e690583010e8a275b453da167f3419c75fc4e064
[ffmpeg.git] / libavcodec / h263dec.c
1 /*
2  * H.263 decoder
3  * Copyright (c) 2001 Fabrice Bellard
4  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
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 libavcodec/h263dec.c
25  * H.263 decoder.
26  */
27
28 #include "internal.h"
29 #include "avcodec.h"
30 #include "dsputil.h"
31 #include "mpegvideo.h"
32 #include "h263.h"
33 #include "h263_parser.h"
34 #include "mpeg4video_parser.h"
35 #include "msmpeg4.h"
36 #include "vdpau_internal.h"
37 #include "flv.h"
38 #include "mpeg4video.h"
39
40 //#define DEBUG
41 //#define PRINT_FRAME_TIME
42
43 av_cold int ff_h263_decode_init(AVCodecContext *avctx)
44 {
45     MpegEncContext *s = avctx->priv_data;
46
47     s->avctx = avctx;
48     s->out_format = FMT_H263;
49
50     s->width  = avctx->coded_width;
51     s->height = avctx->coded_height;
52     s->workaround_bugs= avctx->workaround_bugs;
53
54     // set defaults
55     MPV_decode_defaults(s);
56     s->quant_precision=5;
57     s->decode_mb= ff_h263_decode_mb;
58     s->low_delay= 1;
59     avctx->pix_fmt= avctx->get_format(avctx, avctx->codec->pix_fmts);
60     s->unrestricted_mv= 1;
61
62     /* select sub codec */
63     switch(avctx->codec->id) {
64     case CODEC_ID_H263:
65         s->unrestricted_mv= 0;
66         avctx->chroma_sample_location = AVCHROMA_LOC_CENTER;
67         break;
68     case CODEC_ID_MPEG4:
69         break;
70     case CODEC_ID_MSMPEG4V1:
71         s->h263_msmpeg4 = 1;
72         s->h263_pred = 1;
73         s->msmpeg4_version=1;
74         break;
75     case CODEC_ID_MSMPEG4V2:
76         s->h263_msmpeg4 = 1;
77         s->h263_pred = 1;
78         s->msmpeg4_version=2;
79         break;
80     case CODEC_ID_MSMPEG4V3:
81         s->h263_msmpeg4 = 1;
82         s->h263_pred = 1;
83         s->msmpeg4_version=3;
84         break;
85     case CODEC_ID_WMV1:
86         s->h263_msmpeg4 = 1;
87         s->h263_pred = 1;
88         s->msmpeg4_version=4;
89         break;
90     case CODEC_ID_WMV2:
91         s->h263_msmpeg4 = 1;
92         s->h263_pred = 1;
93         s->msmpeg4_version=5;
94         break;
95     case CODEC_ID_VC1:
96     case CODEC_ID_WMV3:
97         s->h263_msmpeg4 = 1;
98         s->h263_pred = 1;
99         s->msmpeg4_version=6;
100         avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
101         break;
102     case CODEC_ID_H263I:
103         break;
104     case CODEC_ID_FLV1:
105         s->h263_flv = 1;
106         break;
107     default:
108         return -1;
109     }
110     s->codec_id= avctx->codec->id;
111     avctx->hwaccel= ff_find_hwaccel(avctx->codec->id, avctx->pix_fmt);
112
113     /* for h263, we allocate the images after having read the header */
114     if (avctx->codec->id != CODEC_ID_H263 && avctx->codec->id != CODEC_ID_MPEG4)
115         if (MPV_common_init(s) < 0)
116             return -1;
117
118         h263_decode_init_vlc(s);
119
120     return 0;
121 }
122
123 av_cold int ff_h263_decode_end(AVCodecContext *avctx)
124 {
125     MpegEncContext *s = avctx->priv_data;
126
127     MPV_common_end(s);
128     return 0;
129 }
130
131 /**
132  * returns the number of bytes consumed for building the current frame
133  */
134 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
135     int pos= (get_bits_count(&s->gb)+7)>>3;
136
137     if(s->divx_packed || s->avctx->hwaccel){
138         //we would have to scan through the whole buf to handle the weird reordering ...
139         return buf_size;
140     }else if(s->flags&CODEC_FLAG_TRUNCATED){
141         pos -= s->parse_context.last_index;
142         if(pos<0) pos=0; // padding is not really read so this might be -1
143         return pos;
144     }else{
145         if(pos==0) pos=1; //avoid infinite loops (i doubt that is needed but ...)
146         if(pos+10>buf_size) pos=buf_size; // oops ;)
147
148         return pos;
149     }
150 }
151
152 static int decode_slice(MpegEncContext *s){
153     const int part_mask= s->partitioned_frame ? (AC_END|AC_ERROR) : 0x7F;
154     const int mb_size= 16>>s->avctx->lowres;
155     s->last_resync_gb= s->gb;
156     s->first_slice_line= 1;
157
158     s->resync_mb_x= s->mb_x;
159     s->resync_mb_y= s->mb_y;
160
161     ff_set_qscale(s, s->qscale);
162
163     if (s->avctx->hwaccel) {
164         const uint8_t *start= s->gb.buffer + get_bits_count(&s->gb)/8;
165         const uint8_t *end  = ff_h263_find_resync_marker(start + 1, s->gb.buffer_end);
166         skip_bits_long(&s->gb, 8*(end - start));
167         return s->avctx->hwaccel->decode_slice(s->avctx, start, end - start);
168     }
169
170     if(s->partitioned_frame){
171         const int qscale= s->qscale;
172
173         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
174             if(ff_mpeg4_decode_partitions(s) < 0)
175                 return -1;
176         }
177
178         /* restore variables which were modified */
179         s->first_slice_line=1;
180         s->mb_x= s->resync_mb_x;
181         s->mb_y= s->resync_mb_y;
182         ff_set_qscale(s, qscale);
183     }
184
185     for(; s->mb_y < s->mb_height; s->mb_y++) {
186         /* per-row end of slice checks */
187         if(s->msmpeg4_version){
188             if(s->resync_mb_y + s->slice_height == s->mb_y){
189                 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, AC_END|DC_END|MV_END);
190
191                 return 0;
192             }
193         }
194
195         if(s->msmpeg4_version==1){
196             s->last_dc[0]=
197             s->last_dc[1]=
198             s->last_dc[2]= 128;
199         }
200
201         ff_init_block_index(s);
202         for(; s->mb_x < s->mb_width; s->mb_x++) {
203             int ret;
204
205             ff_update_block_index(s);
206
207             if(s->resync_mb_x == s->mb_x && s->resync_mb_y+1 == s->mb_y){
208                 s->first_slice_line=0;
209             }
210
211             /* DCT & quantize */
212
213             s->mv_dir = MV_DIR_FORWARD;
214             s->mv_type = MV_TYPE_16X16;
215 //            s->mb_skipped = 0;
216 //printf("%d %d %06X\n", ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
217             ret= s->decode_mb(s, s->block);
218
219             if (s->pict_type!=FF_B_TYPE)
220                 ff_h263_update_motion_val(s);
221
222             if(ret<0){
223                 const int xy= s->mb_x + s->mb_y*s->mb_stride;
224                 if(ret==SLICE_END){
225                     MPV_decode_mb(s, s->block);
226                     if(s->loop_filter)
227                         ff_h263_loop_filter(s);
228
229 //printf("%d %d %d %06X\n", s->mb_x, s->mb_y, s->gb.size*8 - get_bits_count(&s->gb), show_bits(&s->gb, 24));
230                     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, (AC_END|DC_END|MV_END)&part_mask);
231
232                     s->padding_bug_score--;
233
234                     if(++s->mb_x >= s->mb_width){
235                         s->mb_x=0;
236                         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
237                         s->mb_y++;
238                     }
239                     return 0;
240                 }else if(ret==SLICE_NOEND){
241                     av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
242                     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x+1, s->mb_y, (AC_END|DC_END|MV_END)&part_mask);
243                     return -1;
244                 }
245                 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
246                 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, (AC_ERROR|DC_ERROR|MV_ERROR)&part_mask);
247
248                 return -1;
249             }
250
251             MPV_decode_mb(s, s->block);
252             if(s->loop_filter)
253                 ff_h263_loop_filter(s);
254         }
255
256         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
257
258         s->mb_x= 0;
259     }
260
261     assert(s->mb_x==0 && s->mb_y==s->mb_height);
262
263     /* try to detect the padding bug */
264     if(      s->codec_id==CODEC_ID_MPEG4
265        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
266        &&    get_bits_left(&s->gb) >=0
267        &&    get_bits_left(&s->gb) < 48
268 //       &&   !s->resync_marker
269        &&   !s->data_partitioning){
270
271         const int bits_count= get_bits_count(&s->gb);
272         const int bits_left = s->gb.size_in_bits - bits_count;
273
274         if(bits_left==0){
275             s->padding_bug_score+=16;
276         } else if(bits_left != 1){
277             int v= show_bits(&s->gb, 8);
278             v|= 0x7F >> (7-(bits_count&7));
279
280             if(v==0x7F && bits_left<=8)
281                 s->padding_bug_score--;
282             else if(v==0x7F && ((get_bits_count(&s->gb)+8)&8) && bits_left<=16)
283                 s->padding_bug_score+= 4;
284             else
285                 s->padding_bug_score++;
286         }
287     }
288
289     if(s->workaround_bugs&FF_BUG_AUTODETECT){
290         if(s->padding_bug_score > -2 && !s->data_partitioning /*&& (s->divx_version>=0 || !s->resync_marker)*/)
291             s->workaround_bugs |=  FF_BUG_NO_PADDING;
292         else
293             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
294     }
295
296     // handle formats which don't have unique end markers
297     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
298         int left= get_bits_left(&s->gb);
299         int max_extra=7;
300
301         /* no markers in M$ crap */
302         if(s->msmpeg4_version && s->pict_type==FF_I_TYPE)
303             max_extra+= 17;
304
305         /* buggy padding but the frame should still end approximately at the bitstream end */
306         if((s->workaround_bugs&FF_BUG_NO_PADDING) && s->error_recognition>=3)
307             max_extra+= 48;
308         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
309             max_extra+= 256*256*256*64;
310
311         if(left>max_extra){
312             av_log(s->avctx, AV_LOG_ERROR, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
313         }
314         else if(left<0){
315             av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
316         }else
317             ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, AC_END|DC_END|MV_END);
318
319         return 0;
320     }
321
322     av_log(s->avctx, AV_LOG_ERROR, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
323             get_bits_left(&s->gb),
324             show_bits(&s->gb, 24), s->padding_bug_score);
325
326     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, (AC_END|DC_END|MV_END)&part_mask);
327
328     return -1;
329 }
330
331 int ff_h263_decode_frame(AVCodecContext *avctx,
332                              void *data, int *data_size,
333                              AVPacket *avpkt)
334 {
335     const uint8_t *buf = avpkt->data;
336     int buf_size = avpkt->size;
337     MpegEncContext *s = avctx->priv_data;
338     int ret;
339     AVFrame *pict = data;
340
341 #ifdef PRINT_FRAME_TIME
342 uint64_t time= rdtsc();
343 #endif
344     s->flags= avctx->flags;
345     s->flags2= avctx->flags2;
346
347     /* no supplementary picture */
348     if (buf_size == 0) {
349         /* special case for last picture */
350         if (s->low_delay==0 && s->next_picture_ptr) {
351             *pict= *(AVFrame*)s->next_picture_ptr;
352             s->next_picture_ptr= NULL;
353
354             *data_size = sizeof(AVFrame);
355         }
356
357         return 0;
358     }
359
360     if(s->flags&CODEC_FLAG_TRUNCATED){
361         int next;
362
363         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
364             next= ff_mpeg4_find_frame_end(&s->parse_context, buf, buf_size);
365         }else if(CONFIG_H263_DECODER && s->codec_id==CODEC_ID_H263){
366             next= ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
367         }else{
368             av_log(s->avctx, AV_LOG_ERROR, "this codec does not support truncated bitstreams\n");
369             return -1;
370         }
371
372         if( ff_combine_frame(&s->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
373             return buf_size;
374     }
375
376
377 retry:
378
379     if(s->bitstream_buffer_size && (s->divx_packed || buf_size<20)){ //divx 5.01+/xvid frame reorder
380         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
381     }else
382         init_get_bits(&s->gb, buf, buf_size*8);
383     s->bitstream_buffer_size=0;
384
385     if (!s->context_initialized) {
386         if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
387             return -1;
388     }
389
390     /* We need to set current_picture_ptr before reading the header,
391      * otherwise we cannot store anyting in there */
392     if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
393         int i= ff_find_unused_picture(s, 0);
394         s->current_picture_ptr= &s->picture[i];
395     }
396
397     /* let's go :-) */
398     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
399         ret= ff_wmv2_decode_picture_header(s);
400     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
401         ret = msmpeg4_decode_picture_header(s);
402     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
403         if(s->avctx->extradata_size && s->picture_number==0){
404             GetBitContext gb;
405
406             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
407             ret = ff_mpeg4_decode_picture_header(s, &gb);
408         }
409         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
410     } else if (CONFIG_H263I_DECODER && s->codec_id == CODEC_ID_H263I) {
411         ret = ff_intel_h263_decode_picture_header(s);
412     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
413         ret = ff_flv_decode_picture_header(s);
414     } else {
415         ret = h263_decode_picture_header(s);
416     }
417
418     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
419
420     /* skip if the header was thrashed */
421     if (ret < 0){
422         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
423         return -1;
424     }
425
426     avctx->has_b_frames= !s->low_delay;
427
428     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
429         if(s->stream_codec_tag == AV_RL32("XVID") ||
430            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
431            s->codec_tag == AV_RL32("RMP4"))
432             s->xvid_build= 0;
433 #if 0
434         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
435            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
436             s->xvid_build= 0;
437 #endif
438     }
439
440     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
441         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
442             s->divx_version= 400; //divx 4
443     }
444
445     if(s->xvid_build>=0 && s->divx_version>=0){
446         s->divx_version=
447         s->divx_build= -1;
448     }
449
450     if(s->workaround_bugs&FF_BUG_AUTODETECT){
451         if(s->codec_tag == AV_RL32("XVIX"))
452             s->workaround_bugs|= FF_BUG_XVID_ILACE;
453
454         if(s->codec_tag == AV_RL32("UMP4")){
455             s->workaround_bugs|= FF_BUG_UMP4;
456         }
457
458         if(s->divx_version>=500 && s->divx_build<1814){
459             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
460         }
461
462         if(s->divx_version>502 && s->divx_build<1814){
463             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
464         }
465
466         if(s->xvid_build<=3U)
467             s->padding_bug_score= 256*256*256*64;
468
469         if(s->xvid_build<=1U)
470             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
471
472         if(s->xvid_build<=12U)
473             s->workaround_bugs|= FF_BUG_EDGE;
474
475         if(s->xvid_build<=32U)
476             s->workaround_bugs|= FF_BUG_DC_CLIP;
477
478 #define SET_QPEL_FUNC(postfix1, postfix2) \
479     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
480     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
481     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
482
483         if(s->lavc_build<4653U)
484             s->workaround_bugs|= FF_BUG_STD_QPEL;
485
486         if(s->lavc_build<4655U)
487             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
488
489         if(s->lavc_build<4670U){
490             s->workaround_bugs|= FF_BUG_EDGE;
491         }
492
493         if(s->lavc_build<=4712U)
494             s->workaround_bugs|= FF_BUG_DC_CLIP;
495
496         if(s->divx_version>=0)
497             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
498 //printf("padding_bug_score: %d\n", s->padding_bug_score);
499         if(s->divx_version==501 && s->divx_build==20020416)
500             s->padding_bug_score= 256*256*256*64;
501
502         if(s->divx_version<500U){
503             s->workaround_bugs|= FF_BUG_EDGE;
504         }
505
506         if(s->divx_version>=0)
507             s->workaround_bugs|= FF_BUG_HPEL_CHROMA;
508 #if 0
509         if(s->divx_version==500)
510             s->padding_bug_score= 256*256*256*64;
511
512         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
513          * Let us hope this at least works.
514          */
515         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==-1
516            && s->codec_id==CODEC_ID_MPEG4 && s->vo_type==0)
517             s->workaround_bugs|= FF_BUG_NO_PADDING;
518
519         if(s->lavc_build<4609U) //FIXME not sure about the version num but a 4609 file seems ok
520             s->workaround_bugs|= FF_BUG_NO_PADDING;
521 #endif
522     }
523
524     if(s->workaround_bugs& FF_BUG_STD_QPEL){
525         SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
526         SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
527         SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
528         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
529         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
530         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
531
532         SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
533         SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
534         SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
535         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
536         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
537         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
538     }
539
540     if(avctx->debug & FF_DEBUG_BUGS)
541         av_log(s->avctx, AV_LOG_DEBUG, "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
542                s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
543                s->divx_packed ? "p" : "");
544
545 #if 0 // dump bits per frame / qp / complexity
546 {
547     static FILE *f=NULL;
548     if(!f) f=fopen("rate_qp_cplx.txt", "w");
549     fprintf(f, "%d %d %f\n", buf_size, s->qscale, buf_size*(double)s->qscale);
550 }
551 #endif
552
553 #if HAVE_MMX
554     if(s->codec_id == CODEC_ID_MPEG4 && s->xvid_build>=0 && avctx->idct_algo == FF_IDCT_AUTO && (mm_flags & FF_MM_MMX)){
555         avctx->idct_algo= FF_IDCT_XVIDMMX;
556         avctx->coded_width= 0; // force reinit
557 //        dsputil_init(&s->dsp, avctx);
558         s->picture_number=0;
559     }
560 #endif
561
562         /* After H263 & mpeg4 header decode we have the height, width,*/
563         /* and other parameters. So then we could init the picture   */
564         /* FIXME: By the way H263 decoder is evolving it should have */
565         /* an H263EncContext                                         */
566
567     if (   s->width  != avctx->coded_width
568         || s->height != avctx->coded_height) {
569         /* H.263 could change picture size any time */
570         ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
571         s->parse_context.buffer=0;
572         MPV_common_end(s);
573         s->parse_context= pc;
574     }
575     if (!s->context_initialized) {
576         avcodec_set_dimensions(avctx, s->width, s->height);
577
578         goto retry;
579     }
580
581     if((s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P || s->codec_id == CODEC_ID_H263I))
582         s->gob_index = ff_h263_get_gob_height(s);
583
584     // for hurry_up==5
585     s->current_picture.pict_type= s->pict_type;
586     s->current_picture.key_frame= s->pict_type == FF_I_TYPE;
587
588     /* skip B-frames if we don't have reference frames */
589     if(s->last_picture_ptr==NULL && (s->pict_type==FF_B_TYPE || s->dropable)) return get_consumed_bytes(s, buf_size);
590     /* skip b frames if we are in a hurry */
591     if(avctx->hurry_up && s->pict_type==FF_B_TYPE) return get_consumed_bytes(s, buf_size);
592     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==FF_B_TYPE)
593        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=FF_I_TYPE)
594        ||  avctx->skip_frame >= AVDISCARD_ALL)
595         return get_consumed_bytes(s, buf_size);
596     /* skip everything if we are in a hurry>=5 */
597     if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
598
599     if(s->next_p_frame_damaged){
600         if(s->pict_type==FF_B_TYPE)
601             return get_consumed_bytes(s, buf_size);
602         else
603             s->next_p_frame_damaged=0;
604     }
605
606     if((s->avctx->flags2 & CODEC_FLAG2_FAST) && s->pict_type==FF_B_TYPE){
607         s->me.qpel_put= s->dsp.put_2tap_qpel_pixels_tab;
608         s->me.qpel_avg= s->dsp.avg_2tap_qpel_pixels_tab;
609     }else if((!s->no_rounding) || s->pict_type==FF_B_TYPE){
610         s->me.qpel_put= s->dsp.put_qpel_pixels_tab;
611         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
612     }else{
613         s->me.qpel_put= s->dsp.put_no_rnd_qpel_pixels_tab;
614         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
615     }
616
617     if(MPV_frame_start(s, avctx) < 0)
618         return -1;
619
620     if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
621         ff_vdpau_mpeg4_decode_picture(s, s->gb.buffer, s->gb.buffer_end - s->gb.buffer);
622         goto frame_end;
623     }
624
625     if (avctx->hwaccel) {
626         if (avctx->hwaccel->start_frame(avctx, s->gb.buffer, s->gb.buffer_end - s->gb.buffer) < 0)
627             return -1;
628     }
629
630     ff_er_frame_start(s);
631
632     //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
633     //which is not available before MPV_frame_start()
634     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5){
635         ret = ff_wmv2_decode_secondary_picture_header(s);
636         if(ret<0) return ret;
637         if(ret==1) goto intrax8_decoded;
638     }
639
640     /* decode each macroblock */
641     s->mb_x=0;
642     s->mb_y=0;
643
644     decode_slice(s);
645     while(s->mb_y<s->mb_height){
646         if(s->msmpeg4_version){
647             if(s->slice_height==0 || s->mb_x!=0 || (s->mb_y%s->slice_height)!=0 || get_bits_count(&s->gb) > s->gb.size_in_bits)
648                 break;
649         }else{
650             if(ff_h263_resync(s)<0)
651                 break;
652         }
653
654         if(s->msmpeg4_version<4 && s->h263_pred)
655             ff_mpeg4_clean_buffers(s);
656
657         decode_slice(s);
658     }
659
660     if (s->h263_msmpeg4 && s->msmpeg4_version<4 && s->pict_type==FF_I_TYPE)
661         if(!CONFIG_MSMPEG4_DECODER || msmpeg4_decode_ext_header(s, buf_size) < 0){
662             s->error_status_table[s->mb_num-1]= AC_ERROR|DC_ERROR|MV_ERROR;
663         }
664
665     assert(s->bitstream_buffer_size==0);
666 frame_end:
667     /* divx 5.01+ bistream reorder stuff */
668     if(s->codec_id==CODEC_ID_MPEG4 && s->divx_packed){
669         int current_pos= get_bits_count(&s->gb)>>3;
670         int startcode_found=0;
671
672         if(buf_size - current_pos > 5){
673             int i;
674             for(i=current_pos; i<buf_size-3; i++){
675                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
676                     startcode_found=1;
677                     break;
678                 }
679             }
680         }
681         if(s->gb.buffer == s->bitstream_buffer && buf_size>7 && s->xvid_build>=0){ //xvid style
682             startcode_found=1;
683             current_pos=0;
684         }
685
686         if(startcode_found){
687             av_fast_malloc(
688                 &s->bitstream_buffer,
689                 &s->allocated_bitstream_buffer_size,
690                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
691             if (!s->bitstream_buffer)
692                 return AVERROR(ENOMEM);
693             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
694             s->bitstream_buffer_size= buf_size - current_pos;
695         }
696     }
697
698 intrax8_decoded:
699     ff_er_frame_end(s);
700
701     if (avctx->hwaccel) {
702         if (avctx->hwaccel->end_frame(avctx) < 0)
703             return -1;
704     }
705
706     MPV_frame_end(s);
707
708 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
709 assert(s->current_picture.pict_type == s->pict_type);
710     if (s->pict_type == FF_B_TYPE || s->low_delay) {
711         *pict= *(AVFrame*)s->current_picture_ptr;
712     } else if (s->last_picture_ptr != NULL) {
713         *pict= *(AVFrame*)s->last_picture_ptr;
714     }
715
716     if(s->last_picture_ptr || s->low_delay){
717         *data_size = sizeof(AVFrame);
718         ff_print_debug_info(s, pict);
719     }
720
721 #ifdef PRINT_FRAME_TIME
722 av_log(avctx, AV_LOG_DEBUG, "%"PRId64"\n", rdtsc()-time);
723 #endif
724
725     return get_consumed_bytes(s, buf_size);
726 }
727
728 AVCodec h263_decoder = {
729     "h263",
730     CODEC_TYPE_VIDEO,
731     CODEC_ID_H263,
732     sizeof(MpegEncContext),
733     ff_h263_decode_init,
734     NULL,
735     ff_h263_decode_end,
736     ff_h263_decode_frame,
737     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
738     .flush= ff_mpeg_flush,
739     .long_name= NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
740     .pix_fmts= ff_hwaccel_pixfmt_list_420,
741 };