Libav
webp.c
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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 
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] = {
69 };
70 
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 
96 };
97 
103 };
104 
110 };
111 
127 };
128 
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. */
146 
147  /* Entropy Image: Defines which Huffman group to use for different areas of
148  * the primary image. */
150 
151  /* Predictors: Defines which predictor type to use for different areas of
152  * the primary image. */
154 
155  /* Color Transform Data: Defines the color transformation for different
156  * areas of the primary image. */
158 
159  /* Color Index: Stored as an image of height == 1. */
161 
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 */
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  */
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 
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 
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 
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,
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) {
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 
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 p = GET_PIXEL_COMP(img->frame, x, y, 2);
480  max = FFMAX(max, p);
481  }
482  }
483  s->nb_huffman_groups = max + 1;
484 
485  return 0;
486 }
487 
489 {
490  int block_bits, blocks_w, blocks_h, ret;
491 
492  PARSE_BLOCK_SIZE(s->width, s->height);
493 
495  blocks_h);
496  if (ret < 0)
497  return ret;
498 
499  s->image[IMAGE_ROLE_PREDICTOR].size_reduction = block_bits;
500 
501  return 0;
502 }
503 
505 {
506  int block_bits, blocks_w, blocks_h, ret;
507 
508  PARSE_BLOCK_SIZE(s->width, s->height);
509 
511  blocks_h);
512  if (ret < 0)
513  return ret;
514 
516 
517  return 0;
518 }
519 
521 {
522  ImageContext *img;
523  int width_bits, index_size, ret, x;
524  uint8_t *ct;
525 
526  index_size = get_bits(&s->gb, 8) + 1;
527 
528  if (index_size <= 2)
529  width_bits = 3;
530  else if (index_size <= 4)
531  width_bits = 2;
532  else if (index_size <= 16)
533  width_bits = 1;
534  else
535  width_bits = 0;
536 
538  index_size, 1);
539  if (ret < 0)
540  return ret;
541 
542  img = &s->image[IMAGE_ROLE_COLOR_INDEXING];
543  img->size_reduction = width_bits;
544  if (width_bits > 0)
545  s->reduced_width = (s->width + ((1 << width_bits) - 1)) >> width_bits;
546 
547  /* color index values are delta-coded */
548  ct = img->frame->data[0] + 4;
549  for (x = 4; x < img->frame->width * 4; x++, ct++)
550  ct[0] += ct[-4];
551 
552  return 0;
553 }
554 
556  int x, int y)
557 {
559  int group = 0;
560 
561  if (gimg->size_reduction > 0) {
562  int group_x = x >> gimg->size_reduction;
563  int group_y = y >> gimg->size_reduction;
564  group = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2);
565  }
566 
567  return &img->huffman_groups[group * HUFFMAN_CODES_PER_META_CODE];
568 }
569 
570 static av_always_inline void color_cache_put(ImageContext *img, uint32_t c)
571 {
572  uint32_t cache_idx = (0x1E35A7BD * c) >> (32 - img->color_cache_bits);
573  img->color_cache[cache_idx] = c;
574 }
575 
577  int w, int h)
578 {
579  ImageContext *img;
580  HuffReader *hg;
581  int i, j, ret, x, y, width;
582 
583  img = &s->image[role];
584  img->role = role;
585 
586  if (!img->frame) {
587  img->frame = av_frame_alloc();
588  if (!img->frame)
589  return AVERROR(ENOMEM);
590  }
591 
592  img->frame->format = AV_PIX_FMT_ARGB;
593  img->frame->width = w;
594  img->frame->height = h;
595 
596  if (role == IMAGE_ROLE_ARGB && !img->is_alpha_primary) {
597  ThreadFrame pt = { .f = img->frame };
598  ret = ff_thread_get_buffer(s->avctx, &pt, 0);
599  } else
600  ret = av_frame_get_buffer(img->frame, 1);
601  if (ret < 0)
602  return ret;
603 
604  if (get_bits1(&s->gb)) {
605  img->color_cache_bits = get_bits(&s->gb, 4);
606  if (img->color_cache_bits < 1 || img->color_cache_bits > 11) {
607  av_log(s->avctx, AV_LOG_ERROR, "invalid color cache bits: %d\n",
608  img->color_cache_bits);
609  return AVERROR_INVALIDDATA;
610  }
612  sizeof(*img->color_cache));
613  if (!img->color_cache)
614  return AVERROR(ENOMEM);
615  } else {
616  img->color_cache_bits = 0;
617  }
618 
619  img->nb_huffman_groups = 1;
620  if (role == IMAGE_ROLE_ARGB && get_bits1(&s->gb)) {
621  ret = decode_entropy_image(s);
622  if (ret < 0)
623  return ret;
625  }
628  sizeof(*img->huffman_groups));
629  if (!img->huffman_groups)
630  return AVERROR(ENOMEM);
631 
632  for (i = 0; i < img->nb_huffman_groups; i++) {
634  for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++) {
635  int alphabet_size = alphabet_sizes[j];
636  if (!j && img->color_cache_bits > 0)
637  alphabet_size += 1 << img->color_cache_bits;
638 
639  if (get_bits1(&s->gb)) {
640  read_huffman_code_simple(s, &hg[j]);
641  } else {
642  ret = read_huffman_code_normal(s, &hg[j], alphabet_size);
643  if (ret < 0)
644  return ret;
645  }
646  }
647  }
648 
649  width = img->frame->width;
650  if (role == IMAGE_ROLE_ARGB && s->reduced_width > 0)
651  width = s->reduced_width;
652 
653  x = 0; y = 0;
654  while (y < img->frame->height) {
655  int v;
656 
657  hg = get_huffman_group(s, img, x, y);
659  if (v < NUM_LITERAL_CODES) {
660  /* literal pixel values */
661  uint8_t *p = GET_PIXEL(img->frame, x, y);
662  p[2] = v;
663  p[1] = huff_reader_get_symbol(&hg[HUFF_IDX_RED], &s->gb);
664  p[3] = huff_reader_get_symbol(&hg[HUFF_IDX_BLUE], &s->gb);
665  p[0] = huff_reader_get_symbol(&hg[HUFF_IDX_ALPHA], &s->gb);
666  if (img->color_cache_bits)
667  color_cache_put(img, AV_RB32(p));
668  x++;
669  if (x == width) {
670  x = 0;
671  y++;
672  }
673  } else if (v < NUM_LITERAL_CODES + NUM_LENGTH_CODES) {
674  /* LZ77 backwards mapping */
675  int prefix_code, length, distance, ref_x, ref_y;
676 
677  /* parse length and distance */
678  prefix_code = v - NUM_LITERAL_CODES;
679  if (prefix_code < 4) {
680  length = prefix_code + 1;
681  } else {
682  int extra_bits = (prefix_code - 2) >> 1;
683  int offset = 2 + (prefix_code & 1) << extra_bits;
684  length = offset + get_bits(&s->gb, extra_bits) + 1;
685  }
686  prefix_code = huff_reader_get_symbol(&hg[HUFF_IDX_DIST], &s->gb);
687  if (prefix_code < 4) {
688  distance = prefix_code + 1;
689  } else {
690  int extra_bits = prefix_code - 2 >> 1;
691  int offset = 2 + (prefix_code & 1) << extra_bits;
692  distance = offset + get_bits(&s->gb, extra_bits) + 1;
693  }
694 
695  /* find reference location */
696  if (distance <= NUM_SHORT_DISTANCES) {
697  int xi = lz77_distance_offsets[distance - 1][0];
698  int yi = lz77_distance_offsets[distance - 1][1];
699  distance = FFMAX(1, xi + yi * width);
700  } else {
701  distance -= NUM_SHORT_DISTANCES;
702  }
703  ref_x = x;
704  ref_y = y;
705  if (distance <= x) {
706  ref_x -= distance;
707  distance = 0;
708  } else {
709  ref_x = 0;
710  distance -= x;
711  }
712  while (distance >= width) {
713  ref_y--;
714  distance -= width;
715  }
716  if (distance > 0) {
717  ref_x = width - distance;
718  ref_y--;
719  }
720  ref_x = FFMAX(0, ref_x);
721  ref_y = FFMAX(0, ref_y);
722 
723  /* copy pixels
724  * source and dest regions can overlap and wrap lines, so just
725  * copy per-pixel */
726  for (i = 0; i < length; i++) {
727  uint8_t *p_ref = GET_PIXEL(img->frame, ref_x, ref_y);
728  uint8_t *p = GET_PIXEL(img->frame, x, y);
729 
730  AV_COPY32(p, p_ref);
731  if (img->color_cache_bits)
732  color_cache_put(img, AV_RB32(p));
733  x++;
734  ref_x++;
735  if (x == width) {
736  x = 0;
737  y++;
738  }
739  if (ref_x == width) {
740  ref_x = 0;
741  ref_y++;
742  }
743  if (y == img->frame->height || ref_y == img->frame->height)
744  break;
745  }
746  } else {
747  /* read from color cache */
748  uint8_t *p = GET_PIXEL(img->frame, x, y);
749  int cache_idx = v - (NUM_LITERAL_CODES + NUM_LENGTH_CODES);
750 
751  if (!img->color_cache_bits) {
752  av_log(s->avctx, AV_LOG_ERROR, "color cache not found\n");
753  return AVERROR_INVALIDDATA;
754  }
755  if (cache_idx >= 1 << img->color_cache_bits) {
757  "color cache index out-of-bounds\n");
758  return AVERROR_INVALIDDATA;
759  }
760  AV_WB32(p, img->color_cache[cache_idx]);
761  x++;
762  if (x == width) {
763  x = 0;
764  y++;
765  }
766  }
767  }
768 
769  return 0;
770 }
771 
772 /* PRED_MODE_BLACK */
773 static void inv_predict_0(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
774  const uint8_t *p_t, const uint8_t *p_tr)
775 {
776  AV_WB32(p, 0xFF000000);
777 }
778 
779 /* PRED_MODE_L */
780 static void inv_predict_1(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
781  const uint8_t *p_t, const uint8_t *p_tr)
782 {
783  AV_COPY32(p, p_l);
784 }
785 
786 /* PRED_MODE_T */
787 static void inv_predict_2(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
788  const uint8_t *p_t, const uint8_t *p_tr)
789 {
790  AV_COPY32(p, p_t);
791 }
792 
793 /* PRED_MODE_TR */
794 static void inv_predict_3(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
795  const uint8_t *p_t, const uint8_t *p_tr)
796 {
797  AV_COPY32(p, p_tr);
798 }
799 
800 /* PRED_MODE_TL */
801 static void inv_predict_4(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
802  const uint8_t *p_t, const uint8_t *p_tr)
803 {
804  AV_COPY32(p, p_tl);
805 }
806 
807 /* PRED_MODE_AVG_T_AVG_L_TR */
808 static void inv_predict_5(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
809  const uint8_t *p_t, const uint8_t *p_tr)
810 {
811  p[0] = p_t[0] + (p_l[0] + p_tr[0] >> 1) >> 1;
812  p[1] = p_t[1] + (p_l[1] + p_tr[1] >> 1) >> 1;
813  p[2] = p_t[2] + (p_l[2] + p_tr[2] >> 1) >> 1;
814  p[3] = p_t[3] + (p_l[3] + p_tr[3] >> 1) >> 1;
815 }
816 
817 /* PRED_MODE_AVG_L_TL */
818 static void inv_predict_6(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
819  const uint8_t *p_t, const uint8_t *p_tr)
820 {
821  p[0] = p_l[0] + p_tl[0] >> 1;
822  p[1] = p_l[1] + p_tl[1] >> 1;
823  p[2] = p_l[2] + p_tl[2] >> 1;
824  p[3] = p_l[3] + p_tl[3] >> 1;
825 }
826 
827 /* PRED_MODE_AVG_L_T */
828 static void inv_predict_7(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
829  const uint8_t *p_t, const uint8_t *p_tr)
830 {
831  p[0] = p_l[0] + p_t[0] >> 1;
832  p[1] = p_l[1] + p_t[1] >> 1;
833  p[2] = p_l[2] + p_t[2] >> 1;
834  p[3] = p_l[3] + p_t[3] >> 1;
835 }
836 
837 /* PRED_MODE_AVG_TL_T */
838 static void inv_predict_8(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
839  const uint8_t *p_t, const uint8_t *p_tr)
840 {
841  p[0] = p_tl[0] + p_t[0] >> 1;
842  p[1] = p_tl[1] + p_t[1] >> 1;
843  p[2] = p_tl[2] + p_t[2] >> 1;
844  p[3] = p_tl[3] + p_t[3] >> 1;
845 }
846 
847 /* PRED_MODE_AVG_T_TR */
848 static void inv_predict_9(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
849  const uint8_t *p_t, const uint8_t *p_tr)
850 {
851  p[0] = p_t[0] + p_tr[0] >> 1;
852  p[1] = p_t[1] + p_tr[1] >> 1;
853  p[2] = p_t[2] + p_tr[2] >> 1;
854  p[3] = p_t[3] + p_tr[3] >> 1;
855 }
856 
857 /* PRED_MODE_AVG_AVG_L_TL_AVG_T_TR */
858 static void inv_predict_10(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
859  const uint8_t *p_t, const uint8_t *p_tr)
860 {
861  p[0] = (p_l[0] + p_tl[0] >> 1) + (p_t[0] + p_tr[0] >> 1) >> 1;
862  p[1] = (p_l[1] + p_tl[1] >> 1) + (p_t[1] + p_tr[1] >> 1) >> 1;
863  p[2] = (p_l[2] + p_tl[2] >> 1) + (p_t[2] + p_tr[2] >> 1) >> 1;
864  p[3] = (p_l[3] + p_tl[3] >> 1) + (p_t[3] + p_tr[3] >> 1) >> 1;
865 }
866 
867 /* PRED_MODE_SELECT */
868 static void inv_predict_11(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
869  const uint8_t *p_t, const uint8_t *p_tr)
870 {
871  int diff = (FFABS(p_l[0] - p_tl[0]) - FFABS(p_t[0] - p_tl[0])) +
872  (FFABS(p_l[1] - p_tl[1]) - FFABS(p_t[1] - p_tl[1])) +
873  (FFABS(p_l[2] - p_tl[2]) - FFABS(p_t[2] - p_tl[2])) +
874  (FFABS(p_l[3] - p_tl[3]) - FFABS(p_t[3] - p_tl[3]));
875  if (diff <= 0)
876  AV_COPY32(p, p_t);
877  else
878  AV_COPY32(p, p_l);
879 }
880 
881 /* PRED_MODE_ADD_SUBTRACT_FULL */
882 static void inv_predict_12(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
883  const uint8_t *p_t, const uint8_t *p_tr)
884 {
885  p[0] = av_clip_uint8(p_l[0] + p_t[0] - p_tl[0]);
886  p[1] = av_clip_uint8(p_l[1] + p_t[1] - p_tl[1]);
887  p[2] = av_clip_uint8(p_l[2] + p_t[2] - p_tl[2]);
888  p[3] = av_clip_uint8(p_l[3] + p_t[3] - p_tl[3]);
889 }
890 
892 {
893  int d = a + b >> 1;
894  return av_clip_uint8(d + (d - c) / 2);
895 }
896 
897 /* PRED_MODE_ADD_SUBTRACT_HALF */
898 static void inv_predict_13(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
899  const uint8_t *p_t, const uint8_t *p_tr)
900 {
901  p[0] = clamp_add_subtract_half(p_l[0], p_t[0], p_tl[0]);
902  p[1] = clamp_add_subtract_half(p_l[1], p_t[1], p_tl[1]);
903  p[2] = clamp_add_subtract_half(p_l[2], p_t[2], p_tl[2]);
904  p[3] = clamp_add_subtract_half(p_l[3], p_t[3], p_tl[3]);
905 }
906 
907 typedef void (*inv_predict_func)(uint8_t *p, const uint8_t *p_l,
908  const uint8_t *p_tl, const uint8_t *p_t,
909  const uint8_t *p_tr);
910 
911 static const inv_predict_func inverse_predict[14] = {
916 };
917 
918 static void inverse_prediction(AVFrame *frame, enum PredictionMode m, int x, int y)
919 {
920  uint8_t *dec, *p_l, *p_tl, *p_t, *p_tr;
921  uint8_t p[4];
922 
923  dec = GET_PIXEL(frame, x, y);
924  p_l = GET_PIXEL(frame, x - 1, y);
925  p_tl = GET_PIXEL(frame, x - 1, y - 1);
926  p_t = GET_PIXEL(frame, x, y - 1);
927  if (x == frame->width - 1)
928  p_tr = GET_PIXEL(frame, 0, y);
929  else
930  p_tr = GET_PIXEL(frame, x + 1, y - 1);
931 
932  inverse_predict[m](p, p_l, p_tl, p_t, p_tr);
933 
934  dec[0] += p[0];
935  dec[1] += p[1];
936  dec[2] += p[2];
937  dec[3] += p[3];
938 }
939 
941 {
942  ImageContext *img = &s->image[IMAGE_ROLE_ARGB];
944  int x, y;
945 
946  for (y = 0; y < img->frame->height; y++) {
947  for (x = 0; x < img->frame->width; x++) {
948  int tx = x >> pimg->size_reduction;
949  int ty = y >> pimg->size_reduction;
950  enum PredictionMode m = GET_PIXEL_COMP(pimg->frame, tx, ty, 2);
951 
952  if (x == 0) {
953  if (y == 0)
954  m = PRED_MODE_BLACK;
955  else
956  m = PRED_MODE_T;
957  } else if (y == 0)
958  m = PRED_MODE_L;
959 
960  if (m > 13) {
962  "invalid predictor mode: %d\n", m);
963  return AVERROR_INVALIDDATA;
964  }
965  inverse_prediction(img->frame, m, x, y);
966  }
967  }
968  return 0;
969 }
970 
972  uint8_t color)
973 {
974  return (int)ff_u8_to_s8(color_pred) * ff_u8_to_s8(color) >> 5;
975 }
976 
978 {
979  ImageContext *img, *cimg;
980  int x, y, cx, cy;
981  uint8_t *p, *cp;
982 
983  img = &s->image[IMAGE_ROLE_ARGB];
984  cimg = &s->image[IMAGE_ROLE_COLOR_TRANSFORM];
985 
986  for (y = 0; y < img->frame->height; y++) {
987  for (x = 0; x < img->frame->width; x++) {
988  cx = x >> cimg->size_reduction;
989  cy = y >> cimg->size_reduction;
990  cp = GET_PIXEL(cimg->frame, cx, cy);
991  p = GET_PIXEL(img->frame, x, y);
992 
993  p[1] += color_transform_delta(cp[3], p[2]);
994  p[3] += color_transform_delta(cp[2], p[2]) +
995  color_transform_delta(cp[1], p[1]);
996  }
997  }
998  return 0;
999 }
1000 
1002 {
1003  int x, y;
1004  ImageContext *img = &s->image[IMAGE_ROLE_ARGB];
1005 
1006  for (y = 0; y < img->frame->height; y++) {
1007  for (x = 0; x < img->frame->width; x++) {
1008  uint8_t *p = GET_PIXEL(img->frame, x, y);
1009  p[1] += p[2];
1010  p[3] += p[2];
1011  }
1012  }
1013  return 0;
1014 }
1015 
1017 {
1018  ImageContext *img;
1019  ImageContext *pal;
1020  int i, x, y;
1021  uint8_t *p, *pi;
1022 
1023  img = &s->image[IMAGE_ROLE_ARGB];
1024  pal = &s->image[IMAGE_ROLE_COLOR_INDEXING];
1025 
1026  if (pal->size_reduction > 0) {
1027  GetBitContext gb_g;
1028  uint8_t *line;
1029  int pixel_bits = 8 >> pal->size_reduction;
1030 
1031  line = av_malloc(img->frame->linesize[0]);
1032  if (!line)
1033  return AVERROR(ENOMEM);
1034 
1035  for (y = 0; y < img->frame->height; y++) {
1036  p = GET_PIXEL(img->frame, 0, y);
1037  memcpy(line, p, img->frame->linesize[0]);
1038  init_get_bits(&gb_g, line, img->frame->linesize[0] * 8);
1039  skip_bits(&gb_g, 16);
1040  i = 0;
1041  for (x = 0; x < img->frame->width; x++) {
1042  p = GET_PIXEL(img->frame, x, y);
1043  p[2] = get_bits(&gb_g, pixel_bits);
1044  i++;
1045  if (i == 1 << pal->size_reduction) {
1046  skip_bits(&gb_g, 24);
1047  i = 0;
1048  }
1049  }
1050  }
1051  av_free(line);
1052  }
1053 
1054  for (y = 0; y < img->frame->height; y++) {
1055  for (x = 0; x < img->frame->width; x++) {
1056  p = GET_PIXEL(img->frame, x, y);
1057  i = p[2];
1058  if (i >= pal->frame->width) {
1059  av_log(s->avctx, AV_LOG_ERROR, "invalid palette index %d\n", i);
1060  return AVERROR_INVALIDDATA;
1061  }
1062  pi = GET_PIXEL(pal->frame, i, 0);
1063  AV_COPY32(p, pi);
1064  }
1065  }
1066 
1067  return 0;
1068 }
1069 
1071  int *got_frame, uint8_t *data_start,
1072  unsigned int data_size, int is_alpha_chunk)
1073 {
1074  WebPContext *s = avctx->priv_data;
1075  int w, h, ret, i;
1076 
1077  if (!is_alpha_chunk) {
1078  s->lossless = 1;
1079  avctx->pix_fmt = AV_PIX_FMT_ARGB;
1080  }
1081 
1082  ret = init_get_bits(&s->gb, data_start, data_size * 8);
1083  if (ret < 0)
1084  return ret;
1085 
1086  if (!is_alpha_chunk) {
1087  if (get_bits(&s->gb, 8) != 0x2F) {
1088  av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless signature\n");
1089  return AVERROR_INVALIDDATA;
1090  }
1091 
1092  w = get_bits(&s->gb, 14) + 1;
1093  h = get_bits(&s->gb, 14) + 1;
1094  if (s->width && s->width != w) {
1095  av_log(avctx, AV_LOG_WARNING, "Width mismatch. %d != %d\n",
1096  s->width, w);
1097  }
1098  s->width = w;
1099  if (s->height && s->height != h) {
1100  av_log(avctx, AV_LOG_WARNING, "Height mismatch. %d != %d\n",
1101  s->width, w);
1102  }
1103  s->height = h;
1104 
1105  ret = ff_set_dimensions(avctx, s->width, s->height);
1106  if (ret < 0)
1107  return ret;
1108 
1109  s->has_alpha = get_bits1(&s->gb);
1110 
1111  if (get_bits(&s->gb, 3) != 0x0) {
1112  av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless version\n");
1113  return AVERROR_INVALIDDATA;
1114  }
1115  } else {
1116  if (!s->width || !s->height)
1117  return AVERROR_BUG;
1118  w = s->width;
1119  h = s->height;
1120  }
1121 
1122  /* parse transformations */
1123  s->nb_transforms = 0;
1124  s->reduced_width = 0;
1125  while (get_bits1(&s->gb)) {
1126  enum TransformType transform = get_bits(&s->gb, 2);
1127  s->transforms[s->nb_transforms++] = transform;
1128  switch (transform) {
1129  case PREDICTOR_TRANSFORM:
1130  ret = parse_transform_predictor(s);
1131  break;
1132  case COLOR_TRANSFORM:
1133  ret = parse_transform_color(s);
1134  break;
1137  break;
1138  }
1139  if (ret < 0)
1140  goto free_and_return;
1141  }
1142 
1143  /* decode primary image */
1144  s->image[IMAGE_ROLE_ARGB].frame = p;
1145  if (is_alpha_chunk)
1148  if (ret < 0)
1149  goto free_and_return;
1150 
1151  /* apply transformations */
1152  for (i = s->nb_transforms - 1; i >= 0; i--) {
1153  switch (s->transforms[i]) {
1154  case PREDICTOR_TRANSFORM:
1155  ret = apply_predictor_transform(s);
1156  break;
1157  case COLOR_TRANSFORM:
1158  ret = apply_color_transform(s);
1159  break;
1160  case SUBTRACT_GREEN:
1162  break;
1165  break;
1166  }
1167  if (ret < 0)
1168  goto free_and_return;
1169  }
1170 
1171  *got_frame = 1;
1173  p->key_frame = 1;
1174  ret = data_size;
1175 
1176 free_and_return:
1177  for (i = 0; i < IMAGE_ROLE_NB; i++)
1178  image_ctx_free(&s->image[i]);
1179 
1180  return ret;
1181 }
1182 
1183 static void alpha_inverse_prediction(AVFrame *frame, enum AlphaFilter m)
1184 {
1185  int x, y, ls;
1186  uint8_t *dec;
1187 
1188  ls = frame->linesize[3];
1189 
1190  /* filter first row using horizontal filter */
1191  dec = frame->data[3] + 1;
1192  for (x = 1; x < frame->width; x++, dec++)
1193  *dec += *(dec - 1);
1194 
1195  /* filter first column using vertical filter */
1196  dec = frame->data[3] + ls;
1197  for (y = 1; y < frame->height; y++, dec += ls)
1198  *dec += *(dec - ls);
1199 
1200  /* filter the rest using the specified filter */
1201  switch (m) {
1203  for (y = 1; y < frame->height; y++) {
1204  dec = frame->data[3] + y * ls + 1;
1205  for (x = 1; x < frame->width; x++, dec++)
1206  *dec += *(dec - 1);
1207  }
1208  break;
1209  case ALPHA_FILTER_VERTICAL:
1210  for (y = 1; y < frame->height; y++) {
1211  dec = frame->data[3] + y * ls + 1;
1212  for (x = 1; x < frame->width; x++, dec++)
1213  *dec += *(dec - ls);
1214  }
1215  break;
1216  case ALPHA_FILTER_GRADIENT:
1217  for (y = 1; y < frame->height; y++) {
1218  dec = frame->data[3] + y * ls + 1;
1219  for (x = 1; x < frame->width; x++, dec++)
1220  dec[0] += av_clip_uint8(*(dec - 1) + *(dec - ls) - *(dec - ls - 1));
1221  }
1222  break;
1223  }
1224 }
1225 
1227  uint8_t *data_start,
1228  unsigned int data_size)
1229 {
1230  WebPContext *s = avctx->priv_data;
1231  int x, y, ret;
1232 
1234  GetByteContext gb;
1235 
1236  bytestream2_init(&gb, data_start, data_size);
1237  for (y = 0; y < s->height; y++)
1238  bytestream2_get_buffer(&gb, p->data[3] + p->linesize[3] * y,
1239  s->width);
1240  } else if (s->alpha_compression == ALPHA_COMPRESSION_VP8L) {
1241  uint8_t *ap, *pp;
1242  int alpha_got_frame = 0;
1243 
1244  s->alpha_frame = av_frame_alloc();
1245  if (!s->alpha_frame)
1246  return AVERROR(ENOMEM);
1247 
1248  ret = vp8_lossless_decode_frame(avctx, s->alpha_frame, &alpha_got_frame,
1249  data_start, data_size, 1);
1250  if (ret < 0) {
1252  return ret;
1253  }
1254  if (!alpha_got_frame) {
1256  return AVERROR_INVALIDDATA;
1257  }
1258 
1259  /* copy green component of alpha image to alpha plane of primary image */
1260  for (y = 0; y < s->height; y++) {
1261  ap = GET_PIXEL(s->alpha_frame, 0, y) + 2;
1262  pp = p->data[3] + p->linesize[3] * y;
1263  for (x = 0; x < s->width; x++) {
1264  *pp = *ap;
1265  pp++;
1266  ap += 4;
1267  }
1268  }
1270  }
1271 
1272  /* apply alpha filtering */
1273  if (s->alpha_filter)
1275 
1276  return 0;
1277 }
1278 
1280  int *got_frame, uint8_t *data_start,
1281  unsigned int data_size)
1282 {
1283  WebPContext *s = avctx->priv_data;
1284  AVPacket pkt;
1285  int ret;
1286 
1287  if (!s->initialized) {
1288  ff_vp8_decode_init(avctx);
1289  s->initialized = 1;
1290  if (s->has_alpha)
1291  avctx->pix_fmt = AV_PIX_FMT_YUVA420P;
1292  }
1293  s->lossless = 0;
1294 
1295  if (data_size > INT_MAX) {
1296  av_log(avctx, AV_LOG_ERROR, "unsupported chunk size\n");
1297  return AVERROR_PATCHWELCOME;
1298  }
1299 
1300  av_init_packet(&pkt);
1301  pkt.data = data_start;
1302  pkt.size = data_size;
1303 
1304  ret = ff_vp8_decode_frame(avctx, p, got_frame, &pkt);
1305  if (s->has_alpha) {
1306  ret = vp8_lossy_decode_alpha(avctx, p, s->alpha_data,
1307  s->alpha_data_size);
1308  if (ret < 0)
1309  return ret;
1310  }
1311  return ret;
1312 }
1313 
1314 static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
1315  AVPacket *avpkt)
1316 {
1317  AVFrame * const p = data;
1318  WebPContext *s = avctx->priv_data;
1319  GetByteContext gb;
1320  int ret;
1321  uint32_t chunk_type, chunk_size;
1322  int vp8x_flags = 0;
1323 
1324  s->avctx = avctx;
1325  s->width = 0;
1326  s->height = 0;
1327  *got_frame = 0;
1328  s->has_alpha = 0;
1329  bytestream2_init(&gb, avpkt->data, avpkt->size);
1330 
1331  if (bytestream2_get_bytes_left(&gb) < 12)
1332  return AVERROR_INVALIDDATA;
1333 
1334  if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {
1335  av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");
1336  return AVERROR_INVALIDDATA;
1337  }
1338 
1339  chunk_size = bytestream2_get_le32(&gb);
1340  if (bytestream2_get_bytes_left(&gb) < chunk_size)
1341  return AVERROR_INVALIDDATA;
1342 
1343  if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) {
1344  av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n");
1345  return AVERROR_INVALIDDATA;
1346  }
1347 
1348  while (bytestream2_get_bytes_left(&gb) > 0) {
1349  char chunk_str[5] = { 0 };
1350 
1351  chunk_type = bytestream2_get_le32(&gb);
1352  chunk_size = bytestream2_get_le32(&gb);
1353  if (chunk_size == UINT32_MAX)
1354  return AVERROR_INVALIDDATA;
1355  chunk_size += chunk_size & 1;
1356 
1357  if (bytestream2_get_bytes_left(&gb) < chunk_size)
1358  return AVERROR_INVALIDDATA;
1359 
1360  switch (chunk_type) {
1361  case MKTAG('V', 'P', '8', ' '):
1362  if (!*got_frame) {
1363  ret = vp8_lossy_decode_frame(avctx, p, got_frame,
1364  avpkt->data + bytestream2_tell(&gb),
1365  chunk_size);
1366  if (ret < 0)
1367  return ret;
1368  }
1369  bytestream2_skip(&gb, chunk_size);
1370  break;
1371  case MKTAG('V', 'P', '8', 'L'):
1372  if (!*got_frame) {
1373  ret = vp8_lossless_decode_frame(avctx, p, got_frame,
1374  avpkt->data + bytestream2_tell(&gb),
1375  chunk_size, 0);
1376  if (ret < 0)
1377  return ret;
1378  }
1379  bytestream2_skip(&gb, chunk_size);
1380  break;
1381  case MKTAG('V', 'P', '8', 'X'):
1382  vp8x_flags = bytestream2_get_byte(&gb);
1383  bytestream2_skip(&gb, 3);
1384  s->width = bytestream2_get_le24(&gb) + 1;
1385  s->height = bytestream2_get_le24(&gb) + 1;
1386  ret = av_image_check_size(s->width, s->height, 0, avctx);
1387  if (ret < 0)
1388  return ret;
1389  break;
1390  case MKTAG('A', 'L', 'P', 'H'): {
1391  int alpha_header, filter_m, compression;
1392 
1393  if (!(vp8x_flags & VP8X_FLAG_ALPHA)) {
1394  av_log(avctx, AV_LOG_WARNING,
1395  "ALPHA chunk present, but alpha bit not set in the "
1396  "VP8X header\n");
1397  }
1398  if (chunk_size == 0) {
1399  av_log(avctx, AV_LOG_ERROR, "invalid ALPHA chunk size\n");
1400  return AVERROR_INVALIDDATA;
1401  }
1402  alpha_header = bytestream2_get_byte(&gb);
1403  s->alpha_data = avpkt->data + bytestream2_tell(&gb);
1404  s->alpha_data_size = chunk_size - 1;
1406 
1407  filter_m = (alpha_header >> 2) & 0x03;
1408  compression = alpha_header & 0x03;
1409 
1410  if (compression > ALPHA_COMPRESSION_VP8L) {
1411  av_log(avctx, AV_LOG_VERBOSE,
1412  "skipping unsupported ALPHA chunk\n");
1413  } else {
1414  s->has_alpha = 1;
1415  s->alpha_compression = compression;
1416  s->alpha_filter = filter_m;
1417  }
1418 
1419  break;
1420  }
1421  case MKTAG('I', 'C', 'C', 'P'):
1422  case MKTAG('A', 'N', 'I', 'M'):
1423  case MKTAG('A', 'N', 'M', 'F'):
1424  case MKTAG('E', 'X', 'I', 'F'):
1425  case MKTAG('X', 'M', 'P', ' '):
1426  AV_WL32(chunk_str, chunk_type);
1427  av_log(avctx, AV_LOG_VERBOSE, "skipping unsupported chunk: %s\n",
1428  chunk_str);
1429  bytestream2_skip(&gb, chunk_size);
1430  break;
1431  default:
1432  AV_WL32(chunk_str, chunk_type);
1433  av_log(avctx, AV_LOG_VERBOSE, "skipping unknown chunk: %s\n",
1434  chunk_str);
1435  bytestream2_skip(&gb, chunk_size);
1436  break;
1437  }
1438  }
1439 
1440  if (!*got_frame) {
1441  av_log(avctx, AV_LOG_ERROR, "image data not found\n");
1442  return AVERROR_INVALIDDATA;
1443  }
1444 
1445  return avpkt->size;
1446 }
1447 
1449 {
1450  WebPContext *s = avctx->priv_data;
1451 
1452  if (s->initialized)
1453  return ff_vp8_decode_free(avctx);
1454 
1455  return 0;
1456 }
1457 
1459  .name = "webp",
1460  .long_name = NULL_IF_CONFIG_SMALL("WebP image"),
1461  .type = AVMEDIA_TYPE_VIDEO,
1462  .id = AV_CODEC_ID_WEBP,
1463  .priv_data_size = sizeof(WebPContext),
1466  .capabilities = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,
1467 };