FFmpeg: libavcodec/webp.c Source File

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webp.c

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1 /*

2 * WebP (.webp) image decoder

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 */

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 */

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"

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

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

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 };

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 };

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 };

93 enum AlphaCompression {

94 ALPHA_COMPRESSION_NONE,

95 ALPHA_COMPRESSION_VP8L,

96 };

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, sym, code, ret;

281 int max_code_length = 0;

282 uint16_t *codes;

283

284 for (sym = 0; sym < alphabet_size; sym++)

285 max_code_length = FFMAX(max_code_length, code_lengths[sym]);

286

287 if (max_code_length == 0 || max_code_length > MAX_HUFFMAN_CODE_LENGTH)

288 return AVERROR(EINVAL);

289

290 codes = av_malloc(alphabet_size * sizeof(*codes));

291 if (!codes)

292 return AVERROR(ENOMEM);

293

294 code = 0;

295 r->nb_symbols = 0;

296 for (len = 1; len <= max_code_length; len++) {

297 for (sym = 0; sym < alphabet_size; sym++) {

298 if (code_lengths[sym] != len)

299 continue;

300 codes[sym] = code++;

301 r->nb_symbols++;

302 }

303 code <<= 1;

304 }

305 if (!r->nb_symbols) {

306 av_free(codes);

307 return AVERROR_INVALIDDATA;

308 }

309

310 ret = init_vlc(&r->vlc, 8, alphabet_size,

311 code_lengths, sizeof(*code_lengths), sizeof(*code_lengths),

312 codes, sizeof(*codes), sizeof(*codes), 0);

313 if (ret < 0) {

314 av_free(codes);

315 return ret;

316 }

317 r->simple = 0;

318

319 av_free(codes);

320 return 0;

321 }

322

323 static void read_huffman_code_simple(WebPContext *s, HuffReader *hc)

324 {

325 hc->nb_symbols = get_bits1(&s->gb) + 1;

326

327 if (get_bits1(&s->gb))

328 hc->simple_symbols[0] = get_bits(&s->gb, 8);

329 else

330 hc->simple_symbols[0] = get_bits1(&s->gb);

331

332 if (hc->nb_symbols == 2)

333 hc->simple_symbols[1] = get_bits(&s->gb, 8);

334

335 hc->simple = 1;

336 }

337

338 static int read_huffman_code_normal(WebPContext *s, HuffReader *hc,

339 int alphabet_size)

340 {

341 HuffReader code_len_hc = { { 0 }, 0, 0, { 0 } };

342 int *code_lengths = NULL;

343 int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 };

344 int i, symbol, max_symbol, prev_code_len, ret;

345 int num_codes = 4 + get_bits(&s->gb, 4);

346

347 if (num_codes > NUM_CODE_LENGTH_CODES)

348 return AVERROR_INVALIDDATA;

349

350 for (i = 0; i < num_codes; i++)

351 code_length_code_lengths[code_length_code_order[i]] = get_bits(&s->gb, 3);

352

353 ret = huff_reader_build_canonical(&code_len_hc, code_length_code_lengths,

354 NUM_CODE_LENGTH_CODES);

355 if (ret < 0)

356 goto finish;

357

358 code_lengths = av_mallocz_array(alphabet_size, sizeof(*code_lengths));

359 if (!code_lengths) {

360 ret = AVERROR(ENOMEM);

361 goto finish;

362 }

363

364 if (get_bits1(&s->gb)) {

365 int bits = 2 + 2 * get_bits(&s->gb, 3);

366 max_symbol = 2 + get_bits(&s->gb, bits);

367 if (max_symbol > alphabet_size) {

368 av_log(s->avctx, AV_LOG_ERROR, "max symbol %d > alphabet size %d\n",

369 max_symbol, alphabet_size);

370 ret = AVERROR_INVALIDDATA;

371 goto finish;

372 }

373 } else {

374 max_symbol = alphabet_size;

375 }

376

377 prev_code_len = 8;

378 symbol = 0;

379 while (symbol < alphabet_size) {

380 int code_len;

381

382 if (!max_symbol--)

383 break;

384 code_len = huff_reader_get_symbol(&code_len_hc, &s->gb);

385 if (code_len < 16) {

386 /* Code length code [0..15] indicates literal code lengths. */

387 code_lengths[symbol++] = code_len;

388 if (code_len)

389 prev_code_len = code_len;

390 } else {

391 int repeat = 0, length = 0;

392 switch (code_len) {

393 case 16:

394 /* Code 16 repeats the previous non-zero value [3..6] times,

395 * i.e., 3 + ReadBits(2) times. If code 16 is used before a

396 * non-zero value has been emitted, a value of 8 is repeated. */

397 repeat = 3 + get_bits(&s->gb, 2);

398 length = prev_code_len;

399 break;

400 case 17:

401 /* Code 17 emits a streak of zeros [3..10], i.e.,

402 * 3 + ReadBits(3) times. */

403 repeat = 3 + get_bits(&s->gb, 3);

404 break;

405 case 18:

406 /* Code 18 emits a streak of zeros of length [11..138], i.e.,

407 * 11 + ReadBits(7) times. */

408 repeat = 11 + get_bits(&s->gb, 7);

409 break;

410 }

411 if (symbol + repeat > alphabet_size) {

412 av_log(s->avctx, AV_LOG_ERROR,

413 "invalid symbol %d + repeat %d > alphabet size %d\n",

414 symbol, repeat, alphabet_size);

415 ret = AVERROR_INVALIDDATA;

416 goto finish;

417 }

418 while (repeat-- > 0)

419 code_lengths[symbol++] = length;

420 }

421 }

422

423 ret = huff_reader_build_canonical(hc, code_lengths, alphabet_size);

424

425 finish:

426 ff_free_vlc(&code_len_hc.vlc);

427 av_free(code_lengths);

428 return ret;

429 }

430

431 static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,

432 int w, int h);

433

434 #define PARSE_BLOCK_SIZE(w, h) do { \

435 block_bits = get_bits(&s->gb, 3) + 2; \

436 blocks_w = FFALIGN((w), 1 << block_bits) >> block_bits; \

437 blocks_h = FFALIGN((h), 1 << block_bits) >> block_bits; \

438 } while (0)

439

440 static int decode_entropy_image(WebPContext *s)

441 {

442 ImageContext *img;

443 int ret, block_bits, width, blocks_w, blocks_h, x, y, max;

444

445 width = s->width;

446 if (s->reduced_width > 0)

447 width = s->reduced_width;

448

449 PARSE_BLOCK_SIZE(width, s->height);

450

451 ret = decode_entropy_coded_image(s, IMAGE_ROLE_ENTROPY, blocks_w, blocks_h);

452 if (ret < 0)

453 return ret;

454

455 img = &s->image[IMAGE_ROLE_ENTROPY];

456 img->size_reduction = block_bits;

457

458 /* the number of huffman groups is determined by the maximum group number

459 * coded in the entropy image */

460 max = 0;

461 for (y = 0; y < img->frame->height; y++) {

462 for (x = 0; x < img->frame->width; x++) {

463 int p = GET_PIXEL_COMP(img->frame, x, y, 2);

464 max = FFMAX(max, p);

465 }

466 }

467 s->nb_huffman_groups = max + 1;

468

469 return 0;

470 }

471

472 static int parse_transform_predictor(WebPContext *s)

473 {

474 int block_bits, blocks_w, blocks_h, ret;

475

476 PARSE_BLOCK_SIZE(s->width, s->height);

477

478 ret = decode_entropy_coded_image(s, IMAGE_ROLE_PREDICTOR, blocks_w,

479 blocks_h);

480 if (ret < 0)

481 return ret;

482

483 s->image[IMAGE_ROLE_PREDICTOR].size_reduction = block_bits;

484

485 return 0;

486 }

487

488 static int parse_transform_color(WebPContext *s)

489 {

490 int block_bits, blocks_w, blocks_h, ret;

491

492 PARSE_BLOCK_SIZE(s->width, s->height);

493

494 ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_TRANSFORM, blocks_w,

495 blocks_h);

496 if (ret < 0)

497 return ret;

498

499 s->image[IMAGE_ROLE_COLOR_TRANSFORM].size_reduction = block_bits;

500

501 return 0;

502 }

503

504 static int parse_transform_color_indexing(WebPContext *s)

505 {

506 ImageContext *img;

507 int width_bits, index_size, ret, x;

508 uint8_t *ct;

509

510 index_size = get_bits(&s->gb, 8) + 1;

511

512 if (index_size <= 2)

513 width_bits = 3;

514 else if (index_size <= 4)

515 width_bits = 2;

516 else if (index_size <= 16)

517 width_bits = 1;

518 else

519 width_bits = 0;

520

521 ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_INDEXING,

522 index_size, 1);

523 if (ret < 0)

524 return ret;

525

526 img = &s->image[IMAGE_ROLE_COLOR_INDEXING];

527 img->size_reduction = width_bits;

528 if (width_bits > 0)

529 s->reduced_width = (s->width + ((1 << width_bits) - 1)) >> width_bits;

530

531 /* color index values are delta-coded */

532 ct = img->frame->data[0] + 4;

533 for (x = 4; x < img->frame->width * 4; x++, ct++)

534 ct[0] += ct[-4];

535

536 return 0;

537 }

538

539 static HuffReader *get_huffman_group(WebPContext *s, ImageContext *img,

540 int x, int y)

541 {

542 ImageContext *gimg = &s->image[IMAGE_ROLE_ENTROPY];

543 int group = 0;

544

545 if (gimg->size_reduction > 0) {

546 int group_x = x >> gimg->size_reduction;

547 int group_y = y >> gimg->size_reduction;

548 group = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2);

549 }

550

551 return &img->huffman_groups[group * HUFFMAN_CODES_PER_META_CODE];

552 }

553

554 static av_always_inline void color_cache_put(ImageContext *img, uint32_t c)

555 {

556 uint32_t cache_idx = (0x1E35A7BD * c) >> (32 - img->color_cache_bits);

557 img->color_cache[cache_idx] = c;

558 }

559

560 static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,

561 int w, int h)

562 {

563 ImageContext *img;

564 HuffReader *hg;

565 int i, j, ret, x, y, width;

566

567 img = &s->image[role];

568 img->role = role;

569

570 if (!img->frame) {

571 img->frame = av_frame_alloc();

572 if (!img->frame)

573 return AVERROR(ENOMEM);

574 }

575

576 img->frame->format = AV_PIX_FMT_ARGB;

577 img->frame->width = w;

578 img->frame->height = h;

579

580 if (role == IMAGE_ROLE_ARGB && !img->is_alpha_primary) {

581 ThreadFrame pt = { .f = img->frame };

582 ret = ff_thread_get_buffer(s->avctx, &pt, 0);

583 } else

584 ret = av_frame_get_buffer(img->frame, 1);

585 if (ret < 0)

586 return ret;

587

588 if (get_bits1(&s->gb)) {

589 img->color_cache_bits = get_bits(&s->gb, 4);

590 if (img->color_cache_bits < 1 || img->color_cache_bits > 11) {

591 av_log(s->avctx, AV_LOG_ERROR, "invalid color cache bits: %d\n",

592 img->color_cache_bits);

593 return AVERROR_INVALIDDATA;

594 }

595 img->color_cache = av_mallocz_array(1 << img->color_cache_bits,

596 sizeof(*img->color_cache));

597 if (!img->color_cache)

598 return AVERROR(ENOMEM);

599 } else {

600 img->color_cache_bits = 0;

601 }

602

603 img->nb_huffman_groups = 1;

604 if (role == IMAGE_ROLE_ARGB && get_bits1(&s->gb)) {

605 ret = decode_entropy_image(s);

606 if (ret < 0)

607 return ret;

608 img->nb_huffman_groups = s->nb_huffman_groups;

609 }

610 img->huffman_groups = av_mallocz_array(img->nb_huffman_groups *

611 HUFFMAN_CODES_PER_META_CODE,

612 sizeof(*img->huffman_groups));

613 if (!img->huffman_groups)

614 return AVERROR(ENOMEM);

615

616 for (i = 0; i < img->nb_huffman_groups; i++) {

617 hg = &img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE];

618 for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++) {

619 int alphabet_size = alphabet_sizes[j];

620 if (!j && img->color_cache_bits > 0)

621 alphabet_size += 1 << img->color_cache_bits;

622

623 if (get_bits1(&s->gb)) {

624 read_huffman_code_simple(s, &hg[j]);

625 } else {

626 ret = read_huffman_code_normal(s, &hg[j], alphabet_size);

627 if (ret < 0)

628 return ret;

629 }

630 }

631 }

632

633 width = img->frame->width;

634 if (role == IMAGE_ROLE_ARGB && s->reduced_width > 0)

635 width = s->reduced_width;

636

637 x = 0; y = 0;

638 while (y < img->frame->height) {

639 int v;

640

641 hg = get_huffman_group(s, img, x, y);

642 v = huff_reader_get_symbol(&hg[HUFF_IDX_GREEN], &s->gb);

643 if (v < NUM_LITERAL_CODES) {

644 /* literal pixel values */

645 uint8_t *p = GET_PIXEL(img->frame, x, y);

646 p[2] = v;

647 p[1] = huff_reader_get_symbol(&hg[HUFF_IDX_RED], &s->gb);

648 p[3] = huff_reader_get_symbol(&hg[HUFF_IDX_BLUE], &s->gb);

649 p[0] = huff_reader_get_symbol(&hg[HUFF_IDX_ALPHA], &s->gb);

650 if (img->color_cache_bits)

651 color_cache_put(img, AV_RB32(p));

652 x++;

653 if (x == width) {

654 x = 0;

655 y++;

656 }

657 } else if (v < NUM_LITERAL_CODES + NUM_LENGTH_CODES) {

658 /* LZ77 backwards mapping */

659 int prefix_code, length, distance, ref_x, ref_y;

660

661 /* parse length and distance */

662 prefix_code = v - NUM_LITERAL_CODES;

663 if (prefix_code < 4) {

664 length = prefix_code + 1;

665 } else {

666 int extra_bits = (prefix_code - 2) >> 1;

667 int offset = 2 + (prefix_code & 1) << extra_bits;

668 length = offset + get_bits(&s->gb, extra_bits) + 1;

669 }

670 prefix_code = huff_reader_get_symbol(&hg[HUFF_IDX_DIST], &s->gb);

671 if (prefix_code < 4) {

672 distance = prefix_code + 1;

673 } else {

674 int extra_bits = prefix_code - 2 >> 1;

675 int offset = 2 + (prefix_code & 1) << extra_bits;

676 distance = offset + get_bits(&s->gb, extra_bits) + 1;

677 }

678

679 /* find reference location */

680 if (distance <= NUM_SHORT_DISTANCES) {

681 int xi = lz77_distance_offsets[distance - 1][0];

682 int yi = lz77_distance_offsets[distance - 1][1];

683 distance = FFMAX(1, xi + yi * width);

684 } else {

685 distance -= NUM_SHORT_DISTANCES;

686 }

687 ref_x = x;

688 ref_y = y;

689 if (distance <= x) {

690 ref_x -= distance;

691 distance = 0;

692 } else {

693 ref_x = 0;

694 distance -= x;

695 }

696 while (distance >= width) {

697 ref_y--;

698 distance -= width;

699 }

700 if (distance > 0) {

701 ref_x = width - distance;

702 ref_y--;

703 }

704 ref_x = FFMAX(0, ref_x);

705 ref_y = FFMAX(0, ref_y);

706

707 /* copy pixels

708 * source and dest regions can overlap and wrap lines, so just

709 * copy per-pixel */

710 for (i = 0; i < length; i++) {

711 uint8_t *p_ref = GET_PIXEL(img->frame, ref_x, ref_y);

712 uint8_t *p = GET_PIXEL(img->frame, x, y);

713

714 AV_COPY32(p, p_ref);

715 if (img->color_cache_bits)

716 color_cache_put(img, AV_RB32(p));

717 x++;

718 ref_x++;

719 if (x == width) {

720 x = 0;

721 y++;

722 }

723 if (ref_x == width) {

724 ref_x = 0;

725 ref_y++;

726 }

727 if (y == img->frame->height || ref_y == img->frame->height)

728 break;

729 }

730 } else {

731 /* read from color cache */

732 uint8_t *p = GET_PIXEL(img->frame, x, y);

733 int cache_idx = v - (NUM_LITERAL_CODES + NUM_LENGTH_CODES);

734

735 if (!img->color_cache_bits) {

736 av_log(s->avctx, AV_LOG_ERROR, "color cache not found\n");

737 return AVERROR_INVALIDDATA;

738 }

739 if (cache_idx >= 1 << img->color_cache_bits) {

740 av_log(s->avctx, AV_LOG_ERROR,

741 "color cache index out-of-bounds\n");

742 return AVERROR_INVALIDDATA;

743 }

744 AV_WB32(p, img->color_cache[cache_idx]);

745 x++;

746 if (x == width) {

747 x = 0;

748 y++;

749 }

750 }

751 }

752

753 return 0;

754 }

755

756 /* PRED_MODE_BLACK */

757 static void inv_predict_0(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

758 const uint8_t *p_t, const uint8_t *p_tr)

759 {

760 AV_WB32(p, 0xFF000000);

761 }

762

763 /* PRED_MODE_L */

764 static void inv_predict_1(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

765 const uint8_t *p_t, const uint8_t *p_tr)

766 {

767 AV_COPY32(p, p_l);

768 }

769

770 /* PRED_MODE_T */

771 static void inv_predict_2(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

772 const uint8_t *p_t, const uint8_t *p_tr)

773 {

774 AV_COPY32(p, p_t);

775 }

776

777 /* PRED_MODE_TR */

778 static void inv_predict_3(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

779 const uint8_t *p_t, const uint8_t *p_tr)

780 {

781 AV_COPY32(p, p_tr);

782 }

783

784 /* PRED_MODE_TL */

785 static void inv_predict_4(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

786 const uint8_t *p_t, const uint8_t *p_tr)

787 {

788 AV_COPY32(p, p_tl);

789 }

790

791 /* PRED_MODE_AVG_T_AVG_L_TR */

792 static void inv_predict_5(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

793 const uint8_t *p_t, const uint8_t *p_tr)

794 {

795 p[0] = p_t[0] + (p_l[0] + p_tr[0] >> 1) >> 1;

796 p[1] = p_t[1] + (p_l[1] + p_tr[1] >> 1) >> 1;

797 p[2] = p_t[2] + (p_l[2] + p_tr[2] >> 1) >> 1;

798 p[3] = p_t[3] + (p_l[3] + p_tr[3] >> 1) >> 1;

799 }

800

801 /* PRED_MODE_AVG_L_TL */

802 static void inv_predict_6(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 p[0] = p_l[0] + p_tl[0] >> 1;

806 p[1] = p_l[1] + p_tl[1] >> 1;

807 p[2] = p_l[2] + p_tl[2] >> 1;

808 p[3] = p_l[3] + p_tl[3] >> 1;

809 }

810

811 /* PRED_MODE_AVG_L_T */

812 static void inv_predict_7(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

813 const uint8_t *p_t, const uint8_t *p_tr)

814 {

815 p[0] = p_l[0] + p_t[0] >> 1;

816 p[1] = p_l[1] + p_t[1] >> 1;

817 p[2] = p_l[2] + p_t[2] >> 1;

818 p[3] = p_l[3] + p_t[3] >> 1;

819 }

820

821 /* PRED_MODE_AVG_TL_T */

822 static void inv_predict_8(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

823 const uint8_t *p_t, const uint8_t *p_tr)

824 {

825 p[0] = p_tl[0] + p_t[0] >> 1;

826 p[1] = p_tl[1] + p_t[1] >> 1;

827 p[2] = p_tl[2] + p_t[2] >> 1;

828 p[3] = p_tl[3] + p_t[3] >> 1;

829 }

830

831 /* PRED_MODE_AVG_T_TR */

832 static void inv_predict_9(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

833 const uint8_t *p_t, const uint8_t *p_tr)

834 {

835 p[0] = p_t[0] + p_tr[0] >> 1;

836 p[1] = p_t[1] + p_tr[1] >> 1;

837 p[2] = p_t[2] + p_tr[2] >> 1;

838 p[3] = p_t[3] + p_tr[3] >> 1;

839 }

840

841 /* PRED_MODE_AVG_AVG_L_TL_AVG_T_TR */

842 static void inv_predict_10(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

843 const uint8_t *p_t, const uint8_t *p_tr)

844 {

845 p[0] = (p_l[0] + p_tl[0] >> 1) + (p_t[0] + p_tr[0] >> 1) >> 1;

846 p[1] = (p_l[1] + p_tl[1] >> 1) + (p_t[1] + p_tr[1] >> 1) >> 1;

847 p[2] = (p_l[2] + p_tl[2] >> 1) + (p_t[2] + p_tr[2] >> 1) >> 1;

848 p[3] = (p_l[3] + p_tl[3] >> 1) + (p_t[3] + p_tr[3] >> 1) >> 1;

849 }

850

851 /* PRED_MODE_SELECT */

852 static void inv_predict_11(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

853 const uint8_t *p_t, const uint8_t *p_tr)

854 {

855 int diff = (FFABS(p_l[0] - p_tl[0]) - FFABS(p_t[0] - p_tl[0])) +

856 (FFABS(p_l[1] - p_tl[1]) - FFABS(p_t[1] - p_tl[1])) +

857 (FFABS(p_l[2] - p_tl[2]) - FFABS(p_t[2] - p_tl[2])) +

858 (FFABS(p_l[3] - p_tl[3]) - FFABS(p_t[3] - p_tl[3]));

859 if (diff <= 0)

860 AV_COPY32(p, p_t);

861 else

862 AV_COPY32(p, p_l);

863 }

864

865 /* PRED_MODE_ADD_SUBTRACT_FULL */

866 static void inv_predict_12(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

867 const uint8_t *p_t, const uint8_t *p_tr)

868 {

869 p[0] = av_clip_uint8(p_l[0] + p_t[0] - p_tl[0]);

870 p[1] = av_clip_uint8(p_l[1] + p_t[1] - p_tl[1]);

871 p[2] = av_clip_uint8(p_l[2] + p_t[2] - p_tl[2]);

872 p[3] = av_clip_uint8(p_l[3] + p_t[3] - p_tl[3]);

873 }

874

875 static av_always_inline uint8_t clamp_add_subtract_half(int a, int b, int c)

876 {

877 int d = a + b >> 1;

878 return av_clip_uint8(d + (d - c) / 2);

879 }

880

881 /* PRED_MODE_ADD_SUBTRACT_HALF */

882 static void inv_predict_13(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] = clamp_add_subtract_half(p_l[0], p_t[0], p_tl[0]);

886 p[1] = clamp_add_subtract_half(p_l[1], p_t[1], p_tl[1]);

887 p[2] = clamp_add_subtract_half(p_l[2], p_t[2], p_tl[2]);

888 p[3] = clamp_add_subtract_half(p_l[3], p_t[3], p_tl[3]);

889 }

890

891 typedef void (*inv_predict_func)(uint8_t *p, const uint8_t *p_l,

892 const uint8_t *p_tl, const uint8_t *p_t,

893 const uint8_t *p_tr);

894

895 static const inv_predict_func inverse_predict[14] = {

896 inv_predict_0, inv_predict_1, inv_predict_2, inv_predict_3,

897 inv_predict_4, inv_predict_5, inv_predict_6, inv_predict_7,

898 inv_predict_8, inv_predict_9, inv_predict_10, inv_predict_11,

899 inv_predict_12, inv_predict_13,

900 };

901

902 static void inverse_prediction(AVFrame *frame, enum PredictionMode m, int x, int y)

903 {

904 uint8_t *dec, *p_l, *p_tl, *p_t, *p_tr;

905 uint8_t p[4];

906

907 dec = GET_PIXEL(frame, x, y);

908 p_l = GET_PIXEL(frame, x - 1, y);

909 p_tl = GET_PIXEL(frame, x - 1, y - 1);

910 p_t = GET_PIXEL(frame, x, y - 1);

911 if (x == frame->width - 1)

912 p_tr = GET_PIXEL(frame, 0, y);

913 else

914 p_tr = GET_PIXEL(frame, x + 1, y - 1);

915

916 inverse_predict[m](p, p_l, p_tl, p_t, p_tr);

917

918 dec[0] += p[0];

919 dec[1] += p[1];

920 dec[2] += p[2];

921 dec[3] += p[3];

922 }

923

924 static int apply_predictor_transform(WebPContext *s)

925 {

926 ImageContext *img = &s->image[IMAGE_ROLE_ARGB];

927 ImageContext *pimg = &s->image[IMAGE_ROLE_PREDICTOR];

928 int x, y;

929

930 for (y = 0; y < img->frame->height; y++) {

931 for (x = 0; x < img->frame->width; x++) {

932 int tx = x >> pimg->size_reduction;

933 int ty = y >> pimg->size_reduction;

934 enum PredictionMode m = GET_PIXEL_COMP(pimg->frame, tx, ty, 2);

935

936 if (x == 0) {

937 if (y == 0)

938 m = PRED_MODE_BLACK;

939 else

940 m = PRED_MODE_T;

941 } else if (y == 0)

942 m = PRED_MODE_L;

943

944 if (m > 13) {

945 av_log(s->avctx, AV_LOG_ERROR,

946 "invalid predictor mode: %d\n", m);

947 return AVERROR_INVALIDDATA;

948 }

949 inverse_prediction(img->frame, m, x, y);

950 }

951 }

952 return 0;

953 }

954

955 static av_always_inline uint8_t color_transform_delta(uint8_t color_pred,

956 uint8_t color)

957 {

958 return (int)ff_u8_to_s8(color_pred) * ff_u8_to_s8(color) >> 5;

959 }

960

961 static int apply_color_transform(WebPContext *s)

962 {

963 ImageContext *img, *cimg;

964 int x, y, cx, cy;

965 uint8_t *p, *cp;

966

967 img = &s->image[IMAGE_ROLE_ARGB];

968 cimg = &s->image[IMAGE_ROLE_COLOR_TRANSFORM];

969

970 for (y = 0; y < img->frame->height; y++) {

971 for (x = 0; x < img->frame->width; x++) {

972 cx = x >> cimg->size_reduction;

973 cy = y >> cimg->size_reduction;

974 cp = GET_PIXEL(cimg->frame, cx, cy);

975 p = GET_PIXEL(img->frame, x, y);

976

977 p[1] += color_transform_delta(cp[3], p[2]);

978 p[3] += color_transform_delta(cp[2], p[2]) +

979 color_transform_delta(cp[1], p[1]);

980 }

981 }

982 return 0;

983 }

984

985 static int apply_subtract_green_transform(WebPContext *s)

986 {

987 int x, y;

988 ImageContext *img = &s->image[IMAGE_ROLE_ARGB];

989

990 for (y = 0; y < img->frame->height; y++) {

991 for (x = 0; x < img->frame->width; x++) {

992 uint8_t *p = GET_PIXEL(img->frame, x, y);

993 p[1] += p[2];

994 p[3] += p[2];

995 }

996 }

997 return 0;

998 }

999

1000 static int apply_color_indexing_transform(WebPContext *s)

1001 {

1002 ImageContext *img;

1003 ImageContext *pal;

1004 int i, x, y;

1005 uint8_t *p, *pi;

1006

1007 img = &s->image[IMAGE_ROLE_ARGB];

1008 pal = &s->image[IMAGE_ROLE_COLOR_INDEXING];

1009

1010 if (pal->size_reduction > 0) {

1011 GetBitContext gb_g;

1012 uint8_t *line;

1013 int pixel_bits = 8 >> pal->size_reduction;

1014

1015 line = av_malloc(img->frame->linesize[0]);

1016 if (!line)

1017 return AVERROR(ENOMEM);

1018

1019 for (y = 0; y < img->frame->height; y++) {

1020 p = GET_PIXEL(img->frame, 0, y);

1021 memcpy(line, p, img->frame->linesize[0]);

1022 init_get_bits(&gb_g, line, img->frame->linesize[0] * 8);

1023 skip_bits(&gb_g, 16);

1024 i = 0;

1025 for (x = 0; x < img->frame->width; x++) {

1026 p = GET_PIXEL(img->frame, x, y);

1027 p[2] = get_bits(&gb_g, pixel_bits);

1028 i++;

1029 if (i == 1 << pal->size_reduction) {

1030 skip_bits(&gb_g, 24);

1031 i = 0;

1032 }

1033 }

1034 }

1035 av_free(line);

1036 }

1037

1038 for (y = 0; y < img->frame->height; y++) {

1039 for (x = 0; x < img->frame->width; x++) {

1040 p = GET_PIXEL(img->frame, x, y);

1041 i = p[2];

1042 if (i >= pal->frame->width) {

1043 av_log(s->avctx, AV_LOG_ERROR, "invalid palette index %d\n", i);

1044 return AVERROR_INVALIDDATA;

1045 }

1046 pi = GET_PIXEL(pal->frame, i, 0);

1047 AV_COPY32(p, pi);

1048 }

1049 }

1050

1051 return 0;

1052 }

1053

1054 static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p,

1055 int *got_frame, uint8_t *data_start,

1056 unsigned int data_size, int is_alpha_chunk)

1057 {

1058 WebPContext *s = avctx->priv_data;

1059 int w, h, ret, i;

1060

1061 if (!is_alpha_chunk) {

1062 s->lossless = 1;

1063 avctx->pix_fmt = AV_PIX_FMT_ARGB;

1064 }

1065

1066 ret = init_get_bits(&s->gb, data_start, data_size * 8);

1067 if (ret < 0)

1068 return ret;

1069

1070 if (!is_alpha_chunk) {

1071 if (get_bits(&s->gb, 8) != 0x2F) {

1072 av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless signature\n");

1073 return AVERROR_INVALIDDATA;

1074 }

1075

1076 w = get_bits(&s->gb, 14) + 1;

1077 h = get_bits(&s->gb, 14) + 1;

1078 if (s->width && s->width != w) {

1079 av_log(avctx, AV_LOG_WARNING, "Width mismatch. %d != %d\n",

1080 s->width, w);

1081 }

1082 s->width = w;

1083 if (s->height && s->height != h) {

1084 av_log(avctx, AV_LOG_WARNING, "Height mismatch. %d != %d\n",

1085 s->width, w);

1086 }

1087 s->height = h;

1088 ret = av_image_check_size(s->width, s->height, 0, avctx);

1089 if (ret < 0)

1090 return ret;

1091 avcodec_set_dimensions(avctx, s->width, s->height);

1092

1093 s->has_alpha = get_bits1(&s->gb);

1094

1095 if (get_bits(&s->gb, 3) != 0x0) {

1096 av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless version\n");

1097 return AVERROR_INVALIDDATA;

1098 }

1099 } else {

1100 if (!s->width || !s->height)

1101 return AVERROR_BUG;

1102 w = s->width;

1103 h = s->height;

1104 }

1105

1106 /* parse transformations */

1107 s->nb_transforms = 0;

1108 s->reduced_width = 0;

1109 while (get_bits1(&s->gb)) {

1110 enum TransformType transform = get_bits(&s->gb, 2);

1111 s->transforms[s->nb_transforms++] = transform;

1112 switch (transform) {

1113 case PREDICTOR_TRANSFORM:

1114 ret = parse_transform_predictor(s);

1115 break;

1116 case COLOR_TRANSFORM:

1117 ret = parse_transform_color(s);

1118 break;

1119 case COLOR_INDEXING_TRANSFORM:

1120 ret = parse_transform_color_indexing(s);

1121 break;

1122 }

1123 if (ret < 0)

1124 goto free_and_return;

1125 }

1126

1127 /* decode primary image */

1128 s->image[IMAGE_ROLE_ARGB].frame = p;

1129 if (is_alpha_chunk)

1130 s->image[IMAGE_ROLE_ARGB].is_alpha_primary = 1;

1131 ret = decode_entropy_coded_image(s, IMAGE_ROLE_ARGB, w, h);

1132 if (ret < 0) {

1133 av_frame_free(&p);

1134 goto free_and_return;

1135 }

1136

1137 /* apply transformations */

1138 for (i = s->nb_transforms - 1; i >= 0; i--) {

1139 switch (s->transforms[i]) {

1140 case PREDICTOR_TRANSFORM:

1141 ret = apply_predictor_transform(s);

1142 break;

1143 case COLOR_TRANSFORM:

1144 ret = apply_color_transform(s);

1145 break;

1146 case SUBTRACT_GREEN:

1147 ret = apply_subtract_green_transform(s);

1148 break;

1149 case COLOR_INDEXING_TRANSFORM:

1150 ret = apply_color_indexing_transform(s);

1151 break;

1152 }

1153 if (ret < 0) {

1154 av_frame_free(&p);

1155 goto free_and_return;

1156 }

1157 }

1158

1159 *got_frame = 1;

1160 p->pict_type = AV_PICTURE_TYPE_I;

1161 p->key_frame = 1;

1162 ret = data_size;

1163

1164 free_and_return:

1165 for (i = 0; i < IMAGE_ROLE_NB; i++)

1166 image_ctx_free(&s->image[i]);

1167

1168 return ret;

1169 }

1170

1171 static void alpha_inverse_prediction(AVFrame *frame, enum AlphaFilter m)

1172 {

1173 int x, y, ls;

1174 uint8_t *dec;

1175

1176 ls = frame->linesize[3];

1177

1178 /* filter first row using horizontal filter */

1179 dec = frame->data[3] + 1;

1180 for (x = 1; x < frame->width; x++, dec++)

1181 *dec += *(dec - 1);

1182

1183 /* filter first column using vertical filter */

1184 dec = frame->data[3] + ls;

1185 for (y = 1; y < frame->height; y++, dec += ls)

1186 *dec += *(dec - ls);

1187

1188 /* filter the rest using the specified filter */

1189 switch (m) {

1190 case ALPHA_FILTER_HORIZONTAL:

1191 for (y = 1; y < frame->height; y++) {

1192 dec = frame->data[3] + y * ls + 1;

1193 for (x = 1; x < frame->width; x++, dec++)

1194 *dec += *(dec - 1);

1195 }

1196 break;

1197 case ALPHA_FILTER_VERTICAL:

1198 for (y = 1; y < frame->height; y++) {

1199 dec = frame->data[3] + y * ls + 1;

1200 for (x = 1; x < frame->width; x++, dec++)

1201 *dec += *(dec - ls);

1202 }

1203 break;

1204 case ALPHA_FILTER_GRADIENT:

1205 for (y = 1; y < frame->height; y++) {

1206 dec = frame->data[3] + y * ls + 1;

1207 for (x = 1; x < frame->width; x++, dec++)

1208 dec[0] += av_clip_uint8(*(dec - 1) + *(dec - ls) - *(dec - ls - 1));

1209 }

1210 break;

1211 }

1212 }

1213

1214 static int vp8_lossy_decode_alpha(AVCodecContext *avctx, AVFrame *p,

1215 uint8_t *data_start,

1216 unsigned int data_size)

1217 {

1218 WebPContext *s = avctx->priv_data;

1219 int x, y, ret;

1220

1221 if (s->alpha_compression == ALPHA_COMPRESSION_NONE) {

1222 GetByteContext gb;

1223

1224 bytestream2_init(&gb, data_start, data_size);

1225 for (y = 0; y < s->height; y++)

1226 bytestream2_get_buffer(&gb, p->data[3] + p->linesize[3] * y,

1227 s->width);

1228 } else if (s->alpha_compression == ALPHA_COMPRESSION_VP8L) {

1229 uint8_t *ap, *pp;

1230 int alpha_got_frame = 0;

1231

1232 s->alpha_frame = av_frame_alloc();

1233 if (!s->alpha_frame)

1234 return AVERROR(ENOMEM);

1235

1236 ret = vp8_lossless_decode_frame(avctx, s->alpha_frame, &alpha_got_frame,

1237 data_start, data_size, 1);

1238 if (ret < 0) {

1239 av_frame_free(&s->alpha_frame);

1240 return ret;

1241 }

1242 if (!alpha_got_frame) {

1243 av_frame_free(&s->alpha_frame);

1244 return AVERROR_INVALIDDATA;

1245 }

1246

1247 /* copy green component of alpha image to alpha plane of primary image */

1248 for (y = 0; y < s->height; y++) {

1249 ap = GET_PIXEL(s->alpha_frame, 0, y) + 2;

1250 pp = p->data[3] + p->linesize[3] * y;

1251 for (x = 0; x < s->width; x++) {

1252 *pp = *ap;

1253 pp++;

1254 ap += 4;

1255 }

1256 }

1257 av_frame_free(&s->alpha_frame);

1258 }

1259

1260 /* apply alpha filtering */

1261 if (s->alpha_filter)

1262 alpha_inverse_prediction(p, s->alpha_filter);

1263

1264 return 0;

1265 }

1266

1267 static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,

1268 int *got_frame, uint8_t *data_start,

1269 unsigned int data_size)

1270 {

1271 WebPContext *s = avctx->priv_data;

1272 AVPacket pkt;

1273 int ret;

1274

1275 if (!s->initialized) {

1276 ff_vp8_decode_init(avctx);

1277 s->initialized = 1;

1278 if (s->has_alpha)

1279 avctx->pix_fmt = AV_PIX_FMT_YUVA420P;

1280 }

1281 s->lossless = 0;

1282

1283 if (data_size > INT_MAX) {

1284 av_log(avctx, AV_LOG_ERROR, "unsupported chunk size\n");

1285 return AVERROR_PATCHWELCOME;

1286 }

1287

1288 av_init_packet(&pkt);

1289 pkt.data = data_start;

1290 pkt.size = data_size;

1291

1292 ret = ff_vp8_decode_frame(avctx, p, got_frame, &pkt);

1293 if (s->has_alpha) {

1294 ret = vp8_lossy_decode_alpha(avctx, p, s->alpha_data,

1295 s->alpha_data_size);

1296 if (ret < 0)

1297 return ret;

1298 }

1299 return ret;

1300 }

1301

1302 static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,

1303 AVPacket *avpkt)

1304 {

1305 AVFrame * const p = data;

1306 WebPContext *s = avctx->priv_data;

1307 GetByteContext gb;

1308 int ret;

1309 uint32_t chunk_type, chunk_size;

1310 int vp8x_flags = 0;

1311

1312 s->avctx = avctx;

1313 s->width = 0;

1314 s->height = 0;

1315 *got_frame = 0;

1316 s->has_alpha = 0;

1317 bytestream2_init(&gb, avpkt->data, avpkt->size);

1318

1319 if (bytestream2_get_bytes_left(&gb) < 12)

1320 return AVERROR_INVALIDDATA;

1321

1322 if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {

1323 av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");

1324 return AVERROR_INVALIDDATA;

1325 }

1326

1327 chunk_size = bytestream2_get_le32(&gb);

1328 if (bytestream2_get_bytes_left(&gb) < chunk_size)

1329 return AVERROR_INVALIDDATA;

1330

1331 if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) {

1332 av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n");

1333 return AVERROR_INVALIDDATA;

1334 }

1335

1336 while (bytestream2_get_bytes_left(&gb) > 0) {

1337 char chunk_str[5] = { 0 };

1338

1339 chunk_type = bytestream2_get_le32(&gb);

1340 chunk_size = bytestream2_get_le32(&gb);

1341 if (chunk_size == UINT32_MAX)

1342 return AVERROR_INVALIDDATA;

1343 chunk_size += chunk_size & 1;

1344

1345 if (bytestream2_get_bytes_left(&gb) < chunk_size)

1346 return AVERROR_INVALIDDATA;

1347

1348 switch (chunk_type) {

1349 case MKTAG('V', 'P', '8', ' '):

1350 if (!*got_frame) {

1351 ret = vp8_lossy_decode_frame(avctx, p, got_frame,

1352 avpkt->data + bytestream2_tell(&gb),

1353 chunk_size);

1354 if (ret < 0)

1355 return ret;

1356 }

1357 bytestream2_skip(&gb, chunk_size);

1358 break;

1359 case MKTAG('V', 'P', '8', 'L'):

1360 if (!*got_frame) {

1361 ret = vp8_lossless_decode_frame(avctx, p, got_frame,

1362 avpkt->data + bytestream2_tell(&gb),

1363 chunk_size, 0);

1364 if (ret < 0)

1365 return ret;

1366 }

1367 bytestream2_skip(&gb, chunk_size);

1368 break;

1369 case MKTAG('V', 'P', '8', 'X'):

1370 vp8x_flags = bytestream2_get_byte(&gb);

1371 bytestream2_skip(&gb, 3);

1372 s->width = bytestream2_get_le24(&gb) + 1;

1373 s->height = bytestream2_get_le24(&gb) + 1;

1374 ret = av_image_check_size(s->width, s->height, 0, avctx);

1375 if (ret < 0)

1376 return ret;

1377 break;

1378 case MKTAG('A', 'L', 'P', 'H'): {

1379 int alpha_header, filter_m, compression;

1380

1381 if (!(vp8x_flags & VP8X_FLAG_ALPHA)) {

1382 av_log(avctx, AV_LOG_WARNING,

1383 "ALPHA chunk present, but alpha bit not set in the "

1384 "VP8X header\n");

1385 }

1386 if (chunk_size == 0) {

1387 av_log(avctx, AV_LOG_ERROR, "invalid ALPHA chunk size\n");

1388 return AVERROR_INVALIDDATA;

1389 }

1390 alpha_header = bytestream2_get_byte(&gb);

1391 s->alpha_data = avpkt->data + bytestream2_tell(&gb);

1392 s->alpha_data_size = chunk_size - 1;

1393 bytestream2_skip(&gb, s->alpha_data_size);

1394

1395 filter_m = (alpha_header >> 2) & 0x03;

1396 compression = alpha_header & 0x03;

1397

1398 if (compression > ALPHA_COMPRESSION_VP8L) {

1399 av_log(avctx, AV_LOG_VERBOSE,

1400 "skipping unsupported ALPHA chunk\n");

1401 } else {

1402 s->has_alpha = 1;

1403 s->alpha_compression = compression;

1404 s->alpha_filter = filter_m;

1405 }

1406

1407 break;

1408 }

1409 case MKTAG('I', 'C', 'C', 'P'):

1410 case MKTAG('A', 'N', 'I', 'M'):

1411 case MKTAG('A', 'N', 'M', 'F'):

1412 case MKTAG('E', 'X', 'I', 'F'):

1413 case MKTAG('X', 'M', 'P', ' '):

1414 AV_WL32(chunk_str, chunk_type);

1415 av_log(avctx, AV_LOG_VERBOSE, "skipping unsupported chunk: %s\n",

1416 chunk_str);

1417 bytestream2_skip(&gb, chunk_size);

1418 break;

1419 default:

1420 AV_WL32(chunk_str, chunk_type);

1421 av_log(avctx, AV_LOG_VERBOSE, "skipping unknown chunk: %s\n",

1422 chunk_str);

1423 bytestream2_skip(&gb, chunk_size);

1424 break;

1425 }

1426 }

1427

1428 if (!*got_frame) {

1429 av_log(avctx, AV_LOG_ERROR, "image data not found\n");

1430 return AVERROR_INVALIDDATA;

1431 }

1432

1433 return avpkt->size;

1434 }

1435

1436 static av_cold int webp_decode_close(AVCodecContext *avctx)

1437 {

1438 WebPContext *s = avctx->priv_data;

1439

1440 if (s->initialized)

1441 return ff_vp8_decode_free(avctx);

1442

1443 return 0;

1444 }

1445

1446 AVCodec ff_webp_decoder = {

1447 .name = "webp",

1448 .long_name = NULL_IF_CONFIG_SMALL("WebP image"),

1449 .type = AVMEDIA_TYPE_VIDEO,

1450 .id = AV_CODEC_ID_WEBP,

1451 .priv_data_size = sizeof(WebPContext),

1452 .decode = webp_decode_frame,

1453 .close = webp_decode_close,

1454 .capabilities = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,

1455 };

Generated on Sat Jan 25 2014 19:51:57 for FFmpeg by doxygen 1.8.2