// 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 #include #include "enc_backward_references_enc.h" #include "enc_histogram_enc.h" #include "enc_vp8i_enc.h" #include "enc_vp8li_enc.h" #include "dsp_lossless.h" #include "dsp_lossless_common.h" #include "utils_bit_writer_utils.h" #include "utils_huffman_encode_utils.h" #include "utils_utils.h" #include "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, 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(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_SUBCONFIGS_MAX 2 typedef struct { int lz77_; int do_no_cache_; } CrunchSubConfig; typedef struct { int entropy_idx_; CrunchSubConfig sub_configs_[CRUNCH_SUBCONFIGS_MAX]; int sub_configs_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; // 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); 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) { 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); 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; 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; } } } } // 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 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_array, 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; } err = VP8LGetBackwardReferences( width, height, argb, quality, /*low_effort=*/0, kLZ77Standard | kLZ77RLE, cache_bits, /*do_no_cache=*/0, hash_chain, refs_array, &cache_bits); if (err != VP8_ENC_OK) goto Error; refs = &refs_array[0]; histogram_image = VP8LAllocateHistogramSet(1, cache_bits); if (histogram_image == NULL) { err = 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)) { 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[4], 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_ERROR_OUT_OF_MEMORY; 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; 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); // Make sure we can allocate the different objects. memset(&hash_chain_histogram, 0, sizeof(hash_chain_histogram)); if (huff_tree == NULL || histogram_symbols == NULL || !VP8LHashChainInit(&hash_chain_histogram, histogram_image_xysize) || !VP8LHashChainFill(hash_chain, quality, argb, width, height, low_effort)) { goto Error; } if (use_cache) { // 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; } else { cache_bits_init = 0; } // If several iterations will happen, clone into bw_best. if (!VP8LBitWriterInit(&bw_best, 0) || ((config->sub_configs_size_ > 1 || config->sub_configs_[0].do_no_cache_) && !VP8LBitWriterClone(bw, &bw_best))) { 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; err = 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); if (err != VP8_ENC_OK) 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 || !VP8LGetHistoImageSymbols(width, height, &refs_array[i_cache], quality, low_effort, histogram_bits, cache_bits_tmp, histogram_image, tmp_histo, histogram_symbols)) { 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)) { 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) 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_histogram, &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) 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_array[i_cache], histogram_symbols, huffman_codes); if (err != VP8_ENC_OK) 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); err = VP8_ENC_OK; 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 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], 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], 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; err = AllocateTransformBuffer(enc, width, height); if (err != VP8_ENC_OK) return err; if (enc->argb_content_ == kEncoderARGB) return VP8_ENC_OK; { 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 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], palette_size, 1, /*quality=*/20, 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 < 4; ++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 = ~(size_t)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) || (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); 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 (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_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; 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; } //------------------------------------------------------------------------------