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// 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.
// -----------------------------------------------------------------------------
//
// Selecting filter level
//
// Author: somnath@google.com (Somnath Banerjee)
#include <assert.h>
#include "src/enc/vp8i_enc.h"
#include "src/dsp/dsp.h"
// This table gives, for a given sharpness, the filtering strength to be
// used (at least) in order to filter a given edge step delta.
// This is constructed by brute force inspection: for all delta, we iterate
// over all possible filtering strength / thresh until needs_filter() returns
// true.
#define MAX_DELTA_SIZE 64
static const uint8_t kLevelsFromDelta[8][MAX_DELTA_SIZE] = {
{ 0, 1, 2, 3, 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, 59, 60, 61, 62, 63 },
{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 17, 18,
20, 21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42,
44, 45, 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63,
63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 19,
20, 22, 23, 25, 26, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43,
44, 46, 47, 49, 50, 52, 53, 55, 56, 58, 59, 61, 62, 63, 63, 63,
63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 15, 16, 18, 19,
21, 22, 24, 25, 27, 28, 30, 31, 33, 34, 36, 37, 39, 40, 42, 43,
45, 46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 61, 63, 63, 63, 63,
63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
{ 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 14, 15, 17, 18, 20,
21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44,
45, 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63, 63,
63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
{ 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 17, 19, 20,
22, 23, 25, 26, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43, 44,
46, 47, 49, 50, 52, 53, 55, 56, 58, 59, 61, 62, 63, 63, 63, 63,
63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
{ 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 18, 19, 21,
22, 24, 25, 27, 28, 30, 31, 33, 34, 36, 37, 39, 40, 42, 43, 45,
46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 61, 63, 63, 63, 63, 63,
63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
{ 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21,
23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44, 45,
47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63, 63, 63,
63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 }
};
int VP8FilterStrengthFromDelta(int sharpness, int delta) {
const int pos = (delta < MAX_DELTA_SIZE) ? delta : MAX_DELTA_SIZE - 1;
assert(sharpness >= 0 && sharpness <= 7);
return kLevelsFromDelta[sharpness][pos];
}
//------------------------------------------------------------------------------
// Paragraph 15.4: compute the inner-edge filtering strength
#if !defined(WEBP_REDUCE_SIZE)
static int GetILevel(int sharpness, int level) {
if (sharpness > 0) {
if (sharpness > 4) {
level >>= 2;
} else {
level >>= 1;
}
if (level > 9 - sharpness) {
level = 9 - sharpness;
}
}
if (level < 1) level = 1;
return level;
}
static void DoFilter(const VP8EncIterator* const it, int level) {
const VP8Encoder* const enc = it->enc_;
const int ilevel = GetILevel(enc->config_->filter_sharpness, level);
const int limit = 2 * level + ilevel;
uint8_t* const y_dst = it->yuv_out2_ + Y_OFF_ENC;
uint8_t* const u_dst = it->yuv_out2_ + U_OFF_ENC;
uint8_t* const v_dst = it->yuv_out2_ + V_OFF_ENC;
// copy current block to yuv_out2_
memcpy(y_dst, it->yuv_out_, YUV_SIZE_ENC * sizeof(uint8_t));
if (enc->filter_hdr_.simple_ == 1) { // simple
VP8SimpleHFilter16i(y_dst, BPS, limit);
VP8SimpleVFilter16i(y_dst, BPS, limit);
} else { // complex
const int hev_thresh = (level >= 40) ? 2 : (level >= 15) ? 1 : 0;
VP8HFilter16i(y_dst, BPS, limit, ilevel, hev_thresh);
VP8HFilter8i(u_dst, v_dst, BPS, limit, ilevel, hev_thresh);
VP8VFilter16i(y_dst, BPS, limit, ilevel, hev_thresh);
VP8VFilter8i(u_dst, v_dst, BPS, limit, ilevel, hev_thresh);
}
}
//------------------------------------------------------------------------------
// SSIM metric for one macroblock
static double GetMBSSIM(const uint8_t* yuv1, const uint8_t* yuv2) {
int x, y;
double sum = 0.;
// compute SSIM in a 10 x 10 window
for (y = VP8_SSIM_KERNEL; y < 16 - VP8_SSIM_KERNEL; y++) {
for (x = VP8_SSIM_KERNEL; x < 16 - VP8_SSIM_KERNEL; x++) {
sum += VP8SSIMGetClipped(yuv1 + Y_OFF_ENC, BPS, yuv2 + Y_OFF_ENC, BPS,
x, y, 16, 16);
}
}
for (x = 1; x < 7; x++) {
for (y = 1; y < 7; y++) {
sum += VP8SSIMGetClipped(yuv1 + U_OFF_ENC, BPS, yuv2 + U_OFF_ENC, BPS,
x, y, 8, 8);
sum += VP8SSIMGetClipped(yuv1 + V_OFF_ENC, BPS, yuv2 + V_OFF_ENC, BPS,
x, y, 8, 8);
}
}
return sum;
}
#endif // !defined(WEBP_REDUCE_SIZE)
//------------------------------------------------------------------------------
// Exposed APIs: Encoder should call the following 3 functions to adjust
// loop filter strength
void VP8InitFilter(VP8EncIterator* const it) {
#if !defined(WEBP_REDUCE_SIZE)
if (it->lf_stats_ != NULL) {
int s, i;
for (s = 0; s < NUM_MB_SEGMENTS; s++) {
for (i = 0; i < MAX_LF_LEVELS; i++) {
(*it->lf_stats_)[s][i] = 0;
}
}
VP8SSIMDspInit();
}
#else
(void)it;
#endif
}
void VP8StoreFilterStats(VP8EncIterator* const it) {
#if !defined(WEBP_REDUCE_SIZE)
int d;
VP8Encoder* const enc = it->enc_;
const int s = it->mb_->segment_;
const int level0 = enc->dqm_[s].fstrength_;
// explore +/-quant range of values around level0
const int delta_min = -enc->dqm_[s].quant_;
const int delta_max = enc->dqm_[s].quant_;
const int step_size = (delta_max - delta_min >= 4) ? 4 : 1;
if (it->lf_stats_ == NULL) return;
// NOTE: Currently we are applying filter only across the sublock edges
// There are two reasons for that.
// 1. Applying filter on macro block edges will change the pixels in
// the left and top macro blocks. That will be hard to restore
// 2. Macro Blocks on the bottom and right are not yet compressed. So we
// cannot apply filter on the right and bottom macro block edges.
if (it->mb_->type_ == 1 && it->mb_->skip_) return;
// Always try filter level zero
(*it->lf_stats_)[s][0] += GetMBSSIM(it->yuv_in_, it->yuv_out_);
for (d = delta_min; d <= delta_max; d += step_size) {
const int level = level0 + d;
if (level <= 0 || level >= MAX_LF_LEVELS) {
continue;
}
DoFilter(it, level);
(*it->lf_stats_)[s][level] += GetMBSSIM(it->yuv_in_, it->yuv_out2_);
}
#else // defined(WEBP_REDUCE_SIZE)
(void)it;
#endif // !defined(WEBP_REDUCE_SIZE)
}
void VP8AdjustFilterStrength(VP8EncIterator* const it) {
VP8Encoder* const enc = it->enc_;
#if !defined(WEBP_REDUCE_SIZE)
if (it->lf_stats_ != NULL) {
int s;
for (s = 0; s < NUM_MB_SEGMENTS; s++) {
int i, best_level = 0;
// Improvement over filter level 0 should be at least 1e-5 (relatively)
double best_v = 1.00001 * (*it->lf_stats_)[s][0];
for (i = 1; i < MAX_LF_LEVELS; i++) {
const double v = (*it->lf_stats_)[s][i];
if (v > best_v) {
best_v = v;
best_level = i;
}
}
enc->dqm_[s].fstrength_ = best_level;
}
return;
}
#endif // !defined(WEBP_REDUCE_SIZE)
if (enc->config_->filter_strength > 0) {
int max_level = 0;
int s;
for (s = 0; s < NUM_MB_SEGMENTS; s++) {
VP8SegmentInfo* const dqm = &enc->dqm_[s];
// this '>> 3' accounts for some inverse WHT scaling
const int delta = (dqm->max_edge_ * dqm->y2_.q_[1]) >> 3;
const int level =
VP8FilterStrengthFromDelta(enc->filter_hdr_.sharpness_, delta);
if (level > dqm->fstrength_) {
dqm->fstrength_ = level;
}
if (max_level < dqm->fstrength_) {
max_level = dqm->fstrength_;
}
}
enc->filter_hdr_.level_ = max_level;
}
}
// -----------------------------------------------------------------------------
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