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libwebp/src/enc/vp8l_enc.c
James Zern 45129ee027 Revert "Check all the rows." 
This reverts commit ee26766a89a149afe5f73fdcb8f2493ec808f2b7.

This change also reverts the parent.

Revert "Increase the transform bits if possible."

This reverts commit 7ec51c591608333fd5e6fdddbee16e1d65bef3db.

These changes result in non-lossless encodes.

Bug: oss-fuzz:69231, oss-fuzz:69109, oss-fuzz:69208
Bug: b:341475869, b:342743143
Change-Id: Ia28f558992e0aa6f024af1ff66da52e0a5e26fa3
2024-05-25 11:00:32 -07:00

1907 lines
69 KiB
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// Copyright 2012 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// main entry for the lossless encoder.
//
// Author: Vikas Arora (vikaas.arora@gmail.com)
//
#include <assert.h>
#include <stdlib.h>
#include "src/dsp/lossless.h"
#include "src/dsp/lossless_common.h"
#include "src/enc/backward_references_enc.h"
#include "src/enc/histogram_enc.h"
#include "src/enc/vp8i_enc.h"
#include "src/enc/vp8li_enc.h"
#include "src/utils/bit_writer_utils.h"
#include "src/utils/huffman_encode_utils.h"
#include "src/utils/palette.h"
#include "src/utils/utils.h"
#include "src/webp/encode.h"
#include "src/webp/format_constants.h"
// Maximum number of histogram images (sub-blocks).
#define MAX_HUFF_IMAGE_SIZE 2600
#define MAX_HUFFMAN_BITS (MIN_HUFFMAN_BITS + (1 << NUM_HUFFMAN_BITS) - 1)
// -----------------------------------------------------------------------------
// Palette
// These five modes are evaluated and their respective entropy is computed.
typedef enum {
kDirect = 0,
kSpatial = 1,
kSubGreen = 2,
kSpatialSubGreen = 3,
kPalette = 4,
kPaletteAndSpatial = 5,
kNumEntropyIx = 6
} EntropyIx;
typedef enum {
kHistoAlpha = 0,
kHistoAlphaPred,
kHistoGreen,
kHistoGreenPred,
kHistoRed,
kHistoRedPred,
kHistoBlue,
kHistoBluePred,
kHistoRedSubGreen,
kHistoRedPredSubGreen,
kHistoBlueSubGreen,
kHistoBluePredSubGreen,
kHistoPalette,
kHistoTotal // Must be last.
} HistoIx;
static void AddSingleSubGreen(uint32_t p,
uint32_t* const r, uint32_t* const b) {
const int green = (int)p >> 8; // The upper bits are masked away later.
++r[(((int)p >> 16) - green) & 0xff];
++b[(((int)p >> 0) - green) & 0xff];
}
static void AddSingle(uint32_t p,
uint32_t* const a, uint32_t* const r,
uint32_t* const g, uint32_t* const b) {
++a[(p >> 24) & 0xff];
++r[(p >> 16) & 0xff];
++g[(p >> 8) & 0xff];
++b[(p >> 0) & 0xff];
}
static WEBP_INLINE uint32_t HashPix(uint32_t pix) {
// Note that masking with 0xffffffffu is for preventing an
// 'unsigned int overflow' warning. Doesn't impact the compiled code.
return ((((uint64_t)pix + (pix >> 19)) * 0x39c5fba7ull) & 0xffffffffu) >> 24;
}
static int AnalyzeEntropy(const uint32_t* argb,
int width, int height, int argb_stride,
int use_palette,
int palette_size, int transform_bits,
EntropyIx* const min_entropy_ix,
int* const red_and_blue_always_zero) {
// Allocate histogram set with cache_bits = 0.
uint32_t* histo;
if (use_palette && palette_size <= 16) {
// In the case of small palettes, we pack 2, 4 or 8 pixels together. In
// practice, small palettes are better than any other transform.
*min_entropy_ix = kPalette;
*red_and_blue_always_zero = 1;
return 1;
}
histo = (uint32_t*)WebPSafeCalloc(kHistoTotal, sizeof(*histo) * 256);
if (histo != NULL) {
int i, x, y;
const uint32_t* prev_row = NULL;
const uint32_t* curr_row = argb;
uint32_t pix_prev = argb[0]; // Skip the first pixel.
for (y = 0; y < height; ++y) {
for (x = 0; x < width; ++x) {
const uint32_t pix = curr_row[x];
const uint32_t pix_diff = VP8LSubPixels(pix, pix_prev);
pix_prev = pix;
if ((pix_diff == 0) || (prev_row != NULL && pix == prev_row[x])) {
continue;
}
AddSingle(pix,
&histo[kHistoAlpha * 256],
&histo[kHistoRed * 256],
&histo[kHistoGreen * 256],
&histo[kHistoBlue * 256]);
AddSingle(pix_diff,
&histo[kHistoAlphaPred * 256],
&histo[kHistoRedPred * 256],
&histo[kHistoGreenPred * 256],
&histo[kHistoBluePred * 256]);
AddSingleSubGreen(pix,
&histo[kHistoRedSubGreen * 256],
&histo[kHistoBlueSubGreen * 256]);
AddSingleSubGreen(pix_diff,
&histo[kHistoRedPredSubGreen * 256],
&histo[kHistoBluePredSubGreen * 256]);
{
// Approximate the palette by the entropy of the multiplicative hash.
const uint32_t hash = HashPix(pix);
++histo[kHistoPalette * 256 + hash];
}
}
prev_row = curr_row;
curr_row += argb_stride;
}
{
float entropy_comp[kHistoTotal];
float entropy[kNumEntropyIx];
int k;
int last_mode_to_analyze = use_palette ? kPalette : kSpatialSubGreen;
int j;
// Let's add one zero to the predicted histograms. The zeros are removed
// too efficiently by the pix_diff == 0 comparison, at least one of the
// zeros is likely to exist.
++histo[kHistoRedPredSubGreen * 256];
++histo[kHistoBluePredSubGreen * 256];
++histo[kHistoRedPred * 256];
++histo[kHistoGreenPred * 256];
++histo[kHistoBluePred * 256];
++histo[kHistoAlphaPred * 256];
for (j = 0; j < kHistoTotal; ++j) {
entropy_comp[j] = VP8LBitsEntropy(&histo[j * 256], 256);
}
entropy[kDirect] = entropy_comp[kHistoAlpha] +
entropy_comp[kHistoRed] +
entropy_comp[kHistoGreen] +
entropy_comp[kHistoBlue];
entropy[kSpatial] = entropy_comp[kHistoAlphaPred] +
entropy_comp[kHistoRedPred] +
entropy_comp[kHistoGreenPred] +
entropy_comp[kHistoBluePred];
entropy[kSubGreen] = entropy_comp[kHistoAlpha] +
entropy_comp[kHistoRedSubGreen] +
entropy_comp[kHistoGreen] +
entropy_comp[kHistoBlueSubGreen];
entropy[kSpatialSubGreen] = entropy_comp[kHistoAlphaPred] +
entropy_comp[kHistoRedPredSubGreen] +
entropy_comp[kHistoGreenPred] +
entropy_comp[kHistoBluePredSubGreen];
entropy[kPalette] = entropy_comp[kHistoPalette];
// When including transforms, there is an overhead in bits from
// storing them. This overhead is small but matters for small images.
// For spatial, there are 14 transformations.
entropy[kSpatial] += VP8LSubSampleSize(width, transform_bits) *
VP8LSubSampleSize(height, transform_bits) *
VP8LFastLog2(14);
// For color transforms: 24 as only 3 channels are considered in a
// ColorTransformElement.
entropy[kSpatialSubGreen] += VP8LSubSampleSize(width, transform_bits) *
VP8LSubSampleSize(height, transform_bits) *
VP8LFastLog2(24);
// For palettes, add the cost of storing the palette.
// We empirically estimate the cost of a compressed entry as 8 bits.
// The palette is differential-coded when compressed hence a much
// lower cost than sizeof(uint32_t)*8.
entropy[kPalette] += palette_size * 8;
*min_entropy_ix = kDirect;
for (k = kDirect + 1; k <= last_mode_to_analyze; ++k) {
if (entropy[*min_entropy_ix] > entropy[k]) {
*min_entropy_ix = (EntropyIx)k;
}
}
assert((int)*min_entropy_ix <= last_mode_to_analyze);
*red_and_blue_always_zero = 1;
// Let's check if the histogram of the chosen entropy mode has
// non-zero red and blue values. If all are zero, we can later skip
// the cross color optimization.
{
static const uint8_t kHistoPairs[5][2] = {
{ kHistoRed, kHistoBlue },
{ kHistoRedPred, kHistoBluePred },
{ kHistoRedSubGreen, kHistoBlueSubGreen },
{ kHistoRedPredSubGreen, kHistoBluePredSubGreen },
{ kHistoRed, kHistoBlue }
};
const uint32_t* const red_histo =
&histo[256 * kHistoPairs[*min_entropy_ix][0]];
const uint32_t* const blue_histo =
&histo[256 * kHistoPairs[*min_entropy_ix][1]];
for (i = 1; i < 256; ++i) {
if ((red_histo[i] | blue_histo[i]) != 0) {
*red_and_blue_always_zero = 0;
break;
}
}
}
}
WebPSafeFree(histo);
return 1;
} else {
return 0;
}
}
static int GetHistoBits(int method, int use_palette, int width, int height) {
// Make tile size a function of encoding method (Range: 0 to 6).
int histo_bits = (use_palette ? 9 : 7) - method;
while (1) {
const int huff_image_size = VP8LSubSampleSize(width, histo_bits) *
VP8LSubSampleSize(height, histo_bits);
if (huff_image_size <= MAX_HUFF_IMAGE_SIZE) break;
++histo_bits;
}
return (histo_bits < MIN_HUFFMAN_BITS) ? MIN_HUFFMAN_BITS :
(histo_bits > MAX_HUFFMAN_BITS) ? MAX_HUFFMAN_BITS : histo_bits;
}
static int GetTransformBits(int method, int histo_bits) {
const int max_transform_bits = (method < 4) ? 6 : (method > 4) ? 4 : 5;
const int res =
(histo_bits > max_transform_bits) ? max_transform_bits : histo_bits;
assert(res <= MAX_TRANSFORM_BITS);
return res;
}
// Set of parameters to be used in each iteration of the cruncher.
#define CRUNCH_SUBCONFIGS_MAX 2
typedef struct {
int lz77_;
int do_no_cache_;
} CrunchSubConfig;
typedef struct {
int entropy_idx_;
PaletteSorting palette_sorting_type_;
CrunchSubConfig sub_configs_[CRUNCH_SUBCONFIGS_MAX];
int sub_configs_size_;
} CrunchConfig;
// +2 because we add a palette sorting configuration for kPalette and
// kPaletteAndSpatial.
#define CRUNCH_CONFIGS_MAX (kNumEntropyIx + 2 * kPaletteSortingNum)
static int EncoderAnalyze(VP8LEncoder* const enc,
CrunchConfig crunch_configs[CRUNCH_CONFIGS_MAX],
int* const crunch_configs_size,
int* const red_and_blue_always_zero) {
const WebPPicture* const pic = enc->pic_;
const int width = pic->width;
const int height = pic->height;
const WebPConfig* const config = enc->config_;
const int method = config->method;
const int low_effort = (config->method == 0);
int i;
int use_palette, transform_bits;
int n_lz77s;
// If set to 0, analyze the cache with the computed cache value. If 1, also
// analyze with no-cache.
int do_no_cache = 0;
assert(pic != NULL && pic->argb != NULL);
// Check whether a palette is possible.
enc->palette_size_ = GetColorPalette(pic, enc->palette_sorted_);
use_palette = (enc->palette_size_ <= MAX_PALETTE_SIZE);
if (!use_palette) {
enc->palette_size_ = 0;
}
// Empirical bit sizes.
enc->histo_bits_ = GetHistoBits(method, use_palette,
pic->width, pic->height);
transform_bits = GetTransformBits(method, enc->histo_bits_);
enc->predictor_transform_bits_ = transform_bits;
enc->cross_color_transform_bits_ = transform_bits;
if (low_effort) {
// AnalyzeEntropy is somewhat slow.
crunch_configs[0].entropy_idx_ = use_palette ? kPalette : kSpatialSubGreen;
crunch_configs[0].palette_sorting_type_ =
use_palette ? kSortedDefault : kUnusedPalette;
n_lz77s = 1;
*crunch_configs_size = 1;
} else {
EntropyIx min_entropy_ix;
// Try out multiple LZ77 on images with few colors.
n_lz77s = (enc->palette_size_ > 0 && enc->palette_size_ <= 16) ? 2 : 1;
if (!AnalyzeEntropy(pic->argb, width, height, pic->argb_stride, use_palette,
enc->palette_size_, transform_bits, &min_entropy_ix,
red_and_blue_always_zero)) {
return 0;
}
if (method == 6 && config->quality == 100) {
do_no_cache = 1;
// Go brute force on all transforms.
*crunch_configs_size = 0;
for (i = 0; i < kNumEntropyIx; ++i) {
// We can only apply kPalette or kPaletteAndSpatial if we can indeed use
// a palette.
if ((i != kPalette && i != kPaletteAndSpatial) || use_palette) {
assert(*crunch_configs_size < CRUNCH_CONFIGS_MAX);
if (use_palette && (i == kPalette || i == kPaletteAndSpatial)) {
int sorting_method;
for (sorting_method = 0; sorting_method < kPaletteSortingNum;
++sorting_method) {
const PaletteSorting typed_sorting_method =
(PaletteSorting)sorting_method;
// TODO(vrabaud) kSortedDefault should be tested. It is omitted
// for now for backward compatibility.
if (typed_sorting_method == kUnusedPalette ||
typed_sorting_method == kSortedDefault) {
continue;
}
crunch_configs[(*crunch_configs_size)].entropy_idx_ = i;
crunch_configs[(*crunch_configs_size)].palette_sorting_type_ =
typed_sorting_method;
++*crunch_configs_size;
}
} else {
crunch_configs[(*crunch_configs_size)].entropy_idx_ = i;
crunch_configs[(*crunch_configs_size)].palette_sorting_type_ =
kUnusedPalette;
++*crunch_configs_size;
}
}
}
} else {
// Only choose the guessed best transform.
*crunch_configs_size = 1;
crunch_configs[0].entropy_idx_ = min_entropy_ix;
crunch_configs[0].palette_sorting_type_ =
use_palette ? kMinimizeDelta : kUnusedPalette;
if (config->quality >= 75 && method == 5) {
// Test with and without color cache.
do_no_cache = 1;
// If we have a palette, also check in combination with spatial.
if (min_entropy_ix == kPalette) {
*crunch_configs_size = 2;
crunch_configs[1].entropy_idx_ = kPaletteAndSpatial;
crunch_configs[1].palette_sorting_type_ = kMinimizeDelta;
}
}
}
}
// Fill in the different LZ77s.
assert(n_lz77s <= CRUNCH_SUBCONFIGS_MAX);
for (i = 0; i < *crunch_configs_size; ++i) {
int j;
for (j = 0; j < n_lz77s; ++j) {
assert(j < CRUNCH_SUBCONFIGS_MAX);
crunch_configs[i].sub_configs_[j].lz77_ =
(j == 0) ? kLZ77Standard | kLZ77RLE : kLZ77Box;
crunch_configs[i].sub_configs_[j].do_no_cache_ = do_no_cache;
}
crunch_configs[i].sub_configs_size_ = n_lz77s;
}
return 1;
}
static int EncoderInit(VP8LEncoder* const enc) {
const WebPPicture* const pic = enc->pic_;
const int width = pic->width;
const int height = pic->height;
const int pix_cnt = width * height;
// we round the block size up, so we're guaranteed to have
// at most MAX_REFS_BLOCK_PER_IMAGE blocks used:
const int refs_block_size = (pix_cnt - 1) / MAX_REFS_BLOCK_PER_IMAGE + 1;
int i;
if (!VP8LHashChainInit(&enc->hash_chain_, pix_cnt)) return 0;
for (i = 0; i < 4; ++i) VP8LBackwardRefsInit(&enc->refs_[i], refs_block_size);
return 1;
}
// Returns false in case of memory error.
static int GetHuffBitLengthsAndCodes(
const VP8LHistogramSet* const histogram_image,
HuffmanTreeCode* const huffman_codes) {
int i, k;
int ok = 0;
uint64_t total_length_size = 0;
uint8_t* mem_buf = NULL;
const int histogram_image_size = histogram_image->size;
int max_num_symbols = 0;
uint8_t* buf_rle = NULL;
HuffmanTree* huff_tree = NULL;
// Iterate over all histograms and get the aggregate number of codes used.
for (i = 0; i < histogram_image_size; ++i) {
const VP8LHistogram* const histo = histogram_image->histograms[i];
HuffmanTreeCode* const codes = &huffman_codes[5 * i];
assert(histo != NULL);
for (k = 0; k < 5; ++k) {
const int num_symbols =
(k == 0) ? VP8LHistogramNumCodes(histo->palette_code_bits_) :
(k == 4) ? NUM_DISTANCE_CODES : 256;
codes[k].num_symbols = num_symbols;
total_length_size += num_symbols;
}
}
// Allocate and Set Huffman codes.
{
uint16_t* codes;
uint8_t* lengths;
mem_buf = (uint8_t*)WebPSafeCalloc(total_length_size,
sizeof(*lengths) + sizeof(*codes));
if (mem_buf == NULL) goto End;
codes = (uint16_t*)mem_buf;
lengths = (uint8_t*)&codes[total_length_size];
for (i = 0; i < 5 * histogram_image_size; ++i) {
const int bit_length = huffman_codes[i].num_symbols;
huffman_codes[i].codes = codes;
huffman_codes[i].code_lengths = lengths;
codes += bit_length;
lengths += bit_length;
if (max_num_symbols < bit_length) {
max_num_symbols = bit_length;
}
}
}
buf_rle = (uint8_t*)WebPSafeMalloc(1ULL, max_num_symbols);
huff_tree = (HuffmanTree*)WebPSafeMalloc(3ULL * max_num_symbols,
sizeof(*huff_tree));
if (buf_rle == NULL || huff_tree == NULL) goto End;
// Create Huffman trees.
for (i = 0; i < histogram_image_size; ++i) {
HuffmanTreeCode* const codes = &huffman_codes[5 * i];
VP8LHistogram* const histo = histogram_image->histograms[i];
VP8LCreateHuffmanTree(histo->literal_, 15, buf_rle, huff_tree, codes + 0);
VP8LCreateHuffmanTree(histo->red_, 15, buf_rle, huff_tree, codes + 1);
VP8LCreateHuffmanTree(histo->blue_, 15, buf_rle, huff_tree, codes + 2);
VP8LCreateHuffmanTree(histo->alpha_, 15, buf_rle, huff_tree, codes + 3);
VP8LCreateHuffmanTree(histo->distance_, 15, buf_rle, huff_tree, codes + 4);
}
ok = 1;
End:
WebPSafeFree(huff_tree);
WebPSafeFree(buf_rle);
if (!ok) {
WebPSafeFree(mem_buf);
memset(huffman_codes, 0, 5 * histogram_image_size * sizeof(*huffman_codes));
}
return ok;
}
static void StoreHuffmanTreeOfHuffmanTreeToBitMask(
VP8LBitWriter* const bw, const uint8_t* code_length_bitdepth) {
// RFC 1951 will calm you down if you are worried about this funny sequence.
// This sequence is tuned from that, but more weighted for lower symbol count,
// and more spiking histograms.
static const uint8_t kStorageOrder[CODE_LENGTH_CODES] = {
17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
};
int i;
// Throw away trailing zeros:
int codes_to_store = CODE_LENGTH_CODES;
for (; codes_to_store > 4; --codes_to_store) {
if (code_length_bitdepth[kStorageOrder[codes_to_store - 1]] != 0) {
break;
}
}
VP8LPutBits(bw, codes_to_store - 4, 4);
for (i = 0; i < codes_to_store; ++i) {
VP8LPutBits(bw, code_length_bitdepth[kStorageOrder[i]], 3);
}
}
static void ClearHuffmanTreeIfOnlyOneSymbol(
HuffmanTreeCode* const huffman_code) {
int k;
int count = 0;
for (k = 0; k < huffman_code->num_symbols; ++k) {
if (huffman_code->code_lengths[k] != 0) {
++count;
if (count > 1) return;
}
}
for (k = 0; k < huffman_code->num_symbols; ++k) {
huffman_code->code_lengths[k] = 0;
huffman_code->codes[k] = 0;
}
}
static void StoreHuffmanTreeToBitMask(
VP8LBitWriter* const bw,
const HuffmanTreeToken* const tokens, const int num_tokens,
const HuffmanTreeCode* const huffman_code) {
int i;
for (i = 0; i < num_tokens; ++i) {
const int ix = tokens[i].code;
const int extra_bits = tokens[i].extra_bits;
VP8LPutBits(bw, huffman_code->codes[ix], huffman_code->code_lengths[ix]);
switch (ix) {
case 16:
VP8LPutBits(bw, extra_bits, 2);
break;
case 17:
VP8LPutBits(bw, extra_bits, 3);
break;
case 18:
VP8LPutBits(bw, extra_bits, 7);
break;
}
}
}
// 'huff_tree' and 'tokens' are pre-alloacted buffers.
static void StoreFullHuffmanCode(VP8LBitWriter* const bw,
HuffmanTree* const huff_tree,
HuffmanTreeToken* const tokens,
const HuffmanTreeCode* const tree) {
uint8_t code_length_bitdepth[CODE_LENGTH_CODES] = { 0 };
uint16_t code_length_bitdepth_symbols[CODE_LENGTH_CODES] = { 0 };
const int max_tokens = tree->num_symbols;
int num_tokens;
HuffmanTreeCode huffman_code;
huffman_code.num_symbols = CODE_LENGTH_CODES;
huffman_code.code_lengths = code_length_bitdepth;
huffman_code.codes = code_length_bitdepth_symbols;
VP8LPutBits(bw, 0, 1);
num_tokens = VP8LCreateCompressedHuffmanTree(tree, tokens, max_tokens);
{
uint32_t histogram[CODE_LENGTH_CODES] = { 0 };
uint8_t buf_rle[CODE_LENGTH_CODES] = { 0 };
int i;
for (i = 0; i < num_tokens; ++i) {
++histogram[tokens[i].code];
}
VP8LCreateHuffmanTree(histogram, 7, buf_rle, huff_tree, &huffman_code);
}
StoreHuffmanTreeOfHuffmanTreeToBitMask(bw, code_length_bitdepth);
ClearHuffmanTreeIfOnlyOneSymbol(&huffman_code);
{
int trailing_zero_bits = 0;
int trimmed_length = num_tokens;
int write_trimmed_length;
int length;
int i = num_tokens;
while (i-- > 0) {
const int ix = tokens[i].code;
if (ix == 0 || ix == 17 || ix == 18) {
--trimmed_length; // discount trailing zeros
trailing_zero_bits += code_length_bitdepth[ix];
if (ix == 17) {
trailing_zero_bits += 3;
} else if (ix == 18) {
trailing_zero_bits += 7;
}
} else {
break;
}
}
write_trimmed_length = (trimmed_length > 1 && trailing_zero_bits > 12);
length = write_trimmed_length ? trimmed_length : num_tokens;
VP8LPutBits(bw, write_trimmed_length, 1);
if (write_trimmed_length) {
if (trimmed_length == 2) {
VP8LPutBits(bw, 0, 3 + 2); // nbitpairs=1, trimmed_length=2
} else {
const int nbits = BitsLog2Floor(trimmed_length - 2);
const int nbitpairs = nbits / 2 + 1;
assert(trimmed_length > 2);
assert(nbitpairs - 1 < 8);
VP8LPutBits(bw, nbitpairs - 1, 3);
VP8LPutBits(bw, trimmed_length - 2, nbitpairs * 2);
}
}
StoreHuffmanTreeToBitMask(bw, tokens, length, &huffman_code);
}
}
// 'huff_tree' and 'tokens' are pre-alloacted buffers.
static void StoreHuffmanCode(VP8LBitWriter* const bw,
HuffmanTree* const huff_tree,
HuffmanTreeToken* const tokens,
const HuffmanTreeCode* const huffman_code) {
int i;
int count = 0;
int symbols[2] = { 0, 0 };
const int kMaxBits = 8;
const int kMaxSymbol = 1 << kMaxBits;
// Check whether it's a small tree.
for (i = 0; i < huffman_code->num_symbols && count < 3; ++i) {
if (huffman_code->code_lengths[i] != 0) {
if (count < 2) symbols[count] = i;
++count;
}
}
if (count == 0) { // emit minimal tree for empty cases
// bits: small tree marker: 1, count-1: 0, large 8-bit code: 0, code: 0
VP8LPutBits(bw, 0x01, 4);
} else if (count <= 2 && symbols[0] < kMaxSymbol && symbols[1] < kMaxSymbol) {
VP8LPutBits(bw, 1, 1); // Small tree marker to encode 1 or 2 symbols.
VP8LPutBits(bw, count - 1, 1);
if (symbols[0] <= 1) {
VP8LPutBits(bw, 0, 1); // Code bit for small (1 bit) symbol value.
VP8LPutBits(bw, symbols[0], 1);
} else {
VP8LPutBits(bw, 1, 1);
VP8LPutBits(bw, symbols[0], 8);
}
if (count == 2) {
VP8LPutBits(bw, symbols[1], 8);
}
} else {
StoreFullHuffmanCode(bw, huff_tree, tokens, huffman_code);
}
}
static WEBP_INLINE void WriteHuffmanCode(VP8LBitWriter* const bw,
const HuffmanTreeCode* const code,
int code_index) {
const int depth = code->code_lengths[code_index];
const int symbol = code->codes[code_index];
VP8LPutBits(bw, symbol, depth);
}
static WEBP_INLINE void WriteHuffmanCodeWithExtraBits(
VP8LBitWriter* const bw,
const HuffmanTreeCode* const code,
int code_index,
int bits,
int n_bits) {
const int depth = code->code_lengths[code_index];
const int symbol = code->codes[code_index];
VP8LPutBits(bw, (bits << depth) | symbol, depth + n_bits);
}
static int StoreImageToBitMask(
VP8LBitWriter* const bw, int width, int histo_bits,
const VP8LBackwardRefs* const refs,
const uint16_t* histogram_symbols,
const HuffmanTreeCode* const huffman_codes, const WebPPicture* const pic) {
const int histo_xsize = histo_bits ? VP8LSubSampleSize(width, histo_bits) : 1;
const int tile_mask = (histo_bits == 0) ? 0 : -(1 << histo_bits);
// x and y trace the position in the image.
int x = 0;
int y = 0;
int tile_x = x & tile_mask;
int tile_y = y & tile_mask;
int histogram_ix = histogram_symbols[0];
const HuffmanTreeCode* codes = huffman_codes + 5 * histogram_ix;
VP8LRefsCursor c = VP8LRefsCursorInit(refs);
while (VP8LRefsCursorOk(&c)) {
const PixOrCopy* const v = c.cur_pos;
if ((tile_x != (x & tile_mask)) || (tile_y != (y & tile_mask))) {
tile_x = x & tile_mask;
tile_y = y & tile_mask;
histogram_ix = histogram_symbols[(y >> histo_bits) * histo_xsize +
(x >> histo_bits)];
codes = huffman_codes + 5 * histogram_ix;
}
if (PixOrCopyIsLiteral(v)) {
static const uint8_t order[] = { 1, 2, 0, 3 };
int k;
for (k = 0; k < 4; ++k) {
const int code = PixOrCopyLiteral(v, order[k]);
WriteHuffmanCode(bw, codes + k, code);
}
} else if (PixOrCopyIsCacheIdx(v)) {
const int code = PixOrCopyCacheIdx(v);
const int literal_ix = 256 + NUM_LENGTH_CODES + code;
WriteHuffmanCode(bw, codes, literal_ix);
} else {
int bits, n_bits;
int code;
const int distance = PixOrCopyDistance(v);
VP8LPrefixEncode(v->len, &code, &n_bits, &bits);
WriteHuffmanCodeWithExtraBits(bw, codes, 256 + code, bits, n_bits);
// Don't write the distance with the extra bits code since
// the distance can be up to 18 bits of extra bits, and the prefix
// 15 bits, totaling to 33, and our PutBits only supports up to 32 bits.
VP8LPrefixEncode(distance, &code, &n_bits, &bits);
WriteHuffmanCode(bw, codes + 4, code);
VP8LPutBits(bw, bits, n_bits);
}
x += PixOrCopyLength(v);
while (x >= width) {
x -= width;
++y;
}
VP8LRefsCursorNext(&c);
}
if (bw->error_) {
return WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
}
return 1;
}
// Special case of EncodeImageInternal() for cache-bits=0, histo_bits=31.
// pic and percent are for progress.
static int EncodeImageNoHuffman(VP8LBitWriter* const bw,
const uint32_t* const argb,
VP8LHashChain* const hash_chain,
VP8LBackwardRefs* const refs_array, int width,
int height, int quality, int low_effort,
const WebPPicture* const pic, int percent_range,
int* const percent) {
int i;
int max_tokens = 0;
VP8LBackwardRefs* refs;
HuffmanTreeToken* tokens = NULL;
HuffmanTreeCode huffman_codes[5] = {{0, NULL, NULL}};
const uint16_t histogram_symbols[1] = {0}; // only one tree, one symbol
int cache_bits = 0;
VP8LHistogramSet* histogram_image = NULL;
HuffmanTree* const huff_tree = (HuffmanTree*)WebPSafeMalloc(
3ULL * CODE_LENGTH_CODES, sizeof(*huff_tree));
if (huff_tree == NULL) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
// Calculate backward references from ARGB image.
if (!VP8LHashChainFill(hash_chain, quality, argb, width, height, low_effort,
pic, percent_range / 2, percent)) {
goto Error;
}
if (!VP8LGetBackwardReferences(width, height, argb, quality, /*low_effort=*/0,
kLZ77Standard | kLZ77RLE, cache_bits,
/*do_no_cache=*/0, hash_chain, refs_array,
&cache_bits, pic,
percent_range - percent_range / 2, percent)) {
goto Error;
}
refs = &refs_array[0];
histogram_image = VP8LAllocateHistogramSet(1, cache_bits);
if (histogram_image == NULL) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
VP8LHistogramSetClear(histogram_image);
// Build histogram image and symbols from backward references.
VP8LHistogramStoreRefs(refs, histogram_image->histograms[0]);
// Create Huffman bit lengths and codes for each histogram image.
assert(histogram_image->size == 1);
if (!GetHuffBitLengthsAndCodes(histogram_image, huffman_codes)) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
// No color cache, no Huffman image.
VP8LPutBits(bw, 0, 1);
// Find maximum number of symbols for the huffman tree-set.
for (i = 0; i < 5; ++i) {
HuffmanTreeCode* const codes = &huffman_codes[i];
if (max_tokens < codes->num_symbols) {
max_tokens = codes->num_symbols;
}
}
tokens = (HuffmanTreeToken*)WebPSafeMalloc(max_tokens, sizeof(*tokens));
if (tokens == NULL) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
// Store Huffman codes.
for (i = 0; i < 5; ++i) {
HuffmanTreeCode* const codes = &huffman_codes[i];
StoreHuffmanCode(bw, huff_tree, tokens, codes);
ClearHuffmanTreeIfOnlyOneSymbol(codes);
}
// Store actual literals.
if (!StoreImageToBitMask(bw, width, 0, refs, histogram_symbols, huffman_codes,
pic)) {
goto Error;
}
Error:
WebPSafeFree(tokens);
WebPSafeFree(huff_tree);
VP8LFreeHistogramSet(histogram_image);
WebPSafeFree(huffman_codes[0].codes);
return (pic->error_code == VP8_ENC_OK);
}
// pic and percent are for progress.
static int EncodeImageInternal(
VP8LBitWriter* const bw, const uint32_t* const argb,
VP8LHashChain* const hash_chain, VP8LBackwardRefs refs_array[4], int width,
int height, int quality, int low_effort, const CrunchConfig* const config,
int* cache_bits, int histogram_bits, size_t init_byte_position,
int* const hdr_size, int* const data_size, const WebPPicture* const pic,
int percent_range, int* const percent) {
const uint32_t histogram_image_xysize =
VP8LSubSampleSize(width, histogram_bits) *
VP8LSubSampleSize(height, histogram_bits);
int remaining_percent = percent_range;
int percent_start = *percent;
VP8LHistogramSet* histogram_image = NULL;
VP8LHistogram* tmp_histo = NULL;
int histogram_image_size = 0;
size_t bit_array_size = 0;
HuffmanTree* const huff_tree = (HuffmanTree*)WebPSafeMalloc(
3ULL * CODE_LENGTH_CODES, sizeof(*huff_tree));
HuffmanTreeToken* tokens = NULL;
HuffmanTreeCode* huffman_codes = NULL;
uint16_t* const histogram_symbols = (uint16_t*)WebPSafeMalloc(
histogram_image_xysize, sizeof(*histogram_symbols));
int sub_configs_idx;
int cache_bits_init, write_histogram_image;
VP8LBitWriter bw_init = *bw, bw_best;
int hdr_size_tmp;
VP8LHashChain hash_chain_histogram; // histogram image hash chain
size_t bw_size_best = ~(size_t)0;
assert(histogram_bits >= MIN_HUFFMAN_BITS);
assert(histogram_bits <= MAX_HUFFMAN_BITS);
assert(hdr_size != NULL);
assert(data_size != NULL);
memset(&hash_chain_histogram, 0, sizeof(hash_chain_histogram));
if (!VP8LBitWriterInit(&bw_best, 0)) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
// Make sure we can allocate the different objects.
if (huff_tree == NULL || histogram_symbols == NULL ||
!VP8LHashChainInit(&hash_chain_histogram, histogram_image_xysize)) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
percent_range = remaining_percent / 5;
if (!VP8LHashChainFill(hash_chain, quality, argb, width, height,
low_effort, pic, percent_range, percent)) {
goto Error;
}
percent_start += percent_range;
remaining_percent -= percent_range;
// If the value is different from zero, it has been set during the palette
// analysis.
cache_bits_init = (*cache_bits == 0) ? MAX_COLOR_CACHE_BITS : *cache_bits;
// If several iterations will happen, clone into bw_best.
if ((config->sub_configs_size_ > 1 || config->sub_configs_[0].do_no_cache_) &&
!VP8LBitWriterClone(bw, &bw_best)) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
for (sub_configs_idx = 0; sub_configs_idx < config->sub_configs_size_;
++sub_configs_idx) {
const CrunchSubConfig* const sub_config =
&config->sub_configs_[sub_configs_idx];
int cache_bits_best, i_cache;
int i_remaining_percent = remaining_percent / config->sub_configs_size_;
int i_percent_range = i_remaining_percent / 4;
i_remaining_percent -= i_percent_range;
if (!VP8LGetBackwardReferences(
width, height, argb, quality, low_effort, sub_config->lz77_,
cache_bits_init, sub_config->do_no_cache_, hash_chain,
&refs_array[0], &cache_bits_best, pic, i_percent_range, percent)) {
goto Error;
}
for (i_cache = 0; i_cache < (sub_config->do_no_cache_ ? 2 : 1); ++i_cache) {
const int cache_bits_tmp = (i_cache == 0) ? cache_bits_best : 0;
// Speed-up: no need to study the no-cache case if it was already studied
// in i_cache == 0.
if (i_cache == 1 && cache_bits_best == 0) break;
// Reset the bit writer for this iteration.
VP8LBitWriterReset(&bw_init, bw);
// Build histogram image and symbols from backward references.
histogram_image =
VP8LAllocateHistogramSet(histogram_image_xysize, cache_bits_tmp);
tmp_histo = VP8LAllocateHistogram(cache_bits_tmp);
if (histogram_image == NULL || tmp_histo == NULL) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
i_percent_range = i_remaining_percent / 3;
i_remaining_percent -= i_percent_range;
if (!VP8LGetHistoImageSymbols(
width, height, &refs_array[i_cache], quality, low_effort,
histogram_bits, cache_bits_tmp, histogram_image, tmp_histo,
histogram_symbols, pic, i_percent_range, percent)) {
goto Error;
}
// Create Huffman bit lengths and codes for each histogram image.
histogram_image_size = histogram_image->size;
bit_array_size = 5 * histogram_image_size;
huffman_codes = (HuffmanTreeCode*)WebPSafeCalloc(bit_array_size,
sizeof(*huffman_codes));
// Note: some histogram_image entries may point to tmp_histos[], so the
// latter need to outlive the following call to
// GetHuffBitLengthsAndCodes().
if (huffman_codes == NULL ||
!GetHuffBitLengthsAndCodes(histogram_image, huffman_codes)) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
// Free combined histograms.
VP8LFreeHistogramSet(histogram_image);
histogram_image = NULL;
// Free scratch histograms.
VP8LFreeHistogram(tmp_histo);
tmp_histo = NULL;
// Color Cache parameters.
if (cache_bits_tmp > 0) {
VP8LPutBits(bw, 1, 1);
VP8LPutBits(bw, cache_bits_tmp, 4);
} else {
VP8LPutBits(bw, 0, 1);
}
// Huffman image + meta huffman.
write_histogram_image = (histogram_image_size > 1);
VP8LPutBits(bw, write_histogram_image, 1);
if (write_histogram_image) {
uint32_t* const histogram_argb = (uint32_t*)WebPSafeMalloc(
histogram_image_xysize, sizeof(*histogram_argb));
int max_index = 0;
uint32_t i;
if (histogram_argb == NULL) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
for (i = 0; i < histogram_image_xysize; ++i) {
const int symbol_index = histogram_symbols[i] & 0xffff;
histogram_argb[i] = (symbol_index << 8);
if (symbol_index >= max_index) {
max_index = symbol_index + 1;
}
}
histogram_image_size = max_index;
VP8LPutBits(bw, histogram_bits - 2, 3);
i_percent_range = i_remaining_percent / 2;
i_remaining_percent -= i_percent_range;
if (!EncodeImageNoHuffman(
bw, histogram_argb, &hash_chain_histogram, &refs_array[2],
VP8LSubSampleSize(width, histogram_bits),
VP8LSubSampleSize(height, histogram_bits), quality, low_effort,
pic, i_percent_range, percent)) {
WebPSafeFree(histogram_argb);
goto Error;
}
WebPSafeFree(histogram_argb);
}
// Store Huffman codes.
{
int i;
int max_tokens = 0;
// Find maximum number of symbols for the huffman tree-set.
for (i = 0; i < 5 * histogram_image_size; ++i) {
HuffmanTreeCode* const codes = &huffman_codes[i];
if (max_tokens < codes->num_symbols) {
max_tokens = codes->num_symbols;
}
}
tokens = (HuffmanTreeToken*)WebPSafeMalloc(max_tokens, sizeof(*tokens));
if (tokens == NULL) {
WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
for (i = 0; i < 5 * histogram_image_size; ++i) {
HuffmanTreeCode* const codes = &huffman_codes[i];
StoreHuffmanCode(bw, huff_tree, tokens, codes);
ClearHuffmanTreeIfOnlyOneSymbol(codes);
}
}
// Store actual literals.
hdr_size_tmp = (int)(VP8LBitWriterNumBytes(bw) - init_byte_position);
if (!StoreImageToBitMask(bw, width, histogram_bits, &refs_array[i_cache],
histogram_symbols, huffman_codes, pic)) {
goto Error;
}
// Keep track of the smallest image so far.
if (VP8LBitWriterNumBytes(bw) < bw_size_best) {
bw_size_best = VP8LBitWriterNumBytes(bw);
*cache_bits = cache_bits_tmp;
*hdr_size = hdr_size_tmp;
*data_size =
(int)(VP8LBitWriterNumBytes(bw) - init_byte_position - *hdr_size);
VP8LBitWriterSwap(bw, &bw_best);
}
WebPSafeFree(tokens);
tokens = NULL;
if (huffman_codes != NULL) {
WebPSafeFree(huffman_codes->codes);
WebPSafeFree(huffman_codes);
huffman_codes = NULL;
}
}
}
VP8LBitWriterSwap(bw, &bw_best);
if (!WebPReportProgress(pic, percent_start + remaining_percent, percent)) {
goto Error;
}
Error:
WebPSafeFree(tokens);
WebPSafeFree(huff_tree);
VP8LFreeHistogramSet(histogram_image);
VP8LFreeHistogram(tmp_histo);
VP8LHashChainClear(&hash_chain_histogram);
if (huffman_codes != NULL) {
WebPSafeFree(huffman_codes->codes);
WebPSafeFree(huffman_codes);
}
WebPSafeFree(histogram_symbols);
VP8LBitWriterWipeOut(&bw_best);
return (pic->error_code == VP8_ENC_OK);
}
// -----------------------------------------------------------------------------
// Transforms
static void ApplySubtractGreen(VP8LEncoder* const enc, int width, int height,
VP8LBitWriter* const bw) {
VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
VP8LPutBits(bw, SUBTRACT_GREEN_TRANSFORM, 2);
VP8LSubtractGreenFromBlueAndRed(enc->argb_, width * height);
}
static int ApplyPredictFilter(VP8LEncoder* const enc, int width, int height,
int quality, int low_effort,
int used_subtract_green, VP8LBitWriter* const bw,
int percent_range, int* const percent) {
const int pred_bits = enc->predictor_transform_bits_;
const int transform_width = VP8LSubSampleSize(width, pred_bits);
const int transform_height = VP8LSubSampleSize(height, pred_bits);
// we disable near-lossless quantization if palette is used.
const int near_lossless_strength =
enc->use_palette_ ? 100 : enc->config_->near_lossless;
if (!VP8LResidualImage(
width, height, pred_bits, low_effort, enc->argb_, enc->argb_scratch_,
enc->transform_data_, near_lossless_strength, enc->config_->exact,
used_subtract_green, enc->pic_, percent_range / 2, percent)) {
return 0;
}
VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
VP8LPutBits(bw, PREDICTOR_TRANSFORM, 2);
assert(pred_bits >= MIN_TRANSFORM_BITS && pred_bits <= MAX_TRANSFORM_BITS);
VP8LPutBits(bw, pred_bits - MIN_TRANSFORM_BITS, NUM_TRANSFORM_BITS);
return EncodeImageNoHuffman(
bw, enc->transform_data_, (VP8LHashChain*)&enc->hash_chain_,
(VP8LBackwardRefs*)&enc->refs_[0], transform_width, transform_height,
quality, low_effort, enc->pic_, percent_range - percent_range / 2,
percent);
}
static int ApplyCrossColorFilter(VP8LEncoder* const enc, int width, int height,
int quality, int low_effort,
VP8LBitWriter* const bw, int percent_range,
int* const percent) {
const int ccolor_transform_bits = enc->cross_color_transform_bits_;
const int transform_width = VP8LSubSampleSize(width, ccolor_transform_bits);
const int transform_height = VP8LSubSampleSize(height, ccolor_transform_bits);
if (!VP8LColorSpaceTransform(width, height, ccolor_transform_bits, quality,
enc->argb_, enc->transform_data_, enc->pic_,
percent_range / 2, percent)) {
return 0;
}
VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
VP8LPutBits(bw, CROSS_COLOR_TRANSFORM, 2);
assert(ccolor_transform_bits >= MIN_TRANSFORM_BITS &&
ccolor_transform_bits <= MAX_TRANSFORM_BITS);
VP8LPutBits(bw, ccolor_transform_bits - MIN_TRANSFORM_BITS,
NUM_TRANSFORM_BITS);
return EncodeImageNoHuffman(
bw, enc->transform_data_, (VP8LHashChain*)&enc->hash_chain_,
(VP8LBackwardRefs*)&enc->refs_[0], transform_width, transform_height,
quality, low_effort, enc->pic_, percent_range - percent_range / 2,
percent);
}
// -----------------------------------------------------------------------------
static int WriteRiffHeader(const WebPPicture* const pic, size_t riff_size,
size_t vp8l_size) {
uint8_t riff[RIFF_HEADER_SIZE + CHUNK_HEADER_SIZE + VP8L_SIGNATURE_SIZE] = {
'R', 'I', 'F', 'F', 0, 0, 0, 0, 'W', 'E', 'B', 'P',
'V', 'P', '8', 'L', 0, 0, 0, 0, VP8L_MAGIC_BYTE,
};
PutLE32(riff + TAG_SIZE, (uint32_t)riff_size);
PutLE32(riff + RIFF_HEADER_SIZE + TAG_SIZE, (uint32_t)vp8l_size);
return pic->writer(riff, sizeof(riff), pic);
}
static int WriteImageSize(const WebPPicture* const pic,
VP8LBitWriter* const bw) {
const int width = pic->width - 1;
const int height = pic->height - 1;
assert(width < WEBP_MAX_DIMENSION && height < WEBP_MAX_DIMENSION);
VP8LPutBits(bw, width, VP8L_IMAGE_SIZE_BITS);
VP8LPutBits(bw, height, VP8L_IMAGE_SIZE_BITS);
return !bw->error_;
}
static int WriteRealAlphaAndVersion(VP8LBitWriter* const bw, int has_alpha) {
VP8LPutBits(bw, has_alpha, 1);
VP8LPutBits(bw, VP8L_VERSION, VP8L_VERSION_BITS);
return !bw->error_;
}
static int WriteImage(const WebPPicture* const pic, VP8LBitWriter* const bw,
size_t* const coded_size) {
const uint8_t* const webpll_data = VP8LBitWriterFinish(bw);
const size_t webpll_size = VP8LBitWriterNumBytes(bw);
const size_t vp8l_size = VP8L_SIGNATURE_SIZE + webpll_size;
const size_t pad = vp8l_size & 1;
const size_t riff_size = TAG_SIZE + CHUNK_HEADER_SIZE + vp8l_size + pad;
*coded_size = 0;
if (bw->error_) {
return WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
}
if (!WriteRiffHeader(pic, riff_size, vp8l_size) ||
!pic->writer(webpll_data, webpll_size, pic)) {
return WebPEncodingSetError(pic, VP8_ENC_ERROR_BAD_WRITE);
}
if (pad) {
const uint8_t pad_byte[1] = { 0 };
if (!pic->writer(pad_byte, 1, pic)) {
return WebPEncodingSetError(pic, VP8_ENC_ERROR_BAD_WRITE);
}
}
*coded_size = CHUNK_HEADER_SIZE + riff_size;
return 1;
}
// -----------------------------------------------------------------------------
static void ClearTransformBuffer(VP8LEncoder* const enc) {
WebPSafeFree(enc->transform_mem_);
enc->transform_mem_ = NULL;
enc->transform_mem_size_ = 0;
}
// Allocates the memory for argb (W x H) buffer, 2 rows of context for
// prediction and transform data.
// Flags influencing the memory allocated:
// enc->transform_bits_
// enc->use_predict_, enc->use_cross_color_
static int AllocateTransformBuffer(VP8LEncoder* const enc, int width,
int height) {
const uint64_t image_size = (uint64_t)width * height;
// VP8LResidualImage needs room for 2 scanlines of uint32 pixels with an extra
// pixel in each, plus 2 regular scanlines of bytes.
// TODO(skal): Clean up by using arithmetic in bytes instead of words.
const uint64_t argb_scratch_size =
enc->use_predict_ ? (width + 1) * 2 + (width * 2 + sizeof(uint32_t) - 1) /
sizeof(uint32_t)
: 0;
const int min_transform_bits =
(enc->predictor_transform_bits_ < enc->cross_color_transform_bits_)
? enc->predictor_transform_bits_
: enc->cross_color_transform_bits_;
const uint64_t transform_data_size =
(enc->use_predict_ || enc->use_cross_color_)
? (uint64_t)VP8LSubSampleSize(width, min_transform_bits) *
VP8LSubSampleSize(height, min_transform_bits)
: 0;
const uint64_t max_alignment_in_words =
(WEBP_ALIGN_CST + sizeof(uint32_t) - 1) / sizeof(uint32_t);
const uint64_t mem_size = image_size + max_alignment_in_words +
argb_scratch_size + max_alignment_in_words +
transform_data_size;
uint32_t* mem = enc->transform_mem_;
if (mem == NULL || mem_size > enc->transform_mem_size_) {
ClearTransformBuffer(enc);
mem = (uint32_t*)WebPSafeMalloc(mem_size, sizeof(*mem));
if (mem == NULL) {
return WebPEncodingSetError(enc->pic_, VP8_ENC_ERROR_OUT_OF_MEMORY);
}
enc->transform_mem_ = mem;
enc->transform_mem_size_ = (size_t)mem_size;
enc->argb_content_ = kEncoderNone;
}
enc->argb_ = mem;
mem = (uint32_t*)WEBP_ALIGN(mem + image_size);
enc->argb_scratch_ = mem;
mem = (uint32_t*)WEBP_ALIGN(mem + argb_scratch_size);
enc->transform_data_ = mem;
enc->current_width_ = width;
return 1;
}
static int MakeInputImageCopy(VP8LEncoder* const enc) {
const WebPPicture* const picture = enc->pic_;
const int width = picture->width;
const int height = picture->height;
if (!AllocateTransformBuffer(enc, width, height)) return 0;
if (enc->argb_content_ == kEncoderARGB) return 1;
{
uint32_t* dst = enc->argb_;
const uint32_t* src = picture->argb;
int y;
for (y = 0; y < height; ++y) {
memcpy(dst, src, width * sizeof(*dst));
dst += width;
src += picture->argb_stride;
}
}
enc->argb_content_ = kEncoderARGB;
assert(enc->current_width_ == width);
return 1;
}
// -----------------------------------------------------------------------------
#define APPLY_PALETTE_GREEDY_MAX 4
static WEBP_INLINE uint32_t SearchColorGreedy(const uint32_t palette[],
int palette_size,
uint32_t color) {
(void)palette_size;
assert(palette_size < APPLY_PALETTE_GREEDY_MAX);
assert(3 == APPLY_PALETTE_GREEDY_MAX - 1);
if (color == palette[0]) return 0;
if (color == palette[1]) return 1;
if (color == palette[2]) return 2;
return 3;
}
static WEBP_INLINE uint32_t ApplyPaletteHash0(uint32_t color) {
// Focus on the green color.
return (color >> 8) & 0xff;
}
#define PALETTE_INV_SIZE_BITS 11
#define PALETTE_INV_SIZE (1 << PALETTE_INV_SIZE_BITS)
static WEBP_INLINE uint32_t ApplyPaletteHash1(uint32_t color) {
// Forget about alpha.
return ((uint32_t)((color & 0x00ffffffu) * 4222244071ull)) >>
(32 - PALETTE_INV_SIZE_BITS);
}
static WEBP_INLINE uint32_t ApplyPaletteHash2(uint32_t color) {
// Forget about alpha.
return ((uint32_t)((color & 0x00ffffffu) * ((1ull << 31) - 1))) >>
(32 - PALETTE_INV_SIZE_BITS);
}
// Use 1 pixel cache for ARGB pixels.
#define APPLY_PALETTE_FOR(COLOR_INDEX) do { \
uint32_t prev_pix = palette[0]; \
uint32_t prev_idx = 0; \
for (y = 0; y < height; ++y) { \
for (x = 0; x < width; ++x) { \
const uint32_t pix = src[x]; \
if (pix != prev_pix) { \
prev_idx = COLOR_INDEX; \
prev_pix = pix; \
} \
tmp_row[x] = prev_idx; \
} \
VP8LBundleColorMap(tmp_row, width, xbits, dst); \
src += src_stride; \
dst += dst_stride; \
} \
} while (0)
// Remap argb values in src[] to packed palettes entries in dst[]
// using 'row' as a temporary buffer of size 'width'.
// We assume that all src[] values have a corresponding entry in the palette.
// Note: src[] can be the same as dst[]
static int ApplyPalette(const uint32_t* src, uint32_t src_stride, uint32_t* dst,
uint32_t dst_stride, const uint32_t* palette,
int palette_size, int width, int height, int xbits,
const WebPPicture* const pic) {
// TODO(skal): this tmp buffer is not needed if VP8LBundleColorMap() can be
// made to work in-place.
uint8_t* const tmp_row = (uint8_t*)WebPSafeMalloc(width, sizeof(*tmp_row));
int x, y;
if (tmp_row == NULL) {
return WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
}
if (palette_size < APPLY_PALETTE_GREEDY_MAX) {
APPLY_PALETTE_FOR(SearchColorGreedy(palette, palette_size, pix));
} else {
int i, j;
uint16_t buffer[PALETTE_INV_SIZE];
uint32_t (*const hash_functions[])(uint32_t) = {
ApplyPaletteHash0, ApplyPaletteHash1, ApplyPaletteHash2
};
// Try to find a perfect hash function able to go from a color to an index
// within 1 << PALETTE_INV_SIZE_BITS in order to build a hash map to go
// from color to index in palette.
for (i = 0; i < 3; ++i) {
int use_LUT = 1;
// Set each element in buffer to max uint16_t.
memset(buffer, 0xff, sizeof(buffer));
for (j = 0; j < palette_size; ++j) {
const uint32_t ind = hash_functions[i](palette[j]);
if (buffer[ind] != 0xffffu) {
use_LUT = 0;
break;
} else {
buffer[ind] = j;
}
}
if (use_LUT) break;
}
if (i == 0) {
APPLY_PALETTE_FOR(buffer[ApplyPaletteHash0(pix)]);
} else if (i == 1) {
APPLY_PALETTE_FOR(buffer[ApplyPaletteHash1(pix)]);
} else if (i == 2) {
APPLY_PALETTE_FOR(buffer[ApplyPaletteHash2(pix)]);
} else {
uint32_t idx_map[MAX_PALETTE_SIZE];
uint32_t palette_sorted[MAX_PALETTE_SIZE];
PrepareMapToPalette(palette, palette_size, palette_sorted, idx_map);
APPLY_PALETTE_FOR(
idx_map[SearchColorNoIdx(palette_sorted, pix, palette_size)]);
}
}
WebPSafeFree(tmp_row);
return 1;
}
#undef APPLY_PALETTE_FOR
#undef PALETTE_INV_SIZE_BITS
#undef PALETTE_INV_SIZE
#undef APPLY_PALETTE_GREEDY_MAX
// Note: Expects "enc->palette_" to be set properly.
static int MapImageFromPalette(VP8LEncoder* const enc, int in_place) {
const WebPPicture* const pic = enc->pic_;
const int width = pic->width;
const int height = pic->height;
const uint32_t* const palette = enc->palette_;
const uint32_t* src = in_place ? enc->argb_ : pic->argb;
const int src_stride = in_place ? enc->current_width_ : pic->argb_stride;
const int palette_size = enc->palette_size_;
int xbits;
// Replace each input pixel by corresponding palette index.
// This is done line by line.
if (palette_size <= 4) {
xbits = (palette_size <= 2) ? 3 : 2;
} else {
xbits = (palette_size <= 16) ? 1 : 0;
}
if (!AllocateTransformBuffer(enc, VP8LSubSampleSize(width, xbits), height)) {
return 0;
}
if (!ApplyPalette(src, src_stride,
enc->argb_, enc->current_width_,
palette, palette_size, width, height, xbits, pic)) {
return 0;
}
enc->argb_content_ = kEncoderPalette;
return 1;
}
// Save palette_[] to bitstream.
static WebPEncodingError EncodePalette(VP8LBitWriter* const bw, int low_effort,
VP8LEncoder* const enc,
int percent_range, int* const percent) {
int i;
uint32_t tmp_palette[MAX_PALETTE_SIZE];
const int palette_size = enc->palette_size_;
const uint32_t* const palette = enc->palette_;
VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
VP8LPutBits(bw, COLOR_INDEXING_TRANSFORM, 2);
assert(palette_size >= 1 && palette_size <= MAX_PALETTE_SIZE);
VP8LPutBits(bw, palette_size - 1, 8);
for (i = palette_size - 1; i >= 1; --i) {
tmp_palette[i] = VP8LSubPixels(palette[i], palette[i - 1]);
}
tmp_palette[0] = palette[0];
return EncodeImageNoHuffman(bw, tmp_palette, &enc->hash_chain_,
&enc->refs_[0], palette_size, 1, /*quality=*/20,
low_effort, enc->pic_, percent_range, percent);
}
// -----------------------------------------------------------------------------
// VP8LEncoder
static VP8LEncoder* VP8LEncoderNew(const WebPConfig* const config,
const WebPPicture* const picture) {
VP8LEncoder* const enc = (VP8LEncoder*)WebPSafeCalloc(1ULL, sizeof(*enc));
if (enc == NULL) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
return NULL;
}
enc->config_ = config;
enc->pic_ = picture;
enc->argb_content_ = kEncoderNone;
VP8LEncDspInit();
return enc;
}
static void VP8LEncoderDelete(VP8LEncoder* enc) {
if (enc != NULL) {
int i;
VP8LHashChainClear(&enc->hash_chain_);
for (i = 0; i < 4; ++i) VP8LBackwardRefsClear(&enc->refs_[i]);
ClearTransformBuffer(enc);
WebPSafeFree(enc);
}
}
// -----------------------------------------------------------------------------
// Main call
typedef struct {
const WebPConfig* config_;
const WebPPicture* picture_;
VP8LBitWriter* bw_;
VP8LEncoder* enc_;
CrunchConfig crunch_configs_[CRUNCH_CONFIGS_MAX];
int num_crunch_configs_;
int red_and_blue_always_zero_;
WebPAuxStats* stats_;
} StreamEncodeContext;
static int EncodeStreamHook(void* input, void* data2) {
StreamEncodeContext* const params = (StreamEncodeContext*)input;
const WebPConfig* const config = params->config_;
const WebPPicture* const picture = params->picture_;
VP8LBitWriter* const bw = params->bw_;
VP8LEncoder* const enc = params->enc_;
const CrunchConfig* const crunch_configs = params->crunch_configs_;
const int num_crunch_configs = params->num_crunch_configs_;
const int red_and_blue_always_zero = params->red_and_blue_always_zero_;
#if !defined(WEBP_DISABLE_STATS)
WebPAuxStats* const stats = params->stats_;
#endif
const int quality = (int)config->quality;
const int low_effort = (config->method == 0);
#if (WEBP_NEAR_LOSSLESS == 1)
const int width = picture->width;
#endif
const int height = picture->height;
const size_t byte_position = VP8LBitWriterNumBytes(bw);
int percent = 2; // for WebPProgressHook
#if (WEBP_NEAR_LOSSLESS == 1)
int use_near_lossless = 0;
#endif
int hdr_size = 0;
int data_size = 0;
int use_delta_palette = 0;
int idx;
size_t best_size = ~(size_t)0;
VP8LBitWriter bw_init = *bw, bw_best;
(void)data2;
if (!VP8LBitWriterInit(&bw_best, 0) ||
(num_crunch_configs > 1 && !VP8LBitWriterClone(bw, &bw_best))) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
for (idx = 0; idx < num_crunch_configs; ++idx) {
const int entropy_idx = crunch_configs[idx].entropy_idx_;
int remaining_percent = 97 / num_crunch_configs, percent_range;
enc->use_palette_ =
(entropy_idx == kPalette) || (entropy_idx == kPaletteAndSpatial);
enc->use_subtract_green_ =
(entropy_idx == kSubGreen) || (entropy_idx == kSpatialSubGreen);
enc->use_predict_ = (entropy_idx == kSpatial) ||
(entropy_idx == kSpatialSubGreen) ||
(entropy_idx == kPaletteAndSpatial);
// When using a palette, R/B==0, hence no need to test for cross-color.
if (low_effort || enc->use_palette_) {
enc->use_cross_color_ = 0;
} else {
enc->use_cross_color_ = red_and_blue_always_zero ? 0 : enc->use_predict_;
}
// Reset any parameter in the encoder that is set in the previous iteration.
enc->cache_bits_ = 0;
VP8LBackwardRefsClear(&enc->refs_[0]);
VP8LBackwardRefsClear(&enc->refs_[1]);
#if (WEBP_NEAR_LOSSLESS == 1)
// Apply near-lossless preprocessing.
use_near_lossless = (config->near_lossless < 100) && !enc->use_palette_ &&
!enc->use_predict_;
if (use_near_lossless) {
if (!AllocateTransformBuffer(enc, width, height)) goto Error;
if ((enc->argb_content_ != kEncoderNearLossless) &&
!VP8ApplyNearLossless(picture, config->near_lossless, enc->argb_)) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
enc->argb_content_ = kEncoderNearLossless;
} else {
enc->argb_content_ = kEncoderNone;
}
#else
enc->argb_content_ = kEncoderNone;
#endif
// Encode palette
if (enc->use_palette_) {
if (!PaletteSort(crunch_configs[idx].palette_sorting_type_, enc->pic_,
enc->palette_sorted_, enc->palette_size_,
enc->palette_)) {
WebPEncodingSetError(enc->pic_, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
percent_range = remaining_percent / 4;
if (!EncodePalette(bw, low_effort, enc, percent_range, &percent)) {
goto Error;
}
remaining_percent -= percent_range;
if (!MapImageFromPalette(enc, use_delta_palette)) goto Error;
// If using a color cache, do not have it bigger than the number of
// colors.
if (enc->palette_size_ < (1 << MAX_COLOR_CACHE_BITS)) {
enc->cache_bits_ = BitsLog2Floor(enc->palette_size_) + 1;
}
}
if (!use_delta_palette) {
// In case image is not packed.
if (enc->argb_content_ != kEncoderNearLossless &&
enc->argb_content_ != kEncoderPalette) {
if (!MakeInputImageCopy(enc)) goto Error;
}
// -----------------------------------------------------------------------
// Apply transforms and write transform data.
if (enc->use_subtract_green_) {
ApplySubtractGreen(enc, enc->current_width_, height, bw);
}
if (enc->use_predict_) {
percent_range = remaining_percent / 3;
if (!ApplyPredictFilter(enc, enc->current_width_, height, quality,
low_effort, enc->use_subtract_green_, bw,
percent_range, &percent)) {
goto Error;
}
remaining_percent -= percent_range;
}
if (enc->use_cross_color_) {
percent_range = remaining_percent / 2;
if (!ApplyCrossColorFilter(enc, enc->current_width_, height, quality,
low_effort, bw, percent_range, &percent)) {
goto Error;
}
remaining_percent -= percent_range;
}
}
VP8LPutBits(bw, !TRANSFORM_PRESENT, 1); // No more transforms.
// -------------------------------------------------------------------------
// Encode and write the transformed image.
if (!EncodeImageInternal(
bw, enc->argb_, &enc->hash_chain_, enc->refs_, enc->current_width_,
height, quality, low_effort, &crunch_configs[idx],
&enc->cache_bits_, enc->histo_bits_, byte_position, &hdr_size,
&data_size, picture, remaining_percent, &percent)) {
goto Error;
}
// If we are better than what we already have.
if (VP8LBitWriterNumBytes(bw) < best_size) {
best_size = VP8LBitWriterNumBytes(bw);
// Store the BitWriter.
VP8LBitWriterSwap(bw, &bw_best);
#if !defined(WEBP_DISABLE_STATS)
// Update the stats.
if (stats != NULL) {
stats->lossless_features = 0;
if (enc->use_predict_) stats->lossless_features |= 1;
if (enc->use_cross_color_) stats->lossless_features |= 2;
if (enc->use_subtract_green_) stats->lossless_features |= 4;
if (enc->use_palette_) stats->lossless_features |= 8;
stats->histogram_bits = enc->histo_bits_;
stats->transform_bits = enc->predictor_transform_bits_;
stats->cross_color_transform_bits = enc->cross_color_transform_bits_;
stats->cache_bits = enc->cache_bits_;
stats->palette_size = enc->palette_size_;
stats->lossless_size = (int)(best_size - byte_position);
stats->lossless_hdr_size = hdr_size;
stats->lossless_data_size = data_size;
}
#endif
}
// Reset the bit writer for the following iteration if any.
if (num_crunch_configs > 1) VP8LBitWriterReset(&bw_init, bw);
}
VP8LBitWriterSwap(&bw_best, bw);
Error:
VP8LBitWriterWipeOut(&bw_best);
// The hook should return false in case of error.
return (params->picture_->error_code == VP8_ENC_OK);
}
int VP8LEncodeStream(const WebPConfig* const config,
const WebPPicture* const picture,
VP8LBitWriter* const bw_main) {
VP8LEncoder* const enc_main = VP8LEncoderNew(config, picture);
VP8LEncoder* enc_side = NULL;
CrunchConfig crunch_configs[CRUNCH_CONFIGS_MAX];
int num_crunch_configs_main, num_crunch_configs_side = 0;
int idx;
int red_and_blue_always_zero = 0;
WebPWorker worker_main, worker_side;
StreamEncodeContext params_main, params_side;
// The main thread uses picture->stats, the side thread uses stats_side.
WebPAuxStats stats_side;
VP8LBitWriter bw_side;
WebPPicture picture_side;
const WebPWorkerInterface* const worker_interface = WebPGetWorkerInterface();
int ok_main;
if (enc_main == NULL || !VP8LBitWriterInit(&bw_side, 0)) {
VP8LEncoderDelete(enc_main);
return WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
}
// Avoid "garbage value" error from Clang's static analysis tool.
if (!WebPPictureInit(&picture_side)) {
goto Error;
}
// Analyze image (entropy, num_palettes etc)
if (!EncoderAnalyze(enc_main, crunch_configs, &num_crunch_configs_main,
&red_and_blue_always_zero) ||
!EncoderInit(enc_main)) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
// Split the configs between the main and side threads (if any).
if (config->thread_level > 0) {
num_crunch_configs_side = num_crunch_configs_main / 2;
for (idx = 0; idx < num_crunch_configs_side; ++idx) {
params_side.crunch_configs_[idx] =
crunch_configs[num_crunch_configs_main - num_crunch_configs_side +
idx];
}
params_side.num_crunch_configs_ = num_crunch_configs_side;
}
num_crunch_configs_main -= num_crunch_configs_side;
for (idx = 0; idx < num_crunch_configs_main; ++idx) {
params_main.crunch_configs_[idx] = crunch_configs[idx];
}
params_main.num_crunch_configs_ = num_crunch_configs_main;
// Fill in the parameters for the thread workers.
{
const int params_size = (num_crunch_configs_side > 0) ? 2 : 1;
for (idx = 0; idx < params_size; ++idx) {
// Create the parameters for each worker.
WebPWorker* const worker = (idx == 0) ? &worker_main : &worker_side;
StreamEncodeContext* const param =
(idx == 0) ? &params_main : &params_side;
param->config_ = config;
param->red_and_blue_always_zero_ = red_and_blue_always_zero;
if (idx == 0) {
param->picture_ = picture;
param->stats_ = picture->stats;
param->bw_ = bw_main;
param->enc_ = enc_main;
} else {
// Create a side picture (error_code is not thread-safe).
if (!WebPPictureView(picture, /*left=*/0, /*top=*/0, picture->width,
picture->height, &picture_side)) {
assert(0);
}
picture_side.progress_hook = NULL; // Progress hook is not thread-safe.
param->picture_ = &picture_side; // No need to free a view afterwards.
param->stats_ = (picture->stats == NULL) ? NULL : &stats_side;
// Create a side bit writer.
if (!VP8LBitWriterClone(bw_main, &bw_side)) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
param->bw_ = &bw_side;
// Create a side encoder.
enc_side = VP8LEncoderNew(config, &picture_side);
if (enc_side == NULL || !EncoderInit(enc_side)) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
// Copy the values that were computed for the main encoder.
enc_side->histo_bits_ = enc_main->histo_bits_;
enc_side->predictor_transform_bits_ =
enc_main->predictor_transform_bits_;
enc_side->cross_color_transform_bits_ =
enc_main->cross_color_transform_bits_;
enc_side->palette_size_ = enc_main->palette_size_;
memcpy(enc_side->palette_, enc_main->palette_,
sizeof(enc_main->palette_));
memcpy(enc_side->palette_sorted_, enc_main->palette_sorted_,
sizeof(enc_main->palette_sorted_));
param->enc_ = enc_side;
}
// Create the workers.
worker_interface->Init(worker);
worker->data1 = param;
worker->data2 = NULL;
worker->hook = EncodeStreamHook;
}
}
// Start the second thread if needed.
if (num_crunch_configs_side != 0) {
if (!worker_interface->Reset(&worker_side)) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
#if !defined(WEBP_DISABLE_STATS)
// This line is here and not in the param initialization above to remove a
// Clang static analyzer warning.
if (picture->stats != NULL) {
memcpy(&stats_side, picture->stats, sizeof(stats_side));
}
#endif
worker_interface->Launch(&worker_side);
}
// Execute the main thread.
worker_interface->Execute(&worker_main);
ok_main = worker_interface->Sync(&worker_main);
worker_interface->End(&worker_main);
if (num_crunch_configs_side != 0) {
// Wait for the second thread.
const int ok_side = worker_interface->Sync(&worker_side);
worker_interface->End(&worker_side);
if (!ok_main || !ok_side) {
if (picture->error_code == VP8_ENC_OK) {
assert(picture_side.error_code != VP8_ENC_OK);
WebPEncodingSetError(picture, picture_side.error_code);
}
goto Error;
}
if (VP8LBitWriterNumBytes(&bw_side) < VP8LBitWriterNumBytes(bw_main)) {
VP8LBitWriterSwap(bw_main, &bw_side);
#if !defined(WEBP_DISABLE_STATS)
if (picture->stats != NULL) {
memcpy(picture->stats, &stats_side, sizeof(*picture->stats));
}
#endif
}
}
Error:
VP8LBitWriterWipeOut(&bw_side);
VP8LEncoderDelete(enc_main);
VP8LEncoderDelete(enc_side);
return (picture->error_code == VP8_ENC_OK);
}
#undef CRUNCH_CONFIGS_MAX
#undef CRUNCH_SUBCONFIGS_MAX
int VP8LEncodeImage(const WebPConfig* const config,
const WebPPicture* const picture) {
int width, height;
int has_alpha;
size_t coded_size;
int percent = 0;
int initial_size;
VP8LBitWriter bw;
if (picture == NULL) return 0;
if (config == NULL || picture->argb == NULL) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER);
}
width = picture->width;
height = picture->height;
// Initialize BitWriter with size corresponding to 16 bpp to photo images and
// 8 bpp for graphical images.
initial_size = (config->image_hint == WEBP_HINT_GRAPH) ?
width * height : width * height * 2;
if (!VP8LBitWriterInit(&bw, initial_size)) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
if (!WebPReportProgress(picture, 1, &percent)) {
UserAbort:
WebPEncodingSetError(picture, VP8_ENC_ERROR_USER_ABORT);
goto Error;
}
// Reset stats (for pure lossless coding)
if (picture->stats != NULL) {
WebPAuxStats* const stats = picture->stats;
memset(stats, 0, sizeof(*stats));
stats->PSNR[0] = 99.f;
stats->PSNR[1] = 99.f;
stats->PSNR[2] = 99.f;
stats->PSNR[3] = 99.f;
stats->PSNR[4] = 99.f;
}
// Write image size.
if (!WriteImageSize(picture, &bw)) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
has_alpha = WebPPictureHasTransparency(picture);
// Write the non-trivial Alpha flag and lossless version.
if (!WriteRealAlphaAndVersion(&bw, has_alpha)) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto Error;
}
if (!WebPReportProgress(picture, 2, &percent)) goto UserAbort;
// Encode main image stream.
if (!VP8LEncodeStream(config, picture, &bw)) goto Error;
if (!WebPReportProgress(picture, 99, &percent)) goto UserAbort;
// Finish the RIFF chunk.
if (!WriteImage(picture, &bw, &coded_size)) goto Error;
if (!WebPReportProgress(picture, 100, &percent)) goto UserAbort;
#if !defined(WEBP_DISABLE_STATS)
// Save size.
if (picture->stats != NULL) {
picture->stats->coded_size += (int)coded_size;
picture->stats->lossless_size = (int)coded_size;
}
#endif
if (picture->extra_info != NULL) {
const int mb_w = (width + 15) >> 4;
const int mb_h = (height + 15) >> 4;
memset(picture->extra_info, 0, mb_w * mb_h * sizeof(*picture->extra_info));
}
Error:
if (bw.error_) {
WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
}
VP8LBitWriterWipeOut(&bw);
return (picture->error_code == VP8_ENC_OK);
}
//------------------------------------------------------------------------------
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