/* * WebP (.webp) image decoder * Copyright (c) 2013 Aneesh Dogra <aneesh@sugarlabs.org> * Copyright (c) 2013 Justin Ruggles <justin.ruggles@gmail.com> * * This file is part of Libav. * * Libav is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * Libav is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * WebP image decoder * * @author Aneesh Dogra <aneesh@sugarlabs.org> * Container and Lossy decoding * * @author Justin Ruggles <justin.ruggles@gmail.com> * Lossless decoder * Compressed alpha for lossy * * Unimplemented: * - Animation * - ICC profile * - Exif and XMP metadata */ #define BITSTREAM_READER_LE #include "libavutil/imgutils.h" #include "avcodec.h" #include "bytestream.h" #include "internal.h" #include "get_bits.h" #include "thread.h" #include "vp8.h" #define VP8X_FLAG_ANIMATION 0x02 #define VP8X_FLAG_XMP_METADATA 0x04 #define VP8X_FLAG_EXIF_METADATA 0x08 #define VP8X_FLAG_ALPHA 0x10 #define VP8X_FLAG_ICC 0x20 #define MAX_PALETTE_SIZE 256 #define MAX_CACHE_BITS 11 #define NUM_CODE_LENGTH_CODES 19 #define HUFFMAN_CODES_PER_META_CODE 5 #define NUM_LITERAL_CODES 256 #define NUM_LENGTH_CODES 24 #define NUM_DISTANCE_CODES 40 #define NUM_SHORT_DISTANCES 120 #define MAX_HUFFMAN_CODE_LENGTH 15 static const uint16_t alphabet_sizes[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 code_length_code_order[NUM_CODE_LENGTH_CODES] = { 17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }; static const int8_t lz77_distance_offsets[NUM_SHORT_DISTANCES][2] = { { 0, 1 }, { 1, 0 }, { 1, 1 }, { -1, 1 }, { 0, 2 }, { 2, 0 }, { 1, 2 }, { -1, 2 }, { 2, 1 }, { -2, 1 }, { 2, 2 }, { -2, 2 }, { 0, 3 }, { 3, 0 }, { 1, 3 }, { -1, 3 }, { 3, 1 }, { -3, 1 }, { 2, 3 }, { -2, 3 }, { 3, 2 }, { -3, 2 }, { 0, 4 }, { 4, 0 }, { 1, 4 }, { -1, 4 }, { 4, 1 }, { -4, 1 }, { 3, 3 }, { -3, 3 }, { 2, 4 }, { -2, 4 }, { 4, 2 }, { -4, 2 }, { 0, 5 }, { 3, 4 }, { -3, 4 }, { 4, 3 }, { -4, 3 }, { 5, 0 }, { 1, 5 }, { -1, 5 }, { 5, 1 }, { -5, 1 }, { 2, 5 }, { -2, 5 }, { 5, 2 }, { -5, 2 }, { 4, 4 }, { -4, 4 }, { 3, 5 }, { -3, 5 }, { 5, 3 }, { -5, 3 }, { 0, 6 }, { 6, 0 }, { 1, 6 }, { -1, 6 }, { 6, 1 }, { -6, 1 }, { 2, 6 }, { -2, 6 }, { 6, 2 }, { -6, 2 }, { 4, 5 }, { -4, 5 }, { 5, 4 }, { -5, 4 }, { 3, 6 }, { -3, 6 }, { 6, 3 }, { -6, 3 }, { 0, 7 }, { 7, 0 }, { 1, 7 }, { -1, 7 }, { 5, 5 }, { -5, 5 }, { 7, 1 }, { -7, 1 }, { 4, 6 }, { -4, 6 }, { 6, 4 }, { -6, 4 }, { 2, 7 }, { -2, 7 }, { 7, 2 }, { -7, 2 }, { 3, 7 }, { -3, 7 }, { 7, 3 }, { -7, 3 }, { 5, 6 }, { -5, 6 }, { 6, 5 }, { -6, 5 }, { 8, 0 }, { 4, 7 }, { -4, 7 }, { 7, 4 }, { -7, 4 }, { 8, 1 }, { 8, 2 }, { 6, 6 }, { -6, 6 }, { 8, 3 }, { 5, 7 }, { -5, 7 }, { 7, 5 }, { -7, 5 }, { 8, 4 }, { 6, 7 }, { -6, 7 }, { 7, 6 }, { -7, 6 }, { 8, 5 }, { 7, 7 }, { -7, 7 }, { 8, 6 }, { 8, 7 } }; enum AlphaCompression { ALPHA_COMPRESSION_NONE, ALPHA_COMPRESSION_VP8L, }; enum AlphaFilter { ALPHA_FILTER_NONE, ALPHA_FILTER_HORIZONTAL, ALPHA_FILTER_VERTICAL, ALPHA_FILTER_GRADIENT, }; enum TransformType { PREDICTOR_TRANSFORM = 0, COLOR_TRANSFORM = 1, SUBTRACT_GREEN = 2, COLOR_INDEXING_TRANSFORM = 3, }; enum PredictionMode { PRED_MODE_BLACK, PRED_MODE_L, PRED_MODE_T, PRED_MODE_TR, PRED_MODE_TL, PRED_MODE_AVG_T_AVG_L_TR, PRED_MODE_AVG_L_TL, PRED_MODE_AVG_L_T, PRED_MODE_AVG_TL_T, PRED_MODE_AVG_T_TR, PRED_MODE_AVG_AVG_L_TL_AVG_T_TR, PRED_MODE_SELECT, PRED_MODE_ADD_SUBTRACT_FULL, PRED_MODE_ADD_SUBTRACT_HALF, }; enum HuffmanIndex { HUFF_IDX_GREEN = 0, HUFF_IDX_RED = 1, HUFF_IDX_BLUE = 2, HUFF_IDX_ALPHA = 3, HUFF_IDX_DIST = 4 }; /* The structure of WebP lossless is an optional series of transformation data, * followed by the primary image. The primary image also optionally contains * an entropy group mapping if there are multiple entropy groups. There is a * basic image type called an "entropy coded image" that is used for all of * these. The type of each entropy coded image is referred to by the * specification as its role. */ enum ImageRole { /* Primary Image: Stores the actual pixels of the image. */ IMAGE_ROLE_ARGB, /* Entropy Image: Defines which Huffman group to use for different areas of * the primary image. */ IMAGE_ROLE_ENTROPY, /* Predictors: Defines which predictor type to use for different areas of * the primary image. */ IMAGE_ROLE_PREDICTOR, /* Color Transform Data: Defines the color transformation for different * areas of the primary image. */ IMAGE_ROLE_COLOR_TRANSFORM, /* Color Index: Stored as an image of height == 1. */ IMAGE_ROLE_COLOR_INDEXING, IMAGE_ROLE_NB, }; typedef struct HuffReader { VLC vlc; /* Huffman decoder context */ int simple; /* whether to use simple mode */ int nb_symbols; /* number of coded symbols */ uint16_t simple_symbols[2]; /* symbols for simple mode */ } HuffReader; typedef struct ImageContext { enum ImageRole role; /* role of this image */ AVFrame *frame; /* AVFrame for data */ int color_cache_bits; /* color cache size, log2 */ uint32_t *color_cache; /* color cache data */ int nb_huffman_groups; /* number of huffman groups */ HuffReader *huffman_groups; /* reader for each huffman group */ int size_reduction; /* relative size compared to primary image, log2 */ int is_alpha_primary; } ImageContext; typedef struct WebPContext { VP8Context v; /* VP8 Context used for lossy decoding */ GetBitContext gb; /* bitstream reader for main image chunk */ AVFrame *alpha_frame; /* AVFrame for alpha data decompressed from VP8L */ AVCodecContext *avctx; /* parent AVCodecContext */ int initialized; /* set once the VP8 context is initialized */ int has_alpha; /* has a separate alpha chunk */ enum AlphaCompression alpha_compression; /* compression type for alpha chunk */ enum AlphaFilter alpha_filter; /* filtering method for alpha chunk */ uint8_t *alpha_data; /* alpha chunk data */ int alpha_data_size; /* alpha chunk data size */ int width; /* image width */ int height; /* image height */ int lossless; /* indicates lossless or lossy */ int nb_transforms; /* number of transforms */ enum TransformType transforms[4]; /* transformations used in the image, in order */ int reduced_width; /* reduced width for index image, if applicable */ int nb_huffman_groups; /* number of huffman groups in the primary image */ ImageContext image[IMAGE_ROLE_NB]; /* image context for each role */ } WebPContext; #define GET_PIXEL(frame, x, y) \ ((frame)->data[0] + (y) * frame->linesize[0] + 4 * (x)) #define GET_PIXEL_COMP(frame, x, y, c) \ (*((frame)->data[0] + (y) * frame->linesize[0] + 4 * (x) + c)) static void image_ctx_free(ImageContext *img) { int i, j; av_free(img->color_cache); if (img->role != IMAGE_ROLE_ARGB && !img->is_alpha_primary) av_frame_free(&img->frame); if (img->huffman_groups) { for (i = 0; i < img->nb_huffman_groups; i++) { for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++) ff_free_vlc(&img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE + j].vlc); } av_free(img->huffman_groups); } memset(img, 0, sizeof(*img)); } /* Differs from get_vlc2() in the following ways: * - codes are bit-reversed * - assumes 8-bit table to make reversal simpler * - assumes max depth of 2 since the max code length for WebP is 15 */ static av_always_inline int webp_get_vlc(GetBitContext *gb, VLC_TYPE (*table)[2]) { int n, nb_bits; unsigned int index; int code; OPEN_READER(re, gb); UPDATE_CACHE(re, gb); index = SHOW_UBITS(re, gb, 8); index = ff_reverse[index]; code = table[index][0]; n = table[index][1]; if (n < 0) { LAST_SKIP_BITS(re, gb, 8); UPDATE_CACHE(re, gb); nb_bits = -n; index = SHOW_UBITS(re, gb, nb_bits); index = (ff_reverse[index] >> (8 - nb_bits)) + code; code = table[index][0]; n = table[index][1]; } SKIP_BITS(re, gb, n); CLOSE_READER(re, gb); return code; } static int huff_reader_get_symbol(HuffReader *r, GetBitContext *gb) { if (r->simple) { if (r->nb_symbols == 1) return r->simple_symbols[0]; else return r->simple_symbols[get_bits1(gb)]; } else return webp_get_vlc(gb, r->vlc.table); } static int huff_reader_build_canonical(HuffReader *r, int *code_lengths, int alphabet_size) { int len = 0, sym, code = 0, ret; int max_code_length = 0; uint16_t *codes; /* special-case 1 symbol since the vlc reader cannot handle it */ for (sym = 0; sym < alphabet_size; sym++) { if (code_lengths[sym] > 0) { len++; code = sym; if (len > 1) break; } } if (len == 1) { r->nb_symbols = 1; r->simple_symbols[0] = code; r->simple = 1; return 0; } for (sym = 0; sym < alphabet_size; sym++) max_code_length = FFMAX(max_code_length, code_lengths[sym]); if (max_code_length == 0 || max_code_length > MAX_HUFFMAN_CODE_LENGTH) return AVERROR(EINVAL); codes = av_malloc(alphabet_size * sizeof(*codes)); if (!codes) return AVERROR(ENOMEM); code = 0; r->nb_symbols = 0; for (len = 1; len <= max_code_length; len++) { for (sym = 0; sym < alphabet_size; sym++) { if (code_lengths[sym] != len) continue; codes[sym] = code++; r->nb_symbols++; } code <<= 1; } if (!r->nb_symbols) { av_free(codes); return AVERROR_INVALIDDATA; } ret = init_vlc(&r->vlc, 8, alphabet_size, code_lengths, sizeof(*code_lengths), sizeof(*code_lengths), codes, sizeof(*codes), sizeof(*codes), 0); if (ret < 0) { av_free(codes); return ret; } r->simple = 0; av_free(codes); return 0; } static void read_huffman_code_simple(WebPContext *s, HuffReader *hc) { hc->nb_symbols = get_bits1(&s->gb) + 1; if (get_bits1(&s->gb)) hc->simple_symbols[0] = get_bits(&s->gb, 8); else hc->simple_symbols[0] = get_bits1(&s->gb); if (hc->nb_symbols == 2) hc->simple_symbols[1] = get_bits(&s->gb, 8); hc->simple = 1; } static int read_huffman_code_normal(WebPContext *s, HuffReader *hc, int alphabet_size) { HuffReader code_len_hc = { { 0 }, 0, 0, { 0 } }; int *code_lengths = NULL; int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 }; int i, symbol, max_symbol, prev_code_len, ret; int num_codes = 4 + get_bits(&s->gb, 4); if (num_codes > NUM_CODE_LENGTH_CODES) return AVERROR_INVALIDDATA; for (i = 0; i < num_codes; i++) code_length_code_lengths[code_length_code_order[i]] = get_bits(&s->gb, 3); ret = huff_reader_build_canonical(&code_len_hc, code_length_code_lengths, NUM_CODE_LENGTH_CODES); if (ret < 0) goto finish; code_lengths = av_mallocz_array(alphabet_size, sizeof(*code_lengths)); if (!code_lengths) { ret = AVERROR(ENOMEM); goto finish; } if (get_bits1(&s->gb)) { int bits = 2 + 2 * get_bits(&s->gb, 3); max_symbol = 2 + get_bits(&s->gb, bits); if (max_symbol > alphabet_size) { av_log(s->avctx, AV_LOG_ERROR, "max symbol %d > alphabet size %d\n", max_symbol, alphabet_size); ret = AVERROR_INVALIDDATA; goto finish; } } else { max_symbol = alphabet_size; } prev_code_len = 8; symbol = 0; while (symbol < alphabet_size) { int code_len; if (!max_symbol--) break; code_len = huff_reader_get_symbol(&code_len_hc, &s->gb); if (code_len < 16) { /* Code length code [0..15] indicates literal code lengths. */ code_lengths[symbol++] = code_len; if (code_len) prev_code_len = code_len; } else { int repeat = 0, length = 0; switch (code_len) { case 16: /* Code 16 repeats the previous non-zero value [3..6] times, * i.e., 3 + ReadBits(2) times. If code 16 is used before a * non-zero value has been emitted, a value of 8 is repeated. */ repeat = 3 + get_bits(&s->gb, 2); length = prev_code_len; break; case 17: /* Code 17 emits a streak of zeros [3..10], i.e., * 3 + ReadBits(3) times. */ repeat = 3 + get_bits(&s->gb, 3); break; case 18: /* Code 18 emits a streak of zeros of length [11..138], i.e., * 11 + ReadBits(7) times. */ repeat = 11 + get_bits(&s->gb, 7); break; } if (symbol + repeat > alphabet_size) { av_log(s->avctx, AV_LOG_ERROR, "invalid symbol %d + repeat %d > alphabet size %d\n", symbol, repeat, alphabet_size); ret = AVERROR_INVALIDDATA; goto finish; } while (repeat-- > 0) code_lengths[symbol++] = length; } } ret = huff_reader_build_canonical(hc, code_lengths, alphabet_size); finish: ff_free_vlc(&code_len_hc.vlc); av_free(code_lengths); return ret; } static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role, int w, int h); #define PARSE_BLOCK_SIZE(w, h) do { \ block_bits = get_bits(&s->gb, 3) + 2; \ blocks_w = FFALIGN((w), 1 << block_bits) >> block_bits; \ blocks_h = FFALIGN((h), 1 << block_bits) >> block_bits; \ } while (0) static int decode_entropy_image(WebPContext *s) { ImageContext *img; int ret, block_bits, width, blocks_w, blocks_h, x, y, max; width = s->width; if (s->reduced_width > 0) width = s->reduced_width; PARSE_BLOCK_SIZE(width, s->height); ret = decode_entropy_coded_image(s, IMAGE_ROLE_ENTROPY, blocks_w, blocks_h); if (ret < 0) return ret; img = &s->image[IMAGE_ROLE_ENTROPY]; img->size_reduction = block_bits; /* the number of huffman groups is determined by the maximum group number * coded in the entropy image */ max = 0; for (y = 0; y < img->frame->height; y++) { for (x = 0; x < img->frame->width; x++) { int p = GET_PIXEL_COMP(img->frame, x, y, 2); max = FFMAX(max, p); } } s->nb_huffman_groups = max + 1; return 0; } static int parse_transform_predictor(WebPContext *s) { int block_bits, blocks_w, blocks_h, ret; PARSE_BLOCK_SIZE(s->width, s->height); ret = decode_entropy_coded_image(s, IMAGE_ROLE_PREDICTOR, blocks_w, blocks_h); if (ret < 0) return ret; s->image[IMAGE_ROLE_PREDICTOR].size_reduction = block_bits; return 0; } static int parse_transform_color(WebPContext *s) { int block_bits, blocks_w, blocks_h, ret; PARSE_BLOCK_SIZE(s->width, s->height); ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_TRANSFORM, blocks_w, blocks_h); if (ret < 0) return ret; s->image[IMAGE_ROLE_COLOR_TRANSFORM].size_reduction = block_bits; return 0; } static int parse_transform_color_indexing(WebPContext *s) { ImageContext *img; int width_bits, index_size, ret, x; uint8_t *ct; index_size = get_bits(&s->gb, 8) + 1; if (index_size <= 2) width_bits = 3; else if (index_size <= 4) width_bits = 2; else if (index_size <= 16) width_bits = 1; else width_bits = 0; ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_INDEXING, index_size, 1); if (ret < 0) return ret; img = &s->image[IMAGE_ROLE_COLOR_INDEXING]; img->size_reduction = width_bits; if (width_bits > 0) s->reduced_width = (s->width + ((1 << width_bits) - 1)) >> width_bits; /* color index values are delta-coded */ ct = img->frame->data[0] + 4; for (x = 4; x < img->frame->width * 4; x++, ct++) ct[0] += ct[-4]; return 0; } static HuffReader *get_huffman_group(WebPContext *s, ImageContext *img, int x, int y) { ImageContext *gimg = &s->image[IMAGE_ROLE_ENTROPY]; int group = 0; if (gimg->size_reduction > 0) { int group_x = x >> gimg->size_reduction; int group_y = y >> gimg->size_reduction; group = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2); } return &img->huffman_groups[group * HUFFMAN_CODES_PER_META_CODE]; } static av_always_inline void color_cache_put(ImageContext *img, uint32_t c) { uint32_t cache_idx = (0x1E35A7BD * c) >> (32 - img->color_cache_bits); img->color_cache[cache_idx] = c; } static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role, int w, int h) { ImageContext *img; HuffReader *hg; int i, j, ret, x, y, width; img = &s->image[role]; img->role = role; if (!img->frame) { img->frame = av_frame_alloc(); if (!img->frame) return AVERROR(ENOMEM); } img->frame->format = AV_PIX_FMT_ARGB; img->frame->width = w; img->frame->height = h; if (role == IMAGE_ROLE_ARGB && !img->is_alpha_primary) { ThreadFrame pt = { .f = img->frame }; ret = ff_thread_get_buffer(s->avctx, &pt, 0); } else ret = av_frame_get_buffer(img->frame, 1); if (ret < 0) return ret; if (get_bits1(&s->gb)) { img->color_cache_bits = get_bits(&s->gb, 4); if (img->color_cache_bits < 1 || img->color_cache_bits > 11) { av_log(s->avctx, AV_LOG_ERROR, "invalid color cache bits: %d\n", img->color_cache_bits); return AVERROR_INVALIDDATA; } img->color_cache = av_mallocz_array(1 << img->color_cache_bits, sizeof(*img->color_cache)); if (!img->color_cache) return AVERROR(ENOMEM); } else { img->color_cache_bits = 0; } img->nb_huffman_groups = 1; if (role == IMAGE_ROLE_ARGB && get_bits1(&s->gb)) { ret = decode_entropy_image(s); if (ret < 0) return ret; img->nb_huffman_groups = s->nb_huffman_groups; } img->huffman_groups = av_mallocz_array(img->nb_huffman_groups * HUFFMAN_CODES_PER_META_CODE, sizeof(*img->huffman_groups)); if (!img->huffman_groups) return AVERROR(ENOMEM); for (i = 0; i < img->nb_huffman_groups; i++) { hg = &img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE]; for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++) { int alphabet_size = alphabet_sizes[j]; if (!j && img->color_cache_bits > 0) alphabet_size += 1 << img->color_cache_bits; if (get_bits1(&s->gb)) { read_huffman_code_simple(s, &hg[j]); } else { ret = read_huffman_code_normal(s, &hg[j], alphabet_size); if (ret < 0) return ret; } } } width = img->frame->width; if (role == IMAGE_ROLE_ARGB && s->reduced_width > 0) width = s->reduced_width; x = 0; y = 0; while (y < img->frame->height) { int v; hg = get_huffman_group(s, img, x, y); v = huff_reader_get_symbol(&hg[HUFF_IDX_GREEN], &s->gb); if (v < NUM_LITERAL_CODES) { /* literal pixel values */ uint8_t *p = GET_PIXEL(img->frame, x, y); p[2] = v; p[1] = huff_reader_get_symbol(&hg[HUFF_IDX_RED], &s->gb); p[3] = huff_reader_get_symbol(&hg[HUFF_IDX_BLUE], &s->gb); p[0] = huff_reader_get_symbol(&hg[HUFF_IDX_ALPHA], &s->gb); if (img->color_cache_bits) color_cache_put(img, AV_RB32(p)); x++; if (x == width) { x = 0; y++; } } else if (v < NUM_LITERAL_CODES + NUM_LENGTH_CODES) { /* LZ77 backwards mapping */ int prefix_code, length, distance, ref_x, ref_y; /* parse length and distance */ prefix_code = v - NUM_LITERAL_CODES; if (prefix_code < 4) { length = prefix_code + 1; } else { int extra_bits = (prefix_code - 2) >> 1; int offset = 2 + (prefix_code & 1) << extra_bits; length = offset + get_bits(&s->gb, extra_bits) + 1; } prefix_code = huff_reader_get_symbol(&hg[HUFF_IDX_DIST], &s->gb); if (prefix_code < 4) { distance = prefix_code + 1; } else { int extra_bits = prefix_code - 2 >> 1; int offset = 2 + (prefix_code & 1) << extra_bits; distance = offset + get_bits(&s->gb, extra_bits) + 1; } /* find reference location */ if (distance <= NUM_SHORT_DISTANCES) { int xi = lz77_distance_offsets[distance - 1][0]; int yi = lz77_distance_offsets[distance - 1][1]; distance = FFMAX(1, xi + yi * width); } else { distance -= NUM_SHORT_DISTANCES; } ref_x = x; ref_y = y; if (distance <= x) { ref_x -= distance; distance = 0; } else { ref_x = 0; distance -= x; } while (distance >= width) { ref_y--; distance -= width; } if (distance > 0) { ref_x = width - distance; ref_y--; } ref_x = FFMAX(0, ref_x); ref_y = FFMAX(0, ref_y); /* copy pixels * source and dest regions can overlap and wrap lines, so just * copy per-pixel */ for (i = 0; i < length; i++) { uint8_t *p_ref = GET_PIXEL(img->frame, ref_x, ref_y); uint8_t *p = GET_PIXEL(img->frame, x, y); AV_COPY32(p, p_ref); if (img->color_cache_bits) color_cache_put(img, AV_RB32(p)); x++; ref_x++; if (x == width) { x = 0; y++; } if (ref_x == width) { ref_x = 0; ref_y++; } if (y == img->frame->height || ref_y == img->frame->height) break; } } else { /* read from color cache */ uint8_t *p = GET_PIXEL(img->frame, x, y); int cache_idx = v - (NUM_LITERAL_CODES + NUM_LENGTH_CODES); if (!img->color_cache_bits) { av_log(s->avctx, AV_LOG_ERROR, "color cache not found\n"); return AVERROR_INVALIDDATA; } if (cache_idx >= 1 << img->color_cache_bits) { av_log(s->avctx, AV_LOG_ERROR, "color cache index out-of-bounds\n"); return AVERROR_INVALIDDATA; } AV_WB32(p, img->color_cache[cache_idx]); x++; if (x == width) { x = 0; y++; } } } return 0; } /* PRED_MODE_BLACK */ static void inv_predict_0(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { AV_WB32(p, 0xFF000000); } /* PRED_MODE_L */ static void inv_predict_1(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { AV_COPY32(p, p_l); } /* PRED_MODE_T */ static void inv_predict_2(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { AV_COPY32(p, p_t); } /* PRED_MODE_TR */ static void inv_predict_3(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { AV_COPY32(p, p_tr); } /* PRED_MODE_TL */ static void inv_predict_4(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { AV_COPY32(p, p_tl); } /* PRED_MODE_AVG_T_AVG_L_TR */ static void inv_predict_5(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { p[0] = p_t[0] + (p_l[0] + p_tr[0] >> 1) >> 1; p[1] = p_t[1] + (p_l[1] + p_tr[1] >> 1) >> 1; p[2] = p_t[2] + (p_l[2] + p_tr[2] >> 1) >> 1; p[3] = p_t[3] + (p_l[3] + p_tr[3] >> 1) >> 1; } /* PRED_MODE_AVG_L_TL */ static void inv_predict_6(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { p[0] = p_l[0] + p_tl[0] >> 1; p[1] = p_l[1] + p_tl[1] >> 1; p[2] = p_l[2] + p_tl[2] >> 1; p[3] = p_l[3] + p_tl[3] >> 1; } /* PRED_MODE_AVG_L_T */ static void inv_predict_7(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { p[0] = p_l[0] + p_t[0] >> 1; p[1] = p_l[1] + p_t[1] >> 1; p[2] = p_l[2] + p_t[2] >> 1; p[3] = p_l[3] + p_t[3] >> 1; } /* PRED_MODE_AVG_TL_T */ static void inv_predict_8(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { p[0] = p_tl[0] + p_t[0] >> 1; p[1] = p_tl[1] + p_t[1] >> 1; p[2] = p_tl[2] + p_t[2] >> 1; p[3] = p_tl[3] + p_t[3] >> 1; } /* PRED_MODE_AVG_T_TR */ static void inv_predict_9(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { p[0] = p_t[0] + p_tr[0] >> 1; p[1] = p_t[1] + p_tr[1] >> 1; p[2] = p_t[2] + p_tr[2] >> 1; p[3] = p_t[3] + p_tr[3] >> 1; } /* PRED_MODE_AVG_AVG_L_TL_AVG_T_TR */ static void inv_predict_10(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { p[0] = (p_l[0] + p_tl[0] >> 1) + (p_t[0] + p_tr[0] >> 1) >> 1; p[1] = (p_l[1] + p_tl[1] >> 1) + (p_t[1] + p_tr[1] >> 1) >> 1; p[2] = (p_l[2] + p_tl[2] >> 1) + (p_t[2] + p_tr[2] >> 1) >> 1; p[3] = (p_l[3] + p_tl[3] >> 1) + (p_t[3] + p_tr[3] >> 1) >> 1; } /* PRED_MODE_SELECT */ static void inv_predict_11(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { int diff = (FFABS(p_l[0] - p_tl[0]) - FFABS(p_t[0] - p_tl[0])) + (FFABS(p_l[1] - p_tl[1]) - FFABS(p_t[1] - p_tl[1])) + (FFABS(p_l[2] - p_tl[2]) - FFABS(p_t[2] - p_tl[2])) + (FFABS(p_l[3] - p_tl[3]) - FFABS(p_t[3] - p_tl[3])); if (diff <= 0) AV_COPY32(p, p_t); else AV_COPY32(p, p_l); } /* PRED_MODE_ADD_SUBTRACT_FULL */ static void inv_predict_12(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { p[0] = av_clip_uint8(p_l[0] + p_t[0] - p_tl[0]); p[1] = av_clip_uint8(p_l[1] + p_t[1] - p_tl[1]); p[2] = av_clip_uint8(p_l[2] + p_t[2] - p_tl[2]); p[3] = av_clip_uint8(p_l[3] + p_t[3] - p_tl[3]); } static av_always_inline uint8_t clamp_add_subtract_half(int a, int b, int c) { int d = a + b >> 1; return av_clip_uint8(d + (d - c) / 2); } /* PRED_MODE_ADD_SUBTRACT_HALF */ static void inv_predict_13(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr) { p[0] = clamp_add_subtract_half(p_l[0], p_t[0], p_tl[0]); p[1] = clamp_add_subtract_half(p_l[1], p_t[1], p_tl[1]); p[2] = clamp_add_subtract_half(p_l[2], p_t[2], p_tl[2]); p[3] = clamp_add_subtract_half(p_l[3], p_t[3], p_tl[3]); } typedef void (*inv_predict_func)(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl, const uint8_t *p_t, const uint8_t *p_tr); static const inv_predict_func inverse_predict[14] = { inv_predict_0, inv_predict_1, inv_predict_2, inv_predict_3, inv_predict_4, inv_predict_5, inv_predict_6, inv_predict_7, inv_predict_8, inv_predict_9, inv_predict_10, inv_predict_11, inv_predict_12, inv_predict_13, }; static void inverse_prediction(AVFrame *frame, enum PredictionMode m, int x, int y) { uint8_t *dec, *p_l, *p_tl, *p_t, *p_tr; uint8_t p[4]; dec = GET_PIXEL(frame, x, y); p_l = GET_PIXEL(frame, x - 1, y); p_tl = GET_PIXEL(frame, x - 1, y - 1); p_t = GET_PIXEL(frame, x, y - 1); if (x == frame->width - 1) p_tr = GET_PIXEL(frame, 0, y); else p_tr = GET_PIXEL(frame, x + 1, y - 1); inverse_predict[m](p, p_l, p_tl, p_t, p_tr); dec[0] += p[0]; dec[1] += p[1]; dec[2] += p[2]; dec[3] += p[3]; } static int apply_predictor_transform(WebPContext *s) { ImageContext *img = &s->image[IMAGE_ROLE_ARGB]; ImageContext *pimg = &s->image[IMAGE_ROLE_PREDICTOR]; int x, y; for (y = 0; y < img->frame->height; y++) { for (x = 0; x < img->frame->width; x++) { int tx = x >> pimg->size_reduction; int ty = y >> pimg->size_reduction; enum PredictionMode m = GET_PIXEL_COMP(pimg->frame, tx, ty, 2); if (x == 0) { if (y == 0) m = PRED_MODE_BLACK; else m = PRED_MODE_T; } else if (y == 0) m = PRED_MODE_L; if (m > 13) { av_log(s->avctx, AV_LOG_ERROR, "invalid predictor mode: %d\n", m); return AVERROR_INVALIDDATA; } inverse_prediction(img->frame, m, x, y); } } return 0; } static av_always_inline uint8_t color_transform_delta(uint8_t color_pred, uint8_t color) { return (int)ff_u8_to_s8(color_pred) * ff_u8_to_s8(color) >> 5; } static int apply_color_transform(WebPContext *s) { ImageContext *img, *cimg; int x, y, cx, cy; uint8_t *p, *cp; img = &s->image[IMAGE_ROLE_ARGB]; cimg = &s->image[IMAGE_ROLE_COLOR_TRANSFORM]; for (y = 0; y < img->frame->height; y++) { for (x = 0; x < img->frame->width; x++) { cx = x >> cimg->size_reduction; cy = y >> cimg->size_reduction; cp = GET_PIXEL(cimg->frame, cx, cy); p = GET_PIXEL(img->frame, x, y); p[1] += color_transform_delta(cp[3], p[2]); p[3] += color_transform_delta(cp[2], p[2]) + color_transform_delta(cp[1], p[1]); } } return 0; } static int apply_subtract_green_transform(WebPContext *s) { int x, y; ImageContext *img = &s->image[IMAGE_ROLE_ARGB]; for (y = 0; y < img->frame->height; y++) { for (x = 0; x < img->frame->width; x++) { uint8_t *p = GET_PIXEL(img->frame, x, y); p[1] += p[2]; p[3] += p[2]; } } return 0; } static int apply_color_indexing_transform(WebPContext *s) { ImageContext *img; ImageContext *pal; int i, x, y; uint8_t *p, *pi; img = &s->image[IMAGE_ROLE_ARGB]; pal = &s->image[IMAGE_ROLE_COLOR_INDEXING]; if (pal->size_reduction > 0) { GetBitContext gb_g; uint8_t *line; int pixel_bits = 8 >> pal->size_reduction; line = av_malloc(img->frame->linesize[0]); if (!line) return AVERROR(ENOMEM); for (y = 0; y < img->frame->height; y++) { p = GET_PIXEL(img->frame, 0, y); memcpy(line, p, img->frame->linesize[0]); init_get_bits(&gb_g, line, img->frame->linesize[0] * 8); skip_bits(&gb_g, 16); i = 0; for (x = 0; x < img->frame->width; x++) { p = GET_PIXEL(img->frame, x, y); p[2] = get_bits(&gb_g, pixel_bits); i++; if (i == 1 << pal->size_reduction) { skip_bits(&gb_g, 24); i = 0; } } } av_free(line); } for (y = 0; y < img->frame->height; y++) { for (x = 0; x < img->frame->width; x++) { p = GET_PIXEL(img->frame, x, y); i = p[2]; if (i >= pal->frame->width) { av_log(s->avctx, AV_LOG_ERROR, "invalid palette index %d\n", i); return AVERROR_INVALIDDATA; } pi = GET_PIXEL(pal->frame, i, 0); AV_COPY32(p, pi); } } return 0; } static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p, int *got_frame, uint8_t *data_start, unsigned int data_size, int is_alpha_chunk) { WebPContext *s = avctx->priv_data; int w, h, ret, i; if (!is_alpha_chunk) { s->lossless = 1; avctx->pix_fmt = AV_PIX_FMT_ARGB; } ret = init_get_bits(&s->gb, data_start, data_size * 8); if (ret < 0) return ret; if (!is_alpha_chunk) { if (get_bits(&s->gb, 8) != 0x2F) { av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless signature\n"); return AVERROR_INVALIDDATA; } w = get_bits(&s->gb, 14) + 1; h = get_bits(&s->gb, 14) + 1; if (s->width && s->width != w) { av_log(avctx, AV_LOG_WARNING, "Width mismatch. %d != %d\n", s->width, w); } s->width = w; if (s->height && s->height != h) { av_log(avctx, AV_LOG_WARNING, "Height mismatch. %d != %d\n", s->width, w); } s->height = h; ret = ff_set_dimensions(avctx, s->width, s->height); if (ret < 0) return ret; s->has_alpha = get_bits1(&s->gb); if (get_bits(&s->gb, 3) != 0x0) { av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless version\n"); return AVERROR_INVALIDDATA; } } else { if (!s->width || !s->height) return AVERROR_BUG; w = s->width; h = s->height; } /* parse transformations */ s->nb_transforms = 0; s->reduced_width = 0; while (get_bits1(&s->gb)) { enum TransformType transform = get_bits(&s->gb, 2); s->transforms[s->nb_transforms++] = transform; switch (transform) { case PREDICTOR_TRANSFORM: ret = parse_transform_predictor(s); break; case COLOR_TRANSFORM: ret = parse_transform_color(s); break; case COLOR_INDEXING_TRANSFORM: ret = parse_transform_color_indexing(s); break; } if (ret < 0) goto free_and_return; } /* decode primary image */ s->image[IMAGE_ROLE_ARGB].frame = p; if (is_alpha_chunk) s->image[IMAGE_ROLE_ARGB].is_alpha_primary = 1; ret = decode_entropy_coded_image(s, IMAGE_ROLE_ARGB, w, h); if (ret < 0) goto free_and_return; /* apply transformations */ for (i = s->nb_transforms - 1; i >= 0; i--) { switch (s->transforms[i]) { case PREDICTOR_TRANSFORM: ret = apply_predictor_transform(s); break; case COLOR_TRANSFORM: ret = apply_color_transform(s); break; case SUBTRACT_GREEN: ret = apply_subtract_green_transform(s); break; case COLOR_INDEXING_TRANSFORM: ret = apply_color_indexing_transform(s); break; } if (ret < 0) goto free_and_return; } *got_frame = 1; p->pict_type = AV_PICTURE_TYPE_I; p->key_frame = 1; ret = data_size; free_and_return: for (i = 0; i < IMAGE_ROLE_NB; i++) image_ctx_free(&s->image[i]); return ret; } static void alpha_inverse_prediction(AVFrame *frame, enum AlphaFilter m) { int x, y, ls; uint8_t *dec; ls = frame->linesize[3]; /* filter first row using horizontal filter */ dec = frame->data[3] + 1; for (x = 1; x < frame->width; x++, dec++) *dec += *(dec - 1); /* filter first column using vertical filter */ dec = frame->data[3] + ls; for (y = 1; y < frame->height; y++, dec += ls) *dec += *(dec - ls); /* filter the rest using the specified filter */ switch (m) { case ALPHA_FILTER_HORIZONTAL: for (y = 1; y < frame->height; y++) { dec = frame->data[3] + y * ls + 1; for (x = 1; x < frame->width; x++, dec++) *dec += *(dec - 1); } break; case ALPHA_FILTER_VERTICAL: for (y = 1; y < frame->height; y++) { dec = frame->data[3] + y * ls + 1; for (x = 1; x < frame->width; x++, dec++) *dec += *(dec - ls); } break; case ALPHA_FILTER_GRADIENT: for (y = 1; y < frame->height; y++) { dec = frame->data[3] + y * ls + 1; for (x = 1; x < frame->width; x++, dec++) dec[0] += av_clip_uint8(*(dec - 1) + *(dec - ls) - *(dec - ls - 1)); } break; } } static int vp8_lossy_decode_alpha(AVCodecContext *avctx, AVFrame *p, uint8_t *data_start, unsigned int data_size) { WebPContext *s = avctx->priv_data; int x, y, ret; if (s->alpha_compression == ALPHA_COMPRESSION_NONE) { GetByteContext gb; bytestream2_init(&gb, data_start, data_size); for (y = 0; y < s->height; y++) bytestream2_get_buffer(&gb, p->data[3] + p->linesize[3] * y, s->width); } else if (s->alpha_compression == ALPHA_COMPRESSION_VP8L) { uint8_t *ap, *pp; int alpha_got_frame = 0; s->alpha_frame = av_frame_alloc(); if (!s->alpha_frame) return AVERROR(ENOMEM); ret = vp8_lossless_decode_frame(avctx, s->alpha_frame, &alpha_got_frame, data_start, data_size, 1); if (ret < 0) { av_frame_free(&s->alpha_frame); return ret; } if (!alpha_got_frame) { av_frame_free(&s->alpha_frame); return AVERROR_INVALIDDATA; } /* copy green component of alpha image to alpha plane of primary image */ for (y = 0; y < s->height; y++) { ap = GET_PIXEL(s->alpha_frame, 0, y) + 2; pp = p->data[3] + p->linesize[3] * y; for (x = 0; x < s->width; x++) { *pp = *ap; pp++; ap += 4; } } av_frame_free(&s->alpha_frame); } /* apply alpha filtering */ if (s->alpha_filter) alpha_inverse_prediction(p, s->alpha_filter); return 0; } static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p, int *got_frame, uint8_t *data_start, unsigned int data_size) { WebPContext *s = avctx->priv_data; AVPacket pkt; int ret; if (!s->initialized) { ff_vp8_decode_init(avctx); s->initialized = 1; if (s->has_alpha) avctx->pix_fmt = AV_PIX_FMT_YUVA420P; } s->lossless = 0; if (data_size > INT_MAX) { av_log(avctx, AV_LOG_ERROR, "unsupported chunk size\n"); return AVERROR_PATCHWELCOME; } av_init_packet(&pkt); pkt.data = data_start; pkt.size = data_size; ret = ff_vp8_decode_frame(avctx, p, got_frame, &pkt); if (s->has_alpha) { ret = vp8_lossy_decode_alpha(avctx, p, s->alpha_data, s->alpha_data_size); if (ret < 0) return ret; } return ret; } static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt) { AVFrame * const p = data; WebPContext *s = avctx->priv_data; GetByteContext gb; int ret; uint32_t chunk_type, chunk_size; int vp8x_flags = 0; s->avctx = avctx; s->width = 0; s->height = 0; *got_frame = 0; s->has_alpha = 0; bytestream2_init(&gb, avpkt->data, avpkt->size); if (bytestream2_get_bytes_left(&gb) < 12) return AVERROR_INVALIDDATA; if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) { av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n"); return AVERROR_INVALIDDATA; } chunk_size = bytestream2_get_le32(&gb); if (bytestream2_get_bytes_left(&gb) < chunk_size) return AVERROR_INVALIDDATA; if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) { av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n"); return AVERROR_INVALIDDATA; } while (bytestream2_get_bytes_left(&gb) > 0) { char chunk_str[5] = { 0 }; chunk_type = bytestream2_get_le32(&gb); chunk_size = bytestream2_get_le32(&gb); if (chunk_size == UINT32_MAX) return AVERROR_INVALIDDATA; chunk_size += chunk_size & 1; if (bytestream2_get_bytes_left(&gb) < chunk_size) return AVERROR_INVALIDDATA; switch (chunk_type) { case MKTAG('V', 'P', '8', ' '): if (!*got_frame) { ret = vp8_lossy_decode_frame(avctx, p, got_frame, avpkt->data + bytestream2_tell(&gb), chunk_size); if (ret < 0) return ret; } bytestream2_skip(&gb, chunk_size); break; case MKTAG('V', 'P', '8', 'L'): if (!*got_frame) { ret = vp8_lossless_decode_frame(avctx, p, got_frame, avpkt->data + bytestream2_tell(&gb), chunk_size, 0); if (ret < 0) return ret; } bytestream2_skip(&gb, chunk_size); break; case MKTAG('V', 'P', '8', 'X'): vp8x_flags = bytestream2_get_byte(&gb); bytestream2_skip(&gb, 3); s->width = bytestream2_get_le24(&gb) + 1; s->height = bytestream2_get_le24(&gb) + 1; ret = av_image_check_size(s->width, s->height, 0, avctx); if (ret < 0) return ret; break; case MKTAG('A', 'L', 'P', 'H'): { int alpha_header, filter_m, compression; if (!(vp8x_flags & VP8X_FLAG_ALPHA)) { av_log(avctx, AV_LOG_WARNING, "ALPHA chunk present, but alpha bit not set in the " "VP8X header\n"); } if (chunk_size == 0) { av_log(avctx, AV_LOG_ERROR, "invalid ALPHA chunk size\n"); return AVERROR_INVALIDDATA; } alpha_header = bytestream2_get_byte(&gb); s->alpha_data = avpkt->data + bytestream2_tell(&gb); s->alpha_data_size = chunk_size - 1; bytestream2_skip(&gb, s->alpha_data_size); filter_m = (alpha_header >> 2) & 0x03; compression = alpha_header & 0x03; if (compression > ALPHA_COMPRESSION_VP8L) { av_log(avctx, AV_LOG_VERBOSE, "skipping unsupported ALPHA chunk\n"); } else { s->has_alpha = 1; s->alpha_compression = compression; s->alpha_filter = filter_m; } break; } case MKTAG('I', 'C', 'C', 'P'): case MKTAG('A', 'N', 'I', 'M'): case MKTAG('A', 'N', 'M', 'F'): case MKTAG('E', 'X', 'I', 'F'): case MKTAG('X', 'M', 'P', ' '): AV_WL32(chunk_str, chunk_type); av_log(avctx, AV_LOG_VERBOSE, "skipping unsupported chunk: %s\n", chunk_str); bytestream2_skip(&gb, chunk_size); break; default: AV_WL32(chunk_str, chunk_type); av_log(avctx, AV_LOG_VERBOSE, "skipping unknown chunk: %s\n", chunk_str); bytestream2_skip(&gb, chunk_size); break; } } if (!*got_frame) { av_log(avctx, AV_LOG_ERROR, "image data not found\n"); return AVERROR_INVALIDDATA; } return avpkt->size; } static av_cold int webp_decode_close(AVCodecContext *avctx) { WebPContext *s = avctx->priv_data; if (s->initialized) return ff_vp8_decode_free(avctx); return 0; } AVCodec ff_webp_decoder = { .name = "webp", .long_name = NULL_IF_CONFIG_SMALL("WebP image"), .type = AVMEDIA_TYPE_VIDEO, .id = AV_CODEC_ID_WEBP, .priv_data_size = sizeof(WebPContext), .decode = webp_decode_frame, .close = webp_decode_close, .capabilities = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS, };