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2ba45a60 DM |
1 | /* |
2 | * H261 decoder | |
3 | * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> | |
4 | * Copyright (c) 2004 Maarten Daniels | |
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 | * H.261 decoder. | |
26 | */ | |
27 | ||
28 | #include "libavutil/avassert.h" | |
29 | #include "avcodec.h" | |
30 | #include "mpeg_er.h" | |
31 | #include "mpegutils.h" | |
32 | #include "mpegvideo.h" | |
33 | #include "h263.h" | |
34 | #include "h261.h" | |
35 | #include "internal.h" | |
36 | ||
37 | #define H261_MBA_VLC_BITS 9 | |
38 | #define H261_MTYPE_VLC_BITS 6 | |
39 | #define H261_MV_VLC_BITS 7 | |
40 | #define H261_CBP_VLC_BITS 9 | |
41 | #define TCOEFF_VLC_BITS 9 | |
42 | #define MBA_STUFFING 33 | |
43 | #define MBA_STARTCODE 34 | |
44 | ||
45 | static VLC h261_mba_vlc; | |
46 | static VLC h261_mtype_vlc; | |
47 | static VLC h261_mv_vlc; | |
48 | static VLC h261_cbp_vlc; | |
49 | ||
50 | static av_cold void h261_decode_init_vlc(H261Context *h) | |
51 | { | |
52 | static int done = 0; | |
53 | ||
54 | if (!done) { | |
55 | done = 1; | |
56 | INIT_VLC_STATIC(&h261_mba_vlc, H261_MBA_VLC_BITS, 35, | |
57 | ff_h261_mba_bits, 1, 1, | |
58 | ff_h261_mba_code, 1, 1, 662); | |
59 | INIT_VLC_STATIC(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10, | |
60 | ff_h261_mtype_bits, 1, 1, | |
61 | ff_h261_mtype_code, 1, 1, 80); | |
62 | INIT_VLC_STATIC(&h261_mv_vlc, H261_MV_VLC_BITS, 17, | |
63 | &ff_h261_mv_tab[0][1], 2, 1, | |
64 | &ff_h261_mv_tab[0][0], 2, 1, 144); | |
65 | INIT_VLC_STATIC(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63, | |
66 | &ff_h261_cbp_tab[0][1], 2, 1, | |
67 | &ff_h261_cbp_tab[0][0], 2, 1, 512); | |
68 | INIT_VLC_RL(ff_h261_rl_tcoeff, 552); | |
69 | } | |
70 | } | |
71 | ||
72 | static av_cold int h261_decode_init(AVCodecContext *avctx) | |
73 | { | |
74 | H261Context *h = avctx->priv_data; | |
75 | MpegEncContext *const s = &h->s; | |
76 | ||
77 | // set defaults | |
78 | ff_mpv_decode_defaults(s); | |
79 | ff_mpv_decode_init(s, avctx); | |
80 | ||
81 | s->out_format = FMT_H261; | |
82 | s->low_delay = 1; | |
83 | avctx->pix_fmt = AV_PIX_FMT_YUV420P; | |
84 | ||
85 | ff_h261_common_init(); | |
86 | h261_decode_init_vlc(h); | |
87 | ||
88 | h->gob_start_code_skipped = 0; | |
89 | ||
90 | return 0; | |
91 | } | |
92 | ||
93 | /** | |
94 | * Decode the group of blocks header or slice header. | |
95 | * @return <0 if an error occurred | |
96 | */ | |
97 | static int h261_decode_gob_header(H261Context *h) | |
98 | { | |
99 | unsigned int val; | |
100 | MpegEncContext *const s = &h->s; | |
101 | ||
102 | if (!h->gob_start_code_skipped) { | |
103 | /* Check for GOB Start Code */ | |
104 | val = show_bits(&s->gb, 15); | |
105 | if (val) | |
106 | return -1; | |
107 | ||
108 | /* We have a GBSC */ | |
109 | skip_bits(&s->gb, 16); | |
110 | } | |
111 | ||
112 | h->gob_start_code_skipped = 0; | |
113 | ||
114 | h->gob_number = get_bits(&s->gb, 4); /* GN */ | |
115 | s->qscale = get_bits(&s->gb, 5); /* GQUANT */ | |
116 | ||
117 | /* Check if gob_number is valid */ | |
118 | if (s->mb_height == 18) { // CIF | |
119 | if ((h->gob_number <= 0) || (h->gob_number > 12)) | |
120 | return -1; | |
121 | } else { // QCIF | |
122 | if ((h->gob_number != 1) && (h->gob_number != 3) && | |
123 | (h->gob_number != 5)) | |
124 | return -1; | |
125 | } | |
126 | ||
127 | /* GEI */ | |
128 | if (skip_1stop_8data_bits(&s->gb) < 0) | |
129 | return AVERROR_INVALIDDATA; | |
130 | ||
131 | if (s->qscale == 0) { | |
132 | av_log(s->avctx, AV_LOG_ERROR, "qscale has forbidden 0 value\n"); | |
133 | if (s->avctx->err_recognition & (AV_EF_BITSTREAM | AV_EF_COMPLIANT)) | |
134 | return -1; | |
135 | } | |
136 | ||
137 | /* For the first transmitted macroblock in a GOB, MBA is the absolute | |
138 | * address. For subsequent macroblocks, MBA is the difference between | |
139 | * the absolute addresses of the macroblock and the last transmitted | |
140 | * macroblock. */ | |
141 | h->current_mba = 0; | |
142 | h->mba_diff = 0; | |
143 | ||
144 | return 0; | |
145 | } | |
146 | ||
147 | /** | |
148 | * Decode the group of blocks / video packet header. | |
149 | * @return <0 if no resync found | |
150 | */ | |
151 | static int h261_resync(H261Context *h) | |
152 | { | |
153 | MpegEncContext *const s = &h->s; | |
154 | int left, ret; | |
155 | ||
156 | if (h->gob_start_code_skipped) { | |
157 | ret = h261_decode_gob_header(h); | |
158 | if (ret >= 0) | |
159 | return 0; | |
160 | } else { | |
161 | if (show_bits(&s->gb, 15) == 0) { | |
162 | ret = h261_decode_gob_header(h); | |
163 | if (ret >= 0) | |
164 | return 0; | |
165 | } | |
166 | // OK, it is not where it is supposed to be ... | |
167 | s->gb = s->last_resync_gb; | |
168 | align_get_bits(&s->gb); | |
169 | left = get_bits_left(&s->gb); | |
170 | ||
171 | for (; left > 15 + 1 + 4 + 5; left -= 8) { | |
172 | if (show_bits(&s->gb, 15) == 0) { | |
173 | GetBitContext bak = s->gb; | |
174 | ||
175 | ret = h261_decode_gob_header(h); | |
176 | if (ret >= 0) | |
177 | return 0; | |
178 | ||
179 | s->gb = bak; | |
180 | } | |
181 | skip_bits(&s->gb, 8); | |
182 | } | |
183 | } | |
184 | ||
185 | return -1; | |
186 | } | |
187 | ||
188 | /** | |
189 | * Decode skipped macroblocks. | |
190 | * @return 0 | |
191 | */ | |
192 | static int h261_decode_mb_skipped(H261Context *h, int mba1, int mba2) | |
193 | { | |
194 | MpegEncContext *const s = &h->s; | |
195 | int i; | |
196 | ||
197 | s->mb_intra = 0; | |
198 | ||
199 | for (i = mba1; i < mba2; i++) { | |
200 | int j, xy; | |
201 | ||
202 | s->mb_x = ((h->gob_number - 1) % 2) * 11 + i % 11; | |
203 | s->mb_y = ((h->gob_number - 1) / 2) * 3 + i / 11; | |
204 | xy = s->mb_x + s->mb_y * s->mb_stride; | |
205 | ff_init_block_index(s); | |
206 | ff_update_block_index(s); | |
207 | ||
208 | for (j = 0; j < 6; j++) | |
209 | s->block_last_index[j] = -1; | |
210 | ||
211 | s->mv_dir = MV_DIR_FORWARD; | |
212 | s->mv_type = MV_TYPE_16X16; | |
213 | s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0; | |
214 | s->mv[0][0][0] = 0; | |
215 | s->mv[0][0][1] = 0; | |
216 | s->mb_skipped = 1; | |
217 | h->mtype &= ~MB_TYPE_H261_FIL; | |
218 | ||
219 | ff_mpv_decode_mb(s, s->block); | |
220 | } | |
221 | ||
222 | return 0; | |
223 | } | |
224 | ||
225 | static const int mvmap[17] = { | |
226 | 0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16 | |
227 | }; | |
228 | ||
229 | static int decode_mv_component(GetBitContext *gb, int v) | |
230 | { | |
231 | int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2); | |
232 | ||
233 | /* check if mv_diff is valid */ | |
234 | if (mv_diff < 0) | |
235 | return v; | |
236 | ||
237 | mv_diff = mvmap[mv_diff]; | |
238 | ||
239 | if (mv_diff && !get_bits1(gb)) | |
240 | mv_diff = -mv_diff; | |
241 | ||
242 | v += mv_diff; | |
243 | if (v <= -16) | |
244 | v += 32; | |
245 | else if (v >= 16) | |
246 | v -= 32; | |
247 | ||
248 | return v; | |
249 | } | |
250 | ||
251 | /** | |
252 | * Decode a macroblock. | |
253 | * @return <0 if an error occurred | |
254 | */ | |
255 | static int h261_decode_block(H261Context *h, int16_t *block, int n, int coded) | |
256 | { | |
257 | MpegEncContext *const s = &h->s; | |
258 | int level, i, j, run; | |
259 | RLTable *rl = &ff_h261_rl_tcoeff; | |
260 | const uint8_t *scan_table; | |
261 | ||
262 | /* For the variable length encoding there are two code tables, one being | |
263 | * used for the first transmitted LEVEL in INTER, INTER + MC and | |
264 | * INTER + MC + FIL blocks, the second for all other LEVELs except the | |
265 | * first one in INTRA blocks which is fixed length coded with 8 bits. | |
266 | * NOTE: The two code tables only differ in one VLC so we handle that | |
267 | * manually. */ | |
268 | scan_table = s->intra_scantable.permutated; | |
269 | if (s->mb_intra) { | |
270 | /* DC coef */ | |
271 | level = get_bits(&s->gb, 8); | |
272 | // 0 (00000000b) and -128 (10000000b) are FORBIDDEN | |
273 | if ((level & 0x7F) == 0) { | |
274 | av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", | |
275 | level, s->mb_x, s->mb_y); | |
276 | return -1; | |
277 | } | |
278 | /* The code 1000 0000 is not used, the reconstruction level of 1024 | |
279 | * being coded as 1111 1111. */ | |
280 | if (level == 255) | |
281 | level = 128; | |
282 | block[0] = level; | |
283 | i = 1; | |
284 | } else if (coded) { | |
285 | // Run Level Code | |
286 | // EOB Not possible for first level when cbp is available (that's why the table is different) | |
287 | // 0 1 1s | |
288 | // * * 0* | |
289 | int check = show_bits(&s->gb, 2); | |
290 | i = 0; | |
291 | if (check & 0x2) { | |
292 | skip_bits(&s->gb, 2); | |
293 | block[0] = (check & 0x1) ? -1 : 1; | |
294 | i = 1; | |
295 | } | |
296 | } else { | |
297 | i = 0; | |
298 | } | |
299 | if (!coded) { | |
300 | s->block_last_index[n] = i - 1; | |
301 | return 0; | |
302 | } | |
303 | { | |
304 | OPEN_READER(re, &s->gb); | |
305 | i--; // offset by -1 to allow direct indexing of scan_table | |
306 | for (;;) { | |
307 | UPDATE_CACHE(re, &s->gb); | |
308 | GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TCOEFF_VLC_BITS, 2, 0); | |
309 | if (run == 66) { | |
310 | if (level) { | |
311 | CLOSE_READER(re, &s->gb); | |
312 | av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", | |
313 | s->mb_x, s->mb_y); | |
314 | return -1; | |
315 | } | |
316 | /* escape */ | |
317 | /* The remaining combinations of (run, level) are encoded with a | |
318 | * 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits | |
319 | * level. */ | |
320 | run = SHOW_UBITS(re, &s->gb, 6) + 1; | |
321 | SKIP_CACHE(re, &s->gb, 6); | |
322 | level = SHOW_SBITS(re, &s->gb, 8); | |
323 | SKIP_COUNTER(re, &s->gb, 6 + 8); | |
324 | } else if (level == 0) { | |
325 | break; | |
326 | } else { | |
327 | if (SHOW_UBITS(re, &s->gb, 1)) | |
328 | level = -level; | |
329 | SKIP_COUNTER(re, &s->gb, 1); | |
330 | } | |
331 | i += run; | |
332 | if (i >= 64) { | |
333 | CLOSE_READER(re, &s->gb); | |
334 | av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", | |
335 | s->mb_x, s->mb_y); | |
336 | return -1; | |
337 | } | |
338 | j = scan_table[i]; | |
339 | block[j] = level; | |
340 | } | |
341 | CLOSE_READER(re, &s->gb); | |
342 | } | |
343 | s->block_last_index[n] = i; | |
344 | return 0; | |
345 | } | |
346 | ||
347 | static int h261_decode_mb(H261Context *h) | |
348 | { | |
349 | MpegEncContext *const s = &h->s; | |
350 | int i, cbp, xy; | |
351 | ||
352 | cbp = 63; | |
353 | // Read mba | |
354 | do { | |
355 | h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table, | |
356 | H261_MBA_VLC_BITS, 2); | |
357 | ||
358 | /* Check for slice end */ | |
359 | /* NOTE: GOB can be empty (no MB data) or exist only of MBA_stuffing */ | |
360 | if (h->mba_diff == MBA_STARTCODE) { // start code | |
361 | h->gob_start_code_skipped = 1; | |
362 | return SLICE_END; | |
363 | } | |
364 | } while (h->mba_diff == MBA_STUFFING); // stuffing | |
365 | ||
366 | if (h->mba_diff < 0) { | |
367 | if (get_bits_left(&s->gb) <= 7) | |
368 | return SLICE_END; | |
369 | ||
370 | av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y); | |
371 | return SLICE_ERROR; | |
372 | } | |
373 | ||
374 | h->mba_diff += 1; | |
375 | h->current_mba += h->mba_diff; | |
376 | ||
377 | if (h->current_mba > MBA_STUFFING) | |
378 | return SLICE_ERROR; | |
379 | ||
380 | s->mb_x = ((h->gob_number - 1) % 2) * 11 + ((h->current_mba - 1) % 11); | |
381 | s->mb_y = ((h->gob_number - 1) / 2) * 3 + ((h->current_mba - 1) / 11); | |
382 | xy = s->mb_x + s->mb_y * s->mb_stride; | |
383 | ff_init_block_index(s); | |
384 | ff_update_block_index(s); | |
385 | ||
386 | // Read mtype | |
387 | h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2); | |
388 | if (h->mtype < 0) { | |
389 | av_log(s->avctx, AV_LOG_ERROR, "Invalid mtype index %d\n", | |
390 | h->mtype); | |
391 | return SLICE_ERROR; | |
392 | } | |
393 | av_assert0(h->mtype < FF_ARRAY_ELEMS(ff_h261_mtype_map)); | |
394 | h->mtype = ff_h261_mtype_map[h->mtype]; | |
395 | ||
396 | // Read mquant | |
397 | if (IS_QUANT(h->mtype)) | |
398 | ff_set_qscale(s, get_bits(&s->gb, 5)); | |
399 | ||
400 | s->mb_intra = IS_INTRA4x4(h->mtype); | |
401 | ||
402 | // Read mv | |
403 | if (IS_16X16(h->mtype)) { | |
404 | /* Motion vector data is included for all MC macroblocks. MVD is | |
405 | * obtained from the macroblock vector by subtracting the vector | |
406 | * of the preceding macroblock. For this calculation the vector | |
407 | * of the preceding macroblock is regarded as zero in the | |
408 | * following three situations: | |
409 | * 1) evaluating MVD for macroblocks 1, 12 and 23; | |
410 | * 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1; | |
411 | * 3) MTYPE of the previous macroblock was not MC. */ | |
412 | if ((h->current_mba == 1) || (h->current_mba == 12) || | |
413 | (h->current_mba == 23) || (h->mba_diff != 1)) { | |
414 | h->current_mv_x = 0; | |
415 | h->current_mv_y = 0; | |
416 | } | |
417 | ||
418 | h->current_mv_x = decode_mv_component(&s->gb, h->current_mv_x); | |
419 | h->current_mv_y = decode_mv_component(&s->gb, h->current_mv_y); | |
420 | } else { | |
421 | h->current_mv_x = 0; | |
422 | h->current_mv_y = 0; | |
423 | } | |
424 | ||
425 | // Read cbp | |
426 | if (HAS_CBP(h->mtype)) | |
427 | cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 2) + 1; | |
428 | ||
429 | if (s->mb_intra) { | |
430 | s->current_picture.mb_type[xy] = MB_TYPE_INTRA; | |
431 | goto intra; | |
432 | } | |
433 | ||
434 | //set motion vectors | |
435 | s->mv_dir = MV_DIR_FORWARD; | |
436 | s->mv_type = MV_TYPE_16X16; | |
437 | s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0; | |
438 | s->mv[0][0][0] = h->current_mv_x * 2; // gets divided by 2 in motion compensation | |
439 | s->mv[0][0][1] = h->current_mv_y * 2; | |
440 | ||
441 | if (s->current_picture.motion_val[0]) { | |
442 | int b_stride = 2*s->mb_width + 1; | |
443 | int b_xy = 2 * s->mb_x + (2 * s->mb_y) * b_stride; | |
444 | s->current_picture.motion_val[0][b_xy][0] = s->mv[0][0][0]; | |
445 | s->current_picture.motion_val[0][b_xy][1] = s->mv[0][0][1]; | |
446 | } | |
447 | ||
448 | intra: | |
449 | /* decode each block */ | |
450 | if (s->mb_intra || HAS_CBP(h->mtype)) { | |
451 | s->bdsp.clear_blocks(s->block[0]); | |
452 | for (i = 0; i < 6; i++) { | |
453 | if (h261_decode_block(h, s->block[i], i, cbp & 32) < 0) | |
454 | return SLICE_ERROR; | |
455 | cbp += cbp; | |
456 | } | |
457 | } else { | |
458 | for (i = 0; i < 6; i++) | |
459 | s->block_last_index[i] = -1; | |
460 | } | |
461 | ||
462 | ff_mpv_decode_mb(s, s->block); | |
463 | ||
464 | return SLICE_OK; | |
465 | } | |
466 | ||
467 | /** | |
468 | * Decode the H.261 picture header. | |
469 | * @return <0 if no startcode found | |
470 | */ | |
471 | static int h261_decode_picture_header(H261Context *h) | |
472 | { | |
473 | MpegEncContext *const s = &h->s; | |
474 | int format, i; | |
475 | uint32_t startcode = 0; | |
476 | ||
477 | for (i = get_bits_left(&s->gb); i > 24; i -= 1) { | |
478 | startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF; | |
479 | ||
480 | if (startcode == 0x10) | |
481 | break; | |
482 | } | |
483 | ||
484 | if (startcode != 0x10) { | |
485 | av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n"); | |
486 | return -1; | |
487 | } | |
488 | ||
489 | /* temporal reference */ | |
490 | i = get_bits(&s->gb, 5); /* picture timestamp */ | |
491 | if (i < (s->picture_number & 31)) | |
492 | i += 32; | |
493 | s->picture_number = (s->picture_number & ~31) + i; | |
494 | ||
f6fa7814 | 495 | s->avctx->framerate = (AVRational) { 30000, 1001 }; |
2ba45a60 DM |
496 | |
497 | /* PTYPE starts here */ | |
498 | skip_bits1(&s->gb); /* split screen off */ | |
499 | skip_bits1(&s->gb); /* camera off */ | |
500 | skip_bits1(&s->gb); /* freeze picture release off */ | |
501 | ||
502 | format = get_bits1(&s->gb); | |
503 | ||
504 | // only 2 formats possible | |
505 | if (format == 0) { // QCIF | |
506 | s->width = 176; | |
507 | s->height = 144; | |
508 | s->mb_width = 11; | |
509 | s->mb_height = 9; | |
510 | } else { // CIF | |
511 | s->width = 352; | |
512 | s->height = 288; | |
513 | s->mb_width = 22; | |
514 | s->mb_height = 18; | |
515 | } | |
516 | ||
517 | s->mb_num = s->mb_width * s->mb_height; | |
518 | ||
519 | skip_bits1(&s->gb); /* still image mode off */ | |
520 | skip_bits1(&s->gb); /* Reserved */ | |
521 | ||
522 | /* PEI */ | |
523 | if (skip_1stop_8data_bits(&s->gb) < 0) | |
524 | return AVERROR_INVALIDDATA; | |
525 | ||
526 | /* H.261 has no I-frames, but if we pass AV_PICTURE_TYPE_I for the first | |
527 | * frame, the codec crashes if it does not contain all I-blocks | |
528 | * (e.g. when a packet is lost). */ | |
529 | s->pict_type = AV_PICTURE_TYPE_P; | |
530 | ||
531 | h->gob_number = 0; | |
532 | return 0; | |
533 | } | |
534 | ||
535 | static int h261_decode_gob(H261Context *h) | |
536 | { | |
537 | MpegEncContext *const s = &h->s; | |
538 | ||
539 | ff_set_qscale(s, s->qscale); | |
540 | ||
541 | /* decode mb's */ | |
542 | while (h->current_mba <= MBA_STUFFING) { | |
543 | int ret; | |
544 | /* DCT & quantize */ | |
545 | ret = h261_decode_mb(h); | |
546 | if (ret < 0) { | |
547 | if (ret == SLICE_END) { | |
548 | h261_decode_mb_skipped(h, h->current_mba, 33); | |
549 | return 0; | |
550 | } | |
551 | av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", | |
552 | s->mb_x + s->mb_y * s->mb_stride); | |
553 | return -1; | |
554 | } | |
555 | ||
556 | h261_decode_mb_skipped(h, | |
557 | h->current_mba - h->mba_diff, | |
558 | h->current_mba - 1); | |
559 | } | |
560 | ||
561 | return -1; | |
562 | } | |
563 | ||
564 | /** | |
565 | * returns the number of bytes consumed for building the current frame | |
566 | */ | |
567 | static int get_consumed_bytes(MpegEncContext *s, int buf_size) | |
568 | { | |
569 | int pos = get_bits_count(&s->gb) >> 3; | |
570 | if (pos == 0) | |
571 | pos = 1; // avoid infinite loops (i doubt that is needed but ...) | |
572 | if (pos + 10 > buf_size) | |
573 | pos = buf_size; // oops ;) | |
574 | ||
575 | return pos; | |
576 | } | |
577 | ||
578 | static int h261_decode_frame(AVCodecContext *avctx, void *data, | |
579 | int *got_frame, AVPacket *avpkt) | |
580 | { | |
581 | const uint8_t *buf = avpkt->data; | |
582 | int buf_size = avpkt->size; | |
583 | H261Context *h = avctx->priv_data; | |
584 | MpegEncContext *s = &h->s; | |
585 | int ret; | |
586 | AVFrame *pict = data; | |
587 | ||
588 | av_dlog(avctx, "*****frame %d size=%d\n", avctx->frame_number, buf_size); | |
589 | av_dlog(avctx, "bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]); | |
590 | s->flags = avctx->flags; | |
591 | s->flags2 = avctx->flags2; | |
592 | ||
593 | h->gob_start_code_skipped = 0; | |
594 | ||
595 | retry: | |
596 | init_get_bits(&s->gb, buf, buf_size * 8); | |
597 | ||
598 | if (!s->context_initialized) | |
599 | // we need the IDCT permutaton for reading a custom matrix | |
600 | ff_mpv_idct_init(s); | |
601 | ||
602 | ret = h261_decode_picture_header(h); | |
603 | ||
604 | /* skip if the header was thrashed */ | |
605 | if (ret < 0) { | |
606 | av_log(s->avctx, AV_LOG_ERROR, "header damaged\n"); | |
607 | return -1; | |
608 | } | |
609 | ||
610 | if (s->width != avctx->coded_width || s->height != avctx->coded_height) { | |
611 | ParseContext pc = s->parse_context; // FIXME move this demuxing hack to libavformat | |
612 | s->parse_context.buffer = 0; | |
613 | ff_mpv_common_end(s); | |
614 | s->parse_context = pc; | |
615 | } | |
616 | ||
617 | if (!s->context_initialized) { | |
618 | if ((ret = ff_mpv_common_init(s)) < 0) | |
619 | return ret; | |
620 | ||
621 | ret = ff_set_dimensions(avctx, s->width, s->height); | |
622 | if (ret < 0) | |
623 | return ret; | |
624 | ||
625 | goto retry; | |
626 | } | |
627 | ||
628 | // for skipping the frame | |
629 | s->current_picture.f->pict_type = s->pict_type; | |
630 | s->current_picture.f->key_frame = s->pict_type == AV_PICTURE_TYPE_I; | |
631 | ||
632 | if ((avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type == AV_PICTURE_TYPE_B) || | |
633 | (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type != AV_PICTURE_TYPE_I) || | |
634 | avctx->skip_frame >= AVDISCARD_ALL) | |
635 | return get_consumed_bytes(s, buf_size); | |
636 | ||
637 | if (ff_mpv_frame_start(s, avctx) < 0) | |
638 | return -1; | |
639 | ||
640 | ff_mpeg_er_frame_start(s); | |
641 | ||
642 | /* decode each macroblock */ | |
643 | s->mb_x = 0; | |
644 | s->mb_y = 0; | |
645 | ||
646 | while (h->gob_number < (s->mb_height == 18 ? 12 : 5)) { | |
647 | if (h261_resync(h) < 0) | |
648 | break; | |
649 | h261_decode_gob(h); | |
650 | } | |
651 | ff_mpv_frame_end(s); | |
652 | ||
653 | av_assert0(s->current_picture.f->pict_type == s->current_picture_ptr->f->pict_type); | |
654 | av_assert0(s->current_picture.f->pict_type == s->pict_type); | |
655 | ||
656 | if ((ret = av_frame_ref(pict, s->current_picture_ptr->f)) < 0) | |
657 | return ret; | |
658 | ff_print_debug_info(s, s->current_picture_ptr, pict); | |
659 | ||
660 | *got_frame = 1; | |
661 | ||
662 | return get_consumed_bytes(s, buf_size); | |
663 | } | |
664 | ||
665 | static av_cold int h261_decode_end(AVCodecContext *avctx) | |
666 | { | |
667 | H261Context *h = avctx->priv_data; | |
668 | MpegEncContext *s = &h->s; | |
669 | ||
670 | ff_mpv_common_end(s); | |
671 | return 0; | |
672 | } | |
673 | ||
674 | AVCodec ff_h261_decoder = { | |
675 | .name = "h261", | |
676 | .long_name = NULL_IF_CONFIG_SMALL("H.261"), | |
677 | .type = AVMEDIA_TYPE_VIDEO, | |
678 | .id = AV_CODEC_ID_H261, | |
679 | .priv_data_size = sizeof(H261Context), | |
680 | .init = h261_decode_init, | |
681 | .close = h261_decode_end, | |
682 | .decode = h261_decode_frame, | |
683 | .capabilities = CODEC_CAP_DR1, | |
684 | .max_lowres = 3, | |
685 | }; |