H.261 decoder improvements
[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 MBA_STUFFING 33
40 #define MBA_STARTCODE 34
41 #define IS_FIL(a) ((a)&MB_TYPE_H261_FIL)
42
43 /**
44 * H261Context
45 */
46 typedef struct H261Context{
47 MpegEncContext s;
48
49 int current_mba;
50 int mba_diff;
51 int mtype;
52 int current_mv_x;
53 int current_mv_y;
54 int gob_number;
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 int gob_start_code_skipped; // 1 if gob start code is already read before gob header is read
58 }H261Context;
59
60 void ff_h261_loop_filter(H261Context * h){
61 MpegEncContext * const s = &h->s;
62 const int linesize = s->linesize;
63 const int uvlinesize= s->uvlinesize;
64 uint8_t *dest_y = s->dest[0];
65 uint8_t *dest_cb= s->dest[1];
66 uint8_t *dest_cr= s->dest[2];
67
68 s->dsp.h261_loop_filter(dest_y , linesize);
69 s->dsp.h261_loop_filter(dest_y + 8, linesize);
70 s->dsp.h261_loop_filter(dest_y + 8 * linesize , linesize);
71 s->dsp.h261_loop_filter(dest_y + 8 * linesize + 8, linesize);
72 s->dsp.h261_loop_filter(dest_cb, uvlinesize);
73 s->dsp.h261_loop_filter(dest_cr, uvlinesize);
74 }
75
76 static int h261_decode_block(H261Context *h, DCTELEM *block,
77 int n, int coded);
78 static int h261_decode_mb(H261Context *h);
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, 35,
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 h->gob_start_code_skipped = 0;
136
137 return 0;
138 }
139
140 /**
141 * decodes the group of blocks header or slice header.
142 * @return <0 if an error occured
143 */
144 static int h261_decode_gob_header(H261Context *h){
145 unsigned int val;
146 MpegEncContext * const s = &h->s;
147
148 if ( !h->gob_start_code_skipped ){
149 /* Check for GOB Start Code */
150 val = show_bits(&s->gb, 15);
151 if(val)
152 return -1;
153
154 /* We have a GBSC */
155 skip_bits(&s->gb, 16);
156 }
157
158 h->gob_start_code_skipped = 0;
159
160 h->gob_number = get_bits(&s->gb, 4); /* GN */
161 s->qscale = get_bits(&s->gb, 5); /* GQUANT */
162
163 /* Check if gob_number is valid */
164 if (s->mb_height==18){ //cif
165 if ((h->gob_number<=0) || (h->gob_number>12))
166 return -1;
167 }
168 else{ //qcif
169 if ((h->gob_number!=1) && (h->gob_number!=3) && (h->gob_number!=5))
170 return -1;
171 }
172
173 /* GEI */
174 while (get_bits1(&s->gb) != 0) {
175 skip_bits(&s->gb, 8);
176 }
177
178 if(s->qscale==0)
179 return -1;
180
181 // For the first transmitted macroblock in a GOB, MBA is the absolute address. For
182 // subsequent macroblocks, MBA is the difference between the absolute addresses of
183 // the macroblock and the last transmitted macroblock.
184 h->current_mba = 0;
185 h->mba_diff = 0;
186
187 return 0;
188 }
189
190 /**
191 * decodes the group of blocks / video packet header.
192 * @return <0 if no resync found
193 */
194 static int ff_h261_resync(H261Context *h){
195 MpegEncContext * const s = &h->s;
196 int left, ret;
197
198 if ( h->gob_start_code_skipped ){
199 ret= h261_decode_gob_header(h);
200 if(ret>=0)
201 return 0;
202 }
203 else{
204 if(show_bits(&s->gb, 15)==0){
205 ret= h261_decode_gob_header(h);
206 if(ret>=0)
207 return 0;
208 }
209 //ok, its not where its supposed to be ...
210 s->gb= s->last_resync_gb;
211 align_get_bits(&s->gb);
212 left= s->gb.size_in_bits - get_bits_count(&s->gb);
213
214 for(;left>15+1+4+5; left-=8){
215 if(show_bits(&s->gb, 15)==0){
216 GetBitContext bak= s->gb;
217
218 ret= h261_decode_gob_header(h);
219 if(ret>=0)
220 return 0;
221
222 s->gb= bak;
223 }
224 skip_bits(&s->gb, 8);
225 }
226 }
227
228 return -1;
229 }
230
231 /**
232 * decodes skipped macroblocks
233 * @return 0
234 */
235 static int h261_decode_mb_skipped(H261Context *h, int mba1, int mba2 )
236 {
237 MpegEncContext * const s = &h->s;
238 int i;
239
240 s->mb_intra = 0;
241
242 for(i=mba1; i<mba2; i++){
243 int j, xy;
244
245 s->mb_x= ((h->gob_number-1) % 2) * 11 + i % 11;
246 s->mb_y= ((h->gob_number-1) / 2) * 3 + i / 11;
247 xy = s->mb_x + s->mb_y * s->mb_stride;
248 ff_init_block_index(s);
249 ff_update_block_index(s);
250 s->dsp.clear_blocks(s->block[0]);
251
252 for(j=0;j<6;j++)
253 s->block_last_index[j] = -1;
254
255 s->mv_dir = MV_DIR_FORWARD;
256 s->mv_type = MV_TYPE_16X16;
257 s->current_picture.mb_type[xy]= MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
258 s->mv[0][0][0] = 0;
259 s->mv[0][0][1] = 0;
260 s->mb_skiped = 1;
261
262 MPV_decode_mb(s, s->block);
263 }
264
265 return 0;
266 }
267
268 static int decode_mv_component(GetBitContext *gb, int v){
269 int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);
270
271 /* check if mv_diff is valid */
272 if ( mv_diff < 0 )
273 return v;
274
275 mv_diff = mvmap[mv_diff];
276
277 if(mv_diff && !get_bits1(gb))
278 mv_diff= -mv_diff;
279
280 v += mv_diff;
281 if (v <=-16) v+= 32;
282 else if(v >= 16) v-= 32;
283
284 return v;
285 }
286
287 static int h261_decode_mb(H261Context *h){
288 MpegEncContext * const s = &h->s;
289 int i, cbp, xy, old_mtype;
290
291 cbp = 63;
292 // Read mba
293 do{
294 h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table, H261_MBA_VLC_BITS, 2);
295
296 /* Check for slice end */
297 /* NOTE: GOB can be empty (no MB data) or exist only of MBA_stuffing */
298 if (h->mba_diff == MBA_STARTCODE){ // start code
299 h->gob_start_code_skipped = 1;
300 return SLICE_END;
301 }
302 }
303 while( h->mba_diff == MBA_STUFFING ); // stuffing
304
305 if ( h->mba_diff < 0 ){
306 if ( get_bits_count(&s->gb) + 7 >= s->gb.size_in_bits )
307 return SLICE_END;
308
309 av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y);
310 return SLICE_ERROR;
311 }
312
313 h->mba_diff += 1;
314 h->current_mba += h->mba_diff;
315
316 if ( h->current_mba > MBA_STUFFING )
317 return SLICE_ERROR;
318
319 s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1) % 11);
320 s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1) / 11);
321 xy = s->mb_x + s->mb_y * s->mb_stride;
322 ff_init_block_index(s);
323 ff_update_block_index(s);
324 s->dsp.clear_blocks(s->block[0]);
325
326 // Read mtype
327 old_mtype = h->mtype;
328 h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
329 h->mtype = h261_mtype_map[h->mtype];
330
331 // Read mquant
332 if ( IS_QUANT ( h->mtype ) ){
333 ff_set_qscale(s, get_bits(&s->gb, 5));
334 }
335
336 s->mb_intra = IS_INTRA4x4(h->mtype);
337
338 // Read mv
339 if ( IS_16X16 ( h->mtype ) ){
340 // Motion vector data is included for all MC macroblocks. MVD is obtained from the macroblock vector by subtracting the
341 // vector of the preceding macroblock. For this calculation the vector of the preceding macroblock is regarded as zero in the
342 // following three situations:
343 // 1) evaluating MVD for macroblocks 1, 12 and 23;
344 // 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
345 // 3) MTYPE of the previous macroblock was not MC.
346 if ( ( h->current_mba == 1 ) || ( h->current_mba == 12 ) || ( h->current_mba == 23 ) ||
347 ( h->mba_diff != 1) || ( !IS_16X16 ( old_mtype ) ))
348 {
349 h->current_mv_x = 0;
350 h->current_mv_y = 0;
351 }
352
353 h->current_mv_x= decode_mv_component(&s->gb, h->current_mv_x);
354 h->current_mv_y= decode_mv_component(&s->gb, h->current_mv_y);
355 }
356
357 // Read cbp
358 if ( HAS_CBP( h->mtype ) ){
359 cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 2) + 1;
360 }
361
362 if(s->mb_intra){
363 s->current_picture.mb_type[xy]= MB_TYPE_INTRA;
364 goto intra;
365 }
366
367 //set motion vectors
368 s->mv_dir = MV_DIR_FORWARD;
369 s->mv_type = MV_TYPE_16X16;
370 s->current_picture.mb_type[xy]= MB_TYPE_16x16 | MB_TYPE_L0;
371 if(IS_16X16 ( h->mtype )){
372 s->mv[0][0][0] = h->current_mv_x * 2;//gets divided by 2 in motion compensation
373 s->mv[0][0][1] = h->current_mv_y * 2;
374 }
375 else{
376 h->current_mv_x = s->mv[0][0][0] = 0;
377 h->current_mv_x = s->mv[0][0][1] = 0;
378 }
379
380 intra:
381 /* decode each block */
382 if(s->mb_intra || HAS_CBP(h->mtype)){
383 for (i = 0; i < 6; i++) {
384 if (h261_decode_block(h, s->block[i], i, cbp&32) < 0){
385 return SLICE_ERROR;
386 }
387 cbp+=cbp;
388 }
389 }
390
391 MPV_decode_mb(s, s->block);
392
393 if(IS_FIL (h->mtype)){
394 ff_h261_loop_filter(h);
395 }
396
397 return SLICE_OK;
398 }
399
400 /**
401 * decodes a macroblock
402 * @return <0 if an error occured
403 */
404 static int h261_decode_block(H261Context * h, DCTELEM * block,
405 int n, int coded)
406 {
407 MpegEncContext * const s = &h->s;
408 int code, level, i, j, run;
409 RLTable *rl = &h261_rl_tcoeff;
410 const uint8_t *scan_table;
411
412 // For the variable length encoding there are two code tables, one being used for
413 // the first transmitted LEVEL in INTER, INTER+MC and INTER+MC+FIL blocks, the second
414 // for all other LEVELs except the first one in INTRA blocks which is fixed length
415 // coded with 8 bits.
416 // NOTE: the two code tables only differ in one VLC so we handle that manually.
417 scan_table = s->intra_scantable.permutated;
418 if (s->mb_intra){
419 /* DC coef */
420 level = get_bits(&s->gb, 8);
421 // 0 (00000000b) and -128 (10000000b) are FORBIDDEN
422 if((level&0x7F) == 0){
423 av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
424 return -1;
425 }
426 // The code 1000 0000 is not used, the reconstruction level of 1024 being coded as 1111 1111.
427 if (level == 255)
428 level = 128;
429 block[0] = level;
430 i = 1;
431 }else if(coded){
432 // Run Level Code
433 // EOB Not possible for first level when cbp is available (that's why the table is different)
434 // 0 1 1s
435 // * * 0*
436 int check = show_bits(&s->gb, 2);
437 i = 0;
438 if ( check & 0x2 ){
439 skip_bits(&s->gb, 2);
440 block[0] = ( check & 0x1 ) ? -1 : 1;
441 i = 1;
442 }
443 }else{
444 i = 0;
445 }
446 if(!coded){
447 s->block_last_index[n] = i - 1;
448 return 0;
449 }
450 for(;;){
451 code = get_vlc2(&s->gb, rl->vlc.table, TCOEFF_VLC_BITS, 2);
452 if (code < 0){
453 av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
454 return -1;
455 }
456 if (code == rl->n) {
457 /* escape */
458 // 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.
459 run = get_bits(&s->gb, 6);
460 level = (int8_t)get_bits(&s->gb, 8);
461 }else if(code == 0){
462 break;
463 }else{
464 run = rl->table_run[code];
465 level = rl->table_level[code];
466 if (get_bits1(&s->gb))
467 level = -level;
468 }
469 i += run;
470 if (i >= 64){
471 av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", s->mb_x, s->mb_y);
472 return -1;
473 }
474 j = scan_table[i];
475 block[j] = level;
476 i++;
477 }
478 s->block_last_index[n] = i-1;
479 return 0;
480 }
481
482 /**
483 * decodes the H261 picture header.
484 * @return <0 if no startcode found
485 */
486 int h261_decode_picture_header(H261Context *h){
487 MpegEncContext * const s = &h->s;
488 int format, i;
489 uint32_t startcode;
490 align_get_bits(&s->gb);
491
492 startcode = (h->last_bits << (12 - (8-h->bits_left))) | get_bits(&s->gb, 20-8 - (8- h->bits_left));
493
494 for(i= s->gb.size_in_bits - get_bits_count(&s->gb); i>24; i-=1){
495 startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;
496
497 if(startcode == 0x10)
498 break;
499 }
500
501 if (startcode != 0x10){
502 av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
503 return -1;
504 }
505
506 /* temporal reference */
507 s->picture_number = get_bits(&s->gb, 5); /* picture timestamp */
508
509 /* PTYPE starts here */
510 skip_bits1(&s->gb); /* split screen off */
511 skip_bits1(&s->gb); /* camera off */
512 skip_bits1(&s->gb); /* freeze picture release off */
513
514 format = get_bits1(&s->gb);
515
516 //only 2 formats possible
517 if (format == 0){//QCIF
518 s->width = 176;
519 s->height = 144;
520 s->mb_width = 11;
521 s->mb_height = 9;
522 }else{//CIF
523 s->width = 352;
524 s->height = 288;
525 s->mb_width = 22;
526 s->mb_height = 18;
527 }
528
529 s->mb_num = s->mb_width * s->mb_height;
530
531 skip_bits1(&s->gb); /* still image mode off */
532 skip_bits1(&s->gb); /* Reserved */
533
534 /* PEI */
535 while (get_bits1(&s->gb) != 0){
536 skip_bits(&s->gb, 8);
537 }
538
539 // h261 has no I-FRAMES, but if we pass I_TYPE for the first frame, the codec crashes if it does
540 // not contain all I-blocks (e.g. when a packet is lost)
541 s->pict_type = P_TYPE;
542
543 h->gob_number = 0;
544 return 0;
545 }
546
547 static int h261_decode_gob(H261Context *h){
548 MpegEncContext * const s = &h->s;
549
550 ff_set_qscale(s, s->qscale);
551
552 /* decode mb's */
553 while(h->current_mba <= MBA_STUFFING)
554 {
555 int ret;
556 /* DCT & quantize */
557 ret= h261_decode_mb(h);
558 if(ret<0){
559 if(ret==SLICE_END){
560 h261_decode_mb_skipped(h, h->current_mba, 33);
561 return 0;
562 }
563 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", s->mb_x + s->mb_y*s->mb_stride);
564 return -1;
565 }
566
567 h261_decode_mb_skipped(h, h->current_mba-h->mba_diff, h->current_mba-1);
568 }
569
570 return -1;
571 }
572
573 static int h261_find_frame_end(ParseContext *pc, AVCodecContext* avctx, const uint8_t *buf, int buf_size){
574 int vop_found, i, j, bits_left, last_bits;
575 uint32_t state;
576
577 H261Context *h = avctx->priv_data;
578
579 if(h){
580 bits_left = h->bits_left;
581 last_bits = h->last_bits;
582 }
583 else{
584 bits_left = 0;
585 last_bits = 0;
586 }
587
588 vop_found= pc->frame_start_found;
589 state= pc->state;
590 if(bits_left!=0 && !vop_found)
591 state = state << (8-bits_left) | last_bits;
592 i=0;
593 if(!vop_found){
594 for(i=0; i<buf_size; i++){
595 state= (state<<8) | buf[i];
596 for(j=0; j<8; j++){
597 if(( ( (state<<j) | (buf[i]>>(8-j)) )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
598 i++;
599 vop_found=1;
600 break;
601 }
602 }
603 if(vop_found)
604 break;
605 }
606 }
607 if(vop_found){
608 for(; i<buf_size; i++){
609 if(avctx->flags & CODEC_FLAG_TRUNCATED)//XXX ffplay workaround, someone a better solution?
610 state= (state<<8) | buf[i];
611 for(j=0; j<8; j++){
612 if(( ( (state<<j) | (buf[i]>>(8-j)) )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
613 pc->frame_start_found=0;
614 pc->state=-1;
615 return i-3;
616 }
617 }
618 }
619 }
620
621 pc->frame_start_found= vop_found;
622 pc->state= state;
623 return END_NOT_FOUND;
624 }
625
626 static int h261_parse(AVCodecParserContext *s,
627 AVCodecContext *avctx,
628 uint8_t **poutbuf, int *poutbuf_size,
629 const uint8_t *buf, int buf_size)
630 {
631 ParseContext *pc = s->priv_data;
632 int next;
633
634 next= h261_find_frame_end(pc,avctx, buf, buf_size);
635 if (ff_combine_frame(pc, next, (uint8_t **)&buf, &buf_size) < 0) {
636 *poutbuf = NULL;
637 *poutbuf_size = 0;
638 return buf_size;
639 }
640 *poutbuf = (uint8_t *)buf;
641 *poutbuf_size = buf_size;
642 return next;
643 }
644
645 /**
646 * returns the number of bytes consumed for building the current frame
647 */
648 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
649 int pos= (get_bits_count(&s->gb)+7)>>3;
650
651 if(s->flags&CODEC_FLAG_TRUNCATED){
652 pos -= s->parse_context.last_index;
653 if(pos<0) pos=0;// padding is not really read so this might be -1
654 return pos;
655 }else{
656 if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
657 if(pos+10>buf_size) pos=buf_size; // oops ;)
658
659 return pos;
660 }
661 }
662
663 static int h261_decode_frame(AVCodecContext *avctx,
664 void *data, int *data_size,
665 uint8_t *buf, int buf_size)
666 {
667 H261Context *h= avctx->priv_data;
668 MpegEncContext *s = &h->s;
669 int ret;
670 AVFrame *pict = data;
671
672 #ifdef DEBUG
673 printf("*****frame %d size=%d\n", avctx->frame_number, buf_size);
674 printf("bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
675 #endif
676 s->flags= avctx->flags;
677 s->flags2= avctx->flags2;
678
679 /* no supplementary picture */
680 if (buf_size == 0) {
681
682 return 0;
683 }
684
685 if(s->flags&CODEC_FLAG_TRUNCATED){
686 int next;
687
688 next= h261_find_frame_end(&s->parse_context,avctx, buf, buf_size);
689
690 if( ff_combine_frame(&s->parse_context, next, &buf, &buf_size) < 0 )
691 return buf_size;
692 }
693
694
695 retry:
696
697 init_get_bits(&s->gb, buf, buf_size*8);
698
699 if(!s->context_initialized){
700 if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
701 return -1;
702 }
703
704 //we need to set current_picture_ptr before reading the header, otherwise we cant store anyting im there
705 if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
706 int i= ff_find_unused_picture(s, 0);
707 s->current_picture_ptr= &s->picture[i];
708 }
709
710 ret = h261_decode_picture_header(h);
711
712 /* skip if the header was thrashed */
713 if (ret < 0){
714 av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
715 return -1;
716 }
717
718 if (s->width != avctx->width || s->height != avctx->height){
719 ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
720 s->parse_context.buffer=0;
721 MPV_common_end(s);
722 s->parse_context= pc;
723 }
724 if (!s->context_initialized) {
725 avctx->width = s->width;
726 avctx->height = s->height;
727
728 goto retry;
729 }
730
731 // for hurry_up==5
732 s->current_picture.pict_type= s->pict_type;
733 s->current_picture.key_frame= s->pict_type == I_TYPE;
734
735 /* skip everything if we are in a hurry>=5 */
736 if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
737
738 if(MPV_frame_start(s, avctx) < 0)
739 return -1;
740
741 ff_er_frame_start(s);
742
743 /* decode each macroblock */
744 s->mb_x=0;
745 s->mb_y=0;
746
747 while(h->gob_number < (s->mb_height==18 ? 12 : 5)){
748 if(ff_h261_resync(h)<0)
749 break;
750 h261_decode_gob(h);
751 }
752 MPV_frame_end(s);
753
754 // h261 doesn't have byte aligned codes
755 // store the bits of the next frame that are left in the last byte
756 // in the H261Context and remember the number of stored bits
757 {
758 int bitsleft;
759 int current_pos= get_bits_count(&s->gb)>>3;
760 bitsleft = (current_pos<<3) - get_bits_count(&s->gb);
761 h->bits_left = - bitsleft;
762 if(bitsleft > 0)
763 h->last_bits= get_bits(&s->gb, 8 - h->bits_left);
764 else
765 h->last_bits = 0;
766 }
767
768 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
769 assert(s->current_picture.pict_type == s->pict_type);
770 *pict= *(AVFrame*)&s->current_picture;
771 ff_print_debug_info(s, pict);
772
773 /* Return the Picture timestamp as the frame number */
774 /* we substract 1 because it is added on utils.c */
775 avctx->frame_number = s->picture_number - 1;
776
777 *data_size = sizeof(AVFrame);
778
779 return get_consumed_bytes(s, buf_size);
780 }
781
782 static int h261_decode_end(AVCodecContext *avctx)
783 {
784 H261Context *h= avctx->priv_data;
785 MpegEncContext *s = &h->s;
786
787 MPV_common_end(s);
788 return 0;
789 }
790
791 AVCodec h261_decoder = {
792 "h261",
793 CODEC_TYPE_VIDEO,
794 CODEC_ID_H261,
795 sizeof(H261Context),
796 h261_decode_init,
797 NULL,
798 h261_decode_end,
799 h261_decode_frame,
800 CODEC_CAP_TRUNCATED,
801 };
802
803 AVCodecParser h261_parser = {
804 { CODEC_ID_H261 },
805 sizeof(ParseContext),
806 NULL,
807 h261_parse,
808 ff_parse_close,
809 };