// 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/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/dsp/lossless.h"
#include "src/dsp/lossless_common.h"
#include "src/utils/bit_writer_utils.h"
#include "src/utils/huffman_encode_utils.h"
#include "src/utils/utils.h"
#include "src/webp/format_constants.h"
// Maximum number of histogram images (sub-blocks).
#define MAX_HUFF_IMAGE_SIZE 2600
// Palette reordering for smaller sum of deltas (and for smaller storage).
static int PaletteCompareColorsForQsort(const void* p1, const void* p2) {
const uint32_t a = WebPMemToUint32((uint8_t*)p1);
const uint32_t b = WebPMemToUint32((uint8_t*)p2);
assert(a != b);
return (a < b) ? -1 : 1;
}
static WEBP_INLINE uint32_t PaletteComponentDistance(uint32_t v) {
return (v <= 128) ? v : (256 - v);
}
// Computes a value that is related to the entropy created by the
// palette entry diff.
//
// Note that the last & 0xff is a no-operation in the next statement, but
// removed by most compilers and is here only for regularity of the code.
static WEBP_INLINE uint32_t PaletteColorDistance(uint32_t col1, uint32_t col2) {
const uint32_t diff = VP8LSubPixels(col1, col2);
const int kMoreWeightForRGBThanForAlpha = 9;
uint32_t score;
score = PaletteComponentDistance((diff >> 0) & 0xff);
score += PaletteComponentDistance((diff >> 8) & 0xff);
score += PaletteComponentDistance((diff >> 16) & 0xff);
score *= kMoreWeightForRGBThanForAlpha;
score += PaletteComponentDistance((diff >> 24) & 0xff);
return score;
}
static WEBP_INLINE void SwapColor(uint32_t* const col1, uint32_t* const col2) {
const uint32_t tmp = *col1;
*col1 = *col2;
*col2 = tmp;
}
static void GreedyMinimizeDeltas(uint32_t palette[], int num_colors) {
// Find greedily always the closest color of the predicted color to minimize
// deltas in the palette. This reduces storage needs since the
// palette is stored with delta encoding.
uint32_t predict = 0x00000000;
int i, k;
for (i = 0; i < num_colors; ++i) {
int best_ix = i;
uint32_t best_score = ~0U;
for (k = i; k < num_colors; ++k) {
const uint32_t cur_score = PaletteColorDistance(palette[k], predict);
if (best_score > cur_score) {
best_score = cur_score;
best_ix = k;
}
}
SwapColor(&palette[best_ix], &palette[i]);
predict = palette[i];
}
}
// The palette has been sorted by alpha. This function checks if the other
// components of the palette have a monotonic development with regards to
// position in the palette. If all have monotonic development, there is
// no benefit to re-organize them greedily. A monotonic development
// would be spotted in green-only situations (like lossy alpha) or gray-scale
// images.
static int PaletteHasNonMonotonousDeltas(uint32_t palette[], int num_colors) {
uint32_t predict = 0x000000;
int i;
uint8_t sign_found = 0x00;
for (i = 0; i < num_colors; ++i) {
const uint32_t diff = VP8LSubPixels(palette[i], predict);
const uint8_t rd = (diff >> 16) & 0xff;
const uint8_t gd = (diff >> 8) & 0xff;
const uint8_t bd = (diff >> 0) & 0xff;
if (rd != 0x00) {
sign_found |= (rd < 0x80) ? 1 : 2;
}
if (gd != 0x00) {
sign_found |= (gd < 0x80) ? 8 : 16;
}
if (bd != 0x00) {
sign_found |= (bd < 0x80) ? 64 : 128;
}
predict = palette[i];
}
return (sign_found & (sign_found << 1)) != 0; // two consequent signs.
}
// -----------------------------------------------------------------------------
// Palette
// If number of colors in the image is less than or equal to MAX_PALETTE_SIZE,
// creates a palette and returns true, else returns false.
static int AnalyzeAndCreatePalette(const WebPPicture* const pic,
int low_effort,
uint32_t palette[MAX_PALETTE_SIZE],
int* const palette_size) {
const int num_colors = WebPGetColorPalette(pic, palette);
if (num_colors > MAX_PALETTE_SIZE) {
*palette_size = 0;
return 0;
}
*palette_size = num_colors;
qsort(palette, num_colors, sizeof(*palette), PaletteCompareColorsForQsort);
if (!low_effort && PaletteHasNonMonotonousDeltas(palette, num_colors)) {
GreedyMinimizeDeltas(palette, num_colors);
}
return 1;
}
// These five modes are evaluated and their respective entropy is computed.
typedef enum {
kDirect = 0,
kSpatial = 1,
kSubGreen = 2,
kSpatialSubGreen = 3,
kPalette = 4,
kNumEntropyIx = 5
} 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(int p, uint32_t* const r, uint32_t* const b) {
const int green = p >> 8; // The upper bits are masked away later.
++r[((p >> 16) - green) & 0xff];
++b[((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;
}
{
double entropy_comp[kHistoTotal];
double 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_CONFIGS_LZ77_MAX 2
typedef struct {
int entropy_idx_;
int lz77s_types_to_try_[CRUNCH_CONFIGS_LZ77_MAX];
int lz77s_types_to_try_size_;
} CrunchConfig;
#define CRUNCH_CONFIGS_MAX kNumEntropyIx
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;
int n_lz77s;
assert(pic != NULL && pic->argb != NULL);
use_palette =
AnalyzeAndCreatePalette(pic, low_effort,
enc->palette_, &enc->palette_size_);
// Empirical bit sizes.
enc->histo_bits_ = GetHistoBits(method, use_palette,
pic->width, pic->height);
enc->transform_bits_ = GetTransformBits(method, enc->histo_bits_);
if (low_effort) {
// AnalyzeEntropy is somewhat slow.
crunch_configs[0].entropy_idx_ = use_palette ? kPalette : kSpatialSubGreen;
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_, enc->transform_bits_,
&min_entropy_ix, red_and_blue_always_zero)) {
return 0;
}
if (method == 6 && config->quality == 100) {
// Go brute force on all transforms.
*crunch_configs_size = 0;
for (i = 0; i < kNumEntropyIx; ++i) {
if (i != kPalette || use_palette) {
assert(*crunch_configs_size < CRUNCH_CONFIGS_MAX);
crunch_configs[(*crunch_configs_size)++].entropy_idx_ = i;
}
}
} else {
// Only choose the guessed best transform.
*crunch_configs_size = 1;
crunch_configs[0].entropy_idx_ = min_entropy_ix;
}
}
// Fill in the different LZ77s.
assert(n_lz77s <= CRUNCH_CONFIGS_LZ77_MAX);
for (i = 0; i < *crunch_configs_size; ++i) {
int j;
for (j = 0; j < n_lz77s; ++j) {
crunch_configs[i].lz77s_types_to_try_[j] =
(j == 0) ? kLZ77Standard | kLZ77RLE : kLZ77Box;
}
crunch_configs[i].lz77s_types_to_try_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 < 3; ++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];
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 WebPEncodingError StoreImageToBitMask(
VP8LBitWriter* const bw, int width, int histo_bits,
const VP8LBackwardRefs* const refs,
const uint16_t* histogram_symbols,
const HuffmanTreeCode* const huffman_codes) {
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);
}
return bw->error_ ? VP8_ENC_ERROR_OUT_OF_MEMORY : VP8_ENC_OK;
}
// Special case of EncodeImageInternal() for cache-bits=0, histo_bits=31
static WebPEncodingError EncodeImageNoHuffman(VP8LBitWriter* const bw,
const uint32_t* const argb,
VP8LHashChain* const hash_chain,
VP8LBackwardRefs* const refs_tmp1,
VP8LBackwardRefs* const refs_tmp2,
int width, int height,
int quality, int low_effort) {
int i;
int max_tokens = 0;
WebPEncodingError err = VP8_ENC_OK;
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) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
// Calculate backward references from ARGB image.
if (!VP8LHashChainFill(hash_chain, quality, argb, width, height,
low_effort)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
refs = VP8LGetBackwardReferences(width, height, argb, quality, 0,
kLZ77Standard | kLZ77RLE, &cache_bits,
hash_chain, refs_tmp1, refs_tmp2);
if (refs == NULL) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
histogram_image = VP8LAllocateHistogramSet(1, cache_bits);
if (histogram_image == NULL) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
// 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)) {
err = 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) {
err = 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.
err = StoreImageToBitMask(bw, width, 0, refs, histogram_symbols,
huffman_codes);
Error:
WebPSafeFree(tokens);
WebPSafeFree(huff_tree);
VP8LFreeHistogramSet(histogram_image);
WebPSafeFree(huffman_codes[0].codes);
return err;
}
static WebPEncodingError EncodeImageInternal(
VP8LBitWriter* const bw, const uint32_t* const argb,
VP8LHashChain* const hash_chain, VP8LBackwardRefs refs_array[3], int width,
int height, int quality, int low_effort, int use_cache,
const CrunchConfig* const config, int* cache_bits, int histogram_bits,
size_t init_byte_position, int* const hdr_size, int* const data_size) {
WebPEncodingError err = VP8_ENC_OK;
const uint32_t histogram_image_xysize =
VP8LSubSampleSize(width, histogram_bits) *
VP8LSubSampleSize(height, histogram_bits);
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;
VP8LBackwardRefs* refs_best;
VP8LBackwardRefs* refs_tmp;
uint16_t* const histogram_symbols =
(uint16_t*)WebPSafeMalloc(histogram_image_xysize,
sizeof(*histogram_symbols));
int lz77s_idx;
VP8LBitWriter bw_init = *bw, bw_best;
int hdr_size_tmp;
assert(histogram_bits >= MIN_HUFFMAN_BITS);
assert(histogram_bits <= MAX_HUFFMAN_BITS);
assert(hdr_size != NULL);
assert(data_size != NULL);
if (histogram_symbols == NULL) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
if (use_cache) {
// If the value is different from zero, it has been set during the
// palette analysis.
if (*cache_bits == 0) *cache_bits = MAX_COLOR_CACHE_BITS;
} else {
*cache_bits = 0;
}
// 'best_refs' is the reference to the best backward refs and points to one
// of refs_array[0] or refs_array[1].
// Calculate backward references from ARGB image.
if (huff_tree == NULL ||
!VP8LHashChainFill(hash_chain, quality, argb, width, height,
low_effort) ||
!VP8LBitWriterInit(&bw_best, 0) ||
(config->lz77s_types_to_try_size_ > 1 &&
!VP8LBitWriterClone(bw, &bw_best))) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
for (lz77s_idx = 0; lz77s_idx < config->lz77s_types_to_try_size_;
++lz77s_idx) {
refs_best = VP8LGetBackwardReferences(
width, height, argb, quality, low_effort,
config->lz77s_types_to_try_[lz77s_idx], cache_bits, hash_chain,
&refs_array[0], &refs_array[1]);
if (refs_best == NULL) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
// Keep the best references aside and use the other element from the first
// two as a temporary for later usage.
refs_tmp = &refs_array[refs_best == &refs_array[0] ? 1 : 0];
histogram_image =
VP8LAllocateHistogramSet(histogram_image_xysize, *cache_bits);
tmp_histo = VP8LAllocateHistogram(*cache_bits);
if (histogram_image == NULL || tmp_histo == NULL) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
// Build histogram image and symbols from backward references.
if (!VP8LGetHistoImageSymbols(width, height, refs_best, quality, low_effort,
histogram_bits, *cache_bits, histogram_image,
tmp_histo, histogram_symbols)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
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)) {
err = 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 > 0) {
VP8LPutBits(bw, 1, 1);
VP8LPutBits(bw, *cache_bits, 4);
} else {
VP8LPutBits(bw, 0, 1);
}
// Huffman image + meta huffman.
{
const int 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) {
err = 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);
err = EncodeImageNoHuffman(
bw, histogram_argb, hash_chain, refs_tmp, &refs_array[2],
VP8LSubSampleSize(width, histogram_bits),
VP8LSubSampleSize(height, histogram_bits), quality, low_effort);
WebPSafeFree(histogram_argb);
if (err != VP8_ENC_OK) goto Error;
}
}
// 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) {
err = 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);
err = StoreImageToBitMask(bw, width, histogram_bits, refs_best,
histogram_symbols, huffman_codes);
// Keep track of the smallest image so far.
if (lz77s_idx == 0 ||
VP8LBitWriterNumBytes(bw) < VP8LBitWriterNumBytes(&bw_best)) {
*hdr_size = hdr_size_tmp;
*data_size =
(int)(VP8LBitWriterNumBytes(bw) - init_byte_position - *hdr_size);
VP8LBitWriterSwap(bw, &bw_best);
}
// Reset the bit writer for the following iteration if any.
if (config->lz77s_types_to_try_size_ > 1) VP8LBitWriterReset(&bw_init, bw);
WebPSafeFree(tokens);
tokens = NULL;
if (huffman_codes != NULL) {
WebPSafeFree(huffman_codes->codes);
WebPSafeFree(huffman_codes);
huffman_codes = NULL;
}
}
VP8LBitWriterSwap(bw, &bw_best);
Error:
WebPSafeFree(tokens);
WebPSafeFree(huff_tree);
VP8LFreeHistogramSet(histogram_image);
VP8LFreeHistogram(tmp_histo);
if (huffman_codes != NULL) {
WebPSafeFree(huffman_codes->codes);
WebPSafeFree(huffman_codes);
}
WebPSafeFree(histogram_symbols);
VP8LBitWriterWipeOut(&bw_best);
return err;
}
// -----------------------------------------------------------------------------
// Transforms
static void ApplySubtractGreen(VP8LEncoder* const enc, int width, int height,
VP8LBitWriter* const bw) {
VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
VP8LPutBits(bw, SUBTRACT_GREEN, 2);
VP8LSubtractGreenFromBlueAndRed(enc->argb_, width * height);
}
static WebPEncodingError ApplyPredictFilter(const VP8LEncoder* const enc,
int width, int height,
int quality, int low_effort,
int used_subtract_green,
VP8LBitWriter* const bw) {
const int pred_bits = enc->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;
VP8LResidualImage(width, height, pred_bits, low_effort, enc->argb_,
enc->argb_scratch_, enc->transform_data_,
near_lossless_strength, enc->config_->exact,
used_subtract_green);
VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
VP8LPutBits(bw, PREDICTOR_TRANSFORM, 2);
assert(pred_bits >= 2);
VP8LPutBits(bw, pred_bits - 2, 3);
return EncodeImageNoHuffman(
bw, enc->transform_data_, (VP8LHashChain*)&enc->hash_chain_,
(VP8LBackwardRefs*)&enc->refs_[0], // cast const away
(VP8LBackwardRefs*)&enc->refs_[1], transform_width, transform_height,
quality, low_effort);
}
static WebPEncodingError ApplyCrossColorFilter(const VP8LEncoder* const enc,
int width, int height,
int quality, int low_effort,
VP8LBitWriter* const bw) {
const int ccolor_transform_bits = enc->transform_bits_;
const int transform_width = VP8LSubSampleSize(width, ccolor_transform_bits);
const int transform_height = VP8LSubSampleSize(height, ccolor_transform_bits);
VP8LColorSpaceTransform(width, height, ccolor_transform_bits, quality,
enc->argb_, enc->transform_data_);
VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
VP8LPutBits(bw, CROSS_COLOR_TRANSFORM, 2);
assert(ccolor_transform_bits >= 2);
VP8LPutBits(bw, ccolor_transform_bits - 2, 3);
return EncodeImageNoHuffman(
bw, enc->transform_data_, (VP8LHashChain*)&enc->hash_chain_,
(VP8LBackwardRefs*)&enc->refs_[0], // cast const away
(VP8LBackwardRefs*)&enc->refs_[1], transform_width, transform_height,
quality, low_effort);
}
// -----------------------------------------------------------------------------
static WebPEncodingError 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);
if (!pic->writer(riff, sizeof(riff), pic)) {
return VP8_ENC_ERROR_BAD_WRITE;
}
return VP8_ENC_OK;
}
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 WebPEncodingError WriteImage(const WebPPicture* const pic,
VP8LBitWriter* const bw,
size_t* const coded_size) {
WebPEncodingError err = VP8_ENC_OK;
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;
err = WriteRiffHeader(pic, riff_size, vp8l_size);
if (err != VP8_ENC_OK) goto Error;
if (!pic->writer(webpll_data, webpll_size, pic)) {
err = VP8_ENC_ERROR_BAD_WRITE;
goto Error;
}
if (pad) {
const uint8_t pad_byte[1] = { 0 };
if (!pic->writer(pad_byte, 1, pic)) {
err = VP8_ENC_ERROR_BAD_WRITE;
goto Error;
}
}
*coded_size = CHUNK_HEADER_SIZE + riff_size;
return VP8_ENC_OK;
Error:
return err;
}
// -----------------------------------------------------------------------------
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 WebPEncodingError AllocateTransformBuffer(VP8LEncoder* const enc,
int width, int height) {
WebPEncodingError err = VP8_ENC_OK;
const uint64_t image_size = 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 uint64_t transform_data_size =
(enc->use_predict_ || enc->use_cross_color_)
? VP8LSubSampleSize(width, enc->transform_bits_) *
VP8LSubSampleSize(height, enc->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) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
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;
Error:
return err;
}
static WebPEncodingError MakeInputImageCopy(VP8LEncoder* const enc) {
WebPEncodingError err = VP8_ENC_OK;
const WebPPicture* const picture = enc->pic_;
const int width = picture->width;
const int height = picture->height;
int y;
err = AllocateTransformBuffer(enc, width, height);
if (err != VP8_ENC_OK) return err;
if (enc->argb_content_ == kEncoderARGB) return VP8_ENC_OK;
for (y = 0; y < height; ++y) {
memcpy(enc->argb_ + y * width,
picture->argb + y * picture->argb_stride,
width * sizeof(*enc->argb_));
}
enc->argb_content_ = kEncoderARGB;
assert(enc->current_width_ == width);
return VP8_ENC_OK;
}
// -----------------------------------------------------------------------------
static WEBP_INLINE int SearchColorNoIdx(const uint32_t sorted[], uint32_t color,
int hi) {
int low = 0;
if (sorted[low] == color) return low; // loop invariant: sorted[low] != color
while (1) {
const int mid = (low + hi) >> 1;
if (sorted[mid] == color) {
return mid;
} else if (sorted[mid] < color) {
low = mid;
} else {
hi = mid;
}
}
}
#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);
}
// Sort palette in increasing order and prepare an inverse mapping array.
static void PrepareMapToPalette(const uint32_t palette[], int num_colors,
uint32_t sorted[], uint32_t idx_map[]) {
int i;
memcpy(sorted, palette, num_colors * sizeof(*sorted));
qsort(sorted, num_colors, sizeof(*sorted), PaletteCompareColorsForQsort);
for (i = 0; i < num_colors; ++i) {
idx_map[SearchColorNoIdx(sorted, palette[i], num_colors)] = i;
}
}
// 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 WebPEncodingError 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) {
// 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 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 VP8_ENC_OK;
}
#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 WebPEncodingError MapImageFromPalette(VP8LEncoder* const enc,
int in_place) {
WebPEncodingError err = VP8_ENC_OK;
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;
}
err = AllocateTransformBuffer(enc, VP8LSubSampleSize(width, xbits), height);
if (err != VP8_ENC_OK) return err;
err = ApplyPalette(src, src_stride,
enc->argb_, enc->current_width_,
palette, palette_size, width, height, xbits);
enc->argb_content_ = kEncoderPalette;
return err;
}
// Save palette_[] to bitstream.
static WebPEncodingError EncodePalette(VP8LBitWriter* const bw, int low_effort,
VP8LEncoder* const enc) {
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], &enc->refs_[1], palette_size, 1,
20 /* quality */, low_effort);
}
// -----------------------------------------------------------------------------
// 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 < 3; ++i) VP8LBackwardRefsClear(&enc->refs_[i]);
ClearTransformBuffer(enc);
WebPSafeFree(enc);
}
}
// -----------------------------------------------------------------------------
// Main call
typedef struct {
const WebPConfig* config_;
const WebPPicture* picture_;
VP8LBitWriter* bw_;
VP8LEncoder* enc_;
int use_cache_;
CrunchConfig crunch_configs_[CRUNCH_CONFIGS_MAX];
int num_crunch_configs_;
int red_and_blue_always_zero_;
WebPEncodingError err_;
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 int use_cache = params->use_cache_;
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
WebPEncodingError err = VP8_ENC_OK;
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);
#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 = 0;
VP8LBitWriter bw_init = *bw, bw_best;
(void)data2;
if (!VP8LBitWriterInit(&bw_best, 0) ||
(num_crunch_configs > 1 && !VP8LBitWriterClone(bw, &bw_best))) {
err = 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_;
enc->use_palette_ = (entropy_idx == kPalette);
enc->use_subtract_green_ =
(entropy_idx == kSubGreen) || (entropy_idx == kSpatialSubGreen);
enc->use_predict_ =
(entropy_idx == kSpatial) || (entropy_idx == kSpatialSubGreen);
if (low_effort) {
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) {
err = AllocateTransformBuffer(enc, width, height);
if (err != VP8_ENC_OK) goto Error;
if ((enc->argb_content_ != kEncoderNearLossless) &&
!VP8ApplyNearLossless(picture, config->near_lossless, enc->argb_)) {
err = 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_) {
err = EncodePalette(bw, low_effort, enc);
if (err != VP8_ENC_OK) goto Error;
err = MapImageFromPalette(enc, use_delta_palette);
if (err != VP8_ENC_OK) goto Error;
// If using a color cache, do not have it bigger than the number of
// colors.
if (use_cache && 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) {
err = MakeInputImageCopy(enc);
if (err != VP8_ENC_OK) goto Error;
}
// -----------------------------------------------------------------------
// Apply transforms and write transform data.
if (enc->use_subtract_green_) {
ApplySubtractGreen(enc, enc->current_width_, height, bw);
}
if (enc->use_predict_) {
err = ApplyPredictFilter(enc, enc->current_width_, height, quality,
low_effort, enc->use_subtract_green_, bw);
if (err != VP8_ENC_OK) goto Error;
}
if (enc->use_cross_color_) {
err = ApplyCrossColorFilter(enc, enc->current_width_, height, quality,
low_effort, bw);
if (err != VP8_ENC_OK) goto Error;
}
}
VP8LPutBits(bw, !TRANSFORM_PRESENT, 1); // No more transforms.
// -------------------------------------------------------------------------
// Encode and write the transformed image.
err = EncodeImageInternal(bw, enc->argb_, &enc->hash_chain_, enc->refs_,
enc->current_width_, height, quality, low_effort,
use_cache, &crunch_configs[idx],
&enc->cache_bits_, enc->histo_bits_,
byte_position, &hdr_size, &data_size);
if (err != VP8_ENC_OK) goto Error;
// If we are better than what we already have.
if (idx == 0 || 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->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);
params->err_ = err;
// The hook should return false in case of error.
return (err == VP8_ENC_OK);
}
WebPEncodingError VP8LEncodeStream(const WebPConfig* const config,
const WebPPicture* const picture,
VP8LBitWriter* const bw_main,
int use_cache) {
WebPEncodingError err = VP8_ENC_OK;
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;
const WebPWorkerInterface* const worker_interface = WebPGetWorkerInterface();
int ok_main;
// Analyze image (entropy, num_palettes etc)
if (enc_main == NULL ||
!EncoderAnalyze(enc_main, crunch_configs, &num_crunch_configs_main,
&red_and_blue_always_zero) ||
!EncoderInit(enc_main) || !VP8LBitWriterInit(&bw_side, 0)) {
err = 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) ? ¶ms_main : ¶ms_side;
param->config_ = config;
param->picture_ = picture;
param->use_cache_ = use_cache;
param->red_and_blue_always_zero_ = red_and_blue_always_zero;
if (idx == 0) {
param->stats_ = picture->stats;
param->bw_ = bw_main;
param->enc_ = enc_main;
} else {
param->stats_ = (picture->stats == NULL) ? NULL : &stats_side;
// Create a side bit writer.
if (!VP8LBitWriterClone(bw_main, &bw_side)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
param->bw_ = &bw_side;
// Create a side encoder.
enc_side = VP8LEncoderNew(config, picture);
if (enc_side == NULL || !EncoderInit(enc_side)) {
err = 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->transform_bits_ = enc_main->transform_bits_;
enc_side->palette_size_ = enc_main->palette_size_;
memcpy(enc_side->palette_, enc_main->palette_,
sizeof(enc_main->palette_));
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)) {
err = 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
// This line is only useful to remove a Clang static analyzer warning.
params_side.err_ = VP8_ENC_OK;
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) {
err = ok_main ? params_side.err_ : params_main.err_;
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
}
} else {
if (!ok_main) {
err = params_main.err_;
goto Error;
}
}
Error:
VP8LBitWriterWipeOut(&bw_side);
VP8LEncoderDelete(enc_main);
VP8LEncoderDelete(enc_side);
return err;
}
#undef CRUNCH_CONFIGS_MAX
#undef CRUNCH_CONFIGS_LZ77_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;
WebPEncodingError err = VP8_ENC_OK;
VP8LBitWriter bw;
if (picture == NULL) return 0;
if (config == NULL || picture->argb == NULL) {
err = VP8_ENC_ERROR_NULL_PARAMETER;
WebPEncodingSetError(picture, err);
return 0;
}
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)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
if (!WebPReportProgress(picture, 1, &percent)) {
UserAbort:
err = 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)) {
err = 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)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
if (!WebPReportProgress(picture, 5, &percent)) goto UserAbort;
// Encode main image stream.
err = VP8LEncodeStream(config, picture, &bw, 1 /*use_cache*/);
if (err != VP8_ENC_OK) goto Error;
if (!WebPReportProgress(picture, 90, &percent)) goto UserAbort;
// Finish the RIFF chunk.
err = WriteImage(picture, &bw, &coded_size);
if (err != VP8_ENC_OK) 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_) err = VP8_ENC_ERROR_OUT_OF_MEMORY;
VP8LBitWriterWipeOut(&bw);
if (err != VP8_ENC_OK) {
WebPEncodingSetError(picture, err);
return 0;
}
return 1;
}
//------------------------------------------------------------------------------