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webp: Make sure enough bytes are available
[libav.git] / libavcodec / webp.c
1 /*
2 * WebP (.webp) image decoder
3 * Copyright (c) 2013 Aneesh Dogra <aneesh@sugarlabs.org>
4 * Copyright (c) 2013 Justin Ruggles <justin.ruggles@gmail.com>
5 *
6 * This file is part of Libav.
7 *
8 * Libav is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * Libav is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with Libav; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 /**
24 * @file
25 * WebP image decoder
26 *
27 * @author Aneesh Dogra <aneesh@sugarlabs.org>
28 * Container and Lossy decoding
29 *
30 * @author Justin Ruggles <justin.ruggles@gmail.com>
31 * Lossless decoder
32 * Compressed alpha for lossy
33 *
34 * Unimplemented:
35 * - Animation
36 * - ICC profile
37 * - Exif and XMP metadata
38 */
39
40 #define BITSTREAM_READER_LE
41 #include "libavutil/imgutils.h"
42 #include "avcodec.h"
43 #include "bytestream.h"
44 #include "internal.h"
45 #include "get_bits.h"
46 #include "thread.h"
47 #include "vp8.h"
48
49 #define VP8X_FLAG_ANIMATION 0x02
50 #define VP8X_FLAG_XMP_METADATA 0x04
51 #define VP8X_FLAG_EXIF_METADATA 0x08
52 #define VP8X_FLAG_ALPHA 0x10
53 #define VP8X_FLAG_ICC 0x20
54
55 #define MAX_PALETTE_SIZE 256
56 #define MAX_CACHE_BITS 11
57 #define NUM_CODE_LENGTH_CODES 19
58 #define HUFFMAN_CODES_PER_META_CODE 5
59 #define NUM_LITERAL_CODES 256
60 #define NUM_LENGTH_CODES 24
61 #define NUM_DISTANCE_CODES 40
62 #define NUM_SHORT_DISTANCES 120
63 #define MAX_HUFFMAN_CODE_LENGTH 15
64
65 static const uint16_t alphabet_sizes[HUFFMAN_CODES_PER_META_CODE] = {
66 NUM_LITERAL_CODES + NUM_LENGTH_CODES,
67 NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES,
68 NUM_DISTANCE_CODES
69 };
70
71 static const uint8_t code_length_code_order[NUM_CODE_LENGTH_CODES] = {
72 17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
73 };
74
75 static const int8_t lz77_distance_offsets[NUM_SHORT_DISTANCES][2] = {
76 { 0, 1 }, { 1, 0 }, { 1, 1 }, { -1, 1 }, { 0, 2 }, { 2, 0 }, { 1, 2 }, { -1, 2 },
77 { 2, 1 }, { -2, 1 }, { 2, 2 }, { -2, 2 }, { 0, 3 }, { 3, 0 }, { 1, 3 }, { -1, 3 },
78 { 3, 1 }, { -3, 1 }, { 2, 3 }, { -2, 3 }, { 3, 2 }, { -3, 2 }, { 0, 4 }, { 4, 0 },
79 { 1, 4 }, { -1, 4 }, { 4, 1 }, { -4, 1 }, { 3, 3 }, { -3, 3 }, { 2, 4 }, { -2, 4 },
80 { 4, 2 }, { -4, 2 }, { 0, 5 }, { 3, 4 }, { -3, 4 }, { 4, 3 }, { -4, 3 }, { 5, 0 },
81 { 1, 5 }, { -1, 5 }, { 5, 1 }, { -5, 1 }, { 2, 5 }, { -2, 5 }, { 5, 2 }, { -5, 2 },
82 { 4, 4 }, { -4, 4 }, { 3, 5 }, { -3, 5 }, { 5, 3 }, { -5, 3 }, { 0, 6 }, { 6, 0 },
83 { 1, 6 }, { -1, 6 }, { 6, 1 }, { -6, 1 }, { 2, 6 }, { -2, 6 }, { 6, 2 }, { -6, 2 },
84 { 4, 5 }, { -4, 5 }, { 5, 4 }, { -5, 4 }, { 3, 6 }, { -3, 6 }, { 6, 3 }, { -6, 3 },
85 { 0, 7 }, { 7, 0 }, { 1, 7 }, { -1, 7 }, { 5, 5 }, { -5, 5 }, { 7, 1 }, { -7, 1 },
86 { 4, 6 }, { -4, 6 }, { 6, 4 }, { -6, 4 }, { 2, 7 }, { -2, 7 }, { 7, 2 }, { -7, 2 },
87 { 3, 7 }, { -3, 7 }, { 7, 3 }, { -7, 3 }, { 5, 6 }, { -5, 6 }, { 6, 5 }, { -6, 5 },
88 { 8, 0 }, { 4, 7 }, { -4, 7 }, { 7, 4 }, { -7, 4 }, { 8, 1 }, { 8, 2 }, { 6, 6 },
89 { -6, 6 }, { 8, 3 }, { 5, 7 }, { -5, 7 }, { 7, 5 }, { -7, 5 }, { 8, 4 }, { 6, 7 },
90 { -6, 7 }, { 7, 6 }, { -7, 6 }, { 8, 5 }, { 7, 7 }, { -7, 7 }, { 8, 6 }, { 8, 7 }
91 };
92
93 enum AlphaCompression {
94 ALPHA_COMPRESSION_NONE,
95 ALPHA_COMPRESSION_VP8L,
96 };
97
98 enum AlphaFilter {
99 ALPHA_FILTER_NONE,
100 ALPHA_FILTER_HORIZONTAL,
101 ALPHA_FILTER_VERTICAL,
102 ALPHA_FILTER_GRADIENT,
103 };
104
105 enum TransformType {
106 PREDICTOR_TRANSFORM = 0,
107 COLOR_TRANSFORM = 1,
108 SUBTRACT_GREEN = 2,
109 COLOR_INDEXING_TRANSFORM = 3,
110 };
111
112 enum PredictionMode {
113 PRED_MODE_BLACK,
114 PRED_MODE_L,
115 PRED_MODE_T,
116 PRED_MODE_TR,
117 PRED_MODE_TL,
118 PRED_MODE_AVG_T_AVG_L_TR,
119 PRED_MODE_AVG_L_TL,
120 PRED_MODE_AVG_L_T,
121 PRED_MODE_AVG_TL_T,
122 PRED_MODE_AVG_T_TR,
123 PRED_MODE_AVG_AVG_L_TL_AVG_T_TR,
124 PRED_MODE_SELECT,
125 PRED_MODE_ADD_SUBTRACT_FULL,
126 PRED_MODE_ADD_SUBTRACT_HALF,
127 };
128
129 enum HuffmanIndex {
130 HUFF_IDX_GREEN = 0,
131 HUFF_IDX_RED = 1,
132 HUFF_IDX_BLUE = 2,
133 HUFF_IDX_ALPHA = 3,
134 HUFF_IDX_DIST = 4
135 };
136
137 /* The structure of WebP lossless is an optional series of transformation data,
138 * followed by the primary image. The primary image also optionally contains
139 * an entropy group mapping if there are multiple entropy groups. There is a
140 * basic image type called an "entropy coded image" that is used for all of
141 * these. The type of each entropy coded image is referred to by the
142 * specification as its role. */
143 enum ImageRole {
144 /* Primary Image: Stores the actual pixels of the image. */
145 IMAGE_ROLE_ARGB,
146
147 /* Entropy Image: Defines which Huffman group to use for different areas of
148 * the primary image. */
149 IMAGE_ROLE_ENTROPY,
150
151 /* Predictors: Defines which predictor type to use for different areas of
152 * the primary image. */
153 IMAGE_ROLE_PREDICTOR,
154
155 /* Color Transform Data: Defines the color transformation for different
156 * areas of the primary image. */
157 IMAGE_ROLE_COLOR_TRANSFORM,
158
159 /* Color Index: Stored as an image of height == 1. */
160 IMAGE_ROLE_COLOR_INDEXING,
161
162 IMAGE_ROLE_NB,
163 };
164
165 typedef struct HuffReader {
166 VLC vlc; /* Huffman decoder context */
167 int simple; /* whether to use simple mode */
168 int nb_symbols; /* number of coded symbols */
169 uint16_t simple_symbols[2]; /* symbols for simple mode */
170 } HuffReader;
171
172 typedef struct ImageContext {
173 enum ImageRole role; /* role of this image */
174 AVFrame *frame; /* AVFrame for data */
175 int color_cache_bits; /* color cache size, log2 */
176 uint32_t *color_cache; /* color cache data */
177 int nb_huffman_groups; /* number of huffman groups */
178 HuffReader *huffman_groups; /* reader for each huffman group */
179 int size_reduction; /* relative size compared to primary image, log2 */
180 int is_alpha_primary;
181 } ImageContext;
182
183 typedef struct WebPContext {
184 VP8Context v; /* VP8 Context used for lossy decoding */
185 GetBitContext gb; /* bitstream reader for main image chunk */
186 AVFrame *alpha_frame; /* AVFrame for alpha data decompressed from VP8L */
187 AVCodecContext *avctx; /* parent AVCodecContext */
188 int initialized; /* set once the VP8 context is initialized */
189 int has_alpha; /* has a separate alpha chunk */
190 enum AlphaCompression alpha_compression; /* compression type for alpha chunk */
191 enum AlphaFilter alpha_filter; /* filtering method for alpha chunk */
192 uint8_t *alpha_data; /* alpha chunk data */
193 int alpha_data_size; /* alpha chunk data size */
194 int width; /* image width */
195 int height; /* image height */
196 int lossless; /* indicates lossless or lossy */
197
198 int nb_transforms; /* number of transforms */
199 enum TransformType transforms[4]; /* transformations used in the image, in order */
200 int reduced_width; /* reduced width for index image, if applicable */
201 int nb_huffman_groups; /* number of huffman groups in the primary image */
202 ImageContext image[IMAGE_ROLE_NB]; /* image context for each role */
203 } WebPContext;
204
205 #define GET_PIXEL(frame, x, y) \
206 ((frame)->data[0] + (y) * frame->linesize[0] + 4 * (x))
207
208 #define GET_PIXEL_COMP(frame, x, y, c) \
209 (*((frame)->data[0] + (y) * frame->linesize[0] + 4 * (x) + c))
210
211 static void image_ctx_free(ImageContext *img)
212 {
213 int i, j;
214
215 av_free(img->color_cache);
216 if (img->role != IMAGE_ROLE_ARGB && !img->is_alpha_primary)
217 av_frame_free(&img->frame);
218 if (img->huffman_groups) {
219 for (i = 0; i < img->nb_huffman_groups; i++) {
220 for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++)
221 ff_free_vlc(&img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE + j].vlc);
222 }
223 av_free(img->huffman_groups);
224 }
225 memset(img, 0, sizeof(*img));
226 }
227
228
229 /* Differs from get_vlc2() in the following ways:
230 * - codes are bit-reversed
231 * - assumes 8-bit table to make reversal simpler
232 * - assumes max depth of 2 since the max code length for WebP is 15
233 */
234 static av_always_inline int webp_get_vlc(GetBitContext *gb, VLC_TYPE (*table)[2])
235 {
236 int n, nb_bits;
237 unsigned int index;
238 int code;
239
240 OPEN_READER(re, gb);
241 UPDATE_CACHE(re, gb);
242
243 index = SHOW_UBITS(re, gb, 8);
244 index = ff_reverse[index];
245 code = table[index][0];
246 n = table[index][1];
247
248 if (n < 0) {
249 LAST_SKIP_BITS(re, gb, 8);
250 UPDATE_CACHE(re, gb);
251
252 nb_bits = -n;
253
254 index = SHOW_UBITS(re, gb, nb_bits);
255 index = (ff_reverse[index] >> (8 - nb_bits)) + code;
256 code = table[index][0];
257 n = table[index][1];
258 }
259 SKIP_BITS(re, gb, n);
260
261 CLOSE_READER(re, gb);
262
263 return code;
264 }
265
266 static int huff_reader_get_symbol(HuffReader *r, GetBitContext *gb)
267 {
268 if (r->simple) {
269 if (r->nb_symbols == 1)
270 return r->simple_symbols[0];
271 else
272 return r->simple_symbols[get_bits1(gb)];
273 } else
274 return webp_get_vlc(gb, r->vlc.table);
275 }
276
277 static int huff_reader_build_canonical(HuffReader *r, int *code_lengths,
278 int alphabet_size)
279 {
280 int len = 0, sym, code = 0, ret;
281 int max_code_length = 0;
282 uint16_t *codes;
283
284 /* special-case 1 symbol since the vlc reader cannot handle it */
285 for (sym = 0; sym < alphabet_size; sym++) {
286 if (code_lengths[sym] > 0) {
287 len++;
288 code = sym;
289 if (len > 1)
290 break;
291 }
292 }
293 if (len == 1) {
294 r->nb_symbols = 1;
295 r->simple_symbols[0] = code;
296 r->simple = 1;
297 return 0;
298 }
299
300 for (sym = 0; sym < alphabet_size; sym++)
301 max_code_length = FFMAX(max_code_length, code_lengths[sym]);
302
303 if (max_code_length == 0 || max_code_length > MAX_HUFFMAN_CODE_LENGTH)
304 return AVERROR(EINVAL);
305
306 codes = av_malloc(alphabet_size * sizeof(*codes));
307 if (!codes)
308 return AVERROR(ENOMEM);
309
310 code = 0;
311 r->nb_symbols = 0;
312 for (len = 1; len <= max_code_length; len++) {
313 for (sym = 0; sym < alphabet_size; sym++) {
314 if (code_lengths[sym] != len)
315 continue;
316 codes[sym] = code++;
317 r->nb_symbols++;
318 }
319 code <<= 1;
320 }
321 if (!r->nb_symbols) {
322 av_free(codes);
323 return AVERROR_INVALIDDATA;
324 }
325
326 ret = init_vlc(&r->vlc, 8, alphabet_size,
327 code_lengths, sizeof(*code_lengths), sizeof(*code_lengths),
328 codes, sizeof(*codes), sizeof(*codes), 0);
329 if (ret < 0) {
330 av_free(codes);
331 return ret;
332 }
333 r->simple = 0;
334
335 av_free(codes);
336 return 0;
337 }
338
339 static void read_huffman_code_simple(WebPContext *s, HuffReader *hc)
340 {
341 hc->nb_symbols = get_bits1(&s->gb) + 1;
342
343 if (get_bits1(&s->gb))
344 hc->simple_symbols[0] = get_bits(&s->gb, 8);
345 else
346 hc->simple_symbols[0] = get_bits1(&s->gb);
347
348 if (hc->nb_symbols == 2)
349 hc->simple_symbols[1] = get_bits(&s->gb, 8);
350
351 hc->simple = 1;
352 }
353
354 static int read_huffman_code_normal(WebPContext *s, HuffReader *hc,
355 int alphabet_size)
356 {
357 HuffReader code_len_hc = { { 0 }, 0, 0, { 0 } };
358 int *code_lengths = NULL;
359 int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 };
360 int i, symbol, max_symbol, prev_code_len, ret;
361 int num_codes = 4 + get_bits(&s->gb, 4);
362
363 if (num_codes > NUM_CODE_LENGTH_CODES)
364 return AVERROR_INVALIDDATA;
365
366 for (i = 0; i < num_codes; i++)
367 code_length_code_lengths[code_length_code_order[i]] = get_bits(&s->gb, 3);
368
369 ret = huff_reader_build_canonical(&code_len_hc, code_length_code_lengths,
370 NUM_CODE_LENGTH_CODES);
371 if (ret < 0)
372 goto finish;
373
374 code_lengths = av_mallocz_array(alphabet_size, sizeof(*code_lengths));
375 if (!code_lengths) {
376 ret = AVERROR(ENOMEM);
377 goto finish;
378 }
379
380 if (get_bits1(&s->gb)) {
381 int bits = 2 + 2 * get_bits(&s->gb, 3);
382 max_symbol = 2 + get_bits(&s->gb, bits);
383 if (max_symbol > alphabet_size) {
384 av_log(s->avctx, AV_LOG_ERROR, "max symbol %d > alphabet size %d\n",
385 max_symbol, alphabet_size);
386 ret = AVERROR_INVALIDDATA;
387 goto finish;
388 }
389 } else {
390 max_symbol = alphabet_size;
391 }
392
393 prev_code_len = 8;
394 symbol = 0;
395 while (symbol < alphabet_size) {
396 int code_len;
397
398 if (!max_symbol--)
399 break;
400 code_len = huff_reader_get_symbol(&code_len_hc, &s->gb);
401 if (code_len < 16) {
402 /* Code length code [0..15] indicates literal code lengths. */
403 code_lengths[symbol++] = code_len;
404 if (code_len)
405 prev_code_len = code_len;
406 } else {
407 int repeat = 0, length = 0;
408 switch (code_len) {
409 case 16:
410 /* Code 16 repeats the previous non-zero value [3..6] times,
411 * i.e., 3 + ReadBits(2) times. If code 16 is used before a
412 * non-zero value has been emitted, a value of 8 is repeated. */
413 repeat = 3 + get_bits(&s->gb, 2);
414 length = prev_code_len;
415 break;
416 case 17:
417 /* Code 17 emits a streak of zeros [3..10], i.e.,
418 * 3 + ReadBits(3) times. */
419 repeat = 3 + get_bits(&s->gb, 3);
420 break;
421 case 18:
422 /* Code 18 emits a streak of zeros of length [11..138], i.e.,
423 * 11 + ReadBits(7) times. */
424 repeat = 11 + get_bits(&s->gb, 7);
425 break;
426 }
427 if (symbol + repeat > alphabet_size) {
428 av_log(s->avctx, AV_LOG_ERROR,
429 "invalid symbol %d + repeat %d > alphabet size %d\n",
430 symbol, repeat, alphabet_size);
431 ret = AVERROR_INVALIDDATA;
432 goto finish;
433 }
434 while (repeat-- > 0)
435 code_lengths[symbol++] = length;
436 }
437 }
438
439 ret = huff_reader_build_canonical(hc, code_lengths, alphabet_size);
440
441 finish:
442 ff_free_vlc(&code_len_hc.vlc);
443 av_free(code_lengths);
444 return ret;
445 }
446
447 static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,
448 int w, int h);
449
450 #define PARSE_BLOCK_SIZE(w, h) do { \
451 block_bits = get_bits(&s->gb, 3) + 2; \
452 blocks_w = FFALIGN((w), 1 << block_bits) >> block_bits; \
453 blocks_h = FFALIGN((h), 1 << block_bits) >> block_bits; \
454 } while (0)
455
456 static int decode_entropy_image(WebPContext *s)
457 {
458 ImageContext *img;
459 int ret, block_bits, width, blocks_w, blocks_h, x, y, max;
460
461 width = s->width;
462 if (s->reduced_width > 0)
463 width = s->reduced_width;
464
465 PARSE_BLOCK_SIZE(width, s->height);
466
467 ret = decode_entropy_coded_image(s, IMAGE_ROLE_ENTROPY, blocks_w, blocks_h);
468 if (ret < 0)
469 return ret;
470
471 img = &s->image[IMAGE_ROLE_ENTROPY];
472 img->size_reduction = block_bits;
473
474 /* the number of huffman groups is determined by the maximum group number
475 * coded in the entropy image */
476 max = 0;
477 for (y = 0; y < img->frame->height; y++) {
478 for (x = 0; x < img->frame->width; x++) {
479 int p0 = GET_PIXEL_COMP(img->frame, x, y, 1);
480 int p1 = GET_PIXEL_COMP(img->frame, x, y, 2);
481 int p = p0 << 8 | p1;
482 max = FFMAX(max, p);
483 }
484 }
485 s->nb_huffman_groups = max + 1;
486
487 return 0;
488 }
489
490 static int parse_transform_predictor(WebPContext *s)
491 {
492 int block_bits, blocks_w, blocks_h, ret;
493
494 PARSE_BLOCK_SIZE(s->width, s->height);
495
496 ret = decode_entropy_coded_image(s, IMAGE_ROLE_PREDICTOR, blocks_w,
497 blocks_h);
498 if (ret < 0)
499 return ret;
500
501 s->image[IMAGE_ROLE_PREDICTOR].size_reduction = block_bits;
502
503 return 0;
504 }
505
506 static int parse_transform_color(WebPContext *s)
507 {
508 int block_bits, blocks_w, blocks_h, ret;
509
510 PARSE_BLOCK_SIZE(s->width, s->height);
511
512 ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_TRANSFORM, blocks_w,
513 blocks_h);
514 if (ret < 0)
515 return ret;
516
517 s->image[IMAGE_ROLE_COLOR_TRANSFORM].size_reduction = block_bits;
518
519 return 0;
520 }
521
522 static int parse_transform_color_indexing(WebPContext *s)
523 {
524 ImageContext *img;
525 int width_bits, index_size, ret, x;
526 uint8_t *ct;
527
528 index_size = get_bits(&s->gb, 8) + 1;
529
530 if (index_size <= 2)
531 width_bits = 3;
532 else if (index_size <= 4)
533 width_bits = 2;
534 else if (index_size <= 16)
535 width_bits = 1;
536 else
537 width_bits = 0;
538
539 ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_INDEXING,
540 index_size, 1);
541 if (ret < 0)
542 return ret;
543
544 img = &s->image[IMAGE_ROLE_COLOR_INDEXING];
545 img->size_reduction = width_bits;
546 if (width_bits > 0)
547 s->reduced_width = (s->width + ((1 << width_bits) - 1)) >> width_bits;
548
549 /* color index values are delta-coded */
550 ct = img->frame->data[0] + 4;
551 for (x = 4; x < img->frame->width * 4; x++, ct++)
552 ct[0] += ct[-4];
553
554 return 0;
555 }
556
557 static HuffReader *get_huffman_group(WebPContext *s, ImageContext *img,
558 int x, int y)
559 {
560 ImageContext *gimg = &s->image[IMAGE_ROLE_ENTROPY];
561 int group = 0;
562
563 if (gimg->size_reduction > 0) {
564 int group_x = x >> gimg->size_reduction;
565 int group_y = y >> gimg->size_reduction;
566 int g0 = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 1);
567 int g1 = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2);
568 group = g0 << 8 | g1;
569 }
570
571 return &img->huffman_groups[group * HUFFMAN_CODES_PER_META_CODE];
572 }
573
574 static av_always_inline void color_cache_put(ImageContext *img, uint32_t c)
575 {
576 uint32_t cache_idx = (0x1E35A7BD * c) >> (32 - img->color_cache_bits);
577 img->color_cache[cache_idx] = c;
578 }
579
580 static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,
581 int w, int h)
582 {
583 ImageContext *img;
584 HuffReader *hg;
585 int i, j, ret, x, y, width;
586
587 img = &s->image[role];
588 img->role = role;
589
590 if (!img->frame) {
591 img->frame = av_frame_alloc();
592 if (!img->frame)
593 return AVERROR(ENOMEM);
594 }
595
596 img->frame->format = AV_PIX_FMT_ARGB;
597 img->frame->width = w;
598 img->frame->height = h;
599
600 if (role == IMAGE_ROLE_ARGB && !img->is_alpha_primary) {
601 ThreadFrame pt = { .f = img->frame };
602 ret = ff_thread_get_buffer(s->avctx, &pt, 0);
603 } else
604 ret = av_frame_get_buffer(img->frame, 1);
605 if (ret < 0)
606 return ret;
607
608 if (get_bits1(&s->gb)) {
609 img->color_cache_bits = get_bits(&s->gb, 4);
610 if (img->color_cache_bits < 1 || img->color_cache_bits > 11) {
611 av_log(s->avctx, AV_LOG_ERROR, "invalid color cache bits: %d\n",
612 img->color_cache_bits);
613 return AVERROR_INVALIDDATA;
614 }
615 img->color_cache = av_mallocz_array(1 << img->color_cache_bits,
616 sizeof(*img->color_cache));
617 if (!img->color_cache)
618 return AVERROR(ENOMEM);
619 } else {
620 img->color_cache_bits = 0;
621 }
622
623 img->nb_huffman_groups = 1;
624 if (role == IMAGE_ROLE_ARGB && get_bits1(&s->gb)) {
625 ret = decode_entropy_image(s);
626 if (ret < 0)
627 return ret;
628 img->nb_huffman_groups = s->nb_huffman_groups;
629 }
630 img->huffman_groups = av_mallocz_array(img->nb_huffman_groups *
631 HUFFMAN_CODES_PER_META_CODE,
632 sizeof(*img->huffman_groups));
633 if (!img->huffman_groups)
634 return AVERROR(ENOMEM);
635
636 for (i = 0; i < img->nb_huffman_groups; i++) {
637 hg = &img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE];
638 for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++) {
639 int alphabet_size = alphabet_sizes[j];
640 if (!j && img->color_cache_bits > 0)
641 alphabet_size += 1 << img->color_cache_bits;
642
643 if (get_bits1(&s->gb)) {
644 read_huffman_code_simple(s, &hg[j]);
645 } else {
646 ret = read_huffman_code_normal(s, &hg[j], alphabet_size);
647 if (ret < 0)
648 return ret;
649 }
650 }
651 }
652
653 width = img->frame->width;
654 if (role == IMAGE_ROLE_ARGB && s->reduced_width > 0)
655 width = s->reduced_width;
656
657 x = 0; y = 0;
658 while (y < img->frame->height) {
659 int v;
660
661 hg = get_huffman_group(s, img, x, y);
662 v = huff_reader_get_symbol(&hg[HUFF_IDX_GREEN], &s->gb);
663 if (v < NUM_LITERAL_CODES) {
664 /* literal pixel values */
665 uint8_t *p = GET_PIXEL(img->frame, x, y);
666 p[2] = v;
667 p[1] = huff_reader_get_symbol(&hg[HUFF_IDX_RED], &s->gb);
668 p[3] = huff_reader_get_symbol(&hg[HUFF_IDX_BLUE], &s->gb);
669 p[0] = huff_reader_get_symbol(&hg[HUFF_IDX_ALPHA], &s->gb);
670 if (img->color_cache_bits)
671 color_cache_put(img, AV_RB32(p));
672 x++;
673 if (x == width) {
674 x = 0;
675 y++;
676 }
677 } else if (v < NUM_LITERAL_CODES + NUM_LENGTH_CODES) {
678 /* LZ77 backwards mapping */
679 int prefix_code, length, distance, ref_x, ref_y;
680
681 /* parse length and distance */
682 prefix_code = v - NUM_LITERAL_CODES;
683 if (prefix_code < 4) {
684 length = prefix_code + 1;
685 } else {
686 int extra_bits = (prefix_code - 2) >> 1;
687 int offset = 2 + (prefix_code & 1) << extra_bits;
688 length = offset + get_bits(&s->gb, extra_bits) + 1;
689 }
690 prefix_code = huff_reader_get_symbol(&hg[HUFF_IDX_DIST], &s->gb);
691 if (prefix_code > 39) {
692 av_log(s->avctx, AV_LOG_ERROR,
693 "distance prefix code too large: %d\n", prefix_code);
694 return AVERROR_INVALIDDATA;
695 }
696 if (prefix_code < 4) {
697 distance = prefix_code + 1;
698 } else {
699 int extra_bits = prefix_code - 2 >> 1;
700 int offset = 2 + (prefix_code & 1) << extra_bits;
701 distance = offset + get_bits(&s->gb, extra_bits) + 1;
702 }
703
704 /* find reference location */
705 if (distance <= NUM_SHORT_DISTANCES) {
706 int xi = lz77_distance_offsets[distance - 1][0];
707 int yi = lz77_distance_offsets[distance - 1][1];
708 distance = FFMAX(1, xi + yi * width);
709 } else {
710 distance -= NUM_SHORT_DISTANCES;
711 }
712 ref_x = x;
713 ref_y = y;
714 if (distance <= x) {
715 ref_x -= distance;
716 distance = 0;
717 } else {
718 ref_x = 0;
719 distance -= x;
720 }
721 while (distance >= width) {
722 ref_y--;
723 distance -= width;
724 }
725 if (distance > 0) {
726 ref_x = width - distance;
727 ref_y--;
728 }
729 ref_x = FFMAX(0, ref_x);
730 ref_y = FFMAX(0, ref_y);
731
732 /* copy pixels
733 * source and dest regions can overlap and wrap lines, so just
734 * copy per-pixel */
735 for (i = 0; i < length; i++) {
736 uint8_t *p_ref = GET_PIXEL(img->frame, ref_x, ref_y);
737 uint8_t *p = GET_PIXEL(img->frame, x, y);
738
739 AV_COPY32(p, p_ref);
740 if (img->color_cache_bits)
741 color_cache_put(img, AV_RB32(p));
742 x++;
743 ref_x++;
744 if (x == width) {
745 x = 0;
746 y++;
747 }
748 if (ref_x == width) {
749 ref_x = 0;
750 ref_y++;
751 }
752 if (y == img->frame->height || ref_y == img->frame->height)
753 break;
754 }
755 } else {
756 /* read from color cache */
757 uint8_t *p = GET_PIXEL(img->frame, x, y);
758 int cache_idx = v - (NUM_LITERAL_CODES + NUM_LENGTH_CODES);
759
760 if (!img->color_cache_bits) {
761 av_log(s->avctx, AV_LOG_ERROR, "color cache not found\n");
762 return AVERROR_INVALIDDATA;
763 }
764 if (cache_idx >= 1 << img->color_cache_bits) {
765 av_log(s->avctx, AV_LOG_ERROR,
766 "color cache index out-of-bounds\n");
767 return AVERROR_INVALIDDATA;
768 }
769 AV_WB32(p, img->color_cache[cache_idx]);
770 x++;
771 if (x == width) {
772 x = 0;
773 y++;
774 }
775 }
776 }
777
778 return 0;
779 }
780
781 /* PRED_MODE_BLACK */
782 static void inv_predict_0(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
783 const uint8_t *p_t, const uint8_t *p_tr)
784 {
785 AV_WB32(p, 0xFF000000);
786 }
787
788 /* PRED_MODE_L */
789 static void inv_predict_1(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
790 const uint8_t *p_t, const uint8_t *p_tr)
791 {
792 AV_COPY32(p, p_l);
793 }
794
795 /* PRED_MODE_T */
796 static void inv_predict_2(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
797 const uint8_t *p_t, const uint8_t *p_tr)
798 {
799 AV_COPY32(p, p_t);
800 }
801
802 /* PRED_MODE_TR */
803 static void inv_predict_3(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
804 const uint8_t *p_t, const uint8_t *p_tr)
805 {
806 AV_COPY32(p, p_tr);
807 }
808
809 /* PRED_MODE_TL */
810 static void inv_predict_4(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
811 const uint8_t *p_t, const uint8_t *p_tr)
812 {
813 AV_COPY32(p, p_tl);
814 }
815
816 /* PRED_MODE_AVG_T_AVG_L_TR */
817 static void inv_predict_5(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
818 const uint8_t *p_t, const uint8_t *p_tr)
819 {
820 p[0] = p_t[0] + (p_l[0] + p_tr[0] >> 1) >> 1;
821 p[1] = p_t[1] + (p_l[1] + p_tr[1] >> 1) >> 1;
822 p[2] = p_t[2] + (p_l[2] + p_tr[2] >> 1) >> 1;
823 p[3] = p_t[3] + (p_l[3] + p_tr[3] >> 1) >> 1;
824 }
825
826 /* PRED_MODE_AVG_L_TL */
827 static void inv_predict_6(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
828 const uint8_t *p_t, const uint8_t *p_tr)
829 {
830 p[0] = p_l[0] + p_tl[0] >> 1;
831 p[1] = p_l[1] + p_tl[1] >> 1;
832 p[2] = p_l[2] + p_tl[2] >> 1;
833 p[3] = p_l[3] + p_tl[3] >> 1;
834 }
835
836 /* PRED_MODE_AVG_L_T */
837 static void inv_predict_7(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
838 const uint8_t *p_t, const uint8_t *p_tr)
839 {
840 p[0] = p_l[0] + p_t[0] >> 1;
841 p[1] = p_l[1] + p_t[1] >> 1;
842 p[2] = p_l[2] + p_t[2] >> 1;
843 p[3] = p_l[3] + p_t[3] >> 1;
844 }
845
846 /* PRED_MODE_AVG_TL_T */
847 static void inv_predict_8(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
848 const uint8_t *p_t, const uint8_t *p_tr)
849 {
850 p[0] = p_tl[0] + p_t[0] >> 1;
851 p[1] = p_tl[1] + p_t[1] >> 1;
852 p[2] = p_tl[2] + p_t[2] >> 1;
853 p[3] = p_tl[3] + p_t[3] >> 1;
854 }
855
856 /* PRED_MODE_AVG_T_TR */
857 static void inv_predict_9(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
858 const uint8_t *p_t, const uint8_t *p_tr)
859 {
860 p[0] = p_t[0] + p_tr[0] >> 1;
861 p[1] = p_t[1] + p_tr[1] >> 1;
862 p[2] = p_t[2] + p_tr[2] >> 1;
863 p[3] = p_t[3] + p_tr[3] >> 1;
864 }
865
866 /* PRED_MODE_AVG_AVG_L_TL_AVG_T_TR */
867 static void inv_predict_10(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
868 const uint8_t *p_t, const uint8_t *p_tr)
869 {
870 p[0] = (p_l[0] + p_tl[0] >> 1) + (p_t[0] + p_tr[0] >> 1) >> 1;
871 p[1] = (p_l[1] + p_tl[1] >> 1) + (p_t[1] + p_tr[1] >> 1) >> 1;
872 p[2] = (p_l[2] + p_tl[2] >> 1) + (p_t[2] + p_tr[2] >> 1) >> 1;
873 p[3] = (p_l[3] + p_tl[3] >> 1) + (p_t[3] + p_tr[3] >> 1) >> 1;
874 }
875
876 /* PRED_MODE_SELECT */
877 static void inv_predict_11(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
878 const uint8_t *p_t, const uint8_t *p_tr)
879 {
880 int diff = (FFABS(p_l[0] - p_tl[0]) - FFABS(p_t[0] - p_tl[0])) +
881 (FFABS(p_l[1] - p_tl[1]) - FFABS(p_t[1] - p_tl[1])) +
882 (FFABS(p_l[2] - p_tl[2]) - FFABS(p_t[2] - p_tl[2])) +
883 (FFABS(p_l[3] - p_tl[3]) - FFABS(p_t[3] - p_tl[3]));
884 if (diff <= 0)
885 AV_COPY32(p, p_t);
886 else
887 AV_COPY32(p, p_l);
888 }
889
890 /* PRED_MODE_ADD_SUBTRACT_FULL */
891 static void inv_predict_12(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
892 const uint8_t *p_t, const uint8_t *p_tr)
893 {
894 p[0] = av_clip_uint8(p_l[0] + p_t[0] - p_tl[0]);
895 p[1] = av_clip_uint8(p_l[1] + p_t[1] - p_tl[1]);
896 p[2] = av_clip_uint8(p_l[2] + p_t[2] - p_tl[2]);
897 p[3] = av_clip_uint8(p_l[3] + p_t[3] - p_tl[3]);
898 }
899
900 static av_always_inline uint8_t clamp_add_subtract_half(int a, int b, int c)
901 {
902 int d = a + b >> 1;
903 return av_clip_uint8(d + (d - c) / 2);
904 }
905
906 /* PRED_MODE_ADD_SUBTRACT_HALF */
907 static void inv_predict_13(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
908 const uint8_t *p_t, const uint8_t *p_tr)
909 {
910 p[0] = clamp_add_subtract_half(p_l[0], p_t[0], p_tl[0]);
911 p[1] = clamp_add_subtract_half(p_l[1], p_t[1], p_tl[1]);
912 p[2] = clamp_add_subtract_half(p_l[2], p_t[2], p_tl[2]);
913 p[3] = clamp_add_subtract_half(p_l[3], p_t[3], p_tl[3]);
914 }
915
916 typedef void (*inv_predict_func)(uint8_t *p, const uint8_t *p_l,
917 const uint8_t *p_tl, const uint8_t *p_t,
918 const uint8_t *p_tr);
919
920 static const inv_predict_func inverse_predict[14] = {
921 inv_predict_0, inv_predict_1, inv_predict_2, inv_predict_3,
922 inv_predict_4, inv_predict_5, inv_predict_6, inv_predict_7,
923 inv_predict_8, inv_predict_9, inv_predict_10, inv_predict_11,
924 inv_predict_12, inv_predict_13,
925 };
926
927 static void inverse_prediction(AVFrame *frame, enum PredictionMode m, int x, int y)
928 {
929 uint8_t *dec, *p_l, *p_tl, *p_t, *p_tr;
930 uint8_t p[4];
931
932 dec = GET_PIXEL(frame, x, y);
933 p_l = GET_PIXEL(frame, x - 1, y);
934 p_tl = GET_PIXEL(frame, x - 1, y - 1);
935 p_t = GET_PIXEL(frame, x, y - 1);
936 if (x == frame->width - 1)
937 p_tr = GET_PIXEL(frame, 0, y);
938 else
939 p_tr = GET_PIXEL(frame, x + 1, y - 1);
940
941 inverse_predict[m](p, p_l, p_tl, p_t, p_tr);
942
943 dec[0] += p[0];
944 dec[1] += p[1];
945 dec[2] += p[2];
946 dec[3] += p[3];
947 }
948
949 static int apply_predictor_transform(WebPContext *s)
950 {
951 ImageContext *img = &s->image[IMAGE_ROLE_ARGB];
952 ImageContext *pimg = &s->image[IMAGE_ROLE_PREDICTOR];
953 int x, y;
954
955 for (y = 0; y < img->frame->height; y++) {
956 for (x = 0; x < img->frame->width; x++) {
957 int tx = x >> pimg->size_reduction;
958 int ty = y >> pimg->size_reduction;
959 enum PredictionMode m = GET_PIXEL_COMP(pimg->frame, tx, ty, 2);
960
961 if (x == 0) {
962 if (y == 0)
963 m = PRED_MODE_BLACK;
964 else
965 m = PRED_MODE_T;
966 } else if (y == 0)
967 m = PRED_MODE_L;
968
969 if (m > 13) {
970 av_log(s->avctx, AV_LOG_ERROR,
971 "invalid predictor mode: %d\n", m);
972 return AVERROR_INVALIDDATA;
973 }
974 inverse_prediction(img->frame, m, x, y);
975 }
976 }
977 return 0;
978 }
979
980 static av_always_inline uint8_t color_transform_delta(uint8_t color_pred,
981 uint8_t color)
982 {
983 return (int)ff_u8_to_s8(color_pred) * ff_u8_to_s8(color) >> 5;
984 }
985
986 static int apply_color_transform(WebPContext *s)
987 {
988 ImageContext *img, *cimg;
989 int x, y, cx, cy;
990 uint8_t *p, *cp;
991
992 img = &s->image[IMAGE_ROLE_ARGB];
993 cimg = &s->image[IMAGE_ROLE_COLOR_TRANSFORM];
994
995 for (y = 0; y < img->frame->height; y++) {
996 for (x = 0; x < img->frame->width; x++) {
997 cx = x >> cimg->size_reduction;
998 cy = y >> cimg->size_reduction;
999 cp = GET_PIXEL(cimg->frame, cx, cy);
1000 p = GET_PIXEL(img->frame, x, y);
1001
1002 p[1] += color_transform_delta(cp[3], p[2]);
1003 p[3] += color_transform_delta(cp[2], p[2]) +
1004 color_transform_delta(cp[1], p[1]);
1005 }
1006 }
1007 return 0;
1008 }
1009
1010 static int apply_subtract_green_transform(WebPContext *s)
1011 {
1012 int x, y;
1013 ImageContext *img = &s->image[IMAGE_ROLE_ARGB];
1014
1015 for (y = 0; y < img->frame->height; y++) {
1016 for (x = 0; x < img->frame->width; x++) {
1017 uint8_t *p = GET_PIXEL(img->frame, x, y);
1018 p[1] += p[2];
1019 p[3] += p[2];
1020 }
1021 }
1022 return 0;
1023 }
1024
1025 static int apply_color_indexing_transform(WebPContext *s)
1026 {
1027 ImageContext *img;
1028 ImageContext *pal;
1029 int i, x, y;
1030 uint8_t *p, *pi;
1031
1032 img = &s->image[IMAGE_ROLE_ARGB];
1033 pal = &s->image[IMAGE_ROLE_COLOR_INDEXING];
1034
1035 if (pal->size_reduction > 0) {
1036 GetBitContext gb_g;
1037 uint8_t *line;
1038 int pixel_bits = 8 >> pal->size_reduction;
1039
1040 line = av_malloc(img->frame->linesize[0]);
1041 if (!line)
1042 return AVERROR(ENOMEM);
1043
1044 for (y = 0; y < img->frame->height; y++) {
1045 p = GET_PIXEL(img->frame, 0, y);
1046 memcpy(line, p, img->frame->linesize[0]);
1047 init_get_bits(&gb_g, line, img->frame->linesize[0] * 8);
1048 skip_bits(&gb_g, 16);
1049 i = 0;
1050 for (x = 0; x < img->frame->width; x++) {
1051 p = GET_PIXEL(img->frame, x, y);
1052 p[2] = get_bits(&gb_g, pixel_bits);
1053 i++;
1054 if (i == 1 << pal->size_reduction) {
1055 skip_bits(&gb_g, 24);
1056 i = 0;
1057 }
1058 }
1059 }
1060 av_free(line);
1061 }
1062
1063 for (y = 0; y < img->frame->height; y++) {
1064 for (x = 0; x < img->frame->width; x++) {
1065 p = GET_PIXEL(img->frame, x, y);
1066 i = p[2];
1067 if (i >= pal->frame->width) {
1068 av_log(s->avctx, AV_LOG_ERROR, "invalid palette index %d\n", i);
1069 return AVERROR_INVALIDDATA;
1070 }
1071 pi = GET_PIXEL(pal->frame, i, 0);
1072 AV_COPY32(p, pi);
1073 }
1074 }
1075
1076 return 0;
1077 }
1078
1079 static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p,
1080 int *got_frame, uint8_t *data_start,
1081 unsigned int data_size, int is_alpha_chunk)
1082 {
1083 WebPContext *s = avctx->priv_data;
1084 int w, h, ret, i, used;
1085
1086 if (!is_alpha_chunk) {
1087 s->lossless = 1;
1088 avctx->pix_fmt = AV_PIX_FMT_ARGB;
1089 }
1090
1091 ret = init_get_bits(&s->gb, data_start, data_size * 8);
1092 if (ret < 0)
1093 return ret;
1094
1095 if (!is_alpha_chunk) {
1096 if (get_bits(&s->gb, 8) != 0x2F) {
1097 av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless signature\n");
1098 return AVERROR_INVALIDDATA;
1099 }
1100
1101 w = get_bits(&s->gb, 14) + 1;
1102 h = get_bits(&s->gb, 14) + 1;
1103 if (s->width && s->width != w) {
1104 av_log(avctx, AV_LOG_WARNING, "Width mismatch. %d != %d\n",
1105 s->width, w);
1106 }
1107 s->width = w;
1108 if (s->height && s->height != h) {
1109 av_log(avctx, AV_LOG_WARNING, "Height mismatch. %d != %d\n",
1110 s->width, w);
1111 }
1112 s->height = h;
1113
1114 ret = ff_set_dimensions(avctx, s->width, s->height);
1115 if (ret < 0)
1116 return ret;
1117
1118 s->has_alpha = get_bits1(&s->gb);
1119
1120 if (get_bits(&s->gb, 3) != 0x0) {
1121 av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless version\n");
1122 return AVERROR_INVALIDDATA;
1123 }
1124 } else {
1125 if (!s->width || !s->height)
1126 return AVERROR_BUG;
1127 w = s->width;
1128 h = s->height;
1129 }
1130
1131 /* parse transformations */
1132 s->nb_transforms = 0;
1133 s->reduced_width = 0;
1134 used = 0;
1135 while (get_bits1(&s->gb)) {
1136 enum TransformType transform = get_bits(&s->gb, 2);
1137 s->transforms[s->nb_transforms++] = transform;
1138 if (used & (1 << transform)) {
1139 av_log(avctx, AV_LOG_ERROR, "Transform %d used more than once\n",
1140 transform);
1141 ret = AVERROR_INVALIDDATA;
1142 goto free_and_return;
1143 }
1144 used |= (1 << transform);
1145 switch (transform) {
1146 case PREDICTOR_TRANSFORM:
1147 ret = parse_transform_predictor(s);
1148 break;
1149 case COLOR_TRANSFORM:
1150 ret = parse_transform_color(s);
1151 break;
1152 case COLOR_INDEXING_TRANSFORM:
1153 ret = parse_transform_color_indexing(s);
1154 break;
1155 }
1156 if (ret < 0)
1157 goto free_and_return;
1158 }
1159
1160 /* decode primary image */
1161 s->image[IMAGE_ROLE_ARGB].frame = p;
1162 if (is_alpha_chunk)
1163 s->image[IMAGE_ROLE_ARGB].is_alpha_primary = 1;
1164 ret = decode_entropy_coded_image(s, IMAGE_ROLE_ARGB, w, h);
1165 if (ret < 0)
1166 goto free_and_return;
1167
1168 /* apply transformations */
1169 for (i = s->nb_transforms - 1; i >= 0; i--) {
1170 switch (s->transforms[i]) {
1171 case PREDICTOR_TRANSFORM:
1172 ret = apply_predictor_transform(s);
1173 break;
1174 case COLOR_TRANSFORM:
1175 ret = apply_color_transform(s);
1176 break;
1177 case SUBTRACT_GREEN:
1178 ret = apply_subtract_green_transform(s);
1179 break;
1180 case COLOR_INDEXING_TRANSFORM:
1181 ret = apply_color_indexing_transform(s);
1182 break;
1183 }
1184 if (ret < 0)
1185 goto free_and_return;
1186 }
1187
1188 *got_frame = 1;
1189 p->pict_type = AV_PICTURE_TYPE_I;
1190 p->key_frame = 1;
1191 ret = data_size;
1192
1193 free_and_return:
1194 for (i = 0; i < IMAGE_ROLE_NB; i++)
1195 image_ctx_free(&s->image[i]);
1196
1197 return ret;
1198 }
1199
1200 static void alpha_inverse_prediction(AVFrame *frame, enum AlphaFilter m)
1201 {
1202 int x, y, ls;
1203 uint8_t *dec;
1204
1205 ls = frame->linesize[3];
1206
1207 /* filter first row using horizontal filter */
1208 dec = frame->data[3] + 1;
1209 for (x = 1; x < frame->width; x++, dec++)
1210 *dec += *(dec - 1);
1211
1212 /* filter first column using vertical filter */
1213 dec = frame->data[3] + ls;
1214 for (y = 1; y < frame->height; y++, dec += ls)
1215 *dec += *(dec - ls);
1216
1217 /* filter the rest using the specified filter */
1218 switch (m) {
1219 case ALPHA_FILTER_HORIZONTAL:
1220 for (y = 1; y < frame->height; y++) {
1221 dec = frame->data[3] + y * ls + 1;
1222 for (x = 1; x < frame->width; x++, dec++)
1223 *dec += *(dec - 1);
1224 }
1225 break;
1226 case ALPHA_FILTER_VERTICAL:
1227 for (y = 1; y < frame->height; y++) {
1228 dec = frame->data[3] + y * ls + 1;
1229 for (x = 1; x < frame->width; x++, dec++)
1230 *dec += *(dec - ls);
1231 }
1232 break;
1233 case ALPHA_FILTER_GRADIENT:
1234 for (y = 1; y < frame->height; y++) {
1235 dec = frame->data[3] + y * ls + 1;
1236 for (x = 1; x < frame->width; x++, dec++)
1237 dec[0] += av_clip_uint8(*(dec - 1) + *(dec - ls) - *(dec - ls - 1));
1238 }
1239 break;
1240 }
1241 }
1242
1243 static int vp8_lossy_decode_alpha(AVCodecContext *avctx, AVFrame *p,
1244 uint8_t *data_start,
1245 unsigned int data_size)
1246 {
1247 WebPContext *s = avctx->priv_data;
1248 int x, y, ret;
1249
1250 if (s->alpha_compression == ALPHA_COMPRESSION_NONE) {
1251 GetByteContext gb;
1252
1253 bytestream2_init(&gb, data_start, data_size);
1254 for (y = 0; y < s->height; y++)
1255 bytestream2_get_buffer(&gb, p->data[3] + p->linesize[3] * y,
1256 s->width);
1257 } else if (s->alpha_compression == ALPHA_COMPRESSION_VP8L) {
1258 uint8_t *ap, *pp;
1259 int alpha_got_frame = 0;
1260
1261 s->alpha_frame = av_frame_alloc();
1262 if (!s->alpha_frame)
1263 return AVERROR(ENOMEM);
1264
1265 ret = vp8_lossless_decode_frame(avctx, s->alpha_frame, &alpha_got_frame,
1266 data_start, data_size, 1);
1267 if (ret < 0) {
1268 av_frame_free(&s->alpha_frame);
1269 return ret;
1270 }
1271 if (!alpha_got_frame) {
1272 av_frame_free(&s->alpha_frame);
1273 return AVERROR_INVALIDDATA;
1274 }
1275
1276 /* copy green component of alpha image to alpha plane of primary image */
1277 for (y = 0; y < s->height; y++) {
1278 ap = GET_PIXEL(s->alpha_frame, 0, y) + 2;
1279 pp = p->data[3] + p->linesize[3] * y;
1280 for (x = 0; x < s->width; x++) {
1281 *pp = *ap;
1282 pp++;
1283 ap += 4;
1284 }
1285 }
1286 av_frame_free(&s->alpha_frame);
1287 }
1288
1289 /* apply alpha filtering */
1290 if (s->alpha_filter)
1291 alpha_inverse_prediction(p, s->alpha_filter);
1292
1293 return 0;
1294 }
1295
1296 static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,
1297 int *got_frame, uint8_t *data_start,
1298 unsigned int data_size)
1299 {
1300 WebPContext *s = avctx->priv_data;
1301 AVPacket pkt;
1302 int ret;
1303
1304 if (!s->initialized) {
1305 ff_vp8_decode_init(avctx);
1306 s->initialized = 1;
1307 if (s->has_alpha)
1308 avctx->pix_fmt = AV_PIX_FMT_YUVA420P;
1309 }
1310 s->lossless = 0;
1311
1312 if (data_size > INT_MAX) {
1313 av_log(avctx, AV_LOG_ERROR, "unsupported chunk size\n");
1314 return AVERROR_PATCHWELCOME;
1315 }
1316
1317 av_init_packet(&pkt);
1318 pkt.data = data_start;
1319 pkt.size = data_size;
1320
1321 ret = ff_vp8_decode_frame(avctx, p, got_frame, &pkt);
1322 if (s->has_alpha) {
1323 ret = vp8_lossy_decode_alpha(avctx, p, s->alpha_data,
1324 s->alpha_data_size);
1325 if (ret < 0)
1326 return ret;
1327 }
1328 return ret;
1329 }
1330
1331 static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
1332 AVPacket *avpkt)
1333 {
1334 AVFrame * const p = data;
1335 WebPContext *s = avctx->priv_data;
1336 GetByteContext gb;
1337 int ret;
1338 uint32_t chunk_type, chunk_size;
1339 int vp8x_flags = 0;
1340
1341 s->avctx = avctx;
1342 s->width = 0;
1343 s->height = 0;
1344 *got_frame = 0;
1345 s->has_alpha = 0;
1346 bytestream2_init(&gb, avpkt->data, avpkt->size);
1347
1348 if (bytestream2_get_bytes_left(&gb) < 12)
1349 return AVERROR_INVALIDDATA;
1350
1351 if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {
1352 av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");
1353 return AVERROR_INVALIDDATA;
1354 }
1355
1356 chunk_size = bytestream2_get_le32(&gb);
1357 if (bytestream2_get_bytes_left(&gb) < chunk_size)
1358 return AVERROR_INVALIDDATA;
1359
1360 if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) {
1361 av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n");
1362 return AVERROR_INVALIDDATA;
1363 }
1364
1365 while (bytestream2_get_bytes_left(&gb) > 8) {
1366 char chunk_str[5] = { 0 };
1367
1368 chunk_type = bytestream2_get_le32(&gb);
1369 chunk_size = bytestream2_get_le32(&gb);
1370 if (chunk_size == UINT32_MAX)
1371 return AVERROR_INVALIDDATA;
1372 chunk_size += chunk_size & 1;
1373
1374 if (bytestream2_get_bytes_left(&gb) < chunk_size)
1375 return AVERROR_INVALIDDATA;
1376
1377 switch (chunk_type) {
1378 case MKTAG('V', 'P', '8', ' '):
1379 if (!*got_frame) {
1380 ret = vp8_lossy_decode_frame(avctx, p, got_frame,
1381 avpkt->data + bytestream2_tell(&gb),
1382 chunk_size);
1383 if (ret < 0)
1384 return ret;
1385 }
1386 bytestream2_skip(&gb, chunk_size);
1387 break;
1388 case MKTAG('V', 'P', '8', 'L'):
1389 if (!*got_frame) {
1390 ret = vp8_lossless_decode_frame(avctx, p, got_frame,
1391 avpkt->data + bytestream2_tell(&gb),
1392 chunk_size, 0);
1393 if (ret < 0)
1394 return ret;
1395 }
1396 bytestream2_skip(&gb, chunk_size);
1397 break;
1398 case MKTAG('V', 'P', '8', 'X'):
1399 vp8x_flags = bytestream2_get_byte(&gb);
1400 bytestream2_skip(&gb, 3);
1401 s->width = bytestream2_get_le24(&gb) + 1;
1402 s->height = bytestream2_get_le24(&gb) + 1;
1403 ret = av_image_check_size(s->width, s->height, 0, avctx);
1404 if (ret < 0)
1405 return ret;
1406 break;
1407 case MKTAG('A', 'L', 'P', 'H'): {
1408 int alpha_header, filter_m, compression;
1409
1410 if (!(vp8x_flags & VP8X_FLAG_ALPHA)) {
1411 av_log(avctx, AV_LOG_WARNING,
1412 "ALPHA chunk present, but alpha bit not set in the "
1413 "VP8X header\n");
1414 }
1415 if (chunk_size == 0) {
1416 av_log(avctx, AV_LOG_ERROR, "invalid ALPHA chunk size\n");
1417 return AVERROR_INVALIDDATA;
1418 }
1419 alpha_header = bytestream2_get_byte(&gb);
1420 s->alpha_data = avpkt->data + bytestream2_tell(&gb);
1421 s->alpha_data_size = chunk_size - 1;
1422 bytestream2_skip(&gb, s->alpha_data_size);
1423
1424 filter_m = (alpha_header >> 2) & 0x03;
1425 compression = alpha_header & 0x03;
1426
1427 if (compression > ALPHA_COMPRESSION_VP8L) {
1428 av_log(avctx, AV_LOG_VERBOSE,
1429 "skipping unsupported ALPHA chunk\n");
1430 } else {
1431 s->has_alpha = 1;
1432 s->alpha_compression = compression;
1433 s->alpha_filter = filter_m;
1434 }
1435
1436 break;
1437 }
1438 case MKTAG('I', 'C', 'C', 'P'):
1439 case MKTAG('A', 'N', 'I', 'M'):
1440 case MKTAG('A', 'N', 'M', 'F'):
1441 case MKTAG('E', 'X', 'I', 'F'):
1442 case MKTAG('X', 'M', 'P', ' '):
1443 AV_WL32(chunk_str, chunk_type);
1444 av_log(avctx, AV_LOG_VERBOSE, "skipping unsupported chunk: %s\n",
1445 chunk_str);
1446 bytestream2_skip(&gb, chunk_size);
1447 break;
1448 default:
1449 AV_WL32(chunk_str, chunk_type);
1450 av_log(avctx, AV_LOG_VERBOSE, "skipping unknown chunk: %s\n",
1451 chunk_str);
1452 bytestream2_skip(&gb, chunk_size);
1453 break;
1454 }
1455 }
1456
1457 if (!*got_frame) {
1458 av_log(avctx, AV_LOG_ERROR, "image data not found\n");
1459 return AVERROR_INVALIDDATA;
1460 }
1461
1462 return avpkt->size;
1463 }
1464
1465 static av_cold int webp_decode_close(AVCodecContext *avctx)
1466 {
1467 WebPContext *s = avctx->priv_data;
1468
1469 if (s->initialized)
1470 return ff_vp8_decode_free(avctx);
1471
1472 return 0;
1473 }
1474
1475 AVCodec ff_webp_decoder = {
1476 .name = "webp",
1477 .long_name = NULL_IF_CONFIG_SMALL("WebP image"),
1478 .type = AVMEDIA_TYPE_VIDEO,
1479 .id = AV_CODEC_ID_WEBP,
1480 .priv_data_size = sizeof(WebPContext),
1481 .decode = webp_decode_frame,
1482 .close = webp_decode_close,
1483 .capabilities = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,
1484 };
Libav master