removing h263 specific code
[libav.git] / libavcodec / h261.c
1 /*
2 * H261 decoder
3 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
4 * Copyright (c) 2004 Maarten Daniels
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20
21 /**
22 * @file h261.c
23 * h261codec.
24 */
25
26 #include "common.h"
27 #include "dsputil.h"
28 #include "avcodec.h"
29 #include "mpegvideo.h"
30 #include "h261data.h"
31
32
33 #define H261_MBA_VLC_BITS 9
34 #define H261_MTYPE_VLC_BITS 6
35 #define H261_MV_VLC_BITS 7
36 #define H261_CBP_VLC_BITS 9
37 #define TCOEFF_VLC_BITS 9
38
39 #define MAX_MBA 33
40 #define IS_FIL(a) ((a)&MB_TYPE_H261_FIL)
41
42 /**
43 * H261Context
44 */
45 typedef struct H261Context{
46 MpegEncContext s;
47
48 int current_mba;
49 int mba_diff;
50 int mtype;
51 int current_mv_x;
52 int current_mv_y;
53 int gob_number;
54 int loop_filter;
55 int bits_left; //8 - nr of bits left of the following frame in the last byte in this frame
56 int last_bits; //bits left of the following frame in the last byte in this frame
57 }H261Context;
58
59 void ff_h261_loop_filter(H261Context * h){
60 MpegEncContext * const s = &h->s;
61 const int linesize = s->linesize;
62 const int uvlinesize= s->uvlinesize;
63 uint8_t *dest_y = s->dest[0];
64 uint8_t *dest_cb= s->dest[1];
65 uint8_t *dest_cr= s->dest[2];
66
67 s->dsp.h261_loop_filter(dest_y , linesize);
68 s->dsp.h261_loop_filter(dest_y + 8, linesize);
69 s->dsp.h261_loop_filter(dest_y + 8 * linesize , linesize);
70 s->dsp.h261_loop_filter(dest_y + 8 * linesize + 8, linesize);
71 s->dsp.h261_loop_filter(dest_cb, uvlinesize);
72 s->dsp.h261_loop_filter(dest_cr, uvlinesize);
73 }
74
75 static int h261_decode_block(H261Context *h, DCTELEM *block,
76 int n, int coded);
77 static int h261_decode_mb(H261Context *h,
78 DCTELEM block[6][64]);
79 void ff_set_qscale(MpegEncContext * s, int qscale);
80
81 /***********************************************/
82 /* decoding */
83
84 static VLC h261_mba_vlc;
85 static VLC h261_mtype_vlc;
86 static VLC h261_mv_vlc;
87 static VLC h261_cbp_vlc;
88
89 void init_vlc_rl(RLTable *rl);
90
91 static void h261_decode_init_vlc(H261Context *h){
92 static int done = 0;
93
94 if(!done){
95 done = 1;
96 init_vlc(&h261_mba_vlc, H261_MBA_VLC_BITS, 34,
97 h261_mba_bits, 1, 1,
98 h261_mba_code, 1, 1);
99 init_vlc(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
100 h261_mtype_bits, 1, 1,
101 h261_mtype_code, 1, 1);
102 init_vlc(&h261_mv_vlc, H261_MV_VLC_BITS, 17,
103 &h261_mv_tab[0][1], 2, 1,
104 &h261_mv_tab[0][0], 2, 1);
105 init_vlc(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63,
106 &h261_cbp_tab[0][1], 2, 1,
107 &h261_cbp_tab[0][0], 2, 1);
108 init_rl(&h261_rl_tcoeff);
109 init_vlc_rl(&h261_rl_tcoeff);
110 }
111 }
112
113 static int h261_decode_init(AVCodecContext *avctx){
114 H261Context *h= avctx->priv_data;
115 MpegEncContext * const s = &h->s;
116
117 // set defaults
118 MPV_decode_defaults(s);
119 s->avctx = avctx;
120
121 s->width = s->avctx->width;
122 s->height = s->avctx->height;
123 s->codec_id = s->avctx->codec->id;
124
125 s->out_format = FMT_H261;
126 s->low_delay= 1;
127 avctx->pix_fmt= PIX_FMT_YUV420P;
128
129 s->codec_id= avctx->codec->id;
130
131 h261_decode_init_vlc(h);
132
133 h->bits_left = 0;
134 h->last_bits = 0;
135
136 return 0;
137 }
138
139 /**
140 * decodes the group of blocks header or slice header.
141 * @return <0 if an error occured
142 */
143 static int h261_decode_gob_header(H261Context *h){
144 unsigned int val;
145 MpegEncContext * const s = &h->s;
146
147 /* Check for GOB Start Code */
148 val = show_bits(&s->gb, 15);
149 if(val)
150 return -1;
151
152 /* We have a GBSC */
153 skip_bits(&s->gb, 16);
154
155 h->gob_number = get_bits(&s->gb, 4); /* GN */
156 s->qscale = get_bits(&s->gb, 5); /* GQUANT */
157
158 /* GEI */
159 while (get_bits1(&s->gb) != 0) {
160 skip_bits(&s->gb, 8);
161 }
162
163 if(s->qscale==0)
164 return -1;
165
166 // For the first transmitted macroblock in a GOB, MBA is the absolute address. For
167 // subsequent macroblocks, MBA is the difference between the absolute addresses of
168 // the macroblock and the last transmitted macroblock.
169 h->current_mba = 0;
170 h->mba_diff = 0;
171
172 return 0;
173 }
174
175 /**
176 * decodes the group of blocks / video packet header.
177 * @return <0 if no resync found
178 */
179 static int ff_h261_resync(H261Context *h){
180 MpegEncContext * const s = &h->s;
181 int left, ret;
182
183 if(show_bits(&s->gb, 15)==0){
184 ret= h261_decode_gob_header(h);
185 if(ret>=0)
186 return 0;
187 }
188 //ok, its not where its supposed to be ...
189 s->gb= s->last_resync_gb;
190 align_get_bits(&s->gb);
191 left= s->gb.size_in_bits - get_bits_count(&s->gb);
192
193 for(;left>15+1+4+5; left-=8){
194 if(show_bits(&s->gb, 15)==0){
195 GetBitContext bak= s->gb;
196
197 ret= h261_decode_gob_header(h);
198 if(ret>=0)
199 return 0;
200
201 s->gb= bak;
202 }
203 skip_bits(&s->gb, 8);
204 }
205
206 return -1;
207 }
208
209 /**
210 * decodes a skipped macroblock, called when when mba_diff > 1.
211 * @return 0
212 */
213 static int h261_decode_mb_skipped(H261Context *h,
214 DCTELEM block[6][64])
215 {
216 MpegEncContext * const s = &h->s;
217 int i;
218 const int xy = s->mb_x + s->mb_y * s->mb_stride;
219 s->mb_intra = 0;
220 for(i=0;i<6;i++)
221 s->block_last_index[i] = -1;
222 s->mv_dir = MV_DIR_FORWARD;
223 s->mv_type = MV_TYPE_16X16;
224 s->current_picture.mb_type[xy]= MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
225 s->mv[0][0][0] = 0;
226 s->mv[0][0][1] = 0;
227 s->mb_skiped = 1;
228 return 0;
229 }
230
231 static int decode_mv_component(GetBitContext *gb, int v){
232 int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);
233 mv_diff = mvmap[mv_diff];
234
235 if(mv_diff && !get_bits1(gb))
236 mv_diff= -mv_diff;
237
238 v += mv_diff;
239 if (v <=-16) v+= 32;
240 else if(v >= 16) v-= 32;
241
242 return v;
243 }
244
245 static int h261_decode_mb(H261Context *h,
246 DCTELEM block[6][64])
247 {
248 MpegEncContext * const s = &h->s;
249 int i, cbp, xy;
250
251 cbp = 63;
252 // Read mba
253 do{
254 h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table, H261_MBA_VLC_BITS, 2)+1;
255 }
256 while( h->mba_diff == MAX_MBA + 1 ); // stuffing
257
258 if ( h->mba_diff < 0 )
259 return -1;
260
261 h->current_mba += h->mba_diff;
262
263 if ( h->current_mba > MAX_MBA )
264 return -1;
265
266 s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1) % 11);
267 s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1) / 11);
268
269 xy = s->mb_x + s->mb_y * s->mb_stride;
270
271 ff_init_block_index(s);
272 ff_update_block_index(s);
273
274 // Read mtype
275 int old_mtype = h->mtype;
276 h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
277 h->mtype = h261_mtype_map[h->mtype];
278
279 if (IS_FIL (h->mtype))
280 h->loop_filter = 1;
281
282 // Read mquant
283 if ( IS_QUANT ( h->mtype ) ){
284 s->qscale = get_bits(&s->gb, 5);
285 }
286
287 s->mb_intra = IS_INTRA4x4(h->mtype);
288
289 // Read mv
290 if ( IS_16X16 ( h->mtype ) ){
291 // Motion vector data is included for all MC macroblocks. MVD is obtained from the macroblock vector by subtracting the
292 // vector of the preceding macroblock. For this calculation the vector of the preceding macroblock is regarded as zero in the
293 // following three situations:
294 // 1) evaluating MVD for macroblocks 1, 12 and 23;
295 // 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
296 // 3) MTYPE of the previous macroblock was not MC.
297 if ( ( h->current_mba == 1 ) || ( h->current_mba == 12 ) || ( h->current_mba == 23 ) ||
298 ( h->mba_diff != 1) || ( !IS_16X16 ( old_mtype ) ))
299 {
300 h->current_mv_x = 0;
301 h->current_mv_y = 0;
302 }
303
304 h->current_mv_x= decode_mv_component(&s->gb, h->current_mv_x);
305 h->current_mv_y= decode_mv_component(&s->gb, h->current_mv_y);
306 }
307
308 // Read cbp
309 if ( HAS_CBP( h->mtype ) ){
310 cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 2) + 1;
311 }
312
313 if(s->mb_intra){
314 s->current_picture.mb_type[xy]= MB_TYPE_INTRA;
315 goto intra;
316 }
317
318 //set motion vectors
319 s->mv_dir = MV_DIR_FORWARD;
320 s->mv_type = MV_TYPE_16X16;
321 s->current_picture.mb_type[xy]= MB_TYPE_16x16 | MB_TYPE_L0;
322 if(IS_16X16 ( h->mtype )){
323 s->mv[0][0][0] = h->current_mv_x * 2;//gets divided by 2 in motion compensation
324 s->mv[0][0][1] = h->current_mv_y * 2;
325 }
326 else{
327 h->current_mv_x = s->mv[0][0][0] = 0;
328 h->current_mv_x = s->mv[0][0][1] = 0;
329 }
330
331 intra:
332 /* decode each block */
333 if(s->mb_intra || HAS_CBP(h->mtype)){
334 for (i = 0; i < 6; i++) {
335 if (h261_decode_block(h, block[i], i, cbp&32) < 0){
336 return -1;
337 }
338 cbp+=cbp;
339 }
340 }
341
342 /* per-MB end of slice check */
343 {
344 int v= show_bits(&s->gb, 15);
345
346 if(get_bits_count(&s->gb) + 15 > s->gb.size_in_bits){
347 v>>= get_bits_count(&s->gb) + 15 - s->gb.size_in_bits;
348 }
349
350 if(v==0){
351 return SLICE_END;
352 }
353 }
354 return SLICE_OK;
355 }
356
357 /**
358 * decodes a macroblock
359 * @return <0 if an error occured
360 */
361 static int h261_decode_block(H261Context * h, DCTELEM * block,
362 int n, int coded)
363 {
364 MpegEncContext * const s = &h->s;
365 int code, level, i, j, run;
366 RLTable *rl = &h261_rl_tcoeff;
367 const uint8_t *scan_table;
368
369 // For the variable length encoding there are two code tables, one being used for
370 // the first transmitted LEVEL in INTER, INTER+MC and INTER+MC+FIL blocks, the second
371 // for all other LEVELs except the first one in INTRA blocks which is fixed length
372 // coded with 8 bits.
373 // NOTE: the two code tables only differ in one VLC so we handle that manually.
374 scan_table = s->intra_scantable.permutated;
375 if (s->mb_intra){
376 /* DC coef */
377 level = get_bits(&s->gb, 8);
378 // 0 (00000000b) and -128 (10000000b) are FORBIDDEN
379 if((level&0x7F) == 0){
380 av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
381 return -1;
382 }
383 // The code 1000 0000 is not used, the reconstruction level of 1024 being coded as 1111 1111.
384 if (level == 255)
385 level = 128;
386 block[0] = level;
387 i = 1;
388 }else if(coded){
389 // Run Level Code
390 // EOB Not possible for first level when cbp is available (that's why the table is different)
391 // 0 1 1s
392 // * * 0*
393 int check = show_bits(&s->gb, 2);
394 i = 0;
395 if ( check & 0x2 ){
396 skip_bits(&s->gb, 2);
397 block[0] = ( check & 0x1 ) ? -1 : 1;
398 i = 1;
399 }
400 }else{
401 i = 0;
402 }
403 if(!coded){
404 s->block_last_index[n] = i - 1;
405 return 0;
406 }
407 for(;;){
408 code = get_vlc2(&s->gb, rl->vlc.table, TCOEFF_VLC_BITS, 2);
409 if (code < 0){
410 av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
411 return -1;
412 }
413 if (code == rl->n) {
414 /* escape */
415 // The remaining combinations of (run, level) are encoded with a 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits level.
416 run = get_bits(&s->gb, 6);
417 level = (int8_t)get_bits(&s->gb, 8);
418 }else if(code == 0){
419 break;
420 }else{
421 run = rl->table_run[code];
422 level = rl->table_level[code];
423 if (get_bits1(&s->gb))
424 level = -level;
425 }
426 i += run;
427 if (i >= 64){
428 av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", s->mb_x, s->mb_y);
429 return -1;
430 }
431 j = scan_table[i];
432 block[j] = level;
433 i++;
434 }
435 s->block_last_index[n] = i;
436 return 0;
437 }
438
439 /**
440 * decodes the H261 picture header.
441 * @return <0 if no startcode found
442 */
443 int h261_decode_picture_header(H261Context *h){
444 MpegEncContext * const s = &h->s;
445 int format, i;
446 static int h261_framecounter = 0;
447 uint32_t startcode;
448 align_get_bits(&s->gb);
449
450 startcode = (h->last_bits << (12 - (8-h->bits_left))) | get_bits(&s->gb, 20-8 - (8- h->bits_left));
451
452 for(i= s->gb.size_in_bits - get_bits_count(&s->gb); i>24; i-=1){
453 startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;
454
455 if(startcode == 0x10)
456 break;
457 }
458
459 if (startcode != 0x10){
460 av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
461 return -1;
462 }
463
464 /* temporal reference */
465 s->picture_number = get_bits(&s->gb, 5); /* picture timestamp */
466
467 /* PTYPE starts here */
468 skip_bits1(&s->gb); /* split screen off */
469 skip_bits1(&s->gb); /* camera off */
470 skip_bits1(&s->gb); /* freeze picture release off */
471
472 format = get_bits1(&s->gb);
473
474 //only 2 formats possible
475 if (format == 0){//QCIF
476 s->width = 176;
477 s->height = 144;
478 s->mb_width = 11;
479 s->mb_height = 9;
480 }else{//CIF
481 s->width = 352;
482 s->height = 288;
483 s->mb_width = 22;
484 s->mb_height = 18;
485 }
486
487 s->mb_num = s->mb_width * s->mb_height;
488
489 skip_bits1(&s->gb); /* still image mode off */
490 skip_bits1(&s->gb); /* Reserved */
491
492 /* PEI */
493 while (get_bits1(&s->gb) != 0){
494 skip_bits(&s->gb, 8);
495 }
496
497 //h261 has no I-FRAMES, pass the test in MPV_frame_start in mpegvideo.c
498 if(h261_framecounter > 1)
499 s->pict_type = P_TYPE;
500 else
501 s->pict_type = I_TYPE;
502
503 h261_framecounter++;
504
505 h->gob_number = 0;
506 return 0;
507 }
508
509 static int h261_decode_gob(H261Context *h){
510 MpegEncContext * const s = &h->s;
511 int i;
512
513 ff_set_qscale(s, s->qscale);
514 while(h->current_mba <= MAX_MBA)
515 {
516 int ret;
517 /* DCT & quantize */
518 s->dsp.clear_blocks(s->block[0]);
519 ret= h261_decode_mb(h, s->block);
520 if(ret<0){
521 const int xy= s->mb_x + s->mb_y*s->mb_stride;
522 if(ret==SLICE_END){
523 MPV_decode_mb(s, s->block);
524 if(h->loop_filter){
525 ff_h261_loop_filter(h);
526 }
527 h->loop_filter = 0;
528 for(i=1; i<h->mba_diff; i++){
529 s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1-i) % 11);
530 s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1-i) / 11);
531 ff_init_block_index(s);
532 ff_update_block_index(s);
533 s->dsp.clear_blocks(s->block[0]);
534 ret= h261_decode_mb_skipped(h, s->block);
535 MPV_decode_mb(s, s->block);
536 }
537
538 return 0;
539 }else if(ret==SLICE_NOEND){
540 av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
541 return -1;
542 }
543 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
544 return -1;
545 }
546 MPV_decode_mb(s, s->block);
547 if(h->loop_filter){
548 ff_h261_loop_filter(h);
549 }
550
551 h->loop_filter = 0;
552 for(i=1; i<h->mba_diff; i++){
553 s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1-i) % 11);
554 s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1-i) / 11);
555 ff_init_block_index(s);
556 ff_update_block_index(s);
557 s->dsp.clear_blocks(s->block[0]);
558 ret= h261_decode_mb_skipped(h, s->block);
559 MPV_decode_mb(s, s->block);
560 }
561 }
562
563 return -1;
564 }
565
566 static int h261_find_frame_end(ParseContext *pc, AVCodecContext* avctx, const uint8_t *buf, int buf_size){
567 int vop_found, i, j, bits_left, last_bits;
568 uint32_t state;
569
570 H261Context *h = avctx->priv_data;
571
572 if(h){
573 bits_left = h->bits_left;
574 last_bits = h->last_bits;
575 }
576 else{
577 bits_left = 0;
578 last_bits = 0;
579 }
580
581 vop_found= pc->frame_start_found;
582 state= pc->state;
583 if(bits_left!=0 && !vop_found)
584 state = state << (8-bits_left) | last_bits;
585 i=0;
586 if(!vop_found){
587 for(i=0; i<buf_size; i++){
588 state= (state<<8) | buf[i];
589 for(j=0; j<8; j++){
590 if(( ( (state<<j) | (buf[i]>>(8-j)) )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
591 i++;
592 vop_found=1;
593 break;
594 }
595 }
596 if(vop_found)
597 break;
598 }
599 }
600 if(vop_found){
601 for(; i<buf_size; i++){
602 if(avctx->flags & CODEC_FLAG_TRUNCATED)//XXX ffplay workaround, someone a better solution?
603 state= (state<<8) | buf[i];
604 for(j=0; j<8; j++){
605 if(( ( (state<<j) | (buf[i]>>(8-j)) )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
606 pc->frame_start_found=0;
607 pc->state=-1;
608 return i-3;
609 }
610 }
611 }
612 }
613
614 pc->frame_start_found= vop_found;
615 pc->state= state;
616 return END_NOT_FOUND;
617 }
618
619 static int h261_parse(AVCodecParserContext *s,
620 AVCodecContext *avctx,
621 uint8_t **poutbuf, int *poutbuf_size,
622 const uint8_t *buf, int buf_size)
623 {
624 ParseContext *pc = s->priv_data;
625 int next;
626
627 next= h261_find_frame_end(pc,avctx, buf, buf_size);
628 if (ff_combine_frame(pc, next, (uint8_t **)&buf, &buf_size) < 0) {
629 *poutbuf = NULL;
630 *poutbuf_size = 0;
631 return buf_size;
632 }
633 *poutbuf = (uint8_t *)buf;
634 *poutbuf_size = buf_size;
635 return next;
636 }
637
638 /**
639 * returns the number of bytes consumed for building the current frame
640 */
641 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
642 int pos= (get_bits_count(&s->gb)+7)>>3;
643
644 if(s->flags&CODEC_FLAG_TRUNCATED){
645 pos -= s->parse_context.last_index;
646 if(pos<0) pos=0;// padding is not really read so this might be -1
647 return pos;
648 }else{
649 if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
650 if(pos+10>buf_size) pos=buf_size; // oops ;)
651
652 return pos;
653 }
654 }
655
656 static int h261_decode_frame(AVCodecContext *avctx,
657 void *data, int *data_size,
658 uint8_t *buf, int buf_size)
659 {
660 H261Context *h= avctx->priv_data;
661 MpegEncContext *s = &h->s;
662 int ret;
663 AVFrame *pict = data;
664
665 #ifdef DEBUG
666 printf("*****frame %d size=%d\n", avctx->frame_number, buf_size);
667 printf("bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
668 #endif
669 s->flags= avctx->flags;
670 s->flags2= avctx->flags2;
671
672 /* no supplementary picture */
673 if (buf_size == 0) {
674
675 return 0;
676 }
677
678 if(s->flags&CODEC_FLAG_TRUNCATED){
679 int next;
680
681 next= h261_find_frame_end(&s->parse_context,avctx, buf, buf_size);
682
683 if( ff_combine_frame(&s->parse_context, next, &buf, &buf_size) < 0 )
684 return buf_size;
685 }
686
687
688 retry:
689
690 init_get_bits(&s->gb, buf, buf_size*8);
691
692 if(!s->context_initialized){
693 if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
694 return -1;
695 }
696
697 //we need to set current_picture_ptr before reading the header, otherwise we cant store anyting im there
698 if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
699 int i= ff_find_unused_picture(s, 0);
700 s->current_picture_ptr= &s->picture[i];
701 }
702
703 ret = h261_decode_picture_header(h);
704
705 /* skip if the header was thrashed */
706 if (ret < 0){
707 av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
708 return -1;
709 }
710
711 if (s->width != avctx->width || s->height != avctx->height){
712 ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
713 s->parse_context.buffer=0;
714 MPV_common_end(s);
715 s->parse_context= pc;
716 }
717 if (!s->context_initialized) {
718 avctx->width = s->width;
719 avctx->height = s->height;
720
721 goto retry;
722 }
723
724 // for hurry_up==5
725 s->current_picture.pict_type= s->pict_type;
726 s->current_picture.key_frame= s->pict_type == I_TYPE;
727
728 /* skip everything if we are in a hurry>=5 */
729 if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
730
731 if(MPV_frame_start(s, avctx) < 0)
732 return -1;
733
734 ff_er_frame_start(s);
735
736 /* decode each macroblock */
737 s->mb_x=0;
738 s->mb_y=0;
739
740 while(h->gob_number < (s->mb_height==18 ? 12 : 5)){
741 if(ff_h261_resync(h)<0)
742 break;
743 h261_decode_gob(h);
744 }
745 MPV_frame_end(s);
746
747 // h261 doesn't have byte aligned codes
748 // store the bits of the next frame that are left in the last byte
749 // in the H261Context and remember the number of stored bits
750 {
751 int bitsleft;
752 int current_pos= get_bits_count(&s->gb)>>3;
753 bitsleft = (current_pos<<3) - get_bits_count(&s->gb);
754 h->bits_left = - bitsleft;
755 if(bitsleft > 0)
756 h->last_bits= get_bits(&s->gb, 8 - h->bits_left);
757 else
758 h->last_bits = 0;
759 }
760
761 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
762 assert(s->current_picture.pict_type == s->pict_type);
763 *pict= *(AVFrame*)&s->current_picture;
764 ff_print_debug_info(s, pict);
765
766 /* Return the Picture timestamp as the frame number */
767 /* we substract 1 because it is added on utils.c */
768 avctx->frame_number = s->picture_number - 1;
769
770 *data_size = sizeof(AVFrame);
771
772 return get_consumed_bytes(s, buf_size);
773 }
774
775 static int h261_decode_end(AVCodecContext *avctx)
776 {
777 H261Context *h= avctx->priv_data;
778 MpegEncContext *s = &h->s;
779
780 MPV_common_end(s);
781 return 0;
782 }
783
784 AVCodec h261_decoder = {
785 "h261",
786 CODEC_TYPE_VIDEO,
787 CODEC_ID_H261,
788 sizeof(H261Context),
789 h261_decode_init,
790 NULL,
791 h261_decode_end,
792 h261_decode_frame,
793 CODEC_CAP_TRUNCATED,
794 };
795
796 AVCodecParser h261_parser = {
797 { CODEC_ID_H261 },
798 sizeof(ParseContext),
799 NULL,
800 h261_parse,
801 ff_parse_close,
802 };