// Copyright 2012 Google Inc. All Rights Reserved. // // This code is licensed under the same terms as WebM: // Software License Agreement: http://www.webmproject.org/license/software/ // Additional IP Rights Grant: http://www.webmproject.org/license/additional/ // ----------------------------------------------------------------------------- // // main entry for the lossless encoder. // // Author: Vikas Arora (vikaas.arora@gmail.com) // #include #include #include #include "./backward_references.h" #include "./vp8enci.h" #include "./vp8li.h" #include "../dsp/lossless.h" #include "../utils/bit_writer.h" #include "../utils/huffman_encode.h" #include "../utils/utils.h" #include "../webp/format_constants.h" #if defined(__cplusplus) || defined(c_plusplus) extern "C" { #endif #define PALETTE_KEY_RIGHT_SHIFT 22 // Key for 1K buffer. #define MAX_HUFF_IMAGE_SIZE (16 * 1024 * 1024) #define MAX_COLORS_FOR_GRAPH 64 // ----------------------------------------------------------------------------- // Palette static int CompareColors(const void* p1, const void* p2) { const uint32_t a = *(const uint32_t*)p1; const uint32_t b = *(const uint32_t*)p2; return (a < b) ? -1 : (a > b) ? 1 : 0; } // 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, uint32_t palette[MAX_PALETTE_SIZE], int* const palette_size) { int i, x, y, key; int num_colors = 0; uint8_t in_use[MAX_PALETTE_SIZE * 4] = { 0 }; uint32_t colors[MAX_PALETTE_SIZE * 4]; static const uint32_t kHashMul = 0x1e35a7bd; const uint32_t* argb = pic->argb; const int width = pic->width; const int height = pic->height; uint32_t last_pix = ~argb[0]; // so we're sure that last_pix != argb[0] for (y = 0; y < height; ++y) { for (x = 0; x < width; ++x) { if (argb[x] == last_pix) { continue; } last_pix = argb[x]; key = (kHashMul * last_pix) >> PALETTE_KEY_RIGHT_SHIFT; while (1) { if (!in_use[key]) { colors[key] = last_pix; in_use[key] = 1; ++num_colors; if (num_colors > MAX_PALETTE_SIZE) { return 0; } break; } else if (colors[key] == last_pix) { // The color is already there. break; } else { // Some other color sits there. // Do linear conflict resolution. ++key; key &= (MAX_PALETTE_SIZE * 4 - 1); // key mask for 1K buffer. } } } argb += pic->argb_stride; } // TODO(skal): could we reuse in_use[] to speed up ApplyPalette()? num_colors = 0; for (i = 0; i < (int)(sizeof(in_use) / sizeof(in_use[0])); ++i) { if (in_use[i]) { palette[num_colors] = colors[i]; ++num_colors; } } qsort(palette, num_colors, sizeof(*palette), CompareColors); *palette_size = num_colors; return 1; } static int AnalyzeEntropy(const uint32_t* argb, int width, int height, int argb_stride, double* const nonpredicted_bits, double* const predicted_bits) { int x, y; const uint32_t* last_line = NULL; uint32_t last_pix = argb[0]; // so we're sure that pix_diff == 0 VP8LHistogram* nonpredicted = NULL; VP8LHistogram* predicted = (VP8LHistogram*)malloc(2 * sizeof(*predicted)); if (predicted == NULL) return 0; nonpredicted = predicted + 1; VP8LHistogramInit(predicted, 0); VP8LHistogramInit(nonpredicted, 0); for (y = 0; y < height; ++y) { for (x = 0; x < width; ++x) { const uint32_t pix = argb[x]; const uint32_t pix_diff = VP8LSubPixels(pix, last_pix); if (pix_diff == 0) continue; if (last_line != NULL && pix == last_line[x]) { continue; } last_pix = pix; { const PixOrCopy pix_token = PixOrCopyCreateLiteral(pix); const PixOrCopy pix_diff_token = PixOrCopyCreateLiteral(pix_diff); VP8LHistogramAddSinglePixOrCopy(nonpredicted, &pix_token); VP8LHistogramAddSinglePixOrCopy(predicted, &pix_diff_token); } } last_line = argb; argb += argb_stride; } *nonpredicted_bits = VP8LHistogramEstimateBitsBulk(nonpredicted); *predicted_bits = VP8LHistogramEstimateBitsBulk(predicted); free(predicted); return 1; } static int VP8LEncAnalyze(VP8LEncoder* const enc, WebPImageHint image_hint) { const WebPPicture* const pic = enc->pic_; assert(pic != NULL && pic->argb != NULL); enc->use_palette_ = AnalyzeAndCreatePalette(pic, enc->palette_, &enc->palette_size_); if (image_hint == WEBP_HINT_GRAPH) { if (enc->use_palette_ && enc->palette_size_ < MAX_COLORS_FOR_GRAPH) { enc->use_palette_ = 0; } } if (!enc->use_palette_) { if (image_hint == WEBP_HINT_PHOTO) { enc->use_predict_ = 1; enc->use_cross_color_ = 1; } else { double non_pred_entropy, pred_entropy; if (!AnalyzeEntropy(pic->argb, pic->width, pic->height, pic->argb_stride, &non_pred_entropy, &pred_entropy)) { return 0; } if (pred_entropy < 0.95 * non_pred_entropy) { enc->use_predict_ = 1; // TODO(vikasa): Observed some correlation of cross_color transform with // predict. Need to investigate this further and add separate heuristic // for setting use_cross_color flag. enc->use_cross_color_ = 1; } } } return 1; } static int GetHuffBitLengthsAndCodes( const VP8LHistogramSet* const histogram_image, HuffmanTreeCode* const huffman_codes) { int i, k; int ok = 1; uint64_t total_length_size = 0; uint8_t* mem_buf = NULL; const int histogram_image_size = histogram_image->size; // 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) : (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) { ok = 0; 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; } } // 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]; ok = ok && VP8LCreateHuffmanTree(histo->literal_, 15, codes + 0); ok = ok && VP8LCreateHuffmanTree(histo->red_, 15, codes + 1); ok = ok && VP8LCreateHuffmanTree(histo->blue_, 15, codes + 2); ok = ok && VP8LCreateHuffmanTree(histo->alpha_, 15, codes + 3); ok = ok && VP8LCreateHuffmanTree(histo->distance_, 15, codes + 4); } End: if (!ok) free(mem_buf); 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; } } VP8LWriteBits(bw, 4, codes_to_store - 4); for (i = 0; i < codes_to_store; ++i) { VP8LWriteBits(bw, 3, code_length_bitdepth[kStorageOrder[i]]); } } 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; VP8LWriteBits(bw, huffman_code->code_lengths[ix], huffman_code->codes[ix]); switch (ix) { case 16: VP8LWriteBits(bw, 2, extra_bits); break; case 17: VP8LWriteBits(bw, 3, extra_bits); break; case 18: VP8LWriteBits(bw, 7, extra_bits); break; } } } static int StoreFullHuffmanCode(VP8LBitWriter* const bw, const HuffmanTreeCode* const tree) { int ok = 0; 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; HuffmanTreeToken* const tokens = (HuffmanTreeToken*)WebPSafeMalloc((uint64_t)max_tokens, sizeof(*tokens)); if (tokens == NULL) return 0; huffman_code.num_symbols = CODE_LENGTH_CODES; huffman_code.code_lengths = code_length_bitdepth; huffman_code.codes = code_length_bitdepth_symbols; VP8LWriteBits(bw, 1, 0); num_tokens = VP8LCreateCompressedHuffmanTree(tree, tokens, max_tokens); { int histogram[CODE_LENGTH_CODES] = { 0 }; int i; for (i = 0; i < num_tokens; ++i) { ++histogram[tokens[i].code]; } if (!VP8LCreateHuffmanTree(histogram, 7, &huffman_code)) { goto End; } } 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; VP8LWriteBits(bw, 1, write_trimmed_length); if (write_trimmed_length) { const int nbits = VP8LBitsLog2Ceiling(trimmed_length - 1); const int nbitpairs = (nbits == 0) ? 1 : (nbits + 1) / 2; VP8LWriteBits(bw, 3, nbitpairs - 1); assert(trimmed_length >= 2); VP8LWriteBits(bw, nbitpairs * 2, trimmed_length - 2); } StoreHuffmanTreeToBitMask(bw, tokens, length, &huffman_code); } ok = 1; End: free(tokens); return ok; } static int StoreHuffmanCode(VP8LBitWriter* const bw, 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 VP8LWriteBits(bw, 4, 0x01); return 1; } else if (count <= 2 && symbols[0] < kMaxSymbol && symbols[1] < kMaxSymbol) { VP8LWriteBits(bw, 1, 1); // Small tree marker to encode 1 or 2 symbols. VP8LWriteBits(bw, 1, count - 1); if (symbols[0] <= 1) { VP8LWriteBits(bw, 1, 0); // Code bit for small (1 bit) symbol value. VP8LWriteBits(bw, 1, symbols[0]); } else { VP8LWriteBits(bw, 1, 1); VP8LWriteBits(bw, 8, symbols[0]); } if (count == 2) { VP8LWriteBits(bw, 8, symbols[1]); } return 1; } else { return StoreFullHuffmanCode(bw, huffman_code); } } static void WriteHuffmanCode(VP8LBitWriter* const bw, const HuffmanTreeCode* const code, int index) { const int depth = code->code_lengths[index]; const int symbol = code->codes[index]; VP8LWriteBits(bw, depth, symbol); } static void StoreImageToBitMask( VP8LBitWriter* const bw, int width, int histo_bits, const VP8LBackwardRefs* const refs, const uint16_t* histogram_symbols, const HuffmanTreeCode* const huffman_codes) { // x and y trace the position in the image. int x = 0; int y = 0; const int histo_xsize = histo_bits ? VP8LSubSampleSize(width, histo_bits) : 1; int i; for (i = 0; i < refs->size; ++i) { const PixOrCopy* const v = &refs->refs[i]; const int histogram_ix = histogram_symbols[histo_bits ? (y >> histo_bits) * histo_xsize + (x >> histo_bits) : 0]; const HuffmanTreeCode* const codes = huffman_codes + 5 * histogram_ix; if (PixOrCopyIsCacheIdx(v)) { const int code = PixOrCopyCacheIdx(v); const int literal_ix = 256 + NUM_LENGTH_CODES + code; WriteHuffmanCode(bw, codes, literal_ix); } else if (PixOrCopyIsLiteral(v)) { static const int 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 { int bits, n_bits; int code, distance; PrefixEncode(v->len, &code, &n_bits, &bits); WriteHuffmanCode(bw, codes, 256 + code); VP8LWriteBits(bw, n_bits, bits); distance = PixOrCopyDistance(v); PrefixEncode(distance, &code, &n_bits, &bits); WriteHuffmanCode(bw, codes + 4, code); VP8LWriteBits(bw, n_bits, bits); } x += PixOrCopyLength(v); while (x >= width) { x -= width; ++y; } } } // Special case of EncodeImageInternal() for cache-bits=0, histo_bits=31 static int EncodeImageNoHuffman(VP8LBitWriter* const bw, const uint32_t* const argb, int width, int height, int quality) { int i; int ok = 0; VP8LBackwardRefs refs; HuffmanTreeCode huffman_codes[5] = { { 0, NULL, NULL } }; const uint16_t histogram_symbols[1] = { 0 }; // only one tree, one symbol VP8LHistogramSet* const histogram_image = VP8LAllocateHistogramSet(1, 0); if (histogram_image == NULL) return 0; // Calculate backward references from ARGB image. if (!VP8LGetBackwardReferences(width, height, argb, quality, 0, 1, &refs)) { 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)) { goto Error; } // No color cache, no Huffman image. VP8LWriteBits(bw, 1, 0); // Store Huffman codes. for (i = 0; i < 5; ++i) { HuffmanTreeCode* const codes = &huffman_codes[i]; if (!StoreHuffmanCode(bw, codes)) { goto Error; } ClearHuffmanTreeIfOnlyOneSymbol(codes); } // Store actual literals. StoreImageToBitMask(bw, width, 0, &refs, histogram_symbols, huffman_codes); ok = 1; Error: free(histogram_image); VP8LClearBackwardRefs(&refs); free(huffman_codes[0].codes); return ok; } static int EncodeImageInternal(VP8LBitWriter* const bw, const uint32_t* const argb, int width, int height, int quality, int cache_bits, int histogram_bits) { int ok = 0; const int use_2d_locality = 1; const int use_color_cache = (cache_bits > 0); const uint32_t histogram_image_xysize = VP8LSubSampleSize(width, histogram_bits) * VP8LSubSampleSize(height, histogram_bits); VP8LHistogramSet* histogram_image = VP8LAllocateHistogramSet(histogram_image_xysize, 0); int histogram_image_size = 0; size_t bit_array_size = 0; HuffmanTreeCode* huffman_codes = NULL; VP8LBackwardRefs refs; uint16_t* const histogram_symbols = (uint16_t*)WebPSafeMalloc((uint64_t)histogram_image_xysize, sizeof(*histogram_symbols)); assert(histogram_bits >= MIN_HUFFMAN_BITS); assert(histogram_bits <= MAX_HUFFMAN_BITS); if (histogram_image == NULL || histogram_symbols == NULL) { free(histogram_image); free(histogram_symbols); return 0; } // Calculate backward references from ARGB image. if (!VP8LGetBackwardReferences(width, height, argb, quality, cache_bits, use_2d_locality, &refs)) { goto Error; } // Build histogram image and symbols from backward references. if (!VP8LGetHistoImageSymbols(width, height, &refs, quality, histogram_bits, cache_bits, histogram_image, 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)); if (huffman_codes == NULL || !GetHuffBitLengthsAndCodes(histogram_image, huffman_codes)) { goto Error; } // Color Cache parameters. VP8LWriteBits(bw, 1, use_color_cache); if (use_color_cache) { VP8LWriteBits(bw, 4, cache_bits); } // Huffman image + meta huffman. { const int write_histogram_image = (histogram_image_size > 1); VP8LWriteBits(bw, 1, write_histogram_image); if (write_histogram_image) { uint32_t* const histogram_argb = (uint32_t*)WebPSafeMalloc((uint64_t)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 index = histogram_symbols[i] & 0xffff; histogram_argb[i] = 0xff000000 | (index << 8); if (index >= max_index) { max_index = index + 1; } } histogram_image_size = max_index; VP8LWriteBits(bw, 3, histogram_bits - 2); ok = EncodeImageNoHuffman(bw, histogram_argb, VP8LSubSampleSize(width, histogram_bits), VP8LSubSampleSize(height, histogram_bits), quality); free(histogram_argb); if (!ok) goto Error; } } // Store Huffman codes. { int i; for (i = 0; i < 5 * histogram_image_size; ++i) { HuffmanTreeCode* const codes = &huffman_codes[i]; if (!StoreHuffmanCode(bw, codes)) goto Error; ClearHuffmanTreeIfOnlyOneSymbol(codes); } } // Free combined histograms. free(histogram_image); histogram_image = NULL; // Store actual literals. StoreImageToBitMask(bw, width, histogram_bits, &refs, histogram_symbols, huffman_codes); ok = 1; Error: if (!ok) free(histogram_image); VP8LClearBackwardRefs(&refs); if (huffman_codes != NULL) { free(huffman_codes->codes); free(huffman_codes); } free(histogram_symbols); return ok; } // ----------------------------------------------------------------------------- // Transforms // Check if it would be a good idea to subtract green from red and blue. We // only impact entropy in red/blue components, don't bother to look at others. static int EvalAndApplySubtractGreen(VP8LEncoder* const enc, int width, int height, VP8LBitWriter* const bw) { if (!enc->use_palette_) { int i; const uint32_t* const argb = enc->argb_; double bit_cost_before, bit_cost_after; VP8LHistogram* const histo = (VP8LHistogram*)malloc(sizeof(*histo)); if (histo == NULL) return 0; VP8LHistogramInit(histo, 1); for (i = 0; i < width * height; ++i) { const uint32_t c = argb[i]; ++histo->red_[(c >> 16) & 0xff]; ++histo->blue_[(c >> 0) & 0xff]; } bit_cost_before = VP8LHistogramEstimateBits(histo); VP8LHistogramInit(histo, 1); for (i = 0; i < width * height; ++i) { const uint32_t c = argb[i]; const int green = (c >> 8) & 0xff; ++histo->red_[((c >> 16) - green) & 0xff]; ++histo->blue_[((c >> 0) - green) & 0xff]; } bit_cost_after = VP8LHistogramEstimateBits(histo); free(histo); // Check if subtracting green yields low entropy. enc->use_subtract_green_ = (bit_cost_after < bit_cost_before); if (enc->use_subtract_green_) { VP8LWriteBits(bw, 1, TRANSFORM_PRESENT); VP8LWriteBits(bw, 2, SUBTRACT_GREEN); VP8LSubtractGreenFromBlueAndRed(enc->argb_, width * height); } } return 1; } static int ApplyPredictFilter(const VP8LEncoder* const enc, int width, int height, int quality, 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); VP8LResidualImage(width, height, pred_bits, enc->argb_, enc->argb_scratch_, enc->transform_data_); VP8LWriteBits(bw, 1, TRANSFORM_PRESENT); VP8LWriteBits(bw, 2, PREDICTOR_TRANSFORM); assert(pred_bits >= 2); VP8LWriteBits(bw, 3, pred_bits - 2); if (!EncodeImageNoHuffman(bw, enc->transform_data_, transform_width, transform_height, quality)) { return 0; } return 1; } static int ApplyCrossColorFilter(const VP8LEncoder* const enc, int width, int height, int quality, 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); const int step = (quality == 0) ? 32 : 8; VP8LColorSpaceTransform(width, height, ccolor_transform_bits, step, enc->argb_, enc->transform_data_); VP8LWriteBits(bw, 1, TRANSFORM_PRESENT); VP8LWriteBits(bw, 2, CROSS_COLOR_TRANSFORM); assert(ccolor_transform_bits >= 2); VP8LWriteBits(bw, 3, ccolor_transform_bits - 2); if (!EncodeImageNoHuffman(bw, enc->transform_data_, transform_width, transform_height, quality)) { return 0; } return 1; } // ----------------------------------------------------------------------------- static void PutLE32(uint8_t* const data, uint32_t val) { data[0] = (val >> 0) & 0xff; data[1] = (val >> 8) & 0xff; data[2] = (val >> 16) & 0xff; data[3] = (val >> 24) & 0xff; } 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); VP8LWriteBits(bw, VP8L_IMAGE_SIZE_BITS, width); VP8LWriteBits(bw, VP8L_IMAGE_SIZE_BITS, height); return !bw->error_; } static int WriteRealAlphaAndVersion(VP8LBitWriter* const bw, int has_alpha) { VP8LWriteBits(bw, 1, has_alpha); VP8LWriteBits(bw, VP8L_VERSION_BITS, VP8L_VERSION); 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; } // ----------------------------------------------------------------------------- // Allocates the memory for argb (W x H) buffer, 2 rows of context for // prediction and transform data. static WebPEncodingError AllocateTransformBuffer(VP8LEncoder* const enc, int width, int height) { WebPEncodingError err = VP8_ENC_OK; const int tile_size = 1 << enc->transform_bits_; const uint64_t image_size = width * height; const uint64_t argb_scratch_size = tile_size * width + width; const uint64_t transform_data_size = (uint64_t)VP8LSubSampleSize(width, enc->transform_bits_) * (uint64_t)VP8LSubSampleSize(height, enc->transform_bits_); const uint64_t total_size = image_size + argb_scratch_size + transform_data_size; uint32_t* mem = (uint32_t*)WebPSafeMalloc(total_size, sizeof(*mem)); if (mem == NULL) { err = VP8_ENC_ERROR_OUT_OF_MEMORY; goto Error; } enc->argb_ = mem; mem += image_size; enc->argb_scratch_ = mem; mem += argb_scratch_size; enc->transform_data_ = mem; enc->current_width_ = width; Error: return err; } // Bundles multiple (2, 4 or 8) pixels into a single pixel. // Returns the new xsize. static void BundleColorMap(const WebPPicture* const pic, int xbits, uint32_t* bundled_argb, int xs) { int y; const int bit_depth = 1 << (3 - xbits); uint32_t code = 0; const uint32_t* argb = pic->argb; const int width = pic->width; const int height = pic->height; for (y = 0; y < height; ++y) { int x; for (x = 0; x < width; ++x) { const int mask = (1 << xbits) - 1; const int xsub = x & mask; if (xsub == 0) { code = 0; } // TODO(vikasa): simplify the bundling logic. code |= (argb[x] & 0xff00) << (bit_depth * xsub); bundled_argb[y * xs + (x >> xbits)] = 0xff000000 | code; } argb += pic->argb_stride; } } // Note: Expects "enc->palette_" to be set properly. // Also, "enc->palette_" will be modified after this call and should not be used // later. static WebPEncodingError ApplyPalette(VP8LBitWriter* const bw, VP8LEncoder* const enc, int quality) { WebPEncodingError err = VP8_ENC_OK; int i, x, y; const WebPPicture* const pic = enc->pic_; uint32_t* argb = pic->argb; const int width = pic->width; const int height = pic->height; uint32_t* const palette = enc->palette_; const int palette_size = enc->palette_size_; // Replace each input pixel by corresponding palette index. for (y = 0; y < height; ++y) { for (x = 0; x < width; ++x) { const uint32_t pix = argb[x]; for (i = 0; i < palette_size; ++i) { if (pix == palette[i]) { argb[x] = 0xff000000u | (i << 8); break; } } } argb += pic->argb_stride; } // Save palette to bitstream. VP8LWriteBits(bw, 1, TRANSFORM_PRESENT); VP8LWriteBits(bw, 2, COLOR_INDEXING_TRANSFORM); assert(palette_size >= 1); VP8LWriteBits(bw, 8, palette_size - 1); for (i = palette_size - 1; i >= 1; --i) { palette[i] = VP8LSubPixels(palette[i], palette[i - 1]); } if (!EncodeImageNoHuffman(bw, palette, palette_size, 1, quality)) { err = VP8_ENC_ERROR_INVALID_CONFIGURATION; goto Error; } if (palette_size <= 16) { // Image can be packed (multiple pixels per uint32_t). int xbits = 1; if (palette_size <= 2) { xbits = 3; } else if (palette_size <= 4) { xbits = 2; } err = AllocateTransformBuffer(enc, VP8LSubSampleSize(width, xbits), height); if (err != VP8_ENC_OK) goto Error; BundleColorMap(pic, xbits, enc->argb_, enc->current_width_); } Error: return err; } // ----------------------------------------------------------------------------- static int GetHistoBits(const WebPConfig* const config, const WebPPicture* const pic) { const int width = pic->width; const int height = pic->height; const uint64_t hist_size = sizeof(VP8LHistogram); // Make tile size a function of encoding method (Range: 0 to 6). int histo_bits = 7 - config->method; while (1) { const uint64_t huff_image_size = VP8LSubSampleSize(width, histo_bits) * VP8LSubSampleSize(height, histo_bits) * hist_size; 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 void InitEncParams(VP8LEncoder* const enc) { const WebPConfig* const config = enc->config_; const WebPPicture* const picture = enc->pic_; const int method = config->method; const float quality = config->quality; enc->transform_bits_ = (method < 4) ? 5 : (method > 4) ? 3 : 4; enc->histo_bits_ = GetHistoBits(config, picture); enc->cache_bits_ = (quality <= 25.f) ? 0 : 7; } // ----------------------------------------------------------------------------- // VP8LEncoder static VP8LEncoder* VP8LEncoderNew(const WebPConfig* const config, const WebPPicture* const picture) { VP8LEncoder* const enc = (VP8LEncoder*)calloc(1, sizeof(*enc)); if (enc == NULL) { WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY); return NULL; } enc->config_ = config; enc->pic_ = picture; return enc; } static void VP8LEncoderDelete(VP8LEncoder* enc) { free(enc->argb_); free(enc); } // ----------------------------------------------------------------------------- // Main call WebPEncodingError VP8LEncodeStream(const WebPConfig* const config, const WebPPicture* const picture, VP8LBitWriter* const bw) { WebPEncodingError err = VP8_ENC_OK; const int quality = (int)config->quality; const int width = picture->width; const int height = picture->height; VP8LEncoder* const enc = VP8LEncoderNew(config, picture); const size_t byte_position = VP8LBitWriterNumBytes(bw); if (enc == NULL) { err = VP8_ENC_ERROR_OUT_OF_MEMORY; goto Error; } InitEncParams(enc); // --------------------------------------------------------------------------- // Analyze image (entropy, num_palettes etc) if (!VP8LEncAnalyze(enc, config->image_hint)) { err = VP8_ENC_ERROR_OUT_OF_MEMORY; goto Error; } if (enc->use_palette_) { err = ApplyPalette(bw, enc, quality); if (err != VP8_ENC_OK) goto Error; // Color cache is disabled for palette. enc->cache_bits_ = 0; } // In case image is not packed. if (enc->argb_ == NULL) { int y; err = AllocateTransformBuffer(enc, width, height); if (err != VP8_ENC_OK) goto Error; for (y = 0; y < height; ++y) { memcpy(enc->argb_ + y * width, picture->argb + y * picture->argb_stride, width * sizeof(*enc->argb_)); } enc->current_width_ = width; } // --------------------------------------------------------------------------- // Apply transforms and write transform data. if (!EvalAndApplySubtractGreen(enc, enc->current_width_, height, bw)) { err = VP8_ENC_ERROR_OUT_OF_MEMORY; goto Error; } if (enc->use_predict_) { if (!ApplyPredictFilter(enc, enc->current_width_, height, quality, bw)) { err = VP8_ENC_ERROR_INVALID_CONFIGURATION; goto Error; } } if (enc->use_cross_color_) { if (!ApplyCrossColorFilter(enc, enc->current_width_, height, quality, bw)) { err = VP8_ENC_ERROR_INVALID_CONFIGURATION; goto Error; } } VP8LWriteBits(bw, 1, !TRANSFORM_PRESENT); // No more transforms. // --------------------------------------------------------------------------- // Estimate the color cache size. if (enc->cache_bits_ > 0) { if (!VP8LCalculateEstimateForCacheSize(enc->argb_, enc->current_width_, height, &enc->cache_bits_)) { err = VP8_ENC_ERROR_INVALID_CONFIGURATION; goto Error; } } // --------------------------------------------------------------------------- // Encode and write the transformed image. if (!EncodeImageInternal(bw, enc->argb_, enc->current_width_, height, quality, enc->cache_bits_, enc->histo_bits_)) { err = VP8_ENC_ERROR_OUT_OF_MEMORY; goto Error; } if (picture->stats != NULL) { WebPAuxStats* const stats = picture->stats; 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)(VP8LBitWriterNumBytes(bw) - byte_position); } Error: VP8LEncoderDelete(enc); return err; } int VP8LEncodeImage(const WebPConfig* const config, const WebPPicture* const picture) { int width, height; int has_alpha; size_t coded_size; int percent = 0; 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; if (!VP8LBitWriterInit(&bw, (width * height) >> 1)) { 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); if (err != VP8_ENC_OK) goto Error; // TODO(skal): have a fine-grained progress report in VP8LEncodeStream(). 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; // Save size. if (picture->stats != NULL) { picture->stats->coded_size += (int)coded_size; picture->stats->lossless_size = (int)coded_size; } 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; VP8LBitWriterDestroy(&bw); if (err != VP8_ENC_OK) { WebPEncodingSetError(picture, err); return 0; } return 1; } //------------------------------------------------------------------------------ #if defined(__cplusplus) || defined(c_plusplus) } // extern "C" #endif