err = MuxImageGetNth((const WebPMuxImage**)&mux->images_, 1, &frame_frag);
+    assert(err == WEBP_MUX_OK);  // We know that one frame/fragment does exist.
+    if (frame_frag->header_ != NULL) {
+      assert(frame_frag->header_->tag_ == kChunks[IDX_ANMF].tag ||
+             frame_frag->header_->tag_ == kChunks[IDX_FRGM].tag);
+      ChunkDelete(frame_frag->header_);  // Removes ANMF/FRGM chunk.
+      frame_frag->header_ = NULL;
+    }
+    num_frames = 0;
+    num_fragments = 0;
+  }
+  // Remove ANIM chunk if this is a non-animated image.
+  err = WebPMuxNumChunks(mux, kChunks[IDX_ANIM].id, &num_anim_chunks);
+  if (err != WEBP_MUX_OK) return err;
+  if (num_anim_chunks >= 1 && num_frames == 0) {
+    err = MuxDeleteAllNamedData(mux, kChunks[IDX_ANIM].tag);
+    if (err != WEBP_MUX_OK) return err;
+  }
+  return WEBP_MUX_OK;
+}
+
+// Total size of a list of images.
+static size_t ImageListDiskSize(const WebPMuxImage* wpi_list) {
+  size_t size = 0;
+  while (wpi_list != NULL) {
+    size += MuxImageDiskSize(wpi_list);
+    wpi_list = wpi_list->next_;
+  }
+  return size;
+}
+
+// Write out the given list of images into 'dst'.
+static uint8_t* ImageListEmit(const WebPMuxImage* wpi_list, uint8_t* dst) {
+  while (wpi_list != NULL) {
+    dst = MuxImageEmit(wpi_list, dst);
+    wpi_list = wpi_list->next_;
+  }
+  return dst;
+}
+
+WebPMuxError WebPMuxAssemble(WebPMux* mux, WebPData* assembled_data) {
+  size_t size = 0;
+  uint8_t* data = NULL;
+  uint8_t* dst = NULL;
+  WebPMuxError err;
+
+  if (mux == NULL || assembled_data == NULL) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+
+  // Finalize mux.
+  err = MuxCleanup(mux);
+  if (err != WEBP_MUX_OK) return err;
+  err = CreateVP8XChunk(mux);
+  if (err != WEBP_MUX_OK) return err;
+
+  // Allocate data.
+  size = ChunkListDiskSize(mux->vp8x_) + ChunkListDiskSize(mux->iccp_)
+       + ChunkListDiskSize(mux->anim_) + ImageListDiskSize(mux->images_)
+       + ChunkListDiskSize(mux->exif_) + ChunkListDiskSize(mux->xmp_)
+       + ChunkListDiskSize(mux->unknown_) + RIFF_HEADER_SIZE;
+
+  data = (uint8_t*)malloc(size);
+  if (data == NULL) return WEBP_MUX_MEMORY_ERROR;
+
+  // Emit header & chunks.
+  dst = MuxEmitRiffHeader(data, size);
+  dst = ChunkListEmit(mux->vp8x_, dst);
+  dst = ChunkListEmit(mux->iccp_, dst);
+  dst = ChunkListEmit(mux->anim_, dst);
+  dst = ImageListEmit(mux->images_, dst);
+  dst = ChunkListEmit(mux->exif_, dst);
+  dst = ChunkListEmit(mux->xmp_, dst);
+  dst = ChunkListEmit(mux->unknown_, dst);
+  assert(dst == data + size);
+
+  // Validate mux.
+  err = MuxValidate(mux);
+  if (err != WEBP_MUX_OK) {
+    free(data);
+    data = NULL;
+    size = 0;
+  }
+
+  // Finalize data.
+  assembled_data->bytes = data;
+  assembled_data->size = size;
+
+  return err;
+}
+
+//------------------------------------------------------------------------------
+
diff --git a/src/3rdparty/libwebp/src/mux/muxi.h b/src/3rdparty/libwebp/src/mux/muxi.h
new file mode 100644
index 0000000..277d5fb
--- /dev/null
+++ b/src/3rdparty/libwebp/src/mux/muxi.h
@@ -0,0 +1,230 @@
+// 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 for mux library.
+//
+// Author: Urvang (urvang@google.com)
+
+#ifndef WEBP_MUX_MUXI_H_
+#define WEBP_MUX_MUXI_H_
+
+#include <stdlib.h>
+#include "../dec/vp8i.h"
+#include "../dec/vp8li.h"
+#include "../webp/mux.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//------------------------------------------------------------------------------
+// Defines and constants.
+
+#define MUX_MAJ_VERSION 0
+#define MUX_MIN_VERSION 2
+#define MUX_REV_VERSION 0
+
+// Chunk object.
+typedef struct WebPChunk WebPChunk;
+struct WebPChunk {
+  uint32_t        tag_;
+  int             owner_;  // True if *data_ memory is owned internally.
+                           // VP8X, ANIM, and other internally created chunks
+                           // like ANMF/FRGM are always owned.
+  WebPData        data_;
+  WebPChunk*      next_;
+};
+
+// MuxImage object. Store a full WebP image (including ANMF/FRGM chunk, ALPH
+// chunk and VP8/VP8L chunk),
+typedef struct WebPMuxImage WebPMuxImage;
+struct WebPMuxImage {
+  WebPChunk*  header_;      // Corresponds to WEBP_CHUNK_ANMF/WEBP_CHUNK_FRGM.
+  WebPChunk*  alpha_;       // Corresponds to WEBP_CHUNK_ALPHA.
+  WebPChunk*  img_;         // Corresponds to WEBP_CHUNK_IMAGE.
+  WebPChunk*  unknown_;     // Corresponds to WEBP_CHUNK_UNKNOWN.
+  int         width_;
+  int         height_;
+  int         has_alpha_;   // Through ALPH chunk or as part of VP8L.
+  int         is_partial_;  // True if only some of the chunks are filled.
+  WebPMuxImage* next_;
+};
+
+// Main mux object. Stores data chunks.
+struct WebPMux {
+  WebPMuxImage*   images_;
+  WebPChunk*      iccp_;
+  WebPChunk*      exif_;
+  WebPChunk*      xmp_;
+  WebPChunk*      anim_;
+  WebPChunk*      vp8x_;
+
+  WebPChunk*  unknown_;
+};
+
+// CHUNK_INDEX enum: used for indexing within 'kChunks' (defined below) only.
+// Note: the reason for having two enums ('WebPChunkId' and 'CHUNK_INDEX') is to
+// allow two different chunks to have the same id (e.g. WebPChunkId
+// 'WEBP_CHUNK_IMAGE' can correspond to CHUNK_INDEX 'IDX_VP8' or 'IDX_VP8L').
+typedef enum {
+  IDX_VP8X = 0,
+  IDX_ICCP,
+  IDX_ANIM,
+  IDX_ANMF,
+  IDX_FRGM,
+  IDX_ALPHA,
+  IDX_VP8,
+  IDX_VP8L,
+  IDX_EXIF,
+  IDX_XMP,
+  IDX_UNKNOWN,
+
+  IDX_NIL,
+  IDX_LAST_CHUNK
+} CHUNK_INDEX;
+
+#define NIL_TAG 0x00000000u  // To signal void chunk.
+
+typedef struct {
+  uint32_t      tag;
+  WebPChunkId   id;
+  uint32_t      size;
+} ChunkInfo;
+
+extern const ChunkInfo kChunks[IDX_LAST_CHUNK];
+
+//------------------------------------------------------------------------------
+// Chunk object management.
+
+// Initialize.
+void ChunkInit(WebPChunk* const chunk);
+
+// Get chunk index from chunk tag. Returns IDX_UNKNOWN if not found.
+CHUNK_INDEX ChunkGetIndexFromTag(uint32_t tag);
+
+// Get chunk id from chunk tag. Returns WEBP_CHUNK_UNKNOWN if not found.
+WebPChunkId ChunkGetIdFromTag(uint32_t tag);
+
+// Convert a fourcc string to a tag.
+uint32_t ChunkGetTagFromFourCC(const char fourcc[4]);
+
+// Get chunk index from fourcc. Returns IDX_UNKNOWN if given fourcc is unknown.
+CHUNK_INDEX ChunkGetIndexFromFourCC(const char fourcc[4]);
+
+// Search for nth chunk with given 'tag' in the chunk list.
+// nth = 0 means "last of the list".
+WebPChunk* ChunkSearchList(WebPChunk* first, uint32_t nth, uint32_t tag);
+
+// Fill the chunk with the given data.
+WebPMuxError ChunkAssignData(WebPChunk* chunk, const WebPData* const data,
+                             int copy_data, uint32_t tag);
+
+// Sets 'chunk' at nth position in the 'chunk_list'.
+// nth = 0 has the special meaning "last of the list".
+// On success ownership is transferred from 'chunk' to the 'chunk_list'.
+WebPMuxError ChunkSetNth(WebPChunk* chunk, WebPChunk** chunk_list,
+                         uint32_t nth);
+
+// Releases chunk and returns chunk->next_.
+WebPChunk* ChunkRelease(WebPChunk* const chunk);
+
+// Deletes given chunk & returns chunk->next_.
+WebPChunk* ChunkDelete(WebPChunk* const chunk);
+
+// Deletes all chunks in the given chunk list.
+void ChunkListDelete(WebPChunk** const chunk_list);
+
+// Returns size of the chunk including chunk header and padding byte (if any).
+static WEBP_INLINE size_t SizeWithPadding(size_t chunk_size) {
+  return CHUNK_HEADER_SIZE + ((chunk_size + 1) & ~1U);
+}
+
+// Size of a chunk including header and padding.
+static WEBP_INLINE size_t ChunkDiskSize(const WebPChunk* chunk) {
+  const size_t data_size = chunk->data_.size;
+  assert(data_size < MAX_CHUNK_PAYLOAD);
+  return SizeWithPadding(data_size);
+}
+
+// Total size of a list of chunks.
+size_t ChunkListDiskSize(const WebPChunk* chunk_list);
+
+// Write out the given list of chunks into 'dst'.
+uint8_t* ChunkListEmit(const WebPChunk* chunk_list, uint8_t* dst);
+
+//------------------------------------------------------------------------------
+// MuxImage object management.
+
+// Initialize.
+void MuxImageInit(WebPMuxImage* const wpi);
+
+// Releases image 'wpi' and returns wpi->next.
+WebPMuxImage* MuxImageRelease(WebPMuxImage* const wpi);
+
+// Delete image 'wpi' and return the next image in the list or NULL.
+// 'wpi' can be NULL.
+WebPMuxImage* MuxImageDelete(WebPMuxImage* const wpi);
+
+// Count number of images matching the given tag id in the 'wpi_list'.
+// If id == WEBP_CHUNK_NIL, all images will be matched.
+int MuxImageCount(const WebPMuxImage* wpi_list, WebPChunkId id);
+
+// Update width/height/has_alpha info from chunks within wpi.
+// Also remove ALPH chunk if not needed.
+int MuxImageFinalize(WebPMuxImage* const wpi);
+
+// Check if given ID corresponds to an image related chunk.
+static WEBP_INLINE int IsWPI(WebPChunkId id) {
+  switch (id) {
+    case WEBP_CHUNK_ANMF:
+    case WEBP_CHUNK_FRGM:
+    case WEBP_CHUNK_ALPHA:
+    case WEBP_CHUNK_IMAGE:  return 1;
+    default:        return 0;
+  }
+}
+
+// Pushes 'wpi' at the end of 'wpi_list'.
+WebPMuxError MuxImagePush(const WebPMuxImage* wpi, WebPMuxImage** wpi_list);
+
+// Delete nth image in the image list.
+WebPMuxError MuxImageDeleteNth(WebPMuxImage** wpi_list, uint32_t nth);
+
+// Get nth image in the image list.
+WebPMuxError MuxImageGetNth(const WebPMuxImage** wpi_list, uint32_t nth,
+                            WebPMuxImage** wpi);
+
+// Total size of the given image.
+size_t MuxImageDiskSize(const WebPMuxImage* const wpi);
+
+// Write out the given image into 'dst'.
+uint8_t* MuxImageEmit(const WebPMuxImage* const wpi, uint8_t* dst);
+
+//------------------------------------------------------------------------------
+// Helper methods for mux.
+
+// Checks if the given image list contains at least one image with alpha.
+int MuxHasAlpha(const WebPMuxImage* images);
+
+// Write out RIFF header into 'data', given total data size 'size'.
+uint8_t* MuxEmitRiffHeader(uint8_t* const data, size_t size);
+
+// Returns the list where chunk with given ID is to be inserted in mux.
+WebPChunk** MuxGetChunkListFromId(const WebPMux* mux, WebPChunkId id);
+
+// Validates the given mux object.
+WebPMuxError MuxValidate(const WebPMux* const mux);
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_MUX_MUXI_H_ */
diff --git a/src/3rdparty/libwebp/src/mux/muxinternal.c b/src/3rdparty/libwebp/src/mux/muxinternal.c
new file mode 100644
index 0000000..3f992ce
--- /dev/null
+++ b/src/3rdparty/libwebp/src/mux/muxinternal.c
@@ -0,0 +1,551 @@
+// 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 objects and utils for mux.
+//
+// Authors: Urvang (urvang@google.com)
+//          Vikas (vikasa@google.com)
+
+#include <assert.h>
+#include "./muxi.h"
+#include "../utils/utils.h"
+
+#define UNDEFINED_CHUNK_SIZE (-1)
+
+const ChunkInfo kChunks[] = {
+  { MKFOURCC('V', 'P', '8', 'X'),  WEBP_CHUNK_VP8X,    VP8X_CHUNK_SIZE },
+  { MKFOURCC('I', 'C', 'C', 'P'),  WEBP_CHUNK_ICCP,    UNDEFINED_CHUNK_SIZE },
+  { MKFOURCC('A', 'N', 'I', 'M'),  WEBP_CHUNK_ANIM,    ANIM_CHUNK_SIZE },
+  { MKFOURCC('A', 'N', 'M', 'F'),  WEBP_CHUNK_ANMF,    ANMF_CHUNK_SIZE },
+  { MKFOURCC('F', 'R', 'G', 'M'),  WEBP_CHUNK_FRGM,    FRGM_CHUNK_SIZE },
+  { MKFOURCC('A', 'L', 'P', 'H'),  WEBP_CHUNK_ALPHA,   UNDEFINED_CHUNK_SIZE },
+  { MKFOURCC('V', 'P', '8', ' '),  WEBP_CHUNK_IMAGE,   UNDEFINED_CHUNK_SIZE },
+  { MKFOURCC('V', 'P', '8', 'L'),  WEBP_CHUNK_IMAGE,   UNDEFINED_CHUNK_SIZE },
+  { MKFOURCC('E', 'X', 'I', 'F'),  WEBP_CHUNK_EXIF,    UNDEFINED_CHUNK_SIZE },
+  { MKFOURCC('X', 'M', 'P', ' '),  WEBP_CHUNK_XMP,     UNDEFINED_CHUNK_SIZE },
+  { NIL_TAG,                       WEBP_CHUNK_UNKNOWN, UNDEFINED_CHUNK_SIZE },
+
+  { NIL_TAG,                       WEBP_CHUNK_NIL,     UNDEFINED_CHUNK_SIZE }
+};
+
+//------------------------------------------------------------------------------
+
+int WebPGetMuxVersion(void) {
+  return (MUX_MAJ_VERSION << 16) | (MUX_MIN_VERSION << 8) | MUX_REV_VERSION;
+}
+
+//------------------------------------------------------------------------------
+// Life of a chunk object.
+
+void ChunkInit(WebPChunk* const chunk) {
+  assert(chunk);
+  memset(chunk, 0, sizeof(*chunk));
+  chunk->tag_ = NIL_TAG;
+}
+
+WebPChunk* ChunkRelease(WebPChunk* const chunk) {
+  WebPChunk* next;
+  if (chunk == NULL) return NULL;
+  if (chunk->owner_) {
+    WebPDataClear(&chunk->data_);
+  }
+  next = chunk->next_;
+  ChunkInit(chunk);
+  return next;
+}
+
+//------------------------------------------------------------------------------
+// Chunk misc methods.
+
+CHUNK_INDEX ChunkGetIndexFromTag(uint32_t tag) {
+  int i;
+  for (i = 0; kChunks[i].tag != NIL_TAG; ++i) {
+    if (tag == kChunks[i].tag) return (CHUNK_INDEX)i;
+  }
+  return IDX_UNKNOWN;
+}
+
+WebPChunkId ChunkGetIdFromTag(uint32_t tag) {
+  int i;
+  for (i = 0; kChunks[i].tag != NIL_TAG; ++i) {
+    if (tag == kChunks[i].tag) return kChunks[i].id;
+  }
+  return WEBP_CHUNK_UNKNOWN;
+}
+
+uint32_t ChunkGetTagFromFourCC(const char fourcc[4]) {
+  return MKFOURCC(fourcc[0], fourcc[1], fourcc[2], fourcc[3]);
+}
+
+CHUNK_INDEX ChunkGetIndexFromFourCC(const char fourcc[4]) {
+  const uint32_t tag = ChunkGetTagFromFourCC(fourcc);
+  return ChunkGetIndexFromTag(tag);
+}
+
+//------------------------------------------------------------------------------
+// Chunk search methods.
+
+// Returns next chunk in the chunk list with the given tag.
+static WebPChunk* ChunkSearchNextInList(WebPChunk* chunk, uint32_t tag) {
+  while (chunk != NULL && chunk->tag_ != tag) {
+    chunk = chunk->next_;
+  }
+  return chunk;
+}
+
+WebPChunk* ChunkSearchList(WebPChunk* first, uint32_t nth, uint32_t tag) {
+  uint32_t iter = nth;
+  first = ChunkSearchNextInList(first, tag);
+  if (first == NULL) return NULL;
+
+  while (--iter != 0) {
+    WebPChunk* next_chunk = ChunkSearchNextInList(first->next_, tag);
+    if (next_chunk == NULL) break;
+    first = next_chunk;
+  }
+  return ((nth > 0) && (iter > 0)) ? NULL : first;
+}
+
+// Outputs a pointer to 'prev_chunk->next_',
+//   where 'prev_chunk' is the pointer to the chunk at position (nth - 1).
+// Returns true if nth chunk was found.
+static int ChunkSearchListToSet(WebPChunk** chunk_list, uint32_t nth,
+                                WebPChunk*** const location) {
+  uint32_t count = 0;
+  assert(chunk_list != NULL);
+  *location = chunk_list;
+
+  while (*chunk_list != NULL) {
+    WebPChunk* const cur_chunk = *chunk_list;
+    ++count;
+    if (count == nth) return 1;  // Found.
+    chunk_list = &cur_chunk->next_;
+    *location = chunk_list;
+  }
+
+  // *chunk_list is ok to be NULL if adding at last location.
+  return (nth == 0 || (count == nth - 1)) ? 1 : 0;
+}
+
+//------------------------------------------------------------------------------
+// Chunk writer methods.
+
+WebPMuxError ChunkAssignData(WebPChunk* chunk, const WebPData* const data,
+                             int copy_data, uint32_t tag) {
+  // For internally allocated chunks, always copy data & make it owner of data.
+  if (tag == kChunks[IDX_VP8X].tag || tag == kChunks[IDX_ANIM].tag) {
+    copy_data = 1;
+  }
+
+  ChunkRelease(chunk);
+
+  if (data != NULL) {
+    if (copy_data) {        // Copy data.
+      if (!WebPDataCopy(data, &chunk->data_)) return WEBP_MUX_MEMORY_ERROR;
+      chunk->owner_ = 1;    // Chunk is owner of data.
+    } else {                // Don't copy data.
+      chunk->data_ = *data;
+    }
+  }
+  chunk->tag_ = tag;
+  return WEBP_MUX_OK;
+}
+
+WebPMuxError ChunkSetNth(WebPChunk* chunk, WebPChunk** chunk_list,
+                         uint32_t nth) {
+  WebPChunk* new_chunk;
+
+  if (!ChunkSearchListToSet(chunk_list, nth, &chunk_list)) {
+    return WEBP_MUX_NOT_FOUND;
+  }
+
+  new_chunk = (WebPChunk*)malloc(sizeof(*new_chunk));
+  if (new_chunk == NULL) return WEBP_MUX_MEMORY_ERROR;
+  *new_chunk = *chunk;
+  chunk->owner_ = 0;
+  new_chunk->next_ = *chunk_list;
+  *chunk_list = new_chunk;
+  return WEBP_MUX_OK;
+}
+
+//------------------------------------------------------------------------------
+// Chunk deletion method(s).
+
+WebPChunk* ChunkDelete(WebPChunk* const chunk) {
+  WebPChunk* const next = ChunkRelease(chunk);
+  free(chunk);
+  return next;
+}
+
+void ChunkListDelete(WebPChunk** const chunk_list) {
+  while (*chunk_list != NULL) {
+    *chunk_list = ChunkDelete(*chunk_list);
+  }
+}
+
+//------------------------------------------------------------------------------
+// Chunk serialization methods.
+
+static uint8_t* ChunkEmit(const WebPChunk* const chunk, uint8_t* dst) {
+  const size_t chunk_size = chunk->data_.size;
+  assert(chunk);
+  assert(chunk->tag_ != NIL_TAG);
+  PutLE32(dst + 0, chunk->tag_);
+  PutLE32(dst + TAG_SIZE, (uint32_t)chunk_size);
+  assert(chunk_size == (uint32_t)chunk_size);
+  memcpy(dst + CHUNK_HEADER_SIZE, chunk->data_.bytes, chunk_size);
+  if (chunk_size & 1)
+    dst[CHUNK_HEADER_SIZE + chunk_size] = 0;  // Add padding.
+  return dst + ChunkDiskSize(chunk);
+}
+
+uint8_t* ChunkListEmit(const WebPChunk* chunk_list, uint8_t* dst) {
+  while (chunk_list != NULL) {
+    dst = ChunkEmit(chunk_list, dst);
+    chunk_list = chunk_list->next_;
+  }
+  return dst;
+}
+
+size_t ChunkListDiskSize(const WebPChunk* chunk_list) {
+  size_t size = 0;
+  while (chunk_list != NULL) {
+    size += ChunkDiskSize(chunk_list);
+    chunk_list = chunk_list->next_;
+  }
+  return size;
+}
+
+//------------------------------------------------------------------------------
+// Life of a MuxImage object.
+
+void MuxImageInit(WebPMuxImage* const wpi) {
+  assert(wpi);
+  memset(wpi, 0, sizeof(*wpi));
+}
+
+WebPMuxImage* MuxImageRelease(WebPMuxImage* const wpi) {
+  WebPMuxImage* next;
+  if (wpi == NULL) return NULL;
+  ChunkDelete(wpi->header_);
+  ChunkDelete(wpi->alpha_);
+  ChunkDelete(wpi->img_);
+  ChunkListDelete(&wpi->unknown_);
+
+  next = wpi->next_;
+  MuxImageInit(wpi);
+  return next;
+}
+
+//------------------------------------------------------------------------------
+// MuxImage search methods.
+
+// Get a reference to appropriate chunk list within an image given chunk tag.
+static WebPChunk** GetChunkListFromId(const WebPMuxImage* const wpi,
+                                      WebPChunkId id) {
+  assert(wpi != NULL);
+  switch (id) {
+    case WEBP_CHUNK_ANMF:
+    case WEBP_CHUNK_FRGM:  return (WebPChunk**)&wpi->header_;
+    case WEBP_CHUNK_ALPHA: return (WebPChunk**)&wpi->alpha_;
+    case WEBP_CHUNK_IMAGE: return (WebPChunk**)&wpi->img_;
+    default: return NULL;
+  }
+}
+
+int MuxImageCount(const WebPMuxImage* wpi_list, WebPChunkId id) {
+  int count = 0;
+  const WebPMuxImage* current;
+  for (current = wpi_list; current != NULL; current = current->next_) {
+    if (id == WEBP_CHUNK_NIL) {
+      ++count;  // Special case: count all images.
+    } else {
+      const WebPChunk* const wpi_chunk = *GetChunkListFromId(current, id);
+      if (wpi_chunk != NULL) {
+        const WebPChunkId wpi_chunk_id = ChunkGetIdFromTag(wpi_chunk->tag_);
+        if (wpi_chunk_id == id) ++count;  // Count images with a matching 'id'.
+      }
+    }
+  }
+  return count;
+}
+
+// Outputs a pointer to 'prev_wpi->next_',
+//   where 'prev_wpi' is the pointer to the image at position (nth - 1).
+// Returns true if nth image was found.
+static int SearchImageToGetOrDelete(WebPMuxImage** wpi_list, uint32_t nth,
+                                    WebPMuxImage*** const location) {
+  uint32_t count = 0;
+  assert(wpi_list);
+  *location = wpi_list;
+
+  if (nth == 0) {
+    nth = MuxImageCount(*wpi_list, WEBP_CHUNK_NIL);
+    if (nth == 0) return 0;  // Not found.
+  }
+
+  while (*wpi_list != NULL) {
+    WebPMuxImage* const cur_wpi = *wpi_list;
+    ++count;
+    if (count == nth) return 1;  // Found.
+    wpi_list = &cur_wpi->next_;
+    *location = wpi_list;
+  }
+  return 0;  // Not found.
+}
+
+//------------------------------------------------------------------------------
+// MuxImage writer methods.
+
+WebPMuxError MuxImagePush(const WebPMuxImage* wpi, WebPMuxImage** wpi_list) {
+  WebPMuxImage* new_wpi;
+
+  while (*wpi_list != NULL) {
+    WebPMuxImage* const cur_wpi = *wpi_list;
+    if (cur_wpi->next_ == NULL) break;
+    wpi_list = &cur_wpi->next_;
+  }
+
+  new_wpi = (WebPMuxImage*)malloc(sizeof(*new_wpi));
+  if (new_wpi == NULL) return WEBP_MUX_MEMORY_ERROR;
+  *new_wpi = *wpi;
+  new_wpi->next_ = NULL;
+
+  if (*wpi_list != NULL) {
+    (*wpi_list)->next_ = new_wpi;
+  } else {
+    *wpi_list = new_wpi;
+  }
+  return WEBP_MUX_OK;
+}
+
+//------------------------------------------------------------------------------
+// MuxImage deletion methods.
+
+WebPMuxImage* MuxImageDelete(WebPMuxImage* const wpi) {
+  // Delete the components of wpi. If wpi is NULL this is a noop.
+  WebPMuxImage* const next = MuxImageRelease(wpi);
+  free(wpi);
+  return next;
+}
+
+WebPMuxError MuxImageDeleteNth(WebPMuxImage** wpi_list, uint32_t nth) {
+  assert(wpi_list);
+  if (!SearchImageToGetOrDelete(wpi_list, nth, &wpi_list)) {
+    return WEBP_MUX_NOT_FOUND;
+  }
+  *wpi_list = MuxImageDelete(*wpi_list);
+  return WEBP_MUX_OK;
+}
+
+//------------------------------------------------------------------------------
+// MuxImage reader methods.
+
+WebPMuxError MuxImageGetNth(const WebPMuxImage** wpi_list, uint32_t nth,
+                            WebPMuxImage** wpi) {
+  assert(wpi_list);
+  assert(wpi);
+  if (!SearchImageToGetOrDelete((WebPMuxImage**)wpi_list, nth,
+                                (WebPMuxImage***)&wpi_list)) {
+    return WEBP_MUX_NOT_FOUND;
+  }
+  *wpi = (WebPMuxImage*)*wpi_list;
+  return WEBP_MUX_OK;
+}
+
+//------------------------------------------------------------------------------
+// MuxImage serialization methods.
+
+// Size of an image.
+size_t MuxImageDiskSize(const WebPMuxImage* const wpi) {
+  size_t size = 0;
+  if (wpi->header_ != NULL) size += ChunkDiskSize(wpi->header_);
+  if (wpi->alpha_ != NULL) size += ChunkDiskSize(wpi->alpha_);
+  if (wpi->img_ != NULL) size += ChunkDiskSize(wpi->img_);
+  if (wpi->unknown_ != NULL) size += ChunkListDiskSize(wpi->unknown_);
+  return size;
+}
+
+// Special case as ANMF/FRGM chunk encapsulates other image chunks.
+static uint8_t* ChunkEmitSpecial(const WebPChunk* const header,
+                                 size_t total_size, uint8_t* dst) {
+  const size_t header_size = header->data_.size;
+  const size_t offset_to_next = total_size - CHUNK_HEADER_SIZE;
+  assert(header->tag_ == kChunks[IDX_ANMF].tag ||
+         header->tag_ == kChunks[IDX_FRGM].tag);
+  PutLE32(dst + 0, header->tag_);
+  PutLE32(dst + TAG_SIZE, (uint32_t)offset_to_next);
+  assert(header_size == (uint32_t)header_size);
+  memcpy(dst + CHUNK_HEADER_SIZE, header->data_.bytes, header_size);
+  if (header_size & 1) {
+    dst[CHUNK_HEADER_SIZE + header_size] = 0;  // Add padding.
+  }
+  return dst + ChunkDiskSize(header);
+}
+
+uint8_t* MuxImageEmit(const WebPMuxImage* const wpi, uint8_t* dst) {
+  // Ordering of chunks to be emitted is strictly as follows:
+  // 1. ANMF/FRGM chunk (if present).
+  // 2. ALPH chunk (if present).
+  // 3. VP8/VP8L chunk.
+  assert(wpi);
+  if (wpi->header_ != NULL) {
+    dst = ChunkEmitSpecial(wpi->header_, MuxImageDiskSize(wpi), dst);
+  }
+  if (wpi->alpha_ != NULL) dst = ChunkEmit(wpi->alpha_, dst);
+  if (wpi->img_ != NULL) dst = ChunkEmit(wpi->img_, dst);
+  if (wpi->unknown_ != NULL) dst = ChunkListEmit(wpi->unknown_, dst);
+  return dst;
+}
+
+//------------------------------------------------------------------------------
+// Helper methods for mux.
+
+int MuxHasAlpha(const WebPMuxImage* images) {
+  while (images != NULL) {
+    if (images->has_alpha_) return 1;
+    images = images->next_;
+  }
+  return 0;
+}
+
+uint8_t* MuxEmitRiffHeader(uint8_t* const data, size_t size) {
+  PutLE32(data + 0, MKFOURCC('R', 'I', 'F', 'F'));
+  PutLE32(data + TAG_SIZE, (uint32_t)size - CHUNK_HEADER_SIZE);
+  assert(size == (uint32_t)size);
+  PutLE32(data + TAG_SIZE + CHUNK_SIZE_BYTES, MKFOURCC('W', 'E', 'B', 'P'));
+  return data + RIFF_HEADER_SIZE;
+}
+
+WebPChunk** MuxGetChunkListFromId(const WebPMux* mux, WebPChunkId id) {
+  assert(mux != NULL);
+  switch (id) {
+    case WEBP_CHUNK_VP8X:    return (WebPChunk**)&mux->vp8x_;
+    case WEBP_CHUNK_ICCP:    return (WebPChunk**)&mux->iccp_;
+    case WEBP_CHUNK_ANIM:    return (WebPChunk**)&mux->anim_;
+    case WEBP_CHUNK_EXIF:    return (WebPChunk**)&mux->exif_;
+    case WEBP_CHUNK_XMP:     return (WebPChunk**)&mux->xmp_;
+    default:                 return (WebPChunk**)&mux->unknown_;
+  }
+}
+
+static int IsNotCompatible(int feature, int num_items) {
+  return (feature != 0) != (num_items > 0);
+}
+
+#define NO_FLAG 0
+
+// Test basic constraints:
+// retrieval, maximum number of chunks by index (use -1 to skip)
+// and feature incompatibility (use NO_FLAG to skip).
+// On success returns WEBP_MUX_OK and stores the chunk count in *num.
+static WebPMuxError ValidateChunk(const WebPMux* const mux, CHUNK_INDEX idx,
+                                  WebPFeatureFlags feature,
+                                  uint32_t vp8x_flags,
+                                  int max, int* num) {
+  const WebPMuxError err =
+      WebPMuxNumChunks(mux, kChunks[idx].id, num);
+  if (err != WEBP_MUX_OK) return err;
+  if (max > -1 && *num > max) return WEBP_MUX_INVALID_ARGUMENT;
+  if (feature != NO_FLAG && IsNotCompatible(vp8x_flags & feature, *num)) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+  return WEBP_MUX_OK;
+}
+
+WebPMuxError MuxValidate(const WebPMux* const mux) {
+  int num_iccp;
+  int num_exif;
+  int num_xmp;
+  int num_anim;
+  int num_frames;
+  int num_fragments;
+  int num_vp8x;
+  int num_images;
+  int num_alpha;
+  uint32_t flags;
+  WebPMuxError err;
+
+  // Verify mux is not NULL.
+  if (mux == NULL) return WEBP_MUX_INVALID_ARGUMENT;
+
+  // Verify mux has at least one image.
+  if (mux->images_ == NULL) return WEBP_MUX_INVALID_ARGUMENT;
+
+  err = WebPMuxGetFeatures(mux, &flags);
+  if (err != WEBP_MUX_OK) return err;
+
+  // At most one color profile chunk.
+  err = ValidateChunk(mux, IDX_ICCP, ICCP_FLAG, flags, 1, &num_iccp);
+  if (err != WEBP_MUX_OK) return err;
+
+  // At most one EXIF metadata.
+  err = ValidateChunk(mux, IDX_EXIF, EXIF_FLAG, flags, 1, &num_exif);
+  if (err != WEBP_MUX_OK) return err;
+
+  // At most one XMP metadata.
+  err = ValidateChunk(mux, IDX_XMP, XMP_FLAG, flags, 1, &num_xmp);
+  if (err != WEBP_MUX_OK) return err;
+
+  // Animation: ANIMATION_FLAG, ANIM chunk and ANMF chunk(s) are consistent.
+  // At most one ANIM chunk.
+  err = ValidateChunk(mux, IDX_ANIM, NO_FLAG, flags, 1, &num_anim);
+  if (err != WEBP_MUX_OK) return err;
+  err = ValidateChunk(mux, IDX_ANMF, NO_FLAG, flags, -1, &num_frames);
+  if (err != WEBP_MUX_OK) return err;
+
+  {
+    const int has_animation = !!(flags & ANIMATION_FLAG);
+    if (has_animation && (num_anim == 0 || num_frames == 0)) {
+      return WEBP_MUX_INVALID_ARGUMENT;
+    }
+    if (!has_animation && (num_anim == 1 || num_frames > 0)) {
+      return WEBP_MUX_INVALID_ARGUMENT;
+    }
+  }
+
+  // Fragmentation: FRAGMENTS_FLAG and FRGM chunk(s) are consistent.
+  err = ValidateChunk(mux, IDX_FRGM, FRAGMENTS_FLAG, flags, -1, &num_fragments);
+  if (err != WEBP_MUX_OK) return err;
+
+  // Verify either VP8X chunk is present OR there is only one elem in
+  // mux->images_.
+  err = ValidateChunk(mux, IDX_VP8X, NO_FLAG, flags, 1, &num_vp8x);
+  if (err != WEBP_MUX_OK) return err;
+  err = ValidateChunk(mux, IDX_VP8, NO_FLAG, flags, -1, &num_images);
+  if (err != WEBP_MUX_OK) return err;
+  if (num_vp8x == 0 && num_images != 1) return WEBP_MUX_INVALID_ARGUMENT;
+
+  // ALPHA_FLAG & alpha chunk(s) are consistent.
+  if (MuxHasAlpha(mux->images_)) {
+    if (num_vp8x > 0) {
+      // VP8X chunk is present, so it should contain ALPHA_FLAG.
+      if (!(flags & ALPHA_FLAG)) return WEBP_MUX_INVALID_ARGUMENT;
+    } else {
+      // VP8X chunk is not present, so ALPH chunks should NOT be present either.
+      err = WebPMuxNumChunks(mux, WEBP_CHUNK_ALPHA, &num_alpha);
+      if (err != WEBP_MUX_OK) return err;
+      if (num_alpha > 0) return WEBP_MUX_INVALID_ARGUMENT;
+    }
+  } else {  // Mux doesn't need alpha. So, ALPHA_FLAG should NOT be present.
+    if (flags & ALPHA_FLAG) return WEBP_MUX_INVALID_ARGUMENT;
+  }
+
+  // num_fragments & num_images are consistent.
+  if (num_fragments > 0 && num_images != num_fragments) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+
+  return WEBP_MUX_OK;
+}
+
+#undef NO_FLAG
+
+//------------------------------------------------------------------------------
+
diff --git a/src/3rdparty/libwebp/src/mux/muxread.c b/src/3rdparty/libwebp/src/mux/muxread.c
new file mode 100644
index 0000000..6003a25
--- /dev/null
+++ b/src/3rdparty/libwebp/src/mux/muxread.c
@@ -0,0 +1,540 @@
+// 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.
+// -----------------------------------------------------------------------------
+//
+// Read APIs for mux.
+//
+// Authors: Urvang (urvang@google.com)
+//          Vikas (vikasa@google.com)
+
+#include <assert.h>
+#include "./muxi.h"
+#include "../utils/utils.h"
+
+//------------------------------------------------------------------------------
+// Helper method(s).
+
+// Handy MACRO.
+#define SWITCH_ID_LIST(INDEX, LIST)                                           \
+  if (idx == (INDEX)) {                                                       \
+    const WebPChunk* const chunk = ChunkSearchList((LIST), nth,               \
+                                                   kChunks[(INDEX)].tag);     \
+    if (chunk) {                                                              \
+      *data = chunk->data_;                                                   \
+      return WEBP_MUX_OK;                                                     \
+    } else {                                                                  \
+      return WEBP_MUX_NOT_FOUND;                                              \
+    }                                                                         \
+  }
+
+static WebPMuxError MuxGet(const WebPMux* const mux, CHUNK_INDEX idx,
+                           uint32_t nth, WebPData* const data) {
+  assert(mux != NULL);
+  assert(!IsWPI(kChunks[idx].id));
+  WebPDataInit(data);
+
+  SWITCH_ID_LIST(IDX_VP8X, mux->vp8x_);
+  SWITCH_ID_LIST(IDX_ICCP, mux->iccp_);
+  SWITCH_ID_LIST(IDX_ANIM, mux->anim_);
+  SWITCH_ID_LIST(IDX_EXIF, mux->exif_);
+  SWITCH_ID_LIST(IDX_XMP, mux->xmp_);
+  SWITCH_ID_LIST(IDX_UNKNOWN, mux->unknown_);
+  return WEBP_MUX_NOT_FOUND;
+}
+#undef SWITCH_ID_LIST
+
+// Fill the chunk with the given data (includes chunk header bytes), after some
+// verifications.
+static WebPMuxError ChunkVerifyAndAssign(WebPChunk* chunk,
+                                         const uint8_t* data, size_t data_size,
+                                         size_t riff_size, int copy_data) {
+  uint32_t chunk_size;
+  WebPData chunk_data;
+
+  // Sanity checks.
+  if (data_size < TAG_SIZE) return WEBP_MUX_NOT_ENOUGH_DATA;
+  chunk_size = GetLE32(data + TAG_SIZE);
+
+  {
+    const size_t chunk_disk_size = SizeWithPadding(chunk_size);
+    if (chunk_disk_size > riff_size) return WEBP_MUX_BAD_DATA;
+    if (chunk_disk_size > data_size) return WEBP_MUX_NOT_ENOUGH_DATA;
+  }
+
+  // Data assignment.
+  chunk_data.bytes = data + CHUNK_HEADER_SIZE;
+  chunk_data.size = chunk_size;
+  return ChunkAssignData(chunk, &chunk_data, copy_data, GetLE32(data + 0));
+}
+
+int MuxImageFinalize(WebPMuxImage* const wpi) {
+  const WebPChunk* const img = wpi->img_;
+  const WebPData* const image = &img->data_;
+  const int is_lossless = (img->tag_ == kChunks[IDX_VP8L].tag);
+  int w, h;
+  int vp8l_has_alpha = 0;
+  const int ok = is_lossless ?
+      VP8LGetInfo(image->bytes, image->size, &w, &h, &vp8l_has_alpha) :
+      VP8GetInfo(image->bytes, image->size, image->size, &w, &h);
+  assert(img != NULL);
+  if (ok) {
+    // Ignore ALPH chunk accompanying VP8L.
+    if (is_lossless && (wpi->alpha_ != NULL)) {
+      ChunkDelete(wpi->alpha_);
+      wpi->alpha_ = NULL;
+    }
+    wpi->width_ = w;
+    wpi->height_ = h;
+    wpi->has_alpha_ = vp8l_has_alpha || (wpi->alpha_ != NULL);
+  }
+  return ok;
+}
+
+static int MuxImageParse(const WebPChunk* const chunk, int copy_data,
+                         WebPMuxImage* const wpi) {
+  const uint8_t* bytes = chunk->data_.bytes;
+  size_t size = chunk->data_.size;
+  const uint8_t* const last = bytes + size;
+  WebPChunk subchunk;
+  size_t subchunk_size;
+  ChunkInit(&subchunk);
+
+  assert(chunk->tag_ == kChunks[IDX_ANMF].tag ||
+         chunk->tag_ == kChunks[IDX_FRGM].tag);
+  assert(!wpi->is_partial_);
+
+  // ANMF/FRGM.
+  {
+    const size_t hdr_size = (chunk->tag_ == kChunks[IDX_ANMF].tag) ?
+        ANMF_CHUNK_SIZE : FRGM_CHUNK_SIZE;
+    const WebPData temp = { bytes, hdr_size };
+    // Each of ANMF and FRGM chunk contain a header at the beginning. So, its
+    // size should at least be 'hdr_size'.
+    if (size < hdr_size) goto Fail;
+    ChunkAssignData(&subchunk, &temp, copy_data, chunk->tag_);
+  }
+  ChunkSetNth(&subchunk, &wpi->header_, 1);
+  wpi->is_partial_ = 1;  // Waiting for ALPH and/or VP8/VP8L chunks.
+
+  // Rest of the chunks.
+  subchunk_size = ChunkDiskSize(&subchunk) - CHUNK_HEADER_SIZE;
+  bytes += subchunk_size;
+  size -= subchunk_size;
+
+  while (bytes != last) {
+    ChunkInit(&subchunk);
+    if (ChunkVerifyAndAssign(&subchunk, bytes, size, size,
+                             copy_data) != WEBP_MUX_OK) {
+      goto Fail;
+    }
+    switch (ChunkGetIdFromTag(subchunk.tag_)) {
+      case WEBP_CHUNK_ALPHA:
+        if (wpi->alpha_ != NULL) goto Fail;  // Consecutive ALPH chunks.
+        if (ChunkSetNth(&subchunk, &wpi->alpha_, 1) != WEBP_MUX_OK) goto Fail;
+        wpi->is_partial_ = 1;  // Waiting for a VP8 chunk.
+        break;
+      case WEBP_CHUNK_IMAGE:
+        if (ChunkSetNth(&subchunk, &wpi->img_, 1) != WEBP_MUX_OK) goto Fail;
+        if (!MuxImageFinalize(wpi)) goto Fail;
+        wpi->is_partial_ = 0;  // wpi is completely filled.
+        break;
+      case WEBP_CHUNK_UNKNOWN:
+        if (wpi->is_partial_) goto Fail;  // Encountered an unknown chunk
+                                          // before some image chunks.
+        if (ChunkSetNth(&subchunk, &wpi->unknown_, 0) != WEBP_MUX_OK) goto Fail;
+        break;
+      default:
+        goto Fail;
+        break;
+    }
+    subchunk_size = ChunkDiskSize(&subchunk);
+    bytes += subchunk_size;
+    size -= subchunk_size;
+  }
+  if (wpi->is_partial_) goto Fail;
+  return 1;
+
+ Fail:
+  ChunkRelease(&subchunk);
+  return 0;
+}
+
+//------------------------------------------------------------------------------
+// Create a mux object from WebP-RIFF data.
+
+WebPMux* WebPMuxCreateInternal(const WebPData* bitstream, int copy_data,
+                               int version) {
+  size_t riff_size;
+  uint32_t tag;
+  const uint8_t* end;
+  WebPMux* mux = NULL;
+  WebPMuxImage* wpi = NULL;
+  const uint8_t* data;
+  size_t size;
+  WebPChunk chunk;
+  ChunkInit(&chunk);
+
+  // Sanity checks.
+  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_MUX_ABI_VERSION)) {
+    return NULL;  // version mismatch
+  }
+  if (bitstream == NULL) return NULL;
+
+  data = bitstream->bytes;
+  size = bitstream->size;
+
+  if (data == NULL) return NULL;
+  if (size < RIFF_HEADER_SIZE) return NULL;
+  if (GetLE32(data + 0) != MKFOURCC('R', 'I', 'F', 'F') ||
+      GetLE32(data + CHUNK_HEADER_SIZE) != MKFOURCC('W', 'E', 'B', 'P')) {
+    return NULL;
+  }
+
+  mux = WebPMuxNew();
+  if (mux == NULL) return NULL;
+
+  if (size < RIFF_HEADER_SIZE + TAG_SIZE) goto Err;
+
+  tag = GetLE32(data + RIFF_HEADER_SIZE);
+  if (tag != kChunks[IDX_VP8].tag &&
+      tag != kChunks[IDX_VP8L].tag &&
+      tag != kChunks[IDX_VP8X].tag) {
+    goto Err;  // First chunk should be VP8, VP8L or VP8X.
+  }
+
+  riff_size = SizeWithPadding(GetLE32(data + TAG_SIZE));
+  if (riff_size > MAX_CHUNK_PAYLOAD || riff_size > size) {
+    goto Err;
+  } else {
+    if (riff_size < size) {  // Redundant data after last chunk.
+      size = riff_size;  // To make sure we don't read any data beyond mux_size.
+    }
+  }
+
+  end = data + size;
+  data += RIFF_HEADER_SIZE;
+  size -= RIFF_HEADER_SIZE;
+
+  wpi = (WebPMuxImage*)malloc(sizeof(*wpi));
+  if (wpi == NULL) goto Err;
+  MuxImageInit(wpi);
+
+  // Loop over chunks.
+  while (data != end) {
+    size_t data_size;
+    WebPChunkId id;
+    WebPChunk** chunk_list;
+    if (ChunkVerifyAndAssign(&chunk, data, size, riff_size,
+                             copy_data) != WEBP_MUX_OK) {
+      goto Err;
+    }
+    data_size = ChunkDiskSize(&chunk);
+    id = ChunkGetIdFromTag(chunk.tag_);
+    switch (id) {
+      case WEBP_CHUNK_ALPHA:
+        if (wpi->alpha_ != NULL) goto Err;  // Consecutive ALPH chunks.
+        if (ChunkSetNth(&chunk, &wpi->alpha_, 1) != WEBP_MUX_OK) goto Err;
+        wpi->is_partial_ = 1;  // Waiting for a VP8 chunk.
+        break;
+      case WEBP_CHUNK_IMAGE:
+        if (ChunkSetNth(&chunk, &wpi->img_, 1) != WEBP_MUX_OK) goto Err;
+        if (!MuxImageFinalize(wpi)) goto Err;
+        wpi->is_partial_ = 0;  // wpi is completely filled.
+ PushImage:
+        // Add this to mux->images_ list.
+        if (MuxImagePush(wpi, &mux->images_) != WEBP_MUX_OK) goto Err;
+        MuxImageInit(wpi);  // Reset for reading next image.
+        break;
+      case WEBP_CHUNK_ANMF:
+#ifdef WEBP_EXPERIMENTAL_FEATURES
+      case WEBP_CHUNK_FRGM:
+#endif
+        if (wpi->is_partial_) goto Err;  // Previous wpi is still incomplete.
+        if (!MuxImageParse(&chunk, copy_data, wpi)) goto Err;
+        ChunkRelease(&chunk);
+        goto PushImage;
+        break;
+      default:  // A non-image chunk.
+        if (wpi->is_partial_) goto Err;  // Encountered a non-image chunk before
+                                         // getting all chunks of an image.
+        chunk_list = MuxGetChunkListFromId(mux, id);  // List to add this chunk.
+        if (ChunkSetNth(&chunk, chunk_list, 0) != WEBP_MUX_OK) goto Err;
+        break;
+    }
+    data += data_size;
+    size -= data_size;
+    ChunkInit(&chunk);
+  }
+
+  // Validate mux if complete.
+  if (MuxValidate(mux) != WEBP_MUX_OK) goto Err;
+
+  MuxImageDelete(wpi);
+  return mux;  // All OK;
+
+ Err:  // Something bad happened.
+  ChunkRelease(&chunk);
+  MuxImageDelete(wpi);
+  WebPMuxDelete(mux);
+  return NULL;
+}
+
+//------------------------------------------------------------------------------
+// Get API(s).
+
+// Validates that the given mux has a single image.
+static WebPMuxError ValidateForSingleImage(const WebPMux* const mux) {
+  const int num_images = MuxImageCount(mux->images_, WEBP_CHUNK_IMAGE);
+  const int num_frames = MuxImageCount(mux->images_, WEBP_CHUNK_ANMF);
+  const int num_fragments = MuxImageCount(mux->images_, WEBP_CHUNK_FRGM);
+
+  if (num_images == 0) {
+    // No images in mux.
+    return WEBP_MUX_NOT_FOUND;
+  } else if (num_images == 1 && num_frames == 0 && num_fragments == 0) {
+    // Valid case (single image).
+    return WEBP_MUX_OK;
+  } else {
+    // Frame/Fragment case OR an invalid mux.
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+}
+
+// Get the canvas width, height and flags after validating that VP8X/VP8/VP8L
+// chunk and canvas size are valid.
+static WebPMuxError MuxGetCanvasInfo(const WebPMux* const mux,
+                                     int* width, int* height, uint32_t* flags) {
+  int w, h;
+  uint32_t f = 0;
+  WebPData data;
+  assert(mux != NULL);
+
+  // Check if VP8X chunk is present.
+  if (MuxGet(mux, IDX_VP8X, 1, &data) == WEBP_MUX_OK) {
+    if (data.size < VP8X_CHUNK_SIZE) return WEBP_MUX_BAD_DATA;
+    f = GetLE32(data.bytes + 0);
+    w = GetLE24(data.bytes + 4) + 1;
+    h = GetLE24(data.bytes + 7) + 1;
+  } else {  // Single image case.
+    const WebPMuxImage* const wpi = mux->images_;
+    WebPMuxError err = ValidateForSingleImage(mux);
+    if (err != WEBP_MUX_OK) return err;
+    assert(wpi != NULL);
+    w = wpi->width_;
+    h = wpi->height_;
+    if (wpi->has_alpha_) f |= ALPHA_FLAG;
+  }
+  if (w * (uint64_t)h >= MAX_IMAGE_AREA) return WEBP_MUX_BAD_DATA;
+
+  if (width != NULL) *width = w;
+  if (height != NULL) *height = h;
+  if (flags != NULL) *flags = f;
+  return WEBP_MUX_OK;
+}
+
+WebPMuxError WebPMuxGetCanvasSize(const WebPMux* mux, int* width, int* height) {
+  if (mux == NULL || width == NULL || height == NULL) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+  return MuxGetCanvasInfo(mux, width, height, NULL);
+}
+
+WebPMuxError WebPMuxGetFeatures(const WebPMux* mux, uint32_t* flags) {
+  if (mux == NULL || flags == NULL) return WEBP_MUX_INVALID_ARGUMENT;
+  return MuxGetCanvasInfo(mux, NULL, NULL, flags);
+}
+
+static uint8_t* EmitVP8XChunk(uint8_t* const dst, int width,
+                              int height, uint32_t flags) {
+  const size_t vp8x_size = CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE;
+  assert(width >= 1 && height >= 1);
+  assert(width <= MAX_CANVAS_SIZE && height <= MAX_CANVAS_SIZE);
+  assert(width * (uint64_t)height < MAX_IMAGE_AREA);
+  PutLE32(dst, MKFOURCC('V', 'P', '8', 'X'));
+  PutLE32(dst + TAG_SIZE, VP8X_CHUNK_SIZE);
+  PutLE32(dst + CHUNK_HEADER_SIZE, flags);
+  PutLE24(dst + CHUNK_HEADER_SIZE + 4, width - 1);
+  PutLE24(dst + CHUNK_HEADER_SIZE + 7, height - 1);
+  return dst + vp8x_size;
+}
+
+// Assemble a single image WebP bitstream from 'wpi'.
+static WebPMuxError SynthesizeBitstream(const WebPMuxImage* const wpi,
+                                        WebPData* const bitstream) {
+  uint8_t* dst;
+
+  // Allocate data.
+  const int need_vp8x = (wpi->alpha_ != NULL);
+  const size_t vp8x_size = need_vp8x ? CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE : 0;
+  const size_t alpha_size = need_vp8x ? ChunkDiskSize(wpi->alpha_) : 0;
+  // Note: No need to output ANMF/FRGM chunk for a single image.
+  const size_t size = RIFF_HEADER_SIZE + vp8x_size + alpha_size +
+                      ChunkDiskSize(wpi->img_);
+  uint8_t* const data = (uint8_t*)malloc(size);
+  if (data == NULL) return WEBP_MUX_MEMORY_ERROR;
+
+  // Main RIFF header.
+  dst = MuxEmitRiffHeader(data, size);
+
+  if (need_vp8x) {
+    dst = EmitVP8XChunk(dst, wpi->width_, wpi->height_, ALPHA_FLAG);  // VP8X.
+    dst = ChunkListEmit(wpi->alpha_, dst);       // ALPH.
+  }
+
+  // Bitstream.
+  dst = ChunkListEmit(wpi->img_, dst);
+  assert(dst == data + size);
+
+  // Output.
+  bitstream->bytes = data;
+  bitstream->size = size;
+  return WEBP_MUX_OK;
+}
+
+WebPMuxError WebPMuxGetChunk(const WebPMux* mux, const char fourcc[4],
+                             WebPData* chunk_data) {
+  CHUNK_INDEX idx;
+  if (mux == NULL || fourcc == NULL || chunk_data == NULL) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+  idx = ChunkGetIndexFromFourCC(fourcc);
+  if (IsWPI(kChunks[idx].id)) {     // An image chunk.
+    return WEBP_MUX_INVALID_ARGUMENT;
+  } else if (idx != IDX_UNKNOWN) {  // A known chunk type.
+    return MuxGet(mux, idx, 1, chunk_data);
+  } else {                          // An unknown chunk type.
+    const WebPChunk* const chunk =
+        ChunkSearchList(mux->unknown_, 1, ChunkGetTagFromFourCC(fourcc));
+    if (chunk == NULL) return WEBP_MUX_NOT_FOUND;
+    *chunk_data = chunk->data_;
+    return WEBP_MUX_OK;
+  }
+}
+
+static WebPMuxError MuxGetImageInternal(const WebPMuxImage* const wpi,
+                                        WebPMuxFrameInfo* const info) {
+  // Set some defaults for unrelated fields.
+  info->x_offset = 0;
+  info->y_offset = 0;
+  info->duration = 1;
+  info->dispose_method = WEBP_MUX_DISPOSE_NONE;
+  info->blend_method = WEBP_MUX_BLEND;
+  // Extract data for related fields.
+  info->id = ChunkGetIdFromTag(wpi->img_->tag_);
+  return SynthesizeBitstream(wpi, &info->bitstream);
+}
+
+static WebPMuxError MuxGetFrameFragmentInternal(const WebPMuxImage* const wpi,
+                                                WebPMuxFrameInfo* const frame) {
+  const int is_frame = (wpi->header_->tag_ == kChunks[IDX_ANMF].tag);
+  const CHUNK_INDEX idx = is_frame ? IDX_ANMF : IDX_FRGM;
+  const WebPData* frame_frgm_data;
+#ifndef WEBP_EXPERIMENTAL_FEATURES
+  if (!is_frame) return WEBP_MUX_INVALID_ARGUMENT;
+#endif
+  assert(wpi->header_ != NULL);  // Already checked by WebPMuxGetFrame().
+  // Get frame/fragment chunk.
+  frame_frgm_data = &wpi->header_->data_;
+  if (frame_frgm_data->size < kChunks[idx].size) return WEBP_MUX_BAD_DATA;
+  // Extract info.
+  frame->x_offset = 2 * GetLE24(frame_frgm_data->bytes + 0);
+  frame->y_offset = 2 * GetLE24(frame_frgm_data->bytes + 3);
+  if (is_frame) {
+    const uint8_t bits = frame_frgm_data->bytes[15];
+    frame->duration = GetLE24(frame_frgm_data->bytes + 12);
+    frame->dispose_method =
+        (bits & 1) ? WEBP_MUX_DISPOSE_BACKGROUND : WEBP_MUX_DISPOSE_NONE;
+    frame->blend_method = (bits & 2) ? WEBP_MUX_NO_BLEND : WEBP_MUX_BLEND;
+  } else {  // Defaults for unused values.
+    frame->duration = 1;
+    frame->dispose_method = WEBP_MUX_DISPOSE_NONE;
+    frame->blend_method = WEBP_MUX_BLEND;
+  }
+  frame->id = ChunkGetIdFromTag(wpi->header_->tag_);
+  return SynthesizeBitstream(wpi, &frame->bitstream);
+}
+
+WebPMuxError WebPMuxGetFrame(
+    const WebPMux* mux, uint32_t nth, WebPMuxFrameInfo* frame) {
+  WebPMuxError err;
+  WebPMuxImage* wpi;
+
+  // Sanity checks.
+  if (mux == NULL || frame == NULL) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+
+  // Get the nth WebPMuxImage.
+  err = MuxImageGetNth((const WebPMuxImage**)&mux->images_, nth, &wpi);
+  if (err != WEBP_MUX_OK) return err;
+
+  // Get frame info.
+  if (wpi->header_ == NULL) {
+    return MuxGetImageInternal(wpi, frame);
+  } else {
+    return MuxGetFrameFragmentInternal(wpi, frame);
+  }
+}
+
+WebPMuxError WebPMuxGetAnimationParams(const WebPMux* mux,
+                                       WebPMuxAnimParams* params) {
+  WebPData anim;
+  WebPMuxError err;
+
+  if (mux == NULL || params == NULL) return WEBP_MUX_INVALID_ARGUMENT;
+
+  err = MuxGet(mux, IDX_ANIM, 1, &anim);
+  if (err != WEBP_MUX_OK) return err;
+  if (anim.size < kChunks[WEBP_CHUNK_ANIM].size) return WEBP_MUX_BAD_DATA;
+  params->bgcolor = GetLE32(anim.bytes);
+  params->loop_count = GetLE16(anim.bytes + 4);
+
+  return WEBP_MUX_OK;
+}
+
+// Get chunk index from chunk id. Returns IDX_NIL if not found.
+static CHUNK_INDEX ChunkGetIndexFromId(WebPChunkId id) {
+  int i;
+  for (i = 0; kChunks[i].id != WEBP_CHUNK_NIL; ++i) {
+    if (id == kChunks[i].id) return (CHUNK_INDEX)i;
+  }
+  return IDX_NIL;
+}
+
+// Count number of chunks matching 'tag' in the 'chunk_list'.
+// If tag == NIL_TAG, any tag will be matched.
+static int CountChunks(const WebPChunk* const chunk_list, uint32_t tag) {
+  int count = 0;
+  const WebPChunk* current;
+  for (current = chunk_list; current != NULL; current = current->next_) {
+    if (tag == NIL_TAG || current->tag_ == tag) {
+      count++;  // Count chunks whose tags match.
+    }
+  }
+  return count;
+}
+
+WebPMuxError WebPMuxNumChunks(const WebPMux* mux,
+                              WebPChunkId id, int* num_elements) {
+  if (mux == NULL || num_elements == NULL) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+
+  if (IsWPI(id)) {
+    *num_elements = MuxImageCount(mux->images_, id);
+  } else {
+    WebPChunk* const* chunk_list = MuxGetChunkListFromId(mux, id);
+    const CHUNK_INDEX idx = ChunkGetIndexFromId(id);
+    *num_elements = CountChunks(*chunk_list, kChunks[idx].tag);
+  }
+
+  return WEBP_MUX_OK;
+}
+
+//------------------------------------------------------------------------------
+