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opencv/3rdparty/libwebp/enc/frame.c
andrey.morozov 7d5185e8f1 updated webp to version 0.3.1
2013-07-13 14:09:44 +04:00

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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.
// -----------------------------------------------------------------------------
//
// frame coding and analysis
//
// Author: Skal (pascal.massimino@gmail.com)
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "./vp8enci.h"
#include "./cost.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#define SEGMENT_VISU 0
#define DEBUG_SEARCH 0 // useful to track search convergence
// On-the-fly info about the current set of residuals. Handy to avoid
// passing zillions of params.
typedef struct {
int first;
int last;
const int16_t* coeffs;
int coeff_type;
ProbaArray* prob;
StatsArray* stats;
CostArray* cost;
} VP8Residual;
//------------------------------------------------------------------------------
// Tables for level coding
const uint8_t VP8EncBands[16 + 1] = {
0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
0 // sentinel
};
const uint8_t VP8Cat3[] = { 173, 148, 140 };
const uint8_t VP8Cat4[] = { 176, 155, 140, 135 };
const uint8_t VP8Cat5[] = { 180, 157, 141, 134, 130 };
const uint8_t VP8Cat6[] =
{ 254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129 };
//------------------------------------------------------------------------------
// Reset the statistics about: number of skips, token proba, level cost,...
static void ResetStats(VP8Encoder* const enc) {
VP8Proba* const proba = &enc->proba_;
VP8CalculateLevelCosts(proba);
proba->nb_skip_ = 0;
}
//------------------------------------------------------------------------------
// Skip decision probability
#define SKIP_PROBA_THRESHOLD 250 // value below which using skip_proba is OK.
static int CalcSkipProba(uint64_t nb, uint64_t total) {
return (int)(total ? (total - nb) * 255 / total : 255);
}
// Returns the bit-cost for coding the skip probability.
static int FinalizeSkipProba(VP8Encoder* const enc) {
VP8Proba* const proba = &enc->proba_;
const int nb_mbs = enc->mb_w_ * enc->mb_h_;
const int nb_events = proba->nb_skip_;
int size;
proba->skip_proba_ = CalcSkipProba(nb_events, nb_mbs);
proba->use_skip_proba_ = (proba->skip_proba_ < SKIP_PROBA_THRESHOLD);
size = 256; // 'use_skip_proba' bit
if (proba->use_skip_proba_) {
size += nb_events * VP8BitCost(1, proba->skip_proba_)
+ (nb_mbs - nb_events) * VP8BitCost(0, proba->skip_proba_);
size += 8 * 256; // cost of signaling the skip_proba_ itself.
}
return size;
}
//------------------------------------------------------------------------------
// Recording of token probabilities.
static void ResetTokenStats(VP8Encoder* const enc) {
VP8Proba* const proba = &enc->proba_;
memset(proba->stats_, 0, sizeof(proba->stats_));
}
// Record proba context used
static int Record(int bit, proba_t* const stats) {
proba_t p = *stats;
if (p >= 0xffff0000u) { // an overflow is inbound.
p = ((p + 1u) >> 1) & 0x7fff7fffu; // -> divide the stats by 2.
}
// record bit count (lower 16 bits) and increment total count (upper 16 bits).
p += 0x00010000u + bit;
*stats = p;
return bit;
}
// We keep the table free variant around for reference, in case.
#define USE_LEVEL_CODE_TABLE
// Simulate block coding, but only record statistics.
// Note: no need to record the fixed probas.
static int RecordCoeffs(int ctx, const VP8Residual* const res) {
int n = res->first;
// should be stats[VP8EncBands[n]], but it's equivalent for n=0 or 1
proba_t* s = res->stats[n][ctx];
if (res->last < 0) {
Record(0, s + 0);
return 0;
}
while (n <= res->last) {
int v;
Record(1, s + 0); // order of record doesn't matter
while ((v = res->coeffs[n++]) == 0) {
Record(0, s + 1);
s = res->stats[VP8EncBands[n]][0];
}
Record(1, s + 1);
if (!Record(2u < (unsigned int)(v + 1), s + 2)) { // v = -1 or 1
s = res->stats[VP8EncBands[n]][1];
} else {
v = abs(v);
#if !defined(USE_LEVEL_CODE_TABLE)
if (!Record(v > 4, s + 3)) {
if (Record(v != 2, s + 4))
Record(v == 4, s + 5);
} else if (!Record(v > 10, s + 6)) {
Record(v > 6, s + 7);
} else if (!Record((v >= 3 + (8 << 2)), s + 8)) {
Record((v >= 3 + (8 << 1)), s + 9);
} else {
Record((v >= 3 + (8 << 3)), s + 10);
}
#else
if (v > MAX_VARIABLE_LEVEL)
v = MAX_VARIABLE_LEVEL;
{
const int bits = VP8LevelCodes[v - 1][1];
int pattern = VP8LevelCodes[v - 1][0];
int i;
for (i = 0; (pattern >>= 1) != 0; ++i) {
const int mask = 2 << i;
if (pattern & 1) Record(!!(bits & mask), s + 3 + i);
}
}
#endif
s = res->stats[VP8EncBands[n]][2];
}
}
if (n < 16) Record(0, s + 0);
return 1;
}
// Collect statistics and deduce probabilities for next coding pass.
// Return the total bit-cost for coding the probability updates.
static int CalcTokenProba(int nb, int total) {
assert(nb <= total);
return nb ? (255 - nb * 255 / total) : 255;
}
// Cost of coding 'nb' 1's and 'total-nb' 0's using 'proba' probability.
static int BranchCost(int nb, int total, int proba) {
return nb * VP8BitCost(1, proba) + (total - nb) * VP8BitCost(0, proba);
}
static int FinalizeTokenProbas(VP8Proba* const proba) {
int has_changed = 0;
int size = 0;
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 proba_t stats = proba->stats_[t][b][c][p];
const int nb = (stats >> 0) & 0xffff;
const int total = (stats >> 16) & 0xffff;
const int update_proba = VP8CoeffsUpdateProba[t][b][c][p];
const int old_p = VP8CoeffsProba0[t][b][c][p];
const int new_p = CalcTokenProba(nb, total);
const int old_cost = BranchCost(nb, total, old_p)
+ VP8BitCost(0, update_proba);
const int new_cost = BranchCost(nb, total, new_p)
+ VP8BitCost(1, update_proba)
+ 8 * 256;
const int use_new_p = (old_cost > new_cost);
size += VP8BitCost(use_new_p, update_proba);
if (use_new_p) { // only use proba that seem meaningful enough.
proba->coeffs_[t][b][c][p] = new_p;
has_changed |= (new_p != old_p);
size += 8 * 256;
} else {
proba->coeffs_[t][b][c][p] = old_p;
}
}
}
}
}
proba->dirty_ = has_changed;
return size;
}
//------------------------------------------------------------------------------
// Finalize Segment probability based on the coding tree
static int GetProba(int a, int b) {
const int total = a + b;
return (total == 0) ? 255 // that's the default probability.
: (255 * a + total / 2) / total; // rounded proba
}
static void SetSegmentProbas(VP8Encoder* const enc) {
int p[NUM_MB_SEGMENTS] = { 0 };
int n;
for (n = 0; n < enc->mb_w_ * enc->mb_h_; ++n) {
const VP8MBInfo* const mb = &enc->mb_info_[n];
p[mb->segment_]++;
}
if (enc->pic_->stats != NULL) {
for (n = 0; n < NUM_MB_SEGMENTS; ++n) {
enc->pic_->stats->segment_size[n] = p[n];
}
}
if (enc->segment_hdr_.num_segments_ > 1) {
uint8_t* const probas = enc->proba_.segments_;
probas[0] = GetProba(p[0] + p[1], p[2] + p[3]);
probas[1] = GetProba(p[0], p[1]);
probas[2] = GetProba(p[2], p[3]);
enc->segment_hdr_.update_map_ =
(probas[0] != 255) || (probas[1] != 255) || (probas[2] != 255);
enc->segment_hdr_.size_ =
p[0] * (VP8BitCost(0, probas[0]) + VP8BitCost(0, probas[1])) +
p[1] * (VP8BitCost(0, probas[0]) + VP8BitCost(1, probas[1])) +
p[2] * (VP8BitCost(1, probas[0]) + VP8BitCost(0, probas[2])) +
p[3] * (VP8BitCost(1, probas[0]) + VP8BitCost(1, probas[2]));
} else {
enc->segment_hdr_.update_map_ = 0;
enc->segment_hdr_.size_ = 0;
}
}
//------------------------------------------------------------------------------
// helper functions for residuals struct VP8Residual.
static void InitResidual(int first, int coeff_type,
VP8Encoder* const enc, VP8Residual* const res) {
res->coeff_type = coeff_type;
res->prob = enc->proba_.coeffs_[coeff_type];
res->stats = enc->proba_.stats_[coeff_type];
res->cost = enc->proba_.level_cost_[coeff_type];
res->first = first;
}
static void SetResidualCoeffs(const int16_t* const coeffs,
VP8Residual* const res) {
int n;
res->last = -1;
for (n = 15; n >= res->first; --n) {
if (coeffs[n]) {
res->last = n;
break;
}
}
res->coeffs = coeffs;
}
//------------------------------------------------------------------------------
// Mode costs
static int GetResidualCost(int ctx0, const VP8Residual* const res) {
int n = res->first;
// should be prob[VP8EncBands[n]], but it's equivalent for n=0 or 1
int p0 = res->prob[n][ctx0][0];
const uint16_t* t = res->cost[n][ctx0];
int cost;
if (res->last < 0) {
return VP8BitCost(0, p0);
}
cost = 0;
while (n < res->last) {
int v = res->coeffs[n];
const int b = VP8EncBands[n + 1];
++n;
if (v == 0) {
// short-case for VP8LevelCost(t, 0) (note: VP8LevelFixedCosts[0] == 0):
cost += t[0];
t = res->cost[b][0];
continue;
}
v = abs(v);
cost += VP8BitCost(1, p0);
cost += VP8LevelCost(t, v);
{
const int ctx = (v == 1) ? 1 : 2;
p0 = res->prob[b][ctx][0];
t = res->cost[b][ctx];
}
}
// Last coefficient is always non-zero
{
const int v = abs(res->coeffs[n]);
assert(v != 0);
cost += VP8BitCost(1, p0);
cost += VP8LevelCost(t, v);
if (n < 15) {
const int b = VP8EncBands[n + 1];
const int ctx = (v == 1) ? 1 : 2;
const int last_p0 = res->prob[b][ctx][0];
cost += VP8BitCost(0, last_p0);
}
}
return cost;
}
int VP8GetCostLuma4(VP8EncIterator* const it, const int16_t levels[16]) {
const int x = (it->i4_ & 3), y = (it->i4_ >> 2);
VP8Residual res;
VP8Encoder* const enc = it->enc_;
int R = 0;
int ctx;
InitResidual(0, 3, enc, &res);
ctx = it->top_nz_[x] + it->left_nz_[y];
SetResidualCoeffs(levels, &res);
R += GetResidualCost(ctx, &res);
return R;
}
int VP8GetCostLuma16(VP8EncIterator* const it, const VP8ModeScore* const rd) {
VP8Residual res;
VP8Encoder* const enc = it->enc_;
int x, y;
int R = 0;
VP8IteratorNzToBytes(it); // re-import the non-zero context
// DC
InitResidual(0, 1, enc, &res);
SetResidualCoeffs(rd->y_dc_levels, &res);
R += GetResidualCost(it->top_nz_[8] + it->left_nz_[8], &res);
// AC
InitResidual(1, 0, enc, &res);
for (y = 0; y < 4; ++y) {
for (x = 0; x < 4; ++x) {
const int ctx = it->top_nz_[x] + it->left_nz_[y];
SetResidualCoeffs(rd->y_ac_levels[x + y * 4], &res);
R += GetResidualCost(ctx, &res);
it->top_nz_[x] = it->left_nz_[y] = (res.last >= 0);
}
}
return R;
}
int VP8GetCostUV(VP8EncIterator* const it, const VP8ModeScore* const rd) {
VP8Residual res;
VP8Encoder* const enc = it->enc_;
int ch, x, y;
int R = 0;
VP8IteratorNzToBytes(it); // re-import the non-zero context
InitResidual(0, 2, enc, &res);
for (ch = 0; ch <= 2; ch += 2) {
for (y = 0; y < 2; ++y) {
for (x = 0; x < 2; ++x) {
const int ctx = it->top_nz_[4 + ch + x] + it->left_nz_[4 + ch + y];
SetResidualCoeffs(rd->uv_levels[ch * 2 + x + y * 2], &res);
R += GetResidualCost(ctx, &res);
it->top_nz_[4 + ch + x] = it->left_nz_[4 + ch + y] = (res.last >= 0);
}
}
}
return R;
}
//------------------------------------------------------------------------------
// Coefficient coding
static int PutCoeffs(VP8BitWriter* const bw, int ctx, const VP8Residual* res) {
int n = res->first;
// should be prob[VP8EncBands[n]], but it's equivalent for n=0 or 1
const uint8_t* p = res->prob[n][ctx];
if (!VP8PutBit(bw, res->last >= 0, p[0])) {
return 0;
}
while (n < 16) {
const int c = res->coeffs[n++];
const int sign = c < 0;
int v = sign ? -c : c;
if (!VP8PutBit(bw, v != 0, p[1])) {
p = res->prob[VP8EncBands[n]][0];
continue;
}
if (!VP8PutBit(bw, v > 1, p[2])) {
p = res->prob[VP8EncBands[n]][1];
} else {
if (!VP8PutBit(bw, v > 4, p[3])) {
if (VP8PutBit(bw, v != 2, p[4]))
VP8PutBit(bw, v == 4, p[5]);
} else if (!VP8PutBit(bw, v > 10, p[6])) {
if (!VP8PutBit(bw, v > 6, p[7])) {
VP8PutBit(bw, v == 6, 159);
} else {
VP8PutBit(bw, v >= 9, 165);
VP8PutBit(bw, !(v & 1), 145);
}
} else {
int mask;
const uint8_t* tab;
if (v < 3 + (8 << 1)) { // VP8Cat3 (3b)
VP8PutBit(bw, 0, p[8]);
VP8PutBit(bw, 0, p[9]);
v -= 3 + (8 << 0);
mask = 1 << 2;
tab = VP8Cat3;
} else if (v < 3 + (8 << 2)) { // VP8Cat4 (4b)
VP8PutBit(bw, 0, p[8]);
VP8PutBit(bw, 1, p[9]);
v -= 3 + (8 << 1);
mask = 1 << 3;
tab = VP8Cat4;
} else if (v < 3 + (8 << 3)) { // VP8Cat5 (5b)
VP8PutBit(bw, 1, p[8]);
VP8PutBit(bw, 0, p[10]);
v -= 3 + (8 << 2);
mask = 1 << 4;
tab = VP8Cat5;
} else { // VP8Cat6 (11b)
VP8PutBit(bw, 1, p[8]);
VP8PutBit(bw, 1, p[10]);
v -= 3 + (8 << 3);
mask = 1 << 10;
tab = VP8Cat6;
}
while (mask) {
VP8PutBit(bw, !!(v & mask), *tab++);
mask >>= 1;
}
}
p = res->prob[VP8EncBands[n]][2];
}
VP8PutBitUniform(bw, sign);
if (n == 16 || !VP8PutBit(bw, n <= res->last, p[0])) {
return 1; // EOB
}
}
return 1;
}
static void CodeResiduals(VP8BitWriter* const bw, VP8EncIterator* const it,
const VP8ModeScore* const rd) {
int x, y, ch;
VP8Residual res;
uint64_t pos1, pos2, pos3;
const int i16 = (it->mb_->type_ == 1);
const int segment = it->mb_->segment_;
VP8Encoder* const enc = it->enc_;
VP8IteratorNzToBytes(it);
pos1 = VP8BitWriterPos(bw);
if (i16) {
InitResidual(0, 1, enc, &res);
SetResidualCoeffs(rd->y_dc_levels, &res);
it->top_nz_[8] = it->left_nz_[8] =
PutCoeffs(bw, it->top_nz_[8] + it->left_nz_[8], &res);
InitResidual(1, 0, enc, &res);
} else {
InitResidual(0, 3, enc, &res);
}
// luma-AC
for (y = 0; y < 4; ++y) {
for (x = 0; x < 4; ++x) {
const int ctx = it->top_nz_[x] + it->left_nz_[y];
SetResidualCoeffs(rd->y_ac_levels[x + y * 4], &res);
it->top_nz_[x] = it->left_nz_[y] = PutCoeffs(bw, ctx, &res);
}
}
pos2 = VP8BitWriterPos(bw);
// U/V
InitResidual(0, 2, enc, &res);
for (ch = 0; ch <= 2; ch += 2) {
for (y = 0; y < 2; ++y) {
for (x = 0; x < 2; ++x) {
const int ctx = it->top_nz_[4 + ch + x] + it->left_nz_[4 + ch + y];
SetResidualCoeffs(rd->uv_levels[ch * 2 + x + y * 2], &res);
it->top_nz_[4 + ch + x] = it->left_nz_[4 + ch + y] =
PutCoeffs(bw, ctx, &res);
}
}
}
pos3 = VP8BitWriterPos(bw);
it->luma_bits_ = pos2 - pos1;
it->uv_bits_ = pos3 - pos2;
it->bit_count_[segment][i16] += it->luma_bits_;
it->bit_count_[segment][2] += it->uv_bits_;
VP8IteratorBytesToNz(it);
}
// Same as CodeResiduals, but doesn't actually write anything.
// Instead, it just records the event distribution.
static void RecordResiduals(VP8EncIterator* const it,
const VP8ModeScore* const rd) {
int x, y, ch;
VP8Residual res;
VP8Encoder* const enc = it->enc_;
VP8IteratorNzToBytes(it);
if (it->mb_->type_ == 1) { // i16x16
InitResidual(0, 1, enc, &res);
SetResidualCoeffs(rd->y_dc_levels, &res);
it->top_nz_[8] = it->left_nz_[8] =
RecordCoeffs(it->top_nz_[8] + it->left_nz_[8], &res);
InitResidual(1, 0, enc, &res);
} else {
InitResidual(0, 3, enc, &res);
}
// luma-AC
for (y = 0; y < 4; ++y) {
for (x = 0; x < 4; ++x) {
const int ctx = it->top_nz_[x] + it->left_nz_[y];
SetResidualCoeffs(rd->y_ac_levels[x + y * 4], &res);
it->top_nz_[x] = it->left_nz_[y] = RecordCoeffs(ctx, &res);
}
}
// U/V
InitResidual(0, 2, enc, &res);
for (ch = 0; ch <= 2; ch += 2) {
for (y = 0; y < 2; ++y) {
for (x = 0; x < 2; ++x) {
const int ctx = it->top_nz_[4 + ch + x] + it->left_nz_[4 + ch + y];
SetResidualCoeffs(rd->uv_levels[ch * 2 + x + y * 2], &res);
it->top_nz_[4 + ch + x] = it->left_nz_[4 + ch + y] =
RecordCoeffs(ctx, &res);
}
}
}
VP8IteratorBytesToNz(it);
}
//------------------------------------------------------------------------------
// Token buffer
#if !defined(DISABLE_TOKEN_BUFFER)
static void RecordTokens(VP8EncIterator* const it, const VP8ModeScore* const rd,
VP8TBuffer* const tokens) {
int x, y, ch;
VP8Residual res;
VP8Encoder* const enc = it->enc_;
VP8IteratorNzToBytes(it);
if (it->mb_->type_ == 1) { // i16x16
const int ctx = it->top_nz_[8] + it->left_nz_[8];
InitResidual(0, 1, enc, &res);
SetResidualCoeffs(rd->y_dc_levels, &res);
it->top_nz_[8] = it->left_nz_[8] =
VP8RecordCoeffTokens(ctx, 1,
res.first, res.last, res.coeffs, tokens);
RecordCoeffs(ctx, &res);
InitResidual(1, 0, enc, &res);
} else {
InitResidual(0, 3, enc, &res);
}
// luma-AC
for (y = 0; y < 4; ++y) {
for (x = 0; x < 4; ++x) {
const int ctx = it->top_nz_[x] + it->left_nz_[y];
SetResidualCoeffs(rd->y_ac_levels[x + y * 4], &res);
it->top_nz_[x] = it->left_nz_[y] =
VP8RecordCoeffTokens(ctx, res.coeff_type,
res.first, res.last, res.coeffs, tokens);
RecordCoeffs(ctx, &res);
}
}
// U/V
InitResidual(0, 2, enc, &res);
for (ch = 0; ch <= 2; ch += 2) {
for (y = 0; y < 2; ++y) {
for (x = 0; x < 2; ++x) {
const int ctx = it->top_nz_[4 + ch + x] + it->left_nz_[4 + ch + y];
SetResidualCoeffs(rd->uv_levels[ch * 2 + x + y * 2], &res);
it->top_nz_[4 + ch + x] = it->left_nz_[4 + ch + y] =
VP8RecordCoeffTokens(ctx, 2,
res.first, res.last, res.coeffs, tokens);
RecordCoeffs(ctx, &res);
}
}
}
VP8IteratorBytesToNz(it);
}
#endif // !DISABLE_TOKEN_BUFFER
//------------------------------------------------------------------------------
// ExtraInfo map / Debug function
#if SEGMENT_VISU
static void SetBlock(uint8_t* p, int value, int size) {
int y;
for (y = 0; y < size; ++y) {
memset(p, value, size);
p += BPS;
}
}
#endif
static void ResetSSE(VP8Encoder* const enc) {
enc->sse_[0] = 0;
enc->sse_[1] = 0;
enc->sse_[2] = 0;
// Note: enc->sse_[3] is managed by alpha.c
enc->sse_count_ = 0;
}
static void StoreSSE(const VP8EncIterator* const it) {
VP8Encoder* const enc = it->enc_;
const uint8_t* const in = it->yuv_in_;
const uint8_t* const out = it->yuv_out_;
// Note: not totally accurate at boundary. And doesn't include in-loop filter.
enc->sse_[0] += VP8SSE16x16(in + Y_OFF, out + Y_OFF);
enc->sse_[1] += VP8SSE8x8(in + U_OFF, out + U_OFF);
enc->sse_[2] += VP8SSE8x8(in + V_OFF, out + V_OFF);
enc->sse_count_ += 16 * 16;
}
static void StoreSideInfo(const VP8EncIterator* const it) {
VP8Encoder* const enc = it->enc_;
const VP8MBInfo* const mb = it->mb_;
WebPPicture* const pic = enc->pic_;
if (pic->stats != NULL) {
StoreSSE(it);
enc->block_count_[0] += (mb->type_ == 0);
enc->block_count_[1] += (mb->type_ == 1);
enc->block_count_[2] += (mb->skip_ != 0);
}
if (pic->extra_info != NULL) {
uint8_t* const info = &pic->extra_info[it->x_ + it->y_ * enc->mb_w_];
switch (pic->extra_info_type) {
case 1: *info = mb->type_; break;
case 2: *info = mb->segment_; break;
case 3: *info = enc->dqm_[mb->segment_].quant_; break;
case 4: *info = (mb->type_ == 1) ? it->preds_[0] : 0xff; break;
case 5: *info = mb->uv_mode_; break;
case 6: {
const int b = (int)((it->luma_bits_ + it->uv_bits_ + 7) >> 3);
*info = (b > 255) ? 255 : b; break;
}
case 7: *info = mb->alpha_; break;
default: *info = 0; break;
};
}
#if SEGMENT_VISU // visualize segments and prediction modes
SetBlock(it->yuv_out_ + Y_OFF, mb->segment_ * 64, 16);
SetBlock(it->yuv_out_ + U_OFF, it->preds_[0] * 64, 8);
SetBlock(it->yuv_out_ + V_OFF, mb->uv_mode_ * 64, 8);
#endif
}
//------------------------------------------------------------------------------
// StatLoop(): only collect statistics (number of skips, token usage, ...).
// This is used for deciding optimal probabilities. It also modifies the
// quantizer value if some target (size, PNSR) was specified.
#define kHeaderSizeEstimate (15 + 20 + 10) // TODO: fix better
static void SetLoopParams(VP8Encoder* const enc, float q) {
// Make sure the quality parameter is inside valid bounds
if (q < 0.) {
q = 0;
} else if (q > 100.) {
q = 100;
}
VP8SetSegmentParams(enc, q); // setup segment quantizations and filters
SetSegmentProbas(enc); // compute segment probabilities
ResetStats(enc);
ResetTokenStats(enc);
ResetSSE(enc);
}
static int OneStatPass(VP8Encoder* const enc, float q, VP8RDLevel rd_opt,
int nb_mbs, float* const PSNR, int percent_delta) {
VP8EncIterator it;
uint64_t size = 0;
uint64_t distortion = 0;
const uint64_t pixel_count = nb_mbs * 384;
SetLoopParams(enc, q);
VP8IteratorInit(enc, &it);
do {
VP8ModeScore info;
VP8IteratorImport(&it);
if (VP8Decimate(&it, &info, rd_opt)) {
// Just record the number of skips and act like skip_proba is not used.
enc->proba_.nb_skip_++;
}
RecordResiduals(&it, &info);
size += info.R;
distortion += info.D;
if (percent_delta && !VP8IteratorProgress(&it, percent_delta))
return 0;
} while (VP8IteratorNext(&it, it.yuv_out_) && --nb_mbs > 0);
size += FinalizeSkipProba(enc);
size += FinalizeTokenProbas(&enc->proba_);
size += enc->segment_hdr_.size_;
size = ((size + 1024) >> 11) + kHeaderSizeEstimate;
if (PSNR) {
*PSNR = (float)(10.* log10(255. * 255. * pixel_count / distortion));
}
return (int)size;
}
// successive refinement increments.
static const int dqs[] = { 20, 15, 10, 8, 6, 4, 2, 1, 0 };
static int StatLoop(VP8Encoder* const enc) {
const int method = enc->method_;
const int do_search = enc->do_search_;
const int fast_probe = ((method == 0 || method == 3) && !do_search);
float q = enc->config_->quality;
const int max_passes = enc->config_->pass;
const int task_percent = 20;
const int percent_per_pass = (task_percent + max_passes / 2) / max_passes;
const int final_percent = enc->percent_ + task_percent;
int pass;
int nb_mbs;
// Fast mode: quick analysis pass over few mbs. Better than nothing.
nb_mbs = enc->mb_w_ * enc->mb_h_;
if (fast_probe) {
if (method == 3) { // we need more stats for method 3 to be reliable.
nb_mbs = (nb_mbs > 200) ? nb_mbs >> 1 : 100;
} else {
nb_mbs = (nb_mbs > 200) ? nb_mbs >> 2 : 50;
}
}
// No target size: just do several pass without changing 'q'
if (!do_search) {
for (pass = 0; pass < max_passes; ++pass) {
const VP8RDLevel rd_opt = (method >= 3) ? RD_OPT_BASIC : RD_OPT_NONE;
if (!OneStatPass(enc, q, rd_opt, nb_mbs, NULL, percent_per_pass)) {
return 0;
}
}
} else {
// binary search for a size close to target
for (pass = 0; pass < max_passes && (dqs[pass] > 0); ++pass) {
float PSNR;
int criterion;
const int size = OneStatPass(enc, q, RD_OPT_BASIC, nb_mbs, &PSNR,
percent_per_pass);
#if DEBUG_SEARCH
printf("#%d size=%d PSNR=%.2f q=%.2f\n", pass, size, PSNR, q);
#endif
if (size == 0) return 0;
if (enc->config_->target_PSNR > 0) {
criterion = (PSNR < enc->config_->target_PSNR);
} else {
criterion = (size < enc->config_->target_size);
}
// dichotomize
if (criterion) {
q += dqs[pass];
} else {
q -= dqs[pass];
}
}
}
VP8CalculateLevelCosts(&enc->proba_); // finalize costs
return WebPReportProgress(enc->pic_, final_percent, &enc->percent_);
}
//------------------------------------------------------------------------------
// Main loops
//
static const int kAverageBytesPerMB[8] = { 50, 24, 16, 9, 7, 5, 3, 2 };
static int PreLoopInitialize(VP8Encoder* const enc) {
int p;
int ok = 1;
const int average_bytes_per_MB = kAverageBytesPerMB[enc->base_quant_ >> 4];
const int bytes_per_parts =
enc->mb_w_ * enc->mb_h_ * average_bytes_per_MB / enc->num_parts_;
// Initialize the bit-writers
for (p = 0; ok && p < enc->num_parts_; ++p) {
ok = VP8BitWriterInit(enc->parts_ + p, bytes_per_parts);
}
if (!ok) VP8EncFreeBitWriters(enc); // malloc error occurred
return ok;
}
static int PostLoopFinalize(VP8EncIterator* const it, int ok) {
VP8Encoder* const enc = it->enc_;
if (ok) { // Finalize the partitions, check for extra errors.
int p;
for (p = 0; p < enc->num_parts_; ++p) {
VP8BitWriterFinish(enc->parts_ + p);
ok &= !enc->parts_[p].error_;
}
}
if (ok) { // All good. Finish up.
if (enc->pic_->stats) { // finalize byte counters...
int i, s;
for (i = 0; i <= 2; ++i) {
for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
enc->residual_bytes_[i][s] = (int)((it->bit_count_[s][i] + 7) >> 3);
}
}
}
VP8AdjustFilterStrength(it); // ...and store filter stats.
} else {
// Something bad happened -> need to do some memory cleanup.
VP8EncFreeBitWriters(enc);
}
return ok;
}
//------------------------------------------------------------------------------
// VP8EncLoop(): does the final bitstream coding.
static void ResetAfterSkip(VP8EncIterator* const it) {
if (it->mb_->type_ == 1) {
*it->nz_ = 0; // reset all predictors
it->left_nz_[8] = 0;
} else {
*it->nz_ &= (1 << 24); // preserve the dc_nz bit
}
}
int VP8EncLoop(VP8Encoder* const enc) {
VP8EncIterator it;
int ok = PreLoopInitialize(enc);
if (!ok) return 0;
StatLoop(enc); // stats-collection loop
VP8IteratorInit(enc, &it);
VP8InitFilter(&it);
do {
VP8ModeScore info;
const int dont_use_skip = !enc->proba_.use_skip_proba_;
const VP8RDLevel rd_opt = enc->rd_opt_level_;
VP8IteratorImport(&it);
// Warning! order is important: first call VP8Decimate() and
// *then* decide how to code the skip decision if there's one.
if (!VP8Decimate(&it, &info, rd_opt) || dont_use_skip) {
CodeResiduals(it.bw_, &it, &info);
} else { // reset predictors after a skip
ResetAfterSkip(&it);
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (enc->use_layer_) {
VP8EncCodeLayerBlock(&it);
}
#endif
StoreSideInfo(&it);
VP8StoreFilterStats(&it);
VP8IteratorExport(&it);
ok = VP8IteratorProgress(&it, 20);
} while (ok && VP8IteratorNext(&it, it.yuv_out_));
return PostLoopFinalize(&it, ok);
}
//------------------------------------------------------------------------------
// Single pass using Token Buffer.
#if !defined(DISABLE_TOKEN_BUFFER)
#define MIN_COUNT 96 // minimum number of macroblocks before updating stats
int VP8EncTokenLoop(VP8Encoder* const enc) {
int ok;
// Roughly refresh the proba height times per pass
int max_count = (enc->mb_w_ * enc->mb_h_) >> 3;
int cnt;
VP8EncIterator it;
VP8Proba* const proba = &enc->proba_;
const VP8RDLevel rd_opt = enc->rd_opt_level_;
if (max_count < MIN_COUNT) max_count = MIN_COUNT;
cnt = max_count;
assert(enc->num_parts_ == 1);
assert(enc->use_tokens_);
assert(proba->use_skip_proba_ == 0);
assert(rd_opt >= RD_OPT_BASIC); // otherwise, token-buffer won't be useful
assert(!enc->do_search_); // TODO(skal): handle pass and dichotomy
SetLoopParams(enc, enc->config_->quality);
ok = PreLoopInitialize(enc);
if (!ok) return 0;
VP8IteratorInit(enc, &it);
VP8InitFilter(&it);
do {
VP8ModeScore info;
VP8IteratorImport(&it);
if (--cnt < 0) {
FinalizeTokenProbas(proba);
VP8CalculateLevelCosts(proba); // refresh cost tables for rd-opt
cnt = max_count;
}
VP8Decimate(&it, &info, rd_opt);
RecordTokens(&it, &info, &enc->tokens_);
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (enc->use_layer_) {
VP8EncCodeLayerBlock(&it);
}
#endif
StoreSideInfo(&it);
VP8StoreFilterStats(&it);
VP8IteratorExport(&it);
ok = VP8IteratorProgress(&it, 20);
} while (ok && VP8IteratorNext(&it, it.yuv_out_));
ok = ok && WebPReportProgress(enc->pic_, enc->percent_ + 20, &enc->percent_);
if (ok) {
FinalizeTokenProbas(proba);
ok = VP8EmitTokens(&enc->tokens_, enc->parts_ + 0,
(const uint8_t*)proba->coeffs_, 1);
}
return PostLoopFinalize(&it, ok);
}
#else
int VP8EncTokenLoop(VP8Encoder* const enc) {
(void)enc;
return 0; // we shouldn't be here.
}
#endif // DISABLE_TOKEN_BUFFER
//------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif
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