FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
webp.c
Go to the documentation of this file.
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 FFmpeg.
7  *
8  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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  * @author James Almer <jamrial@gmail.com>
35  * Exif metadata
36  *
37  * Unimplemented:
38  * - Animation
39  * - ICC profile
40  * - XMP metadata
41  */
42 
43 #define BITSTREAM_READER_LE
44 #include "libavutil/imgutils.h"
45 #include "avcodec.h"
46 #include "bytestream.h"
47 #include "exif.h"
48 #include "internal.h"
49 #include "get_bits.h"
50 #include "thread.h"
51 #include "vp8.h"
52 
53 #define VP8X_FLAG_ANIMATION 0x02
54 #define VP8X_FLAG_XMP_METADATA 0x04
55 #define VP8X_FLAG_EXIF_METADATA 0x08
56 #define VP8X_FLAG_ALPHA 0x10
57 #define VP8X_FLAG_ICC 0x20
58 
59 #define MAX_PALETTE_SIZE 256
60 #define MAX_CACHE_BITS 11
61 #define NUM_CODE_LENGTH_CODES 19
62 #define HUFFMAN_CODES_PER_META_CODE 5
63 #define NUM_LITERAL_CODES 256
64 #define NUM_LENGTH_CODES 24
65 #define NUM_DISTANCE_CODES 40
66 #define NUM_SHORT_DISTANCES 120
67 #define MAX_HUFFMAN_CODE_LENGTH 15
68 
69 static const uint16_t alphabet_sizes[HUFFMAN_CODES_PER_META_CODE] = {
70  NUM_LITERAL_CODES + NUM_LENGTH_CODES,
71  NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES,
72  NUM_DISTANCE_CODES
73 };
74 
75 static const uint8_t code_length_code_order[NUM_CODE_LENGTH_CODES] = {
76  17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
77 };
78 
79 static const int8_t lz77_distance_offsets[NUM_SHORT_DISTANCES][2] = {
80  { 0, 1 }, { 1, 0 }, { 1, 1 }, { -1, 1 }, { 0, 2 }, { 2, 0 }, { 1, 2 }, { -1, 2 },
81  { 2, 1 }, { -2, 1 }, { 2, 2 }, { -2, 2 }, { 0, 3 }, { 3, 0 }, { 1, 3 }, { -1, 3 },
82  { 3, 1 }, { -3, 1 }, { 2, 3 }, { -2, 3 }, { 3, 2 }, { -3, 2 }, { 0, 4 }, { 4, 0 },
83  { 1, 4 }, { -1, 4 }, { 4, 1 }, { -4, 1 }, { 3, 3 }, { -3, 3 }, { 2, 4 }, { -2, 4 },
84  { 4, 2 }, { -4, 2 }, { 0, 5 }, { 3, 4 }, { -3, 4 }, { 4, 3 }, { -4, 3 }, { 5, 0 },
85  { 1, 5 }, { -1, 5 }, { 5, 1 }, { -5, 1 }, { 2, 5 }, { -2, 5 }, { 5, 2 }, { -5, 2 },
86  { 4, 4 }, { -4, 4 }, { 3, 5 }, { -3, 5 }, { 5, 3 }, { -5, 3 }, { 0, 6 }, { 6, 0 },
87  { 1, 6 }, { -1, 6 }, { 6, 1 }, { -6, 1 }, { 2, 6 }, { -2, 6 }, { 6, 2 }, { -6, 2 },
88  { 4, 5 }, { -4, 5 }, { 5, 4 }, { -5, 4 }, { 3, 6 }, { -3, 6 }, { 6, 3 }, { -6, 3 },
89  { 0, 7 }, { 7, 0 }, { 1, 7 }, { -1, 7 }, { 5, 5 }, { -5, 5 }, { 7, 1 }, { -7, 1 },
90  { 4, 6 }, { -4, 6 }, { 6, 4 }, { -6, 4 }, { 2, 7 }, { -2, 7 }, { 7, 2 }, { -7, 2 },
91  { 3, 7 }, { -3, 7 }, { 7, 3 }, { -7, 3 }, { 5, 6 }, { -5, 6 }, { 6, 5 }, { -6, 5 },
92  { 8, 0 }, { 4, 7 }, { -4, 7 }, { 7, 4 }, { -7, 4 }, { 8, 1 }, { 8, 2 }, { 6, 6 },
93  { -6, 6 }, { 8, 3 }, { 5, 7 }, { -5, 7 }, { 7, 5 }, { -7, 5 }, { 8, 4 }, { 6, 7 },
94  { -6, 7 }, { 7, 6 }, { -7, 6 }, { 8, 5 }, { 7, 7 }, { -7, 7 }, { 8, 6 }, { 8, 7 }
95 };
96 
97 enum AlphaCompression {
98  ALPHA_COMPRESSION_NONE,
99  ALPHA_COMPRESSION_VP8L,
100 };
101 
102 enum AlphaFilter {
103  ALPHA_FILTER_NONE,
104  ALPHA_FILTER_HORIZONTAL,
105  ALPHA_FILTER_VERTICAL,
106  ALPHA_FILTER_GRADIENT,
107 };
108 
109 enum TransformType {
110  PREDICTOR_TRANSFORM = 0,
111  COLOR_TRANSFORM = 1,
112  SUBTRACT_GREEN = 2,
113  COLOR_INDEXING_TRANSFORM = 3,
114 };
115 
116 enum PredictionMode {
117  PRED_MODE_BLACK,
118  PRED_MODE_L,
119  PRED_MODE_T,
120  PRED_MODE_TR,
121  PRED_MODE_TL,
122  PRED_MODE_AVG_T_AVG_L_TR,
123  PRED_MODE_AVG_L_TL,
124  PRED_MODE_AVG_L_T,
125  PRED_MODE_AVG_TL_T,
126  PRED_MODE_AVG_T_TR,
127  PRED_MODE_AVG_AVG_L_TL_AVG_T_TR,
128  PRED_MODE_SELECT,
129  PRED_MODE_ADD_SUBTRACT_FULL,
130  PRED_MODE_ADD_SUBTRACT_HALF,
131 };
132 
133 enum HuffmanIndex {
134  HUFF_IDX_GREEN = 0,
135  HUFF_IDX_RED = 1,
136  HUFF_IDX_BLUE = 2,
137  HUFF_IDX_ALPHA = 3,
138  HUFF_IDX_DIST = 4
139 };
140 
141 /* The structure of WebP lossless is an optional series of transformation data,
142  * followed by the primary image. The primary image also optionally contains
143  * an entropy group mapping if there are multiple entropy groups. There is a
144  * basic image type called an "entropy coded image" that is used for all of
145  * these. The type of each entropy coded image is referred to by the
146  * specification as its role. */
147 enum ImageRole {
148  /* Primary Image: Stores the actual pixels of the image. */
149  IMAGE_ROLE_ARGB,
150 
151  /* Entropy Image: Defines which Huffman group to use for different areas of
152  * the primary image. */
153  IMAGE_ROLE_ENTROPY,
154 
155  /* Predictors: Defines which predictor type to use for different areas of
156  * the primary image. */
157  IMAGE_ROLE_PREDICTOR,
158 
159  /* Color Transform Data: Defines the color transformation for different
160  * areas of the primary image. */
161  IMAGE_ROLE_COLOR_TRANSFORM,
162 
163  /* Color Index: Stored as an image of height == 1. */
164  IMAGE_ROLE_COLOR_INDEXING,
165 
166  IMAGE_ROLE_NB,
167 };
168 
169 typedef struct HuffReader {
170  VLC vlc; /* Huffman decoder context */
171  int simple; /* whether to use simple mode */
172  int nb_symbols; /* number of coded symbols */
173  uint16_t simple_symbols[2]; /* symbols for simple mode */
174 } HuffReader;
175 
176 typedef struct ImageContext {
177  enum ImageRole role; /* role of this image */
178  AVFrame *frame; /* AVFrame for data */
179  int color_cache_bits; /* color cache size, log2 */
180  uint32_t *color_cache; /* color cache data */
181  int nb_huffman_groups; /* number of huffman groups */
182  HuffReader *huffman_groups; /* reader for each huffman group */
183  int size_reduction; /* relative size compared to primary image, log2 */
184  int is_alpha_primary;
185 } ImageContext;
186 
187 typedef struct WebPContext {
188  VP8Context v; /* VP8 Context used for lossy decoding */
189  GetBitContext gb; /* bitstream reader for main image chunk */
190  AVFrame *alpha_frame; /* AVFrame for alpha data decompressed from VP8L */
191  AVCodecContext *avctx; /* parent AVCodecContext */
192  int initialized; /* set once the VP8 context is initialized */
193  int has_alpha; /* has a separate alpha chunk */
194  enum AlphaCompression alpha_compression; /* compression type for alpha chunk */
195  enum AlphaFilter alpha_filter; /* filtering method for alpha chunk */
196  uint8_t *alpha_data; /* alpha chunk data */
197  int alpha_data_size; /* alpha chunk data size */
198  int has_exif; /* set after an EXIF chunk has been processed */
199  AVDictionary *exif_metadata; /* EXIF chunk data */
200  int width; /* image width */
201  int height; /* image height */
202  int lossless; /* indicates lossless or lossy */
203 
204  int nb_transforms; /* number of transforms */
205  enum TransformType transforms[4]; /* transformations used in the image, in order */
206  int reduced_width; /* reduced width for index image, if applicable */
207  int nb_huffman_groups; /* number of huffman groups in the primary image */
208  ImageContext image[IMAGE_ROLE_NB]; /* image context for each role */
209 } WebPContext;
210 
211 #define GET_PIXEL(frame, x, y) \
212  ((frame)->data[0] + (y) * frame->linesize[0] + 4 * (x))
213 
214 #define GET_PIXEL_COMP(frame, x, y, c) \
215  (*((frame)->data[0] + (y) * frame->linesize[0] + 4 * (x) + c))
216 
217 static void image_ctx_free(ImageContext *img)
218 {
219  int i, j;
220 
221  av_free(img->color_cache);
222  if (img->role != IMAGE_ROLE_ARGB && !img->is_alpha_primary)
223  av_frame_free(&img->frame);
224  if (img->huffman_groups) {
225  for (i = 0; i < img->nb_huffman_groups; i++) {
226  for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++)
227  ff_free_vlc(&img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE + j].vlc);
228  }
229  av_free(img->huffman_groups);
230  }
231  memset(img, 0, sizeof(*img));
232 }
233 
234 
235 /* Differs from get_vlc2() in the following ways:
236  * - codes are bit-reversed
237  * - assumes 8-bit table to make reversal simpler
238  * - assumes max depth of 2 since the max code length for WebP is 15
239  */
240 static av_always_inline int webp_get_vlc(GetBitContext *gb, VLC_TYPE (*table)[2])
241 {
242  int n, nb_bits;
243  unsigned int index;
244  int code;
245 
246  OPEN_READER(re, gb);
247  UPDATE_CACHE(re, gb);
248 
249  index = SHOW_UBITS(re, gb, 8);
250  index = ff_reverse[index];
251  code = table[index][0];
252  n = table[index][1];
253 
254  if (n < 0) {
255  LAST_SKIP_BITS(re, gb, 8);
256  UPDATE_CACHE(re, gb);
257 
258  nb_bits = -n;
259 
260  index = SHOW_UBITS(re, gb, nb_bits);
261  index = (ff_reverse[index] >> (8 - nb_bits)) + code;
262  code = table[index][0];
263  n = table[index][1];
264  }
265  SKIP_BITS(re, gb, n);
266 
267  CLOSE_READER(re, gb);
268 
269  return code;
270 }
271 
272 static int huff_reader_get_symbol(HuffReader *r, GetBitContext *gb)
273 {
274  if (r->simple) {
275  if (r->nb_symbols == 1)
276  return r->simple_symbols[0];
277  else
278  return r->simple_symbols[get_bits1(gb)];
279  } else
280  return webp_get_vlc(gb, r->vlc.table);
281 }
282 
283 static int huff_reader_build_canonical(HuffReader *r, int *code_lengths,
284  int alphabet_size)
285 {
286  int len = 0, sym, code = 0, ret;
287  int max_code_length = 0;
288  uint16_t *codes;
289 
290  /* special-case 1 symbol since the vlc reader cannot handle it */
291  for (sym = 0; sym < alphabet_size; sym++) {
292  if (code_lengths[sym] > 0) {
293  len++;
294  code = sym;
295  if (len > 1)
296  break;
297  }
298  }
299  if (len == 1) {
300  r->nb_symbols = 1;
301  r->simple_symbols[0] = code;
302  r->simple = 1;
303  return 0;
304  }
305 
306  for (sym = 0; sym < alphabet_size; sym++)
307  max_code_length = FFMAX(max_code_length, code_lengths[sym]);
308 
309  if (max_code_length == 0 || max_code_length > MAX_HUFFMAN_CODE_LENGTH)
310  return AVERROR(EINVAL);
311 
312  codes = av_malloc_array(alphabet_size, sizeof(*codes));
313  if (!codes)
314  return AVERROR(ENOMEM);
315 
316  code = 0;
317  r->nb_symbols = 0;
318  for (len = 1; len <= max_code_length; len++) {
319  for (sym = 0; sym < alphabet_size; sym++) {
320  if (code_lengths[sym] != len)
321  continue;
322  codes[sym] = code++;
323  r->nb_symbols++;
324  }
325  code <<= 1;
326  }
327  if (!r->nb_symbols) {
328  av_free(codes);
329  return AVERROR_INVALIDDATA;
330  }
331 
332  ret = init_vlc(&r->vlc, 8, alphabet_size,
333  code_lengths, sizeof(*code_lengths), sizeof(*code_lengths),
334  codes, sizeof(*codes), sizeof(*codes), 0);
335  if (ret < 0) {
336  av_free(codes);
337  return ret;
338  }
339  r->simple = 0;
340 
341  av_free(codes);
342  return 0;
343 }
344 
345 static void read_huffman_code_simple(WebPContext *s, HuffReader *hc)
346 {
347  hc->nb_symbols = get_bits1(&s->gb) + 1;
348 
349  if (get_bits1(&s->gb))
350  hc->simple_symbols[0] = get_bits(&s->gb, 8);
351  else
352  hc->simple_symbols[0] = get_bits1(&s->gb);
353 
354  if (hc->nb_symbols == 2)
355  hc->simple_symbols[1] = get_bits(&s->gb, 8);
356 
357  hc->simple = 1;
358 }
359 
360 static int read_huffman_code_normal(WebPContext *s, HuffReader *hc,
361  int alphabet_size)
362 {
363  HuffReader code_len_hc = { { 0 }, 0, 0, { 0 } };
364  int *code_lengths = NULL;
365  int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 };
366  int i, symbol, max_symbol, prev_code_len, ret;
367  int num_codes = 4 + get_bits(&s->gb, 4);
368 
369  if (num_codes > NUM_CODE_LENGTH_CODES)
370  return AVERROR_INVALIDDATA;
371 
372  for (i = 0; i < num_codes; i++)
373  code_length_code_lengths[code_length_code_order[i]] = get_bits(&s->gb, 3);
374 
375  ret = huff_reader_build_canonical(&code_len_hc, code_length_code_lengths,
376  NUM_CODE_LENGTH_CODES);
377  if (ret < 0)
378  goto finish;
379 
380  code_lengths = av_mallocz_array(alphabet_size, sizeof(*code_lengths));
381  if (!code_lengths) {
382  ret = AVERROR(ENOMEM);
383  goto finish;
384  }
385 
386  if (get_bits1(&s->gb)) {
387  int bits = 2 + 2 * get_bits(&s->gb, 3);
388  max_symbol = 2 + get_bits(&s->gb, bits);
389  if (max_symbol > alphabet_size) {
390  av_log(s->avctx, AV_LOG_ERROR, "max symbol %d > alphabet size %d\n",
391  max_symbol, alphabet_size);
392  ret = AVERROR_INVALIDDATA;
393  goto finish;
394  }
395  } else {
396  max_symbol = alphabet_size;
397  }
398 
399  prev_code_len = 8;
400  symbol = 0;
401  while (symbol < alphabet_size) {
402  int code_len;
403 
404  if (!max_symbol--)
405  break;
406  code_len = huff_reader_get_symbol(&code_len_hc, &s->gb);
407  if (code_len < 16) {
408  /* Code length code [0..15] indicates literal code lengths. */
409  code_lengths[symbol++] = code_len;
410  if (code_len)
411  prev_code_len = code_len;
412  } else {
413  int repeat = 0, length = 0;
414  switch (code_len) {
415  case 16:
416  /* Code 16 repeats the previous non-zero value [3..6] times,
417  * i.e., 3 + ReadBits(2) times. If code 16 is used before a
418  * non-zero value has been emitted, a value of 8 is repeated. */
419  repeat = 3 + get_bits(&s->gb, 2);
420  length = prev_code_len;
421  break;
422  case 17:
423  /* Code 17 emits a streak of zeros [3..10], i.e.,
424  * 3 + ReadBits(3) times. */
425  repeat = 3 + get_bits(&s->gb, 3);
426  break;
427  case 18:
428  /* Code 18 emits a streak of zeros of length [11..138], i.e.,
429  * 11 + ReadBits(7) times. */
430  repeat = 11 + get_bits(&s->gb, 7);
431  break;
432  }
433  if (symbol + repeat > alphabet_size) {
434  av_log(s->avctx, AV_LOG_ERROR,
435  "invalid symbol %d + repeat %d > alphabet size %d\n",
436  symbol, repeat, alphabet_size);
437  ret = AVERROR_INVALIDDATA;
438  goto finish;
439  }
440  while (repeat-- > 0)
441  code_lengths[symbol++] = length;
442  }
443  }
444 
445  ret = huff_reader_build_canonical(hc, code_lengths, alphabet_size);
446 
447 finish:
448  ff_free_vlc(&code_len_hc.vlc);
449  av_free(code_lengths);
450  return ret;
451 }
452 
453 static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,
454  int w, int h);
455 
456 #define PARSE_BLOCK_SIZE(w, h) do { \
457  block_bits = get_bits(&s->gb, 3) + 2; \
458  blocks_w = FFALIGN((w), 1 << block_bits) >> block_bits; \
459  blocks_h = FFALIGN((h), 1 << block_bits) >> block_bits; \
460 } while (0)
461 
462 static int decode_entropy_image(WebPContext *s)
463 {
464  ImageContext *img;
465  int ret, block_bits, width, blocks_w, blocks_h, x, y, max;
466 
467  width = s->width;
468  if (s->reduced_width > 0)
469  width = s->reduced_width;
470 
471  PARSE_BLOCK_SIZE(width, s->height);
472 
473  ret = decode_entropy_coded_image(s, IMAGE_ROLE_ENTROPY, blocks_w, blocks_h);
474  if (ret < 0)
475  return ret;
476 
477  img = &s->image[IMAGE_ROLE_ENTROPY];
478  img->size_reduction = block_bits;
479 
480  /* the number of huffman groups is determined by the maximum group number
481  * coded in the entropy image */
482  max = 0;
483  for (y = 0; y < img->frame->height; y++) {
484  for (x = 0; x < img->frame->width; x++) {
485  int p0 = GET_PIXEL_COMP(img->frame, x, y, 1);
486  int p1 = GET_PIXEL_COMP(img->frame, x, y, 2);
487  int p = p0 << 8 | p1;
488  max = FFMAX(max, p);
489  }
490  }
491  s->nb_huffman_groups = max + 1;
492 
493  return 0;
494 }
495 
496 static int parse_transform_predictor(WebPContext *s)
497 {
498  int block_bits, blocks_w, blocks_h, ret;
499 
500  PARSE_BLOCK_SIZE(s->width, s->height);
501 
502  ret = decode_entropy_coded_image(s, IMAGE_ROLE_PREDICTOR, blocks_w,
503  blocks_h);
504  if (ret < 0)
505  return ret;
506 
507  s->image[IMAGE_ROLE_PREDICTOR].size_reduction = block_bits;
508 
509  return 0;
510 }
511 
512 static int parse_transform_color(WebPContext *s)
513 {
514  int block_bits, blocks_w, blocks_h, ret;
515 
516  PARSE_BLOCK_SIZE(s->width, s->height);
517 
518  ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_TRANSFORM, blocks_w,
519  blocks_h);
520  if (ret < 0)
521  return ret;
522 
523  s->image[IMAGE_ROLE_COLOR_TRANSFORM].size_reduction = block_bits;
524 
525  return 0;
526 }
527 
528 static int parse_transform_color_indexing(WebPContext *s)
529 {
530  ImageContext *img;
531  int width_bits, index_size, ret, x;
532  uint8_t *ct;
533 
534  index_size = get_bits(&s->gb, 8) + 1;
535 
536  if (index_size <= 2)
537  width_bits = 3;
538  else if (index_size <= 4)
539  width_bits = 2;
540  else if (index_size <= 16)
541  width_bits = 1;
542  else
543  width_bits = 0;
544 
545  ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_INDEXING,
546  index_size, 1);
547  if (ret < 0)
548  return ret;
549 
550  img = &s->image[IMAGE_ROLE_COLOR_INDEXING];
551  img->size_reduction = width_bits;
552  if (width_bits > 0)
553  s->reduced_width = (s->width + ((1 << width_bits) - 1)) >> width_bits;
554 
555  /* color index values are delta-coded */
556  ct = img->frame->data[0] + 4;
557  for (x = 4; x < img->frame->width * 4; x++, ct++)
558  ct[0] += ct[-4];
559 
560  return 0;
561 }
562 
563 static HuffReader *get_huffman_group(WebPContext *s, ImageContext *img,
564  int x, int y)
565 {
566  ImageContext *gimg = &s->image[IMAGE_ROLE_ENTROPY];
567  int group = 0;
568 
569  if (gimg->size_reduction > 0) {
570  int group_x = x >> gimg->size_reduction;
571  int group_y = y >> gimg->size_reduction;
572  int g0 = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 1);
573  int g1 = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2);
574  group = g0 << 8 | g1;
575  }
576 
577  return &img->huffman_groups[group * HUFFMAN_CODES_PER_META_CODE];
578 }
579 
580 static av_always_inline void color_cache_put(ImageContext *img, uint32_t c)
581 {
582  uint32_t cache_idx = (0x1E35A7BD * c) >> (32 - img->color_cache_bits);
583  img->color_cache[cache_idx] = c;
584 }
585 
586 static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,
587  int w, int h)
588 {
589  ImageContext *img;
590  HuffReader *hg;
591  int i, j, ret, x, y, width;
592 
593  img = &s->image[role];
594  img->role = role;
595 
596  if (!img->frame) {
597  img->frame = av_frame_alloc();
598  if (!img->frame)
599  return AVERROR(ENOMEM);
600  }
601 
602  img->frame->format = AV_PIX_FMT_ARGB;
603  img->frame->width = w;
604  img->frame->height = h;
605 
606  if (role == IMAGE_ROLE_ARGB && !img->is_alpha_primary) {
607  ThreadFrame pt = { .f = img->frame };
608  ret = ff_thread_get_buffer(s->avctx, &pt, 0);
609  } else
610  ret = av_frame_get_buffer(img->frame, 1);
611  if (ret < 0)
612  return ret;
613 
614  if (get_bits1(&s->gb)) {
615  img->color_cache_bits = get_bits(&s->gb, 4);
616  if (img->color_cache_bits < 1 || img->color_cache_bits > 11) {
617  av_log(s->avctx, AV_LOG_ERROR, "invalid color cache bits: %d\n",
618  img->color_cache_bits);
619  return AVERROR_INVALIDDATA;
620  }
621  img->color_cache = av_mallocz_array(1 << img->color_cache_bits,
622  sizeof(*img->color_cache));
623  if (!img->color_cache)
624  return AVERROR(ENOMEM);
625  } else {
626  img->color_cache_bits = 0;
627  }
628 
629  img->nb_huffman_groups = 1;
630  if (role == IMAGE_ROLE_ARGB && get_bits1(&s->gb)) {
631  ret = decode_entropy_image(s);
632  if (ret < 0)
633  return ret;
634  img->nb_huffman_groups = s->nb_huffman_groups;
635  }
636  img->huffman_groups = av_mallocz_array(img->nb_huffman_groups *
637  HUFFMAN_CODES_PER_META_CODE,
638  sizeof(*img->huffman_groups));
639  if (!img->huffman_groups)
640  return AVERROR(ENOMEM);
641 
642  for (i = 0; i < img->nb_huffman_groups; i++) {
643  hg = &img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE];
644  for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++) {
645  int alphabet_size = alphabet_sizes[j];
646  if (!j && img->color_cache_bits > 0)
647  alphabet_size += 1 << img->color_cache_bits;
648 
649  if (get_bits1(&s->gb)) {
650  read_huffman_code_simple(s, &hg[j]);
651  } else {
652  ret = read_huffman_code_normal(s, &hg[j], alphabet_size);
653  if (ret < 0)
654  return ret;
655  }
656  }
657  }
658 
659  width = img->frame->width;
660  if (role == IMAGE_ROLE_ARGB && s->reduced_width > 0)
661  width = s->reduced_width;
662 
663  x = 0; y = 0;
664  while (y < img->frame->height) {
665  int v;
666 
667  hg = get_huffman_group(s, img, x, y);
668  v = huff_reader_get_symbol(&hg[HUFF_IDX_GREEN], &s->gb);
669  if (v < NUM_LITERAL_CODES) {
670  /* literal pixel values */
671  uint8_t *p = GET_PIXEL(img->frame, x, y);
672  p[2] = v;
673  p[1] = huff_reader_get_symbol(&hg[HUFF_IDX_RED], &s->gb);
674  p[3] = huff_reader_get_symbol(&hg[HUFF_IDX_BLUE], &s->gb);
675  p[0] = huff_reader_get_symbol(&hg[HUFF_IDX_ALPHA], &s->gb);
676  if (img->color_cache_bits)
677  color_cache_put(img, AV_RB32(p));
678  x++;
679  if (x == width) {
680  x = 0;
681  y++;
682  }
683  } else if (v < NUM_LITERAL_CODES + NUM_LENGTH_CODES) {
684  /* LZ77 backwards mapping */
685  int prefix_code, length, distance, ref_x, ref_y;
686 
687  /* parse length and distance */
688  prefix_code = v - NUM_LITERAL_CODES;
689  if (prefix_code < 4) {
690  length = prefix_code + 1;
691  } else {
692  int extra_bits = (prefix_code - 2) >> 1;
693  int offset = 2 + (prefix_code & 1) << extra_bits;
694  length = offset + get_bits(&s->gb, extra_bits) + 1;
695  }
696  prefix_code = huff_reader_get_symbol(&hg[HUFF_IDX_DIST], &s->gb);
697  if (prefix_code > 39) {
698  av_log(s->avctx, AV_LOG_ERROR,
699  "distance prefix code too large: %d\n", prefix_code);
700  return AVERROR_INVALIDDATA;
701  }
702  if (prefix_code < 4) {
703  distance = prefix_code + 1;
704  } else {
705  int extra_bits = prefix_code - 2 >> 1;
706  int offset = 2 + (prefix_code & 1) << extra_bits;
707  distance = offset + get_bits(&s->gb, extra_bits) + 1;
708  }
709 
710  /* find reference location */
711  if (distance <= NUM_SHORT_DISTANCES) {
712  int xi = lz77_distance_offsets[distance - 1][0];
713  int yi = lz77_distance_offsets[distance - 1][1];
714  distance = FFMAX(1, xi + yi * width);
715  } else {
716  distance -= NUM_SHORT_DISTANCES;
717  }
718  ref_x = x;
719  ref_y = y;
720  if (distance <= x) {
721  ref_x -= distance;
722  distance = 0;
723  } else {
724  ref_x = 0;
725  distance -= x;
726  }
727  while (distance >= width) {
728  ref_y--;
729  distance -= width;
730  }
731  if (distance > 0) {
732  ref_x = width - distance;
733  ref_y--;
734  }
735  ref_x = FFMAX(0, ref_x);
736  ref_y = FFMAX(0, ref_y);
737 
738  /* copy pixels
739  * source and dest regions can overlap and wrap lines, so just
740  * copy per-pixel */
741  for (i = 0; i < length; i++) {
742  uint8_t *p_ref = GET_PIXEL(img->frame, ref_x, ref_y);
743  uint8_t *p = GET_PIXEL(img->frame, x, y);
744 
745  AV_COPY32(p, p_ref);
746  if (img->color_cache_bits)
747  color_cache_put(img, AV_RB32(p));
748  x++;
749  ref_x++;
750  if (x == width) {
751  x = 0;
752  y++;
753  }
754  if (ref_x == width) {
755  ref_x = 0;
756  ref_y++;
757  }
758  if (y == img->frame->height || ref_y == img->frame->height)
759  break;
760  }
761  } else {
762  /* read from color cache */
763  uint8_t *p = GET_PIXEL(img->frame, x, y);
764  int cache_idx = v - (NUM_LITERAL_CODES + NUM_LENGTH_CODES);
765 
766  if (!img->color_cache_bits) {
767  av_log(s->avctx, AV_LOG_ERROR, "color cache not found\n");
768  return AVERROR_INVALIDDATA;
769  }
770  if (cache_idx >= 1 << img->color_cache_bits) {
771  av_log(s->avctx, AV_LOG_ERROR,
772  "color cache index out-of-bounds\n");
773  return AVERROR_INVALIDDATA;
774  }
775  AV_WB32(p, img->color_cache[cache_idx]);
776  x++;
777  if (x == width) {
778  x = 0;
779  y++;
780  }
781  }
782  }
783 
784  return 0;
785 }
786 
787 /* PRED_MODE_BLACK */
788 static void inv_predict_0(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
789  const uint8_t *p_t, const uint8_t *p_tr)
790 {
791  AV_WB32(p, 0xFF000000);
792 }
793 
794 /* PRED_MODE_L */
795 static void inv_predict_1(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
796  const uint8_t *p_t, const uint8_t *p_tr)
797 {
798  AV_COPY32(p, p_l);
799 }
800 
801 /* PRED_MODE_T */
802 static void inv_predict_2(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
803  const uint8_t *p_t, const uint8_t *p_tr)
804 {
805  AV_COPY32(p, p_t);
806 }
807 
808 /* PRED_MODE_TR */
809 static void inv_predict_3(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
810  const uint8_t *p_t, const uint8_t *p_tr)
811 {
812  AV_COPY32(p, p_tr);
813 }
814 
815 /* PRED_MODE_TL */
816 static void inv_predict_4(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
817  const uint8_t *p_t, const uint8_t *p_tr)
818 {
819  AV_COPY32(p, p_tl);
820 }
821 
822 /* PRED_MODE_AVG_T_AVG_L_TR */
823 static void inv_predict_5(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
824  const uint8_t *p_t, const uint8_t *p_tr)
825 {
826  p[0] = p_t[0] + (p_l[0] + p_tr[0] >> 1) >> 1;
827  p[1] = p_t[1] + (p_l[1] + p_tr[1] >> 1) >> 1;
828  p[2] = p_t[2] + (p_l[2] + p_tr[2] >> 1) >> 1;
829  p[3] = p_t[3] + (p_l[3] + p_tr[3] >> 1) >> 1;
830 }
831 
832 /* PRED_MODE_AVG_L_TL */
833 static void inv_predict_6(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
834  const uint8_t *p_t, const uint8_t *p_tr)
835 {
836  p[0] = p_l[0] + p_tl[0] >> 1;
837  p[1] = p_l[1] + p_tl[1] >> 1;
838  p[2] = p_l[2] + p_tl[2] >> 1;
839  p[3] = p_l[3] + p_tl[3] >> 1;
840 }
841 
842 /* PRED_MODE_AVG_L_T */
843 static void inv_predict_7(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
844  const uint8_t *p_t, const uint8_t *p_tr)
845 {
846  p[0] = p_l[0] + p_t[0] >> 1;
847  p[1] = p_l[1] + p_t[1] >> 1;
848  p[2] = p_l[2] + p_t[2] >> 1;
849  p[3] = p_l[3] + p_t[3] >> 1;
850 }
851 
852 /* PRED_MODE_AVG_TL_T */
853 static void inv_predict_8(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
854  const uint8_t *p_t, const uint8_t *p_tr)
855 {
856  p[0] = p_tl[0] + p_t[0] >> 1;
857  p[1] = p_tl[1] + p_t[1] >> 1;
858  p[2] = p_tl[2] + p_t[2] >> 1;
859  p[3] = p_tl[3] + p_t[3] >> 1;
860 }
861 
862 /* PRED_MODE_AVG_T_TR */
863 static void inv_predict_9(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
864  const uint8_t *p_t, const uint8_t *p_tr)
865 {
866  p[0] = p_t[0] + p_tr[0] >> 1;
867  p[1] = p_t[1] + p_tr[1] >> 1;
868  p[2] = p_t[2] + p_tr[2] >> 1;
869  p[3] = p_t[3] + p_tr[3] >> 1;
870 }
871 
872 /* PRED_MODE_AVG_AVG_L_TL_AVG_T_TR */
873 static void inv_predict_10(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
874  const uint8_t *p_t, const uint8_t *p_tr)
875 {
876  p[0] = (p_l[0] + p_tl[0] >> 1) + (p_t[0] + p_tr[0] >> 1) >> 1;
877  p[1] = (p_l[1] + p_tl[1] >> 1) + (p_t[1] + p_tr[1] >> 1) >> 1;
878  p[2] = (p_l[2] + p_tl[2] >> 1) + (p_t[2] + p_tr[2] >> 1) >> 1;
879  p[3] = (p_l[3] + p_tl[3] >> 1) + (p_t[3] + p_tr[3] >> 1) >> 1;
880 }
881 
882 /* PRED_MODE_SELECT */
883 static void inv_predict_11(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
884  const uint8_t *p_t, const uint8_t *p_tr)
885 {
886  int diff = (FFABS(p_l[0] - p_tl[0]) - FFABS(p_t[0] - p_tl[0])) +
887  (FFABS(p_l[1] - p_tl[1]) - FFABS(p_t[1] - p_tl[1])) +
888  (FFABS(p_l[2] - p_tl[2]) - FFABS(p_t[2] - p_tl[2])) +
889  (FFABS(p_l[3] - p_tl[3]) - FFABS(p_t[3] - p_tl[3]));
890  if (diff <= 0)
891  AV_COPY32(p, p_t);
892  else
893  AV_COPY32(p, p_l);
894 }
895 
896 /* PRED_MODE_ADD_SUBTRACT_FULL */
897 static void inv_predict_12(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
898  const uint8_t *p_t, const uint8_t *p_tr)
899 {
900  p[0] = av_clip_uint8(p_l[0] + p_t[0] - p_tl[0]);
901  p[1] = av_clip_uint8(p_l[1] + p_t[1] - p_tl[1]);
902  p[2] = av_clip_uint8(p_l[2] + p_t[2] - p_tl[2]);
903  p[3] = av_clip_uint8(p_l[3] + p_t[3] - p_tl[3]);
904 }
905 
906 static av_always_inline uint8_t clamp_add_subtract_half(int a, int b, int c)
907 {
908  int d = a + b >> 1;
909  return av_clip_uint8(d + (d - c) / 2);
910 }
911 
912 /* PRED_MODE_ADD_SUBTRACT_HALF */
913 static void inv_predict_13(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
914  const uint8_t *p_t, const uint8_t *p_tr)
915 {
916  p[0] = clamp_add_subtract_half(p_l[0], p_t[0], p_tl[0]);
917  p[1] = clamp_add_subtract_half(p_l[1], p_t[1], p_tl[1]);
918  p[2] = clamp_add_subtract_half(p_l[2], p_t[2], p_tl[2]);
919  p[3] = clamp_add_subtract_half(p_l[3], p_t[3], p_tl[3]);
920 }
921 
922 typedef void (*inv_predict_func)(uint8_t *p, const uint8_t *p_l,
923  const uint8_t *p_tl, const uint8_t *p_t,
924  const uint8_t *p_tr);
925 
926 static const inv_predict_func inverse_predict[14] = {
927  inv_predict_0, inv_predict_1, inv_predict_2, inv_predict_3,
928  inv_predict_4, inv_predict_5, inv_predict_6, inv_predict_7,
929  inv_predict_8, inv_predict_9, inv_predict_10, inv_predict_11,
930  inv_predict_12, inv_predict_13,
931 };
932 
933 static void inverse_prediction(AVFrame *frame, enum PredictionMode m, int x, int y)
934 {
935  uint8_t *dec, *p_l, *p_tl, *p_t, *p_tr;
936  uint8_t p[4];
937 
938  dec = GET_PIXEL(frame, x, y);
939  p_l = GET_PIXEL(frame, x - 1, y);
940  p_tl = GET_PIXEL(frame, x - 1, y - 1);
941  p_t = GET_PIXEL(frame, x, y - 1);
942  if (x == frame->width - 1)
943  p_tr = GET_PIXEL(frame, 0, y);
944  else
945  p_tr = GET_PIXEL(frame, x + 1, y - 1);
946 
947  inverse_predict[m](p, p_l, p_tl, p_t, p_tr);
948 
949  dec[0] += p[0];
950  dec[1] += p[1];
951  dec[2] += p[2];
952  dec[3] += p[3];
953 }
954 
955 static int apply_predictor_transform(WebPContext *s)
956 {
957  ImageContext *img = &s->image[IMAGE_ROLE_ARGB];
958  ImageContext *pimg = &s->image[IMAGE_ROLE_PREDICTOR];
959  int x, y;
960 
961  for (y = 0; y < img->frame->height; y++) {
962  for (x = 0; x < img->frame->width; x++) {
963  int tx = x >> pimg->size_reduction;
964  int ty = y >> pimg->size_reduction;
965  enum PredictionMode m = GET_PIXEL_COMP(pimg->frame, tx, ty, 2);
966 
967  if (x == 0) {
968  if (y == 0)
969  m = PRED_MODE_BLACK;
970  else
971  m = PRED_MODE_T;
972  } else if (y == 0)
973  m = PRED_MODE_L;
974 
975  if (m > 13) {
976  av_log(s->avctx, AV_LOG_ERROR,
977  "invalid predictor mode: %d\n", m);
978  return AVERROR_INVALIDDATA;
979  }
980  inverse_prediction(img->frame, m, x, y);
981  }
982  }
983  return 0;
984 }
985 
986 static av_always_inline uint8_t color_transform_delta(uint8_t color_pred,
987  uint8_t color)
988 {
989  return (int)ff_u8_to_s8(color_pred) * ff_u8_to_s8(color) >> 5;
990 }
991 
992 static int apply_color_transform(WebPContext *s)
993 {
994  ImageContext *img, *cimg;
995  int x, y, cx, cy;
996  uint8_t *p, *cp;
997 
998  img = &s->image[IMAGE_ROLE_ARGB];
999  cimg = &s->image[IMAGE_ROLE_COLOR_TRANSFORM];
1000 
1001  for (y = 0; y < img->frame->height; y++) {
1002  for (x = 0; x < img->frame->width; x++) {
1003  cx = x >> cimg->size_reduction;
1004  cy = y >> cimg->size_reduction;
1005  cp = GET_PIXEL(cimg->frame, cx, cy);
1006  p = GET_PIXEL(img->frame, x, y);
1007 
1008  p[1] += color_transform_delta(cp[3], p[2]);
1009  p[3] += color_transform_delta(cp[2], p[2]) +
1010  color_transform_delta(cp[1], p[1]);
1011  }
1012  }
1013  return 0;
1014 }
1015 
1016 static int apply_subtract_green_transform(WebPContext *s)
1017 {
1018  int x, y;
1019  ImageContext *img = &s->image[IMAGE_ROLE_ARGB];
1020 
1021  for (y = 0; y < img->frame->height; y++) {
1022  for (x = 0; x < img->frame->width; x++) {
1023  uint8_t *p = GET_PIXEL(img->frame, x, y);
1024  p[1] += p[2];
1025  p[3] += p[2];
1026  }
1027  }
1028  return 0;
1029 }
1030 
1031 static int apply_color_indexing_transform(WebPContext *s)
1032 {
1033  ImageContext *img;
1034  ImageContext *pal;
1035  int i, x, y;
1036  uint8_t *p;
1037 
1038  img = &s->image[IMAGE_ROLE_ARGB];
1039  pal = &s->image[IMAGE_ROLE_COLOR_INDEXING];
1040 
1041  if (pal->size_reduction > 0) {
1042  GetBitContext gb_g;
1043  uint8_t *line;
1044  int pixel_bits = 8 >> pal->size_reduction;
1045 
1046  line = av_malloc(img->frame->linesize[0]);
1047  if (!line)
1048  return AVERROR(ENOMEM);
1049 
1050  for (y = 0; y < img->frame->height; y++) {
1051  p = GET_PIXEL(img->frame, 0, y);
1052  memcpy(line, p, img->frame->linesize[0]);
1053  init_get_bits(&gb_g, line, img->frame->linesize[0] * 8);
1054  skip_bits(&gb_g, 16);
1055  i = 0;
1056  for (x = 0; x < img->frame->width; x++) {
1057  p = GET_PIXEL(img->frame, x, y);
1058  p[2] = get_bits(&gb_g, pixel_bits);
1059  i++;
1060  if (i == 1 << pal->size_reduction) {
1061  skip_bits(&gb_g, 24);
1062  i = 0;
1063  }
1064  }
1065  }
1066  av_free(line);
1067  }
1068 
1069  // switch to local palette if it's worth initializing it
1070  if (img->frame->height * img->frame->width > 300) {
1071  uint8_t palette[256 * 4];
1072  const int size = pal->frame->width * 4;
1073  av_assert0(size <= 1024U);
1074  memcpy(palette, GET_PIXEL(pal->frame, 0, 0), size); // copy palette
1075  // set extra entries to transparent black
1076  memset(palette + size, 0, 256 * 4 - size);
1077  for (y = 0; y < img->frame->height; y++) {
1078  for (x = 0; x < img->frame->width; x++) {
1079  p = GET_PIXEL(img->frame, x, y);
1080  i = p[2];
1081  AV_COPY32(p, &palette[i * 4]);
1082  }
1083  }
1084  } else {
1085  for (y = 0; y < img->frame->height; y++) {
1086  for (x = 0; x < img->frame->width; x++) {
1087  p = GET_PIXEL(img->frame, x, y);
1088  i = p[2];
1089  if (i >= pal->frame->width) {
1090  AV_WB32(p, 0x00000000);
1091  } else {
1092  const uint8_t *pi = GET_PIXEL(pal->frame, i, 0);
1093  AV_COPY32(p, pi);
1094  }
1095  }
1096  }
1097  }
1098 
1099  return 0;
1100 }
1101 
1102 static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p,
1103  int *got_frame, uint8_t *data_start,
1104  unsigned int data_size, int is_alpha_chunk)
1105 {
1106  WebPContext *s = avctx->priv_data;
1107  int w, h, ret, i, used;
1108 
1109  if (!is_alpha_chunk) {
1110  s->lossless = 1;
1111  avctx->pix_fmt = AV_PIX_FMT_ARGB;
1112  }
1113 
1114  ret = init_get_bits8(&s->gb, data_start, data_size);
1115  if (ret < 0)
1116  return ret;
1117 
1118  if (!is_alpha_chunk) {
1119  if (get_bits(&s->gb, 8) != 0x2F) {
1120  av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless signature\n");
1121  return AVERROR_INVALIDDATA;
1122  }
1123 
1124  w = get_bits(&s->gb, 14) + 1;
1125  h = get_bits(&s->gb, 14) + 1;
1126  if (s->width && s->width != w) {
1127  av_log(avctx, AV_LOG_WARNING, "Width mismatch. %d != %d\n",
1128  s->width, w);
1129  }
1130  s->width = w;
1131  if (s->height && s->height != h) {
1132  av_log(avctx, AV_LOG_WARNING, "Height mismatch. %d != %d\n",
1133  s->width, w);
1134  }
1135  s->height = h;
1136 
1137  ret = ff_set_dimensions(avctx, s->width, s->height);
1138  if (ret < 0)
1139  return ret;
1140 
1141  s->has_alpha = get_bits1(&s->gb);
1142 
1143  if (get_bits(&s->gb, 3) != 0x0) {
1144  av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless version\n");
1145  return AVERROR_INVALIDDATA;
1146  }
1147  } else {
1148  if (!s->width || !s->height)
1149  return AVERROR_BUG;
1150  w = s->width;
1151  h = s->height;
1152  }
1153 
1154  /* parse transformations */
1155  s->nb_transforms = 0;
1156  s->reduced_width = 0;
1157  used = 0;
1158  while (get_bits1(&s->gb)) {
1159  enum TransformType transform = get_bits(&s->gb, 2);
1160  if (used & (1 << transform)) {
1161  av_log(avctx, AV_LOG_ERROR, "Transform %d used more than once\n",
1162  transform);
1163  ret = AVERROR_INVALIDDATA;
1164  goto free_and_return;
1165  }
1166  used |= (1 << transform);
1167  s->transforms[s->nb_transforms++] = transform;
1168  switch (transform) {
1169  case PREDICTOR_TRANSFORM:
1170  ret = parse_transform_predictor(s);
1171  break;
1172  case COLOR_TRANSFORM:
1173  ret = parse_transform_color(s);
1174  break;
1175  case COLOR_INDEXING_TRANSFORM:
1176  ret = parse_transform_color_indexing(s);
1177  break;
1178  }
1179  if (ret < 0)
1180  goto free_and_return;
1181  }
1182 
1183  /* decode primary image */
1184  s->image[IMAGE_ROLE_ARGB].frame = p;
1185  if (is_alpha_chunk)
1186  s->image[IMAGE_ROLE_ARGB].is_alpha_primary = 1;
1187  ret = decode_entropy_coded_image(s, IMAGE_ROLE_ARGB, w, h);
1188  if (ret < 0)
1189  goto free_and_return;
1190 
1191  /* apply transformations */
1192  for (i = s->nb_transforms - 1; i >= 0; i--) {
1193  switch (s->transforms[i]) {
1194  case PREDICTOR_TRANSFORM:
1195  ret = apply_predictor_transform(s);
1196  break;
1197  case COLOR_TRANSFORM:
1198  ret = apply_color_transform(s);
1199  break;
1200  case SUBTRACT_GREEN:
1201  ret = apply_subtract_green_transform(s);
1202  break;
1203  case COLOR_INDEXING_TRANSFORM:
1204  ret = apply_color_indexing_transform(s);
1205  break;
1206  }
1207  if (ret < 0)
1208  goto free_and_return;
1209  }
1210 
1211  *got_frame = 1;
1212  p->pict_type = AV_PICTURE_TYPE_I;
1213  p->key_frame = 1;
1214  ret = data_size;
1215 
1216 free_and_return:
1217  for (i = 0; i < IMAGE_ROLE_NB; i++)
1218  image_ctx_free(&s->image[i]);
1219 
1220  return ret;
1221 }
1222 
1223 static void alpha_inverse_prediction(AVFrame *frame, enum AlphaFilter m)
1224 {
1225  int x, y, ls;
1226  uint8_t *dec;
1227 
1228  ls = frame->linesize[3];
1229 
1230  /* filter first row using horizontal filter */
1231  dec = frame->data[3] + 1;
1232  for (x = 1; x < frame->width; x++, dec++)
1233  *dec += *(dec - 1);
1234 
1235  /* filter first column using vertical filter */
1236  dec = frame->data[3] + ls;
1237  for (y = 1; y < frame->height; y++, dec += ls)
1238  *dec += *(dec - ls);
1239 
1240  /* filter the rest using the specified filter */
1241  switch (m) {
1242  case ALPHA_FILTER_HORIZONTAL:
1243  for (y = 1; y < frame->height; y++) {
1244  dec = frame->data[3] + y * ls + 1;
1245  for (x = 1; x < frame->width; x++, dec++)
1246  *dec += *(dec - 1);
1247  }
1248  break;
1249  case ALPHA_FILTER_VERTICAL:
1250  for (y = 1; y < frame->height; y++) {
1251  dec = frame->data[3] + y * ls + 1;
1252  for (x = 1; x < frame->width; x++, dec++)
1253  *dec += *(dec - ls);
1254  }
1255  break;
1256  case ALPHA_FILTER_GRADIENT:
1257  for (y = 1; y < frame->height; y++) {
1258  dec = frame->data[3] + y * ls + 1;
1259  for (x = 1; x < frame->width; x++, dec++)
1260  dec[0] += av_clip_uint8(*(dec - 1) + *(dec - ls) - *(dec - ls - 1));
1261  }
1262  break;
1263  }
1264 }
1265 
1266 static int vp8_lossy_decode_alpha(AVCodecContext *avctx, AVFrame *p,
1267  uint8_t *data_start,
1268  unsigned int data_size)
1269 {
1270  WebPContext *s = avctx->priv_data;
1271  int x, y, ret;
1272 
1273  if (s->alpha_compression == ALPHA_COMPRESSION_NONE) {
1274  GetByteContext gb;
1275 
1276  bytestream2_init(&gb, data_start, data_size);
1277  for (y = 0; y < s->height; y++)
1278  bytestream2_get_buffer(&gb, p->data[3] + p->linesize[3] * y,
1279  s->width);
1280  } else if (s->alpha_compression == ALPHA_COMPRESSION_VP8L) {
1281  uint8_t *ap, *pp;
1282  int alpha_got_frame = 0;
1283 
1284  s->alpha_frame = av_frame_alloc();
1285  if (!s->alpha_frame)
1286  return AVERROR(ENOMEM);
1287 
1288  ret = vp8_lossless_decode_frame(avctx, s->alpha_frame, &alpha_got_frame,
1289  data_start, data_size, 1);
1290  if (ret < 0) {
1291  av_frame_free(&s->alpha_frame);
1292  return ret;
1293  }
1294  if (!alpha_got_frame) {
1295  av_frame_free(&s->alpha_frame);
1296  return AVERROR_INVALIDDATA;
1297  }
1298 
1299  /* copy green component of alpha image to alpha plane of primary image */
1300  for (y = 0; y < s->height; y++) {
1301  ap = GET_PIXEL(s->alpha_frame, 0, y) + 2;
1302  pp = p->data[3] + p->linesize[3] * y;
1303  for (x = 0; x < s->width; x++) {
1304  *pp = *ap;
1305  pp++;
1306  ap += 4;
1307  }
1308  }
1309  av_frame_free(&s->alpha_frame);
1310  }
1311 
1312  /* apply alpha filtering */
1313  if (s->alpha_filter)
1314  alpha_inverse_prediction(p, s->alpha_filter);
1315 
1316  return 0;
1317 }
1318 
1319 static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,
1320  int *got_frame, uint8_t *data_start,
1321  unsigned int data_size)
1322 {
1323  WebPContext *s = avctx->priv_data;
1324  AVPacket pkt;
1325  int ret;
1326 
1327  if (!s->initialized) {
1328  ff_vp8_decode_init(avctx);
1329  s->initialized = 1;
1330  if (s->has_alpha)
1331  avctx->pix_fmt = AV_PIX_FMT_YUVA420P;
1332  }
1333  s->lossless = 0;
1334 
1335  if (data_size > INT_MAX) {
1336  av_log(avctx, AV_LOG_ERROR, "unsupported chunk size\n");
1337  return AVERROR_PATCHWELCOME;
1338  }
1339 
1340  av_init_packet(&pkt);
1341  pkt.data = data_start;
1342  pkt.size = data_size;
1343 
1344  ret = ff_vp8_decode_frame(avctx, p, got_frame, &pkt);
1345  if (s->has_alpha) {
1346  ret = vp8_lossy_decode_alpha(avctx, p, s->alpha_data,
1347  s->alpha_data_size);
1348  if (ret < 0)
1349  return ret;
1350  }
1351  return ret;
1352 }
1353 
1354 static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
1355  AVPacket *avpkt)
1356 {
1357  AVFrame * const p = data;
1358  WebPContext *s = avctx->priv_data;
1359  GetByteContext gb;
1360  int ret;
1361  uint32_t chunk_type, chunk_size;
1362  int vp8x_flags = 0;
1363 
1364  s->avctx = avctx;
1365  s->width = 0;
1366  s->height = 0;
1367  *got_frame = 0;
1368  s->has_alpha = 0;
1369  s->has_exif = 0;
1370  bytestream2_init(&gb, avpkt->data, avpkt->size);
1371 
1372  if (bytestream2_get_bytes_left(&gb) < 12)
1373  return AVERROR_INVALIDDATA;
1374 
1375  if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {
1376  av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");
1377  return AVERROR_INVALIDDATA;
1378  }
1379 
1380  chunk_size = bytestream2_get_le32(&gb);
1381  if (bytestream2_get_bytes_left(&gb) < chunk_size)
1382  return AVERROR_INVALIDDATA;
1383 
1384  if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) {
1385  av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n");
1386  return AVERROR_INVALIDDATA;
1387  }
1388 
1389  av_dict_free(&s->exif_metadata);
1390  while (bytestream2_get_bytes_left(&gb) > 0) {
1391  char chunk_str[5] = { 0 };
1392 
1393  chunk_type = bytestream2_get_le32(&gb);
1394  chunk_size = bytestream2_get_le32(&gb);
1395  if (chunk_size == UINT32_MAX)
1396  return AVERROR_INVALIDDATA;
1397  chunk_size += chunk_size & 1;
1398 
1399  if (bytestream2_get_bytes_left(&gb) < chunk_size)
1400  return AVERROR_INVALIDDATA;
1401 
1402  switch (chunk_type) {
1403  case MKTAG('V', 'P', '8', ' '):
1404  if (!*got_frame) {
1405  ret = vp8_lossy_decode_frame(avctx, p, got_frame,
1406  avpkt->data + bytestream2_tell(&gb),
1407  chunk_size);
1408  if (ret < 0)
1409  return ret;
1410  }
1411  bytestream2_skip(&gb, chunk_size);
1412  break;
1413  case MKTAG('V', 'P', '8', 'L'):
1414  if (!*got_frame) {
1415  ret = vp8_lossless_decode_frame(avctx, p, got_frame,
1416  avpkt->data + bytestream2_tell(&gb),
1417  chunk_size, 0);
1418  if (ret < 0)
1419  return ret;
1420  }
1421  bytestream2_skip(&gb, chunk_size);
1422  break;
1423  case MKTAG('V', 'P', '8', 'X'):
1424  vp8x_flags = bytestream2_get_byte(&gb);
1425  bytestream2_skip(&gb, 3);
1426  s->width = bytestream2_get_le24(&gb) + 1;
1427  s->height = bytestream2_get_le24(&gb) + 1;
1428  ret = av_image_check_size(s->width, s->height, 0, avctx);
1429  if (ret < 0)
1430  return ret;
1431  break;
1432  case MKTAG('A', 'L', 'P', 'H'): {
1433  int alpha_header, filter_m, compression;
1434 
1435  if (!(vp8x_flags & VP8X_FLAG_ALPHA)) {
1436  av_log(avctx, AV_LOG_WARNING,
1437  "ALPHA chunk present, but alpha bit not set in the "
1438  "VP8X header\n");
1439  }
1440  if (chunk_size == 0) {
1441  av_log(avctx, AV_LOG_ERROR, "invalid ALPHA chunk size\n");
1442  return AVERROR_INVALIDDATA;
1443  }
1444  alpha_header = bytestream2_get_byte(&gb);
1445  s->alpha_data = avpkt->data + bytestream2_tell(&gb);
1446  s->alpha_data_size = chunk_size - 1;
1447  bytestream2_skip(&gb, s->alpha_data_size);
1448 
1449  filter_m = (alpha_header >> 2) & 0x03;
1450  compression = alpha_header & 0x03;
1451 
1452  if (compression > ALPHA_COMPRESSION_VP8L) {
1453  av_log(avctx, AV_LOG_VERBOSE,
1454  "skipping unsupported ALPHA chunk\n");
1455  } else {
1456  s->has_alpha = 1;
1457  s->alpha_compression = compression;
1458  s->alpha_filter = filter_m;
1459  }
1460 
1461  break;
1462  }
1463  case MKTAG('E', 'X', 'I', 'F'): {
1464  int le, ifd_offset, exif_offset = bytestream2_tell(&gb);
1465  GetByteContext exif_gb;
1466 
1467  if (s->has_exif) {
1468  av_log(avctx, AV_LOG_VERBOSE, "Ignoring extra EXIF chunk\n");
1469  goto exif_end;
1470  }
1471  if (!(vp8x_flags & VP8X_FLAG_EXIF_METADATA))
1472  av_log(avctx, AV_LOG_WARNING,
1473  "EXIF chunk present, but Exif bit not set in the "
1474  "VP8X header\n");
1475 
1476  s->has_exif = 1;
1477  bytestream2_init(&exif_gb, avpkt->data + exif_offset,
1478  avpkt->size - exif_offset);
1479  if (ff_tdecode_header(&exif_gb, &le, &ifd_offset) < 0) {
1480  av_log(avctx, AV_LOG_ERROR, "invalid TIFF header "
1481  "in Exif data\n");
1482  goto exif_end;
1483  }
1484 
1485  bytestream2_seek(&exif_gb, ifd_offset, SEEK_SET);
1486  if (avpriv_exif_decode_ifd(avctx, &exif_gb, le, 0, &s->exif_metadata) < 0) {
1487  av_log(avctx, AV_LOG_ERROR, "error decoding Exif data\n");
1488  goto exif_end;
1489  }
1490 
1491  av_dict_copy(avpriv_frame_get_metadatap(data), s->exif_metadata, 0);
1492 
1493 exif_end:
1494  av_dict_free(&s->exif_metadata);
1495  bytestream2_skip(&gb, chunk_size);
1496  break;
1497  }
1498  case MKTAG('I', 'C', 'C', 'P'):
1499  case MKTAG('A', 'N', 'I', 'M'):
1500  case MKTAG('A', 'N', 'M', 'F'):
1501  case MKTAG('X', 'M', 'P', ' '):
1502  AV_WL32(chunk_str, chunk_type);
1503  av_log(avctx, AV_LOG_VERBOSE, "skipping unsupported chunk: %s\n",
1504  chunk_str);
1505  bytestream2_skip(&gb, chunk_size);
1506  break;
1507  default:
1508  AV_WL32(chunk_str, chunk_type);
1509  av_log(avctx, AV_LOG_VERBOSE, "skipping unknown chunk: %s\n",
1510  chunk_str);
1511  bytestream2_skip(&gb, chunk_size);
1512  break;
1513  }
1514  }
1515 
1516  if (!*got_frame) {
1517  av_log(avctx, AV_LOG_ERROR, "image data not found\n");
1518  return AVERROR_INVALIDDATA;
1519  }
1520 
1521  return avpkt->size;
1522 }
1523 
1524 static av_cold int webp_decode_close(AVCodecContext *avctx)
1525 {
1526  WebPContext *s = avctx->priv_data;
1527 
1528  if (s->initialized)
1529  return ff_vp8_decode_free(avctx);
1530 
1531  return 0;
1532 }
1533 
1534 AVCodec ff_webp_decoder = {
1535  .name = "webp",
1536  .long_name = NULL_IF_CONFIG_SMALL("WebP image"),
1537  .type = AVMEDIA_TYPE_VIDEO,
1538  .id = AV_CODEC_ID_WEBP,
1539  .priv_data_size = sizeof(WebPContext),
1540  .decode = webp_decode_frame,
1541  .close = webp_decode_close,
1542  .capabilities = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,
1543 };
Generated on Sun Mar 8 2015 02:35:03 for FFmpeg by   doxygen 1.8.2