// 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 decoder // // Authors: Vikas Arora (vikaas.arora@gmail.com) // Jyrki Alakuijala (jyrki@google.com) #include <stdlib.h> #include "./alphai.h" #include "./vp8li.h" #include "../dsp/dsp.h" #include "../dsp/lossless.h" #include "../dsp/yuv.h" #include "../utils/endian_inl.h" #include "../utils/huffman.h" #include "../utils/utils.h" #define NUM_ARGB_CACHE_ROWS 16 static const int kCodeLengthLiterals = 16; static const int kCodeLengthRepeatCode = 16; static const int kCodeLengthExtraBits[3] = { 2, 3, 7 }; static const int kCodeLengthRepeatOffsets[3] = { 3, 3, 11 }; // ----------------------------------------------------------------------------- // Five Huffman codes are used at each meta code: // 1. green + length prefix codes + color cache codes, // 2. alpha, // 3. red, // 4. blue, and, // 5. distance prefix codes. typedef enum { GREEN = 0, RED = 1, BLUE = 2, ALPHA = 3, DIST = 4 } HuffIndex; static const uint16_t kAlphabetSize[HUFFMAN_CODES_PER_META_CODE] = { NUM_LITERAL_CODES + NUM_LENGTH_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_DISTANCE_CODES }; static const uint8_t kLiteralMap[HUFFMAN_CODES_PER_META_CODE] = { 0, 1, 1, 1, 0 }; #define NUM_CODE_LENGTH_CODES 19 static const uint8_t kCodeLengthCodeOrder[NUM_CODE_LENGTH_CODES] = { 17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }; #define CODE_TO_PLANE_CODES 120 static const uint8_t kCodeToPlane[CODE_TO_PLANE_CODES] = { 0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a, 0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a, 0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b, 0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03, 0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c, 0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e, 0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b, 0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f, 0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b, 0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41, 0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f, 0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70 }; // Memory needed for lookup tables of one Huffman tree group. Red, blue, alpha // and distance alphabets are constant (256 for red, blue and alpha, 40 for // distance) and lookup table sizes for them in worst case are 630 and 410 // respectively. Size of green alphabet depends on color cache size and is equal // to 256 (green component values) + 24 (length prefix values) // + color_cache_size (between 0 and 2048). // All values computed for 8-bit first level lookup with Mark Adler's tool: // http://www.hdfgroup.org/ftp/lib-external/zlib/zlib-1.2.5/examples/enough.c #define FIXED_TABLE_SIZE (630 * 3 + 410) static const int kTableSize[12] = { FIXED_TABLE_SIZE + 654, FIXED_TABLE_SIZE + 656, FIXED_TABLE_SIZE + 658, FIXED_TABLE_SIZE + 662, FIXED_TABLE_SIZE + 670, FIXED_TABLE_SIZE + 686, FIXED_TABLE_SIZE + 718, FIXED_TABLE_SIZE + 782, FIXED_TABLE_SIZE + 912, FIXED_TABLE_SIZE + 1168, FIXED_TABLE_SIZE + 1680, FIXED_TABLE_SIZE + 2704 }; static int DecodeImageStream(int xsize, int ysize, int is_level0, VP8LDecoder* const dec, uint32_t** const decoded_data); //------------------------------------------------------------------------------ int VP8LCheckSignature(const uint8_t* const data, size_t size) { return (size >= VP8L_FRAME_HEADER_SIZE && data[0] == VP8L_MAGIC_BYTE && (data[4] >> 5) == 0); // version } static int ReadImageInfo(VP8LBitReader* const br, int* const width, int* const height, int* const has_alpha) { if (VP8LReadBits(br, 8) != VP8L_MAGIC_BYTE) return 0; *width = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1; *height = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1; *has_alpha = VP8LReadBits(br, 1); if (VP8LReadBits(br, VP8L_VERSION_BITS) != 0) return 0; return !br->eos_; } int VP8LGetInfo(const uint8_t* data, size_t data_size, int* const width, int* const height, int* const has_alpha) { if (data == NULL || data_size < VP8L_FRAME_HEADER_SIZE) { return 0; // not enough data } else if (!VP8LCheckSignature(data, data_size)) { return 0; // bad signature } else { int w, h, a; VP8LBitReader br; VP8LInitBitReader(&br, data, data_size); if (!ReadImageInfo(&br, &w, &h, &a)) { return 0; } if (width != NULL) *width = w; if (height != NULL) *height = h; if (has_alpha != NULL) *has_alpha = a; return 1; } } //------------------------------------------------------------------------------ static WEBP_INLINE int GetCopyDistance(int distance_symbol, VP8LBitReader* const br) { int extra_bits, offset; if (distance_symbol < 4) { return distance_symbol + 1; } extra_bits = (distance_symbol - 2) >> 1; offset = (2 + (distance_symbol & 1)) << extra_bits; return offset + VP8LReadBits(br, extra_bits) + 1; } static WEBP_INLINE int GetCopyLength(int length_symbol, VP8LBitReader* const br) { // Length and distance prefixes are encoded the same way. return GetCopyDistance(length_symbol, br); } static WEBP_INLINE int PlaneCodeToDistance(int xsize, int plane_code) { if (plane_code > CODE_TO_PLANE_CODES) { return plane_code - CODE_TO_PLANE_CODES; } else { const int dist_code = kCodeToPlane[plane_code - 1]; const int yoffset = dist_code >> 4; const int xoffset = 8 - (dist_code & 0xf); const int dist = yoffset * xsize + xoffset; return (dist >= 1) ? dist : 1; // dist<1 can happen if xsize is very small } } //------------------------------------------------------------------------------ // Decodes the next Huffman code from bit-stream. // FillBitWindow(br) needs to be called at minimum every second call // to ReadSymbol, in order to pre-fetch enough bits. static WEBP_INLINE int ReadSymbol(const HuffmanCode* table, VP8LBitReader* const br) { int nbits; uint32_t val = VP8LPrefetchBits(br); table += val & HUFFMAN_TABLE_MASK; nbits = table->bits - HUFFMAN_TABLE_BITS; if (nbits > 0) { VP8LSetBitPos(br, br->bit_pos_ + HUFFMAN_TABLE_BITS); val = VP8LPrefetchBits(br); table += table->value; table += val & ((1 << nbits) - 1); } VP8LSetBitPos(br, br->bit_pos_ + table->bits); return table->value; } // Reads packed symbol depending on GREEN channel #define BITS_SPECIAL_MARKER 0x100 // something large enough (and a bit-mask) #define PACKED_NON_LITERAL_CODE 0 // must be < NUM_LITERAL_CODES static WEBP_INLINE int ReadPackedSymbols(const HTreeGroup* group, VP8LBitReader* const br, uint32_t* const dst) { const uint32_t val = VP8LPrefetchBits(br) & (HUFFMAN_PACKED_TABLE_SIZE - 1); const HuffmanCode32 code = group->packed_table[val]; assert(group->use_packed_table); if (code.bits < BITS_SPECIAL_MARKER) { VP8LSetBitPos(br, br->bit_pos_ + code.bits); *dst = code.value; return PACKED_NON_LITERAL_CODE; } else { VP8LSetBitPos(br, br->bit_pos_ + code.bits - BITS_SPECIAL_MARKER); assert(code.value >= NUM_LITERAL_CODES); return code.value; } } static int AccumulateHCode(HuffmanCode hcode, int shift, HuffmanCode32* const huff) { huff->bits += hcode.bits; huff->value |= (uint32_t)hcode.value << shift; assert(huff->bits <= HUFFMAN_TABLE_BITS); return hcode.bits; } static void BuildPackedTable(HTreeGroup* const htree_group) { uint32_t code; for (code = 0; code < HUFFMAN_PACKED_TABLE_SIZE; ++code) { uint32_t bits = code; HuffmanCode32* const huff = &htree_group->packed_table[bits]; HuffmanCode hcode = htree_group->htrees[GREEN][bits]; if (hcode.value >= NUM_LITERAL_CODES) { huff->bits = hcode.bits + BITS_SPECIAL_MARKER; huff->value = hcode.value; } else { huff->bits = 0; huff->value = 0; bits >>= AccumulateHCode(hcode, 8, huff); bits >>= AccumulateHCode(htree_group->htrees[RED][bits], 16, huff); bits >>= AccumulateHCode(htree_group->htrees[BLUE][bits], 0, huff); bits >>= AccumulateHCode(htree_group->htrees[ALPHA][bits], 24, huff); (void)bits; } } } static int ReadHuffmanCodeLengths( VP8LDecoder* const dec, const int* const code_length_code_lengths, int num_symbols, int* const code_lengths) { int ok = 0; VP8LBitReader* const br = &dec->br_; int symbol; int max_symbol; int prev_code_len = DEFAULT_CODE_LENGTH; HuffmanCode table[1 << LENGTHS_TABLE_BITS]; if (!VP8LBuildHuffmanTable(table, LENGTHS_TABLE_BITS, code_length_code_lengths, NUM_CODE_LENGTH_CODES)) { goto End; } if (VP8LReadBits(br, 1)) { // use length const int length_nbits = 2 + 2 * VP8LReadBits(br, 3); max_symbol = 2 + VP8LReadBits(br, length_nbits); if (max_symbol > num_symbols) { goto End; } } else { max_symbol = num_symbols; } symbol = 0; while (symbol < num_symbols) { const HuffmanCode* p; int code_len; if (max_symbol-- == 0) break; VP8LFillBitWindow(br); p = &table[VP8LPrefetchBits(br) & LENGTHS_TABLE_MASK]; VP8LSetBitPos(br, br->bit_pos_ + p->bits); code_len = p->value; if (code_len < kCodeLengthLiterals) { code_lengths[symbol++] = code_len; if (code_len != 0) prev_code_len = code_len; } else { const int use_prev = (code_len == kCodeLengthRepeatCode); const int slot = code_len - kCodeLengthLiterals; const int extra_bits = kCodeLengthExtraBits[slot]; const int repeat_offset = kCodeLengthRepeatOffsets[slot]; int repeat = VP8LReadBits(br, extra_bits) + repeat_offset; if (symbol + repeat > num_symbols) { goto End; } else { const int length = use_prev ? prev_code_len : 0; while (repeat-- > 0) code_lengths[symbol++] = length; } } } ok = 1; End: if (!ok) dec->status_ = VP8_STATUS_BITSTREAM_ERROR; return ok; } // 'code_lengths' is pre-allocated temporary buffer, used for creating Huffman // tree. static int ReadHuffmanCode(int alphabet_size, VP8LDecoder* const dec, int* const code_lengths, HuffmanCode* const table) { int ok = 0; int size = 0; VP8LBitReader* const br = &dec->br_; const int simple_code = VP8LReadBits(br, 1); memset(code_lengths, 0, alphabet_size * sizeof(*code_lengths)); if (simple_code) { // Read symbols, codes & code lengths directly. const int num_symbols = VP8LReadBits(br, 1) + 1; const int first_symbol_len_code = VP8LReadBits(br, 1); // The first code is either 1 bit or 8 bit code. int symbol = VP8LReadBits(br, (first_symbol_len_code == 0) ? 1 : 8); code_lengths[symbol] = 1; // The second code (if present), is always 8 bit long. if (num_symbols == 2) { symbol = VP8LReadBits(br, 8); code_lengths[symbol] = 1; } ok = 1; } else { // Decode Huffman-coded code lengths. int i; int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 }; const int num_codes = VP8LReadBits(br, 4) + 4; if (num_codes > NUM_CODE_LENGTH_CODES) { dec->status_ = VP8_STATUS_BITSTREAM_ERROR; return 0; } for (i = 0; i < num_codes; ++i) { code_length_code_lengths[kCodeLengthCodeOrder[i]] = VP8LReadBits(br, 3); } ok = ReadHuffmanCodeLengths(dec, code_length_code_lengths, alphabet_size, code_lengths); } ok = ok && !br->eos_; if (ok) { size = VP8LBuildHuffmanTable(table, HUFFMAN_TABLE_BITS, code_lengths, alphabet_size); } if (!ok || size == 0) { dec->status_ = VP8_STATUS_BITSTREAM_ERROR; return 0; } return size; } static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize, int color_cache_bits, int allow_recursion) { int i, j; VP8LBitReader* const br = &dec->br_; VP8LMetadata* const hdr = &dec->hdr_; uint32_t* huffman_image = NULL; HTreeGroup* htree_groups = NULL; HuffmanCode* huffman_tables = NULL; HuffmanCode* next = NULL; int num_htree_groups = 1; int max_alphabet_size = 0; int* code_lengths = NULL; const int table_size = kTableSize[color_cache_bits]; if (allow_recursion && VP8LReadBits(br, 1)) { // use meta Huffman codes. const int huffman_precision = VP8LReadBits(br, 3) + 2; const int huffman_xsize = VP8LSubSampleSize(xsize, huffman_precision); const int huffman_ysize = VP8LSubSampleSize(ysize, huffman_precision); const int huffman_pixs = huffman_xsize * huffman_ysize; if (!DecodeImageStream(huffman_xsize, huffman_ysize, 0, dec, &huffman_image)) { goto Error; } hdr->huffman_subsample_bits_ = huffman_precision; for (i = 0; i < huffman_pixs; ++i) { // The huffman data is stored in red and green bytes. const int group = (huffman_image[i] >> 8) & 0xffff; huffman_image[i] = group; if (group >= num_htree_groups) { num_htree_groups = group + 1; } } } if (br->eos_) goto Error; // Find maximum alphabet size for the htree group. for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) { int alphabet_size = kAlphabetSize[j]; if (j == 0 && color_cache_bits > 0) { alphabet_size += 1 << color_cache_bits; } if (max_alphabet_size < alphabet_size) { max_alphabet_size = alphabet_size; } } huffman_tables = (HuffmanCode*)WebPSafeMalloc(num_htree_groups * table_size, sizeof(*huffman_tables)); htree_groups = VP8LHtreeGroupsNew(num_htree_groups); code_lengths = (int*)WebPSafeCalloc((uint64_t)max_alphabet_size, sizeof(*code_lengths)); if (htree_groups == NULL || code_lengths == NULL || huffman_tables == NULL) { dec->status_ = VP8_STATUS_OUT_OF_MEMORY; goto Error; } next = huffman_tables; for (i = 0; i < num_htree_groups; ++i) { HTreeGroup* const htree_group = &htree_groups[i]; HuffmanCode** const htrees = htree_group->htrees; int size; int total_size = 0; int is_trivial_literal = 1; int max_bits = 0; for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) { int alphabet_size = kAlphabetSize[j]; htrees[j] = next; if (j == 0 && color_cache_bits > 0) { alphabet_size += 1 << color_cache_bits; } size = ReadHuffmanCode(alphabet_size, dec, code_lengths, next); if (is_trivial_literal && kLiteralMap[j] == 1) { is_trivial_literal = (next->bits == 0); } total_size += next->bits; next += size; if (size == 0) { goto Error; } if (j <= ALPHA) { int local_max_bits = code_lengths[0]; int k; for (k = 1; k < alphabet_size; ++k) { if (code_lengths[k] > local_max_bits) { local_max_bits = code_lengths[k]; } } max_bits += local_max_bits; } } htree_group->is_trivial_literal = is_trivial_literal; htree_group->is_trivial_code = 0; if (is_trivial_literal) { const int red = htrees[RED][0].value; const int blue = htrees[BLUE][0].value; const int alpha = htrees[ALPHA][0].value; htree_group->literal_arb = ((uint32_t)alpha << 24) | (red << 16) | blue; if (total_size == 0 && htrees[GREEN][0].value < NUM_LITERAL_CODES) { htree_group->is_trivial_code = 1; htree_group->literal_arb |= htrees[GREEN][0].value << 8; } } htree_group->use_packed_table = !htree_group->is_trivial_code && (max_bits < HUFFMAN_PACKED_BITS); if (htree_group->use_packed_table) BuildPackedTable(htree_group); } WebPSafeFree(code_lengths); // All OK. Finalize pointers and return. hdr->huffman_image_ = huffman_image; hdr->num_htree_groups_ = num_htree_groups; hdr->htree_groups_ = htree_groups; hdr->huffman_tables_ = huffman_tables; return 1; Error: WebPSafeFree(code_lengths); WebPSafeFree(huffman_image); WebPSafeFree(huffman_tables); VP8LHtreeGroupsFree(htree_groups); return 0; } //------------------------------------------------------------------------------ // Scaling. static int AllocateAndInitRescaler(VP8LDecoder* const dec, VP8Io* const io) { const int num_channels = 4; const int in_width = io->mb_w; const int out_width = io->scaled_width; const int in_height = io->mb_h; const int out_height = io->scaled_height; const uint64_t work_size = 2 * num_channels * (uint64_t)out_width; rescaler_t* work; // Rescaler work area. const uint64_t scaled_data_size = (uint64_t)out_width; uint32_t* scaled_data; // Temporary storage for scaled BGRA data. const uint64_t memory_size = sizeof(*dec->rescaler) + work_size * sizeof(*work) + scaled_data_size * sizeof(*scaled_data); uint8_t* memory = (uint8_t*)WebPSafeMalloc(memory_size, sizeof(*memory)); if (memory == NULL) { dec->status_ = VP8_STATUS_OUT_OF_MEMORY; return 0; } assert(dec->rescaler_memory == NULL); dec->rescaler_memory = memory; dec->rescaler = (WebPRescaler*)memory; memory += sizeof(*dec->rescaler); work = (rescaler_t*)memory; memory += work_size * sizeof(*work); scaled_data = (uint32_t*)memory; WebPRescalerInit(dec->rescaler, in_width, in_height, (uint8_t*)scaled_data, out_width, out_height, 0, num_channels, work); return 1; } //------------------------------------------------------------------------------ // Export to ARGB // We have special "export" function since we need to convert from BGRA static int Export(WebPRescaler* const rescaler, WEBP_CSP_MODE colorspace, int rgba_stride, uint8_t* const rgba) { uint32_t* const src = (uint32_t*)rescaler->dst; const int dst_width = rescaler->dst_width; int num_lines_out = 0; while (WebPRescalerHasPendingOutput(rescaler)) { uint8_t* const dst = rgba + num_lines_out * rgba_stride; WebPRescalerExportRow(rescaler); WebPMultARGBRow(src, dst_width, 1); VP8LConvertFromBGRA(src, dst_width, colorspace, dst); ++num_lines_out; } return num_lines_out; } // Emit scaled rows. static int EmitRescaledRowsRGBA(const VP8LDecoder* const dec, uint8_t* in, int in_stride, int mb_h, uint8_t* const out, int out_stride) { const WEBP_CSP_MODE colorspace = dec->output_->colorspace; int num_lines_in = 0; int num_lines_out = 0; while (num_lines_in < mb_h) { uint8_t* const row_in = in + num_lines_in * in_stride; uint8_t* const row_out = out + num_lines_out * out_stride; const int lines_left = mb_h - num_lines_in; const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left); assert(needed_lines > 0 && needed_lines <= lines_left); WebPMultARGBRows(row_in, in_stride, dec->rescaler->src_width, needed_lines, 0); WebPRescalerImport(dec->rescaler, lines_left, row_in, in_stride); num_lines_in += needed_lines; num_lines_out += Export(dec->rescaler, colorspace, out_stride, row_out); } return num_lines_out; } // Emit rows without any scaling. static int EmitRows(WEBP_CSP_MODE colorspace, const uint8_t* row_in, int in_stride, int mb_w, int mb_h, uint8_t* const out, int out_stride) { int lines = mb_h; uint8_t* row_out = out; while (lines-- > 0) { VP8LConvertFromBGRA((const uint32_t*)row_in, mb_w, colorspace, row_out); row_in += in_stride; row_out += out_stride; } return mb_h; // Num rows out == num rows in. } //------------------------------------------------------------------------------ // Export to YUVA static void ConvertToYUVA(const uint32_t* const src, int width, int y_pos, const WebPDecBuffer* const output) { const WebPYUVABuffer* const buf = &output->u.YUVA; // first, the luma plane WebPConvertARGBToY(src, buf->y + y_pos * buf->y_stride, width); // then U/V planes { uint8_t* const u = buf->u + (y_pos >> 1) * buf->u_stride; uint8_t* const v = buf->v + (y_pos >> 1) * buf->v_stride; // even lines: store values // odd lines: average with previous values WebPConvertARGBToUV(src, u, v, width, !(y_pos & 1)); } // Lastly, store alpha if needed. if (buf->a != NULL) { uint8_t* const a = buf->a + y_pos * buf->a_stride; #if defined(WORDS_BIGENDIAN) WebPExtractAlpha((uint8_t*)src + 0, 0, width, 1, a, 0); #else WebPExtractAlpha((uint8_t*)src + 3, 0, width, 1, a, 0); #endif } } static int ExportYUVA(const VP8LDecoder* const dec, int y_pos) { WebPRescaler* const rescaler = dec->rescaler; uint32_t* const src = (uint32_t*)rescaler->dst; const int dst_width = rescaler->dst_width; int num_lines_out = 0; while (WebPRescalerHasPendingOutput(rescaler)) { WebPRescalerExportRow(rescaler); WebPMultARGBRow(src, dst_width, 1); ConvertToYUVA(src, dst_width, y_pos, dec->output_); ++y_pos; ++num_lines_out; } return num_lines_out; } static int EmitRescaledRowsYUVA(const VP8LDecoder* const dec, uint8_t* in, int in_stride, int mb_h) { int num_lines_in = 0; int y_pos = dec->last_out_row_; while (num_lines_in < mb_h) { const int lines_left = mb_h - num_lines_in; const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left); WebPMultARGBRows(in, in_stride, dec->rescaler->src_width, needed_lines, 0); WebPRescalerImport(dec->rescaler, lines_left, in, in_stride); num_lines_in += needed_lines; in += needed_lines * in_stride; y_pos += ExportYUVA(dec, y_pos); } return y_pos; } static int EmitRowsYUVA(const VP8LDecoder* const dec, const uint8_t* in, int in_stride, int mb_w, int num_rows) { int y_pos = dec->last_out_row_; while (num_rows-- > 0) { ConvertToYUVA((const uint32_t*)in, mb_w, y_pos, dec->output_); in += in_stride; ++y_pos; } return y_pos; } //------------------------------------------------------------------------------ // Cropping. // Sets io->mb_y, io->mb_h & io->mb_w according to start row, end row and // crop options. Also updates the input data pointer, so that it points to the // start of the cropped window. Note that pixels are in ARGB format even if // 'in_data' is uint8_t*. // Returns true if the crop window is not empty. static int SetCropWindow(VP8Io* const io, int y_start, int y_end, uint8_t** const in_data, int pixel_stride) { assert(y_start < y_end); assert(io->crop_left < io->crop_right); if (y_end > io->crop_bottom) { y_end = io->crop_bottom; // make sure we don't overflow on last row. } if (y_start < io->crop_top) { const int delta = io->crop_top - y_start; y_start = io->crop_top; *in_data += delta * pixel_stride; } if (y_start >= y_end) return 0; // Crop window is empty. *in_data += io->crop_left * sizeof(uint32_t); io->mb_y = y_start - io->crop_top; io->mb_w = io->crop_right - io->crop_left; io->mb_h = y_end - y_start; return 1; // Non-empty crop window. } //------------------------------------------------------------------------------ static WEBP_INLINE int GetMetaIndex( const uint32_t* const image, int xsize, int bits, int x, int y) { if (bits == 0) return 0; return image[xsize * (y >> bits) + (x >> bits)]; } static WEBP_INLINE HTreeGroup* GetHtreeGroupForPos(VP8LMetadata* const hdr, int x, int y) { const int meta_index = GetMetaIndex(hdr->huffman_image_, hdr->huffman_xsize_, hdr->huffman_subsample_bits_, x, y); assert(meta_index < hdr->num_htree_groups_); return hdr->htree_groups_ + meta_index; } //------------------------------------------------------------------------------ // Main loop, with custom row-processing function typedef void (*ProcessRowsFunc)(VP8LDecoder* const dec, int row); static void ApplyInverseTransforms(VP8LDecoder* const dec, int num_rows, const uint32_t* const rows) { int n = dec->next_transform_; const int cache_pixs = dec->width_ * num_rows; const int start_row = dec->last_row_; const int end_row = start_row + num_rows; const uint32_t* rows_in = rows; uint32_t* const rows_out = dec->argb_cache_; // Inverse transforms. // TODO: most transforms only need to operate on the cropped region only. memcpy(rows_out, rows_in, cache_pixs * sizeof(*rows_out)); while (n-- > 0) { VP8LTransform* const transform = &dec->transforms_[n]; VP8LInverseTransform(transform, start_row, end_row, rows_in, rows_out); rows_in = rows_out; } } // Special method for paletted alpha data. static void ApplyInverseTransformsAlpha(VP8LDecoder* const dec, int num_rows, const uint8_t* const rows) { const int start_row = dec->last_row_; const int end_row = start_row + num_rows; const uint8_t* rows_in = rows; uint8_t* rows_out = (uint8_t*)dec->io_->opaque + dec->io_->width * start_row; VP8LTransform* const transform = &dec->transforms_[0]; assert(dec->next_transform_ == 1); assert(transform->type_ == COLOR_INDEXING_TRANSFORM); VP8LColorIndexInverseTransformAlpha(transform, start_row, end_row, rows_in, rows_out); } // Processes (transforms, scales & color-converts) the rows decoded after the // last call. static void ProcessRows(VP8LDecoder* const dec, int row) { const uint32_t* const rows = dec->pixels_ + dec->width_ * dec->last_row_; const int num_rows = row - dec->last_row_; if (num_rows <= 0) return; // Nothing to be done. ApplyInverseTransforms(dec, num_rows, rows); // Emit output. { VP8Io* const io = dec->io_; uint8_t* rows_data = (uint8_t*)dec->argb_cache_; const int in_stride = io->width * sizeof(uint32_t); // in unit of RGBA if (!SetCropWindow(io, dec->last_row_, row, &rows_data, in_stride)) { // Nothing to output (this time). } else { const WebPDecBuffer* const output = dec->output_; if (WebPIsRGBMode(output->colorspace)) { // convert to RGBA const WebPRGBABuffer* const buf = &output->u.RGBA; uint8_t* const rgba = buf->rgba + dec->last_out_row_ * buf->stride; const int num_rows_out = io->use_scaling ? EmitRescaledRowsRGBA(dec, rows_data, in_stride, io->mb_h, rgba, buf->stride) : EmitRows(output->colorspace, rows_data, in_stride, io->mb_w, io->mb_h, rgba, buf->stride); // Update 'last_out_row_'. dec->last_out_row_ += num_rows_out; } else { // convert to YUVA dec->last_out_row_ = io->use_scaling ? EmitRescaledRowsYUVA(dec, rows_data, in_stride, io->mb_h) : EmitRowsYUVA(dec, rows_data, in_stride, io->mb_w, io->mb_h); } assert(dec->last_out_row_ <= output->height); } } // Update 'last_row_'. dec->last_row_ = row; assert(dec->last_row_ <= dec->height_); } // Row-processing for the special case when alpha data contains only one // transform (color indexing), and trivial non-green literals. static int Is8bOptimizable(const VP8LMetadata* const hdr) { int i; if (hdr->color_cache_size_ > 0) return 0; // When the Huffman tree contains only one symbol, we can skip the // call to ReadSymbol() for red/blue/alpha channels. for (i = 0; i < hdr->num_htree_groups_; ++i) { HuffmanCode** const htrees = hdr->htree_groups_[i].htrees; if (htrees[RED][0].bits > 0) return 0; if (htrees[BLUE][0].bits > 0) return 0; if (htrees[ALPHA][0].bits > 0) return 0; } return 1; } static void ExtractPalettedAlphaRows(VP8LDecoder* const dec, int row) { const int num_rows = row - dec->last_row_; const uint8_t* const in = (uint8_t*)dec->pixels_ + dec->width_ * dec->last_row_; if (num_rows > 0) { ApplyInverseTransformsAlpha(dec, num_rows, in); } dec->last_row_ = dec->last_out_row_ = row; } //------------------------------------------------------------------------------ // Helper functions for fast pattern copy (8b and 32b) // cyclic rotation of pattern word static WEBP_INLINE uint32_t Rotate8b(uint32_t V) { #if defined(WORDS_BIGENDIAN) return ((V & 0xff000000u) >> 24) | (V << 8); #else return ((V & 0xffu) << 24) | (V >> 8); #endif } // copy 1, 2 or 4-bytes pattern static WEBP_INLINE void CopySmallPattern8b(const uint8_t* src, uint8_t* dst, int length, uint32_t pattern) { int i; // align 'dst' to 4-bytes boundary. Adjust the pattern along the way. while ((uintptr_t)dst & 3) { *dst++ = *src++; pattern = Rotate8b(pattern); --length; } // Copy the pattern 4 bytes at a time. for (i = 0; i < (length >> 2); ++i) { ((uint32_t*)dst)[i] = pattern; } // Finish with left-overs. 'pattern' is still correctly positioned, // so no Rotate8b() call is needed. for (i <<= 2; i < length; ++i) { dst[i] = src[i]; } } static WEBP_INLINE void CopyBlock8b(uint8_t* const dst, int dist, int length) { const uint8_t* src = dst - dist; if (length >= 8) { uint32_t pattern = 0; switch (dist) { case 1: pattern = src[0]; #if defined(__arm__) || defined(_M_ARM) // arm doesn't like multiply that much pattern |= pattern << 8; pattern |= pattern << 16; #elif defined(WEBP_USE_MIPS_DSP_R2) __asm__ volatile ("replv.qb %0, %0" : "+r"(pattern)); #else pattern = 0x01010101u * pattern; #endif break; case 2: memcpy(&pattern, src, sizeof(uint16_t)); #if defined(__arm__) || defined(_M_ARM) pattern |= pattern << 16; #elif defined(WEBP_USE_MIPS_DSP_R2) __asm__ volatile ("replv.ph %0, %0" : "+r"(pattern)); #else pattern = 0x00010001u * pattern; #endif break; case 4: memcpy(&pattern, src, sizeof(uint32_t)); break; default: goto Copy; break; } CopySmallPattern8b(src, dst, length, pattern); return; } Copy: if (dist >= length) { // no overlap -> use memcpy() memcpy(dst, src, length * sizeof(*dst)); } else { int i; for (i = 0; i < length; ++i) dst[i] = src[i]; } } // copy pattern of 1 or 2 uint32_t's static WEBP_INLINE void CopySmallPattern32b(const uint32_t* src, uint32_t* dst, int length, uint64_t pattern) { int i; if ((uintptr_t)dst & 4) { // Align 'dst' to 8-bytes boundary. *dst++ = *src++; pattern = (pattern >> 32) | (pattern << 32); --length; } assert(0 == ((uintptr_t)dst & 7)); for (i = 0; i < (length >> 1); ++i) { ((uint64_t*)dst)[i] = pattern; // Copy the pattern 8 bytes at a time. } if (length & 1) { // Finish with left-over. dst[i << 1] = src[i << 1]; } } static WEBP_INLINE void CopyBlock32b(uint32_t* const dst, int dist, int length) { const uint32_t* const src = dst - dist; if (dist <= 2 && length >= 4 && ((uintptr_t)dst & 3) == 0) { uint64_t pattern; if (dist == 1) { pattern = (uint64_t)src[0]; pattern |= pattern << 32; } else { memcpy(&pattern, src, sizeof(pattern)); } CopySmallPattern32b(src, dst, length, pattern); } else if (dist >= length) { // no overlap memcpy(dst, src, length * sizeof(*dst)); } else { int i; for (i = 0; i < length; ++i) dst[i] = src[i]; } } //------------------------------------------------------------------------------ static int DecodeAlphaData(VP8LDecoder* const dec, uint8_t* const data, int width, int height, int last_row) { int ok = 1; int row = dec->last_pixel_ / width; int col = dec->last_pixel_ % width; VP8LBitReader* const br = &dec->br_; VP8LMetadata* const hdr = &dec->hdr_; const HTreeGroup* htree_group = GetHtreeGroupForPos(hdr, col, row); int pos = dec->last_pixel_; // current position const int end = width * height; // End of data const int last = width * last_row; // Last pixel to decode const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES; const int mask = hdr->huffman_mask_; assert(htree_group != NULL); assert(pos < end); assert(last_row <= height); assert(Is8bOptimizable(hdr)); while (!br->eos_ && pos < last) { int code; // Only update when changing tile. if ((col & mask) == 0) { htree_group = GetHtreeGroupForPos(hdr, col, row); } VP8LFillBitWindow(br); code = ReadSymbol(htree_group->htrees[GREEN], br); if (code < NUM_LITERAL_CODES) { // Literal data[pos] = code; ++pos; ++col; if (col >= width) { col = 0; ++row; if (row % NUM_ARGB_CACHE_ROWS == 0) { ExtractPalettedAlphaRows(dec, row); } } } else if (code < len_code_limit) { // Backward reference int dist_code, dist; const int length_sym = code - NUM_LITERAL_CODES; const int length = GetCopyLength(length_sym, br); const int dist_symbol = ReadSymbol(htree_group->htrees[DIST], br); VP8LFillBitWindow(br); dist_code = GetCopyDistance(dist_symbol, br); dist = PlaneCodeToDistance(width, dist_code); if (pos >= dist && end - pos >= length) { CopyBlock8b(data + pos, dist, length); } else { ok = 0; goto End; } pos += length; col += length; while (col >= width) { col -= width; ++row; if (row % NUM_ARGB_CACHE_ROWS == 0) { ExtractPalettedAlphaRows(dec, row); } } if (pos < last && (col & mask)) { htree_group = GetHtreeGroupForPos(hdr, col, row); } } else { // Not reached ok = 0; goto End; } assert(br->eos_ == VP8LIsEndOfStream(br)); } // Process the remaining rows corresponding to last row-block. ExtractPalettedAlphaRows(dec, row); End: if (!ok || (br->eos_ && pos < end)) { ok = 0; dec->status_ = br->eos_ ? VP8_STATUS_SUSPENDED : VP8_STATUS_BITSTREAM_ERROR; } else { dec->last_pixel_ = pos; } return ok; } static void SaveState(VP8LDecoder* const dec, int last_pixel) { assert(dec->incremental_); dec->saved_br_ = dec->br_; dec->saved_last_pixel_ = last_pixel; if (dec->hdr_.color_cache_size_ > 0) { VP8LColorCacheCopy(&dec->hdr_.color_cache_, &dec->hdr_.saved_color_cache_); } } static void RestoreState(VP8LDecoder* const dec) { assert(dec->br_.eos_); dec->status_ = VP8_STATUS_SUSPENDED; dec->br_ = dec->saved_br_; dec->last_pixel_ = dec->saved_last_pixel_; if (dec->hdr_.color_cache_size_ > 0) { VP8LColorCacheCopy(&dec->hdr_.saved_color_cache_, &dec->hdr_.color_cache_); } } #define SYNC_EVERY_N_ROWS 8 // minimum number of rows between check-points static int DecodeImageData(VP8LDecoder* const dec, uint32_t* const data, int width, int height, int last_row, ProcessRowsFunc process_func) { int row = dec->last_pixel_ / width; int col = dec->last_pixel_ % width; VP8LBitReader* const br = &dec->br_; VP8LMetadata* const hdr = &dec->hdr_; HTreeGroup* htree_group = GetHtreeGroupForPos(hdr, col, row); uint32_t* src = data + dec->last_pixel_; uint32_t* last_cached = src; uint32_t* const src_end = data + width * height; // End of data uint32_t* const src_last = data + width * last_row; // Last pixel to decode const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES; const int color_cache_limit = len_code_limit + hdr->color_cache_size_; int next_sync_row = dec->incremental_ ? row : 1 << 24; VP8LColorCache* const color_cache = (hdr->color_cache_size_ > 0) ? &hdr->color_cache_ : NULL; const int mask = hdr->huffman_mask_; assert(htree_group != NULL); assert(src < src_end); assert(src_last <= src_end); while (src < src_last) { int code; if (row >= next_sync_row) { SaveState(dec, (int)(src - data)); next_sync_row = row + SYNC_EVERY_N_ROWS; } // Only update when changing tile. Note we could use this test: // if "((((prev_col ^ col) | prev_row ^ row)) > mask)" -> tile changed // but that's actually slower and needs storing the previous col/row. if ((col & mask) == 0) htree_group = GetHtreeGroupForPos(hdr, col, row); if (htree_group->is_trivial_code) { *src = htree_group->literal_arb; goto AdvanceByOne; } VP8LFillBitWindow(br); if (htree_group->use_packed_table) { code = ReadPackedSymbols(htree_group, br, src); if (code == PACKED_NON_LITERAL_CODE) goto AdvanceByOne; } else { code = ReadSymbol(htree_group->htrees[GREEN], br); } if (br->eos_) break; // early out if (code < NUM_LITERAL_CODES) { // Literal if (htree_group->is_trivial_literal) { *src = htree_group->literal_arb | (code << 8); } else { int red, blue, alpha; red = ReadSymbol(htree_group->htrees[RED], br); VP8LFillBitWindow(br); blue = ReadSymbol(htree_group->htrees[BLUE], br); alpha = ReadSymbol(htree_group->htrees[ALPHA], br); if (br->eos_) break; *src = ((uint32_t)alpha << 24) | (red << 16) | (code << 8) | blue; } AdvanceByOne: ++src; ++col; if (col >= width) { col = 0; ++row; if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) { process_func(dec, row); } if (color_cache != NULL) { while (last_cached < src) { VP8LColorCacheInsert(color_cache, *last_cached++); } } } } else if (code < len_code_limit) { // Backward reference int dist_code, dist; const int length_sym = code - NUM_LITERAL_CODES; const int length = GetCopyLength(length_sym, br); const int dist_symbol = ReadSymbol(htree_group->htrees[DIST], br); VP8LFillBitWindow(br); dist_code = GetCopyDistance(dist_symbol, br); dist = PlaneCodeToDistance(width, dist_code); if (br->eos_) break; if (src - data < (ptrdiff_t)dist || src_end - src < (ptrdiff_t)length) { goto Error; } else { CopyBlock32b(src, dist, length); } src += length; col += length; while (col >= width) { col -= width; ++row; if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) { process_func(dec, row); } } // Because of the check done above (before 'src' was incremented by // 'length'), the following holds true. assert(src <= src_end); if (col & mask) htree_group = GetHtreeGroupForPos(hdr, col, row); if (color_cache != NULL) { while (last_cached < src) { VP8LColorCacheInsert(color_cache, *last_cached++); } } } else if (code < color_cache_limit) { // Color cache const int key = code - len_code_limit; assert(color_cache != NULL); while (last_cached < src) { VP8LColorCacheInsert(color_cache, *last_cached++); } *src = VP8LColorCacheLookup(color_cache, key); goto AdvanceByOne; } else { // Not reached goto Error; } assert(br->eos_ == VP8LIsEndOfStream(br)); } if (dec->incremental_ && br->eos_ && src < src_end) { RestoreState(dec); } else if (!br->eos_) { // Process the remaining rows corresponding to last row-block. if (process_func != NULL) { process_func(dec, row); } dec->status_ = VP8_STATUS_OK; dec->last_pixel_ = (int)(src - data); // end-of-scan marker } else { // if not incremental, and we are past the end of buffer (eos_=1), then this // is a real bitstream error. goto Error; } return 1; Error: dec->status_ = VP8_STATUS_BITSTREAM_ERROR; return 0; } // ----------------------------------------------------------------------------- // VP8LTransform static void ClearTransform(VP8LTransform* const transform) { WebPSafeFree(transform->data_); transform->data_ = NULL; } // For security reason, we need to remap the color map to span // the total possible bundled values, and not just the num_colors. static int ExpandColorMap(int num_colors, VP8LTransform* const transform) { int i; const int final_num_colors = 1 << (8 >> transform->bits_); uint32_t* const new_color_map = (uint32_t*)WebPSafeMalloc((uint64_t)final_num_colors, sizeof(*new_color_map)); if (new_color_map == NULL) { return 0; } else { uint8_t* const data = (uint8_t*)transform->data_; uint8_t* const new_data = (uint8_t*)new_color_map; new_color_map[0] = transform->data_[0]; for (i = 4; i < 4 * num_colors; ++i) { // Equivalent to AddPixelEq(), on a byte-basis. new_data[i] = (data[i] + new_data[i - 4]) & 0xff; } for (; i < 4 * final_num_colors; ++i) new_data[i] = 0; // black tail. WebPSafeFree(transform->data_); transform->data_ = new_color_map; } return 1; } static int ReadTransform(int* const xsize, int const* ysize, VP8LDecoder* const dec) { int ok = 1; VP8LBitReader* const br = &dec->br_; VP8LTransform* transform = &dec->transforms_[dec->next_transform_]; const VP8LImageTransformType type = (VP8LImageTransformType)VP8LReadBits(br, 2); // Each transform type can only be present once in the stream. if (dec->transforms_seen_ & (1U << type)) { return 0; // Already there, let's not accept the second same transform. } dec->transforms_seen_ |= (1U << type); transform->type_ = type; transform->xsize_ = *xsize; transform->ysize_ = *ysize; transform->data_ = NULL; ++dec->next_transform_; assert(dec->next_transform_ <= NUM_TRANSFORMS); switch (type) { case PREDICTOR_TRANSFORM: case CROSS_COLOR_TRANSFORM: transform->bits_ = VP8LReadBits(br, 3) + 2; ok = DecodeImageStream(VP8LSubSampleSize(transform->xsize_, transform->bits_), VP8LSubSampleSize(transform->ysize_, transform->bits_), 0, dec, &transform->data_); break; case COLOR_INDEXING_TRANSFORM: { const int num_colors = VP8LReadBits(br, 8) + 1; const int bits = (num_colors > 16) ? 0 : (num_colors > 4) ? 1 : (num_colors > 2) ? 2 : 3; *xsize = VP8LSubSampleSize(transform->xsize_, bits); transform->bits_ = bits; ok = DecodeImageStream(num_colors, 1, 0, dec, &transform->data_); ok = ok && ExpandColorMap(num_colors, transform); break; } case SUBTRACT_GREEN: break; default: assert(0); // can't happen break; } return ok; } // ----------------------------------------------------------------------------- // VP8LMetadata static void InitMetadata(VP8LMetadata* const hdr) { assert(hdr != NULL); memset(hdr, 0, sizeof(*hdr)); } static void ClearMetadata(VP8LMetadata* const hdr) { assert(hdr != NULL); WebPSafeFree(hdr->huffman_image_); WebPSafeFree(hdr->huffman_tables_); VP8LHtreeGroupsFree(hdr->htree_groups_); VP8LColorCacheClear(&hdr->color_cache_); VP8LColorCacheClear(&hdr->saved_color_cache_); InitMetadata(hdr); } // ----------------------------------------------------------------------------- // VP8LDecoder VP8LDecoder* VP8LNew(void) { VP8LDecoder* const dec = (VP8LDecoder*)WebPSafeCalloc(1ULL, sizeof(*dec)); if (dec == NULL) return NULL; dec->status_ = VP8_STATUS_OK; dec->state_ = READ_DIM; VP8LDspInit(); // Init critical function pointers. return dec; } void VP8LClear(VP8LDecoder* const dec) { int i; if (dec == NULL) return; ClearMetadata(&dec->hdr_); WebPSafeFree(dec->pixels_); dec->pixels_ = NULL; for (i = 0; i < dec->next_transform_; ++i) { ClearTransform(&dec->transforms_[i]); } dec->next_transform_ = 0; dec->transforms_seen_ = 0; WebPSafeFree(dec->rescaler_memory); dec->rescaler_memory = NULL; dec->output_ = NULL; // leave no trace behind } void VP8LDelete(VP8LDecoder* const dec) { if (dec != NULL) { VP8LClear(dec); WebPSafeFree(dec); } } static void UpdateDecoder(VP8LDecoder* const dec, int width, int height) { VP8LMetadata* const hdr = &dec->hdr_; const int num_bits = hdr->huffman_subsample_bits_; dec->width_ = width; dec->height_ = height; hdr->huffman_xsize_ = VP8LSubSampleSize(width, num_bits); hdr->huffman_mask_ = (num_bits == 0) ? ~0 : (1 << num_bits) - 1; } static int DecodeImageStream(int xsize, int ysize, int is_level0, VP8LDecoder* const dec, uint32_t** const decoded_data) { int ok = 1; int transform_xsize = xsize; int transform_ysize = ysize; VP8LBitReader* const br = &dec->br_; VP8LMetadata* const hdr = &dec->hdr_; uint32_t* data = NULL; int color_cache_bits = 0; // Read the transforms (may recurse). if (is_level0) { while (ok && VP8LReadBits(br, 1)) { ok = ReadTransform(&transform_xsize, &transform_ysize, dec); } } // Color cache if (ok && VP8LReadBits(br, 1)) { color_cache_bits = VP8LReadBits(br, 4); ok = (color_cache_bits >= 1 && color_cache_bits <= MAX_CACHE_BITS); if (!ok) { dec->status_ = VP8_STATUS_BITSTREAM_ERROR; goto End; } } // Read the Huffman codes (may recurse). ok = ok && ReadHuffmanCodes(dec, transform_xsize, transform_ysize, color_cache_bits, is_level0); if (!ok) { dec->status_ = VP8_STATUS_BITSTREAM_ERROR; goto End; } // Finish setting up the color-cache if (color_cache_bits > 0) { hdr->color_cache_size_ = 1 << color_cache_bits; if (!VP8LColorCacheInit(&hdr->color_cache_, color_cache_bits)) { dec->status_ = VP8_STATUS_OUT_OF_MEMORY; ok = 0; goto End; } } else { hdr->color_cache_size_ = 0; } UpdateDecoder(dec, transform_xsize, transform_ysize); if (is_level0) { // level 0 complete dec->state_ = READ_HDR; goto End; } { const uint64_t total_size = (uint64_t)transform_xsize * transform_ysize; data = (uint32_t*)WebPSafeMalloc(total_size, sizeof(*data)); if (data == NULL) { dec->status_ = VP8_STATUS_OUT_OF_MEMORY; ok = 0; goto End; } } // Use the Huffman trees to decode the LZ77 encoded data. ok = DecodeImageData(dec, data, transform_xsize, transform_ysize, transform_ysize, NULL); ok = ok && !br->eos_; End: if (!ok) { WebPSafeFree(data); ClearMetadata(hdr); } else { if (decoded_data != NULL) { *decoded_data = data; } else { // We allocate image data in this function only for transforms. At level 0 // (that is: not the transforms), we shouldn't have allocated anything. assert(data == NULL); assert(is_level0); } dec->last_pixel_ = 0; // Reset for future DECODE_DATA_FUNC() calls. if (!is_level0) ClearMetadata(hdr); // Clean up temporary data behind. } return ok; } //------------------------------------------------------------------------------ // Allocate internal buffers dec->pixels_ and dec->argb_cache_. static int AllocateInternalBuffers32b(VP8LDecoder* const dec, int final_width) { const uint64_t num_pixels = (uint64_t)dec->width_ * dec->height_; // Scratch buffer corresponding to top-prediction row for transforming the // first row in the row-blocks. Not needed for paletted alpha. const uint64_t cache_top_pixels = (uint16_t)final_width; // Scratch buffer for temporary BGRA storage. Not needed for paletted alpha. const uint64_t cache_pixels = (uint64_t)final_width * NUM_ARGB_CACHE_ROWS; const uint64_t total_num_pixels = num_pixels + cache_top_pixels + cache_pixels; assert(dec->width_ <= final_width); dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(uint32_t)); if (dec->pixels_ == NULL) { dec->argb_cache_ = NULL; // for sanity check dec->status_ = VP8_STATUS_OUT_OF_MEMORY; return 0; } dec->argb_cache_ = dec->pixels_ + num_pixels + cache_top_pixels; return 1; } static int AllocateInternalBuffers8b(VP8LDecoder* const dec) { const uint64_t total_num_pixels = (uint64_t)dec->width_ * dec->height_; dec->argb_cache_ = NULL; // for sanity check dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(uint8_t)); if (dec->pixels_ == NULL) { dec->status_ = VP8_STATUS_OUT_OF_MEMORY; return 0; } return 1; } //------------------------------------------------------------------------------ // Special row-processing that only stores the alpha data. static void ExtractAlphaRows(VP8LDecoder* const dec, int row) { const int num_rows = row - dec->last_row_; const uint32_t* const in = dec->pixels_ + dec->width_ * dec->last_row_; if (num_rows <= 0) return; // Nothing to be done. ApplyInverseTransforms(dec, num_rows, in); // Extract alpha (which is stored in the green plane). { const int width = dec->io_->width; // the final width (!= dec->width_) const int cache_pixs = width * num_rows; uint8_t* const dst = (uint8_t*)dec->io_->opaque + width * dec->last_row_; const uint32_t* const src = dec->argb_cache_; int i; for (i = 0; i < cache_pixs; ++i) dst[i] = (src[i] >> 8) & 0xff; } dec->last_row_ = dec->last_out_row_ = row; } int VP8LDecodeAlphaHeader(ALPHDecoder* const alph_dec, const uint8_t* const data, size_t data_size, uint8_t* const output) { int ok = 0; VP8LDecoder* dec; VP8Io* io; assert(alph_dec != NULL); alph_dec->vp8l_dec_ = VP8LNew(); if (alph_dec->vp8l_dec_ == NULL) return 0; dec = alph_dec->vp8l_dec_; dec->width_ = alph_dec->width_; dec->height_ = alph_dec->height_; dec->io_ = &alph_dec->io_; io = dec->io_; VP8InitIo(io); WebPInitCustomIo(NULL, io); // Just a sanity Init. io won't be used. io->opaque = output; io->width = alph_dec->width_; io->height = alph_dec->height_; dec->status_ = VP8_STATUS_OK; VP8LInitBitReader(&dec->br_, data, data_size); if (!DecodeImageStream(alph_dec->width_, alph_dec->height_, 1, dec, NULL)) { goto Err; } // Special case: if alpha data uses only the color indexing transform and // doesn't use color cache (a frequent case), we will use DecodeAlphaData() // method that only needs allocation of 1 byte per pixel (alpha channel). if (dec->next_transform_ == 1 && dec->transforms_[0].type_ == COLOR_INDEXING_TRANSFORM && Is8bOptimizable(&dec->hdr_)) { alph_dec->use_8b_decode = 1; ok = AllocateInternalBuffers8b(dec); } else { // Allocate internal buffers (note that dec->width_ may have changed here). alph_dec->use_8b_decode = 0; ok = AllocateInternalBuffers32b(dec, alph_dec->width_); } if (!ok) goto Err; return 1; Err: VP8LDelete(alph_dec->vp8l_dec_); alph_dec->vp8l_dec_ = NULL; return 0; } int VP8LDecodeAlphaImageStream(ALPHDecoder* const alph_dec, int last_row) { VP8LDecoder* const dec = alph_dec->vp8l_dec_; assert(dec != NULL); assert(last_row <= dec->height_); if (dec->last_pixel_ == dec->width_ * dec->height_) { return 1; // done } // Decode (with special row processing). return alph_dec->use_8b_decode ? DecodeAlphaData(dec, (uint8_t*)dec->pixels_, dec->width_, dec->height_, last_row) : DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_, last_row, ExtractAlphaRows); } //------------------------------------------------------------------------------ int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io) { int width, height, has_alpha; if (dec == NULL) return 0; if (io == NULL) { dec->status_ = VP8_STATUS_INVALID_PARAM; return 0; } dec->io_ = io; dec->status_ = VP8_STATUS_OK; VP8LInitBitReader(&dec->br_, io->data, io->data_size); if (!ReadImageInfo(&dec->br_, &width, &height, &has_alpha)) { dec->status_ = VP8_STATUS_BITSTREAM_ERROR; goto Error; } dec->state_ = READ_DIM; io->width = width; io->height = height; if (!DecodeImageStream(width, height, 1, dec, NULL)) goto Error; return 1; Error: VP8LClear(dec); assert(dec->status_ != VP8_STATUS_OK); return 0; } int VP8LDecodeImage(VP8LDecoder* const dec) { VP8Io* io = NULL; WebPDecParams* params = NULL; // Sanity checks. if (dec == NULL) return 0; assert(dec->hdr_.huffman_tables_ != NULL); assert(dec->hdr_.htree_groups_ != NULL); assert(dec->hdr_.num_htree_groups_ > 0); io = dec->io_; assert(io != NULL); params = (WebPDecParams*)io->opaque; assert(params != NULL); // Initialization. if (dec->state_ != READ_DATA) { dec->output_ = params->output; assert(dec->output_ != NULL); if (!WebPIoInitFromOptions(params->options, io, MODE_BGRA)) { dec->status_ = VP8_STATUS_INVALID_PARAM; goto Err; } if (!AllocateInternalBuffers32b(dec, io->width)) goto Err; if (io->use_scaling && !AllocateAndInitRescaler(dec, io)) goto Err; if (io->use_scaling || WebPIsPremultipliedMode(dec->output_->colorspace)) { // need the alpha-multiply functions for premultiplied output or rescaling WebPInitAlphaProcessing(); } if (!WebPIsRGBMode(dec->output_->colorspace)) { WebPInitConvertARGBToYUV(); if (dec->output_->u.YUVA.a != NULL) WebPInitAlphaProcessing(); } if (dec->incremental_) { if (dec->hdr_.color_cache_size_ > 0 && dec->hdr_.saved_color_cache_.colors_ == NULL) { if (!VP8LColorCacheInit(&dec->hdr_.saved_color_cache_, dec->hdr_.color_cache_.hash_bits_)) { dec->status_ = VP8_STATUS_OUT_OF_MEMORY; goto Err; } } } dec->state_ = READ_DATA; } // Decode. if (!DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_, dec->height_, ProcessRows)) { goto Err; } params->last_y = dec->last_out_row_; return 1; Err: VP8LClear(dec); assert(dec->status_ != VP8_STATUS_OK); return 0; } //------------------------------------------------------------------------------