lavc: remove FF_API_HURRY_UP cruft
[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 Libav.
7  *
8  * Libav 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  * Libav 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 Libav; 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.263 decoder.
26  */
27
28 #include "libavutil/cpu.h"
29 #include "internal.h"
30 #include "avcodec.h"
31 #include "dsputil.h"
32 #include "mpegvideo.h"
33 #include "h263.h"
34 #include "h263_parser.h"
35 #include "mpeg4video_parser.h"
36 #include "msmpeg4.h"
37 #include "vdpau_internal.h"
38 #include "flv.h"
39 #include "mpeg4video.h"
40
41 //#define DEBUG
42 //#define PRINT_FRAME_TIME
43
44 av_cold int ff_h263_decode_init(AVCodecContext *avctx)
45 {
46     MpegEncContext *s = avctx->priv_data;
47
48     s->avctx = avctx;
49     s->out_format = FMT_H263;
50
51     s->width  = avctx->coded_width;
52     s->height = avctx->coded_height;
53     s->workaround_bugs= avctx->workaround_bugs;
54
55     // set defaults
56     MPV_decode_defaults(s);
57     s->quant_precision=5;
58     s->decode_mb= ff_h263_decode_mb;
59     s->low_delay= 1;
60     avctx->pix_fmt= avctx->get_format(avctx, avctx->codec->pix_fmts);
61     s->unrestricted_mv= 1;
62
63     /* select sub codec */
64     switch(avctx->codec->id) {
65     case CODEC_ID_H263:
66         s->unrestricted_mv= 0;
67         avctx->chroma_sample_location = AVCHROMA_LOC_CENTER;
68         break;
69     case CODEC_ID_MPEG4:
70         break;
71     case CODEC_ID_MSMPEG4V1:
72         s->h263_msmpeg4 = 1;
73         s->h263_pred = 1;
74         s->msmpeg4_version=1;
75         break;
76     case CODEC_ID_MSMPEG4V2:
77         s->h263_msmpeg4 = 1;
78         s->h263_pred = 1;
79         s->msmpeg4_version=2;
80         break;
81     case CODEC_ID_MSMPEG4V3:
82         s->h263_msmpeg4 = 1;
83         s->h263_pred = 1;
84         s->msmpeg4_version=3;
85         break;
86     case CODEC_ID_WMV1:
87         s->h263_msmpeg4 = 1;
88         s->h263_pred = 1;
89         s->msmpeg4_version=4;
90         break;
91     case CODEC_ID_WMV2:
92         s->h263_msmpeg4 = 1;
93         s->h263_pred = 1;
94         s->msmpeg4_version=5;
95         break;
96     case CODEC_ID_VC1:
97     case CODEC_ID_WMV3:
98         s->h263_msmpeg4 = 1;
99         s->h263_pred = 1;
100         s->msmpeg4_version=6;
101         avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
102         break;
103     case CODEC_ID_H263I:
104         break;
105     case CODEC_ID_FLV1:
106         s->h263_flv = 1;
107         break;
108     default:
109         return -1;
110     }
111     s->codec_id= avctx->codec->id;
112     avctx->hwaccel= ff_find_hwaccel(avctx->codec->id, avctx->pix_fmt);
113
114     /* for h263, we allocate the images after having read the header */
115     if (avctx->codec->id != CODEC_ID_H263 && avctx->codec->id != CODEC_ID_MPEG4)
116         if (MPV_common_init(s) < 0)
117             return -1;
118
119         h263_decode_init_vlc(s);
120
121     return 0;
122 }
123
124 av_cold int ff_h263_decode_end(AVCodecContext *avctx)
125 {
126     MpegEncContext *s = avctx->priv_data;
127
128     MPV_common_end(s);
129     return 0;
130 }
131
132 /**
133  * returns the number of bytes consumed for building the current frame
134  */
135 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
136     int pos= (get_bits_count(&s->gb)+7)>>3;
137
138     if(s->divx_packed || s->avctx->hwaccel){
139         //we would have to scan through the whole buf to handle the weird reordering ...
140         return buf_size;
141     }else if(s->flags&CODEC_FLAG_TRUNCATED){
142         pos -= s->parse_context.last_index;
143         if(pos<0) pos=0; // padding is not really read so this might be -1
144         return pos;
145     }else{
146         if(pos==0) pos=1; //avoid infinite loops (i doubt that is needed but ...)
147         if(pos+10>buf_size) pos=buf_size; // oops ;)
148
149         return pos;
150     }
151 }
152
153 static int decode_slice(MpegEncContext *s){
154     const int part_mask= s->partitioned_frame ? (AC_END|AC_ERROR) : 0x7F;
155     const int mb_size= 16>>s->avctx->lowres;
156     s->last_resync_gb= s->gb;
157     s->first_slice_line= 1;
158
159     s->resync_mb_x= s->mb_x;
160     s->resync_mb_y= s->mb_y;
161
162     ff_set_qscale(s, s->qscale);
163
164     if (s->avctx->hwaccel) {
165         const uint8_t *start= s->gb.buffer + get_bits_count(&s->gb)/8;
166         const uint8_t *end  = ff_h263_find_resync_marker(start + 1, s->gb.buffer_end);
167         skip_bits_long(&s->gb, 8*(end - start));
168         return s->avctx->hwaccel->decode_slice(s->avctx, start, end - start);
169     }
170
171     if(s->partitioned_frame){
172         const int qscale= s->qscale;
173
174         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
175             if(ff_mpeg4_decode_partitions(s) < 0)
176                 return -1;
177         }
178
179         /* restore variables which were modified */
180         s->first_slice_line=1;
181         s->mb_x= s->resync_mb_x;
182         s->mb_y= s->resync_mb_y;
183         ff_set_qscale(s, qscale);
184     }
185
186     for(; s->mb_y < s->mb_height; s->mb_y++) {
187         /* per-row end of slice checks */
188         if(s->msmpeg4_version){
189             if(s->resync_mb_y + s->slice_height == s->mb_y){
190                 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);
191
192                 return 0;
193             }
194         }
195
196         if(s->msmpeg4_version==1){
197             s->last_dc[0]=
198             s->last_dc[1]=
199             s->last_dc[2]= 128;
200         }
201
202         ff_init_block_index(s);
203         for(; s->mb_x < s->mb_width; s->mb_x++) {
204             int ret;
205
206             ff_update_block_index(s);
207
208             if(s->resync_mb_x == s->mb_x && s->resync_mb_y+1 == s->mb_y){
209                 s->first_slice_line=0;
210             }
211
212             /* DCT & quantize */
213
214             s->mv_dir = MV_DIR_FORWARD;
215             s->mv_type = MV_TYPE_16X16;
216 //            s->mb_skipped = 0;
217 //printf("%d %d %06X\n", ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
218             ret= s->decode_mb(s, s->block);
219
220             if (s->pict_type!=FF_B_TYPE)
221                 ff_h263_update_motion_val(s);
222
223             if(ret<0){
224                 const int xy= s->mb_x + s->mb_y*s->mb_stride;
225                 if(ret==SLICE_END){
226                     MPV_decode_mb(s, s->block);
227                     if(s->loop_filter)
228                         ff_h263_loop_filter(s);
229
230 //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));
231                     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);
232
233                     s->padding_bug_score--;
234
235                     if(++s->mb_x >= s->mb_width){
236                         s->mb_x=0;
237                         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
238                         s->mb_y++;
239                     }
240                     return 0;
241                 }else if(ret==SLICE_NOEND){
242                     av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
243                     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);
244                     return -1;
245                 }
246                 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
247                 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);
248
249                 return -1;
250             }
251
252             MPV_decode_mb(s, s->block);
253             if(s->loop_filter)
254                 ff_h263_loop_filter(s);
255         }
256
257         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
258
259         s->mb_x= 0;
260     }
261
262     assert(s->mb_x==0 && s->mb_y==s->mb_height);
263
264     if(s->codec_id==CODEC_ID_MPEG4
265        && (s->workaround_bugs&FF_BUG_AUTODETECT)
266        && get_bits_left(&s->gb) >= 48
267        && show_bits(&s->gb, 24)==0x4010
268        && !s->data_partitioning)
269         s->padding_bug_score+=32;
270
271     /* try to detect the padding bug */
272     if(      s->codec_id==CODEC_ID_MPEG4
273        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
274        &&    get_bits_left(&s->gb) >=0
275        &&    get_bits_left(&s->gb) < 48
276 //       &&   !s->resync_marker
277        &&   !s->data_partitioning){
278
279         const int bits_count= get_bits_count(&s->gb);
280         const int bits_left = s->gb.size_in_bits - bits_count;
281
282         if(bits_left==0){
283             s->padding_bug_score+=16;
284         } else if(bits_left != 1){
285             int v= show_bits(&s->gb, 8);
286             v|= 0x7F >> (7-(bits_count&7));
287
288             if(v==0x7F && bits_left<=8)
289                 s->padding_bug_score--;
290             else if(v==0x7F && ((get_bits_count(&s->gb)+8)&8) && bits_left<=16)
291                 s->padding_bug_score+= 4;
292             else
293                 s->padding_bug_score++;
294         }
295     }
296
297     if(s->workaround_bugs&FF_BUG_AUTODETECT){
298         if(s->padding_bug_score > -2 && !s->data_partitioning /*&& (s->divx_version>=0 || !s->resync_marker)*/)
299             s->workaround_bugs |=  FF_BUG_NO_PADDING;
300         else
301             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
302     }
303
304     // handle formats which don't have unique end markers
305     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
306         int left= get_bits_left(&s->gb);
307         int max_extra=7;
308
309         /* no markers in M$ crap */
310         if(s->msmpeg4_version && s->pict_type==FF_I_TYPE)
311             max_extra+= 17;
312
313         /* buggy padding but the frame should still end approximately at the bitstream end */
314         if((s->workaround_bugs&FF_BUG_NO_PADDING) && s->error_recognition>=3)
315             max_extra+= 48;
316         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
317             max_extra+= 256*256*256*64;
318
319         if(left>max_extra){
320             av_log(s->avctx, AV_LOG_ERROR, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
321         }
322         else if(left<0){
323             av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
324         }else
325             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);
326
327         return 0;
328     }
329
330     av_log(s->avctx, AV_LOG_ERROR, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
331             get_bits_left(&s->gb),
332             show_bits(&s->gb, 24), s->padding_bug_score);
333
334     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);
335
336     return -1;
337 }
338
339 int ff_h263_decode_frame(AVCodecContext *avctx,
340                              void *data, int *data_size,
341                              AVPacket *avpkt)
342 {
343     const uint8_t *buf = avpkt->data;
344     int buf_size = avpkt->size;
345     MpegEncContext *s = avctx->priv_data;
346     int ret;
347     AVFrame *pict = data;
348
349 #ifdef PRINT_FRAME_TIME
350 uint64_t time= rdtsc();
351 #endif
352     s->flags= avctx->flags;
353     s->flags2= avctx->flags2;
354
355     /* no supplementary picture */
356     if (buf_size == 0) {
357         /* special case for last picture */
358         if (s->low_delay==0 && s->next_picture_ptr) {
359             *pict= *(AVFrame*)s->next_picture_ptr;
360             s->next_picture_ptr= NULL;
361
362             *data_size = sizeof(AVFrame);
363         }
364
365         return 0;
366     }
367
368     if(s->flags&CODEC_FLAG_TRUNCATED){
369         int next;
370
371         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
372             next= ff_mpeg4_find_frame_end(&s->parse_context, buf, buf_size);
373         }else if(CONFIG_H263_DECODER && s->codec_id==CODEC_ID_H263){
374             next= ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
375         }else{
376             av_log(s->avctx, AV_LOG_ERROR, "this codec does not support truncated bitstreams\n");
377             return -1;
378         }
379
380         if( ff_combine_frame(&s->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
381             return buf_size;
382     }
383
384
385 retry:
386
387     if(s->bitstream_buffer_size && (s->divx_packed || buf_size<20)){ //divx 5.01+/xvid frame reorder
388         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
389     }else
390         init_get_bits(&s->gb, buf, buf_size*8);
391     s->bitstream_buffer_size=0;
392
393     if (!s->context_initialized) {
394         if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
395             return -1;
396     }
397
398     /* We need to set current_picture_ptr before reading the header,
399      * otherwise we cannot store anyting in there */
400     if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
401         int i= ff_find_unused_picture(s, 0);
402         s->current_picture_ptr= &s->picture[i];
403     }
404
405     /* let's go :-) */
406     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
407         ret= ff_wmv2_decode_picture_header(s);
408     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
409         ret = msmpeg4_decode_picture_header(s);
410     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
411         if(s->avctx->extradata_size && s->picture_number==0){
412             GetBitContext gb;
413
414             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
415             ret = ff_mpeg4_decode_picture_header(s, &gb);
416         }
417         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
418     } else if (CONFIG_H263I_DECODER && s->codec_id == CODEC_ID_H263I) {
419         ret = ff_intel_h263_decode_picture_header(s);
420     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
421         ret = ff_flv_decode_picture_header(s);
422     } else {
423         ret = h263_decode_picture_header(s);
424     }
425
426     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
427
428     /* skip if the header was thrashed */
429     if (ret < 0){
430         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
431         return -1;
432     }
433
434     avctx->has_b_frames= !s->low_delay;
435
436     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
437         if(s->stream_codec_tag == AV_RL32("XVID") ||
438            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
439            s->codec_tag == AV_RL32("RMP4") ||
440            s->codec_tag == AV_RL32("SIPP")
441            )
442             s->xvid_build= 0;
443 #if 0
444         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
445            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
446             s->xvid_build= 0;
447 #endif
448     }
449
450     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
451         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
452             s->divx_version= 400; //divx 4
453     }
454
455     if(s->xvid_build>=0 && s->divx_version>=0){
456         s->divx_version=
457         s->divx_build= -1;
458     }
459
460     if(s->workaround_bugs&FF_BUG_AUTODETECT){
461         if(s->codec_tag == AV_RL32("XVIX"))
462             s->workaround_bugs|= FF_BUG_XVID_ILACE;
463
464         if(s->codec_tag == AV_RL32("UMP4")){
465             s->workaround_bugs|= FF_BUG_UMP4;
466         }
467
468         if(s->divx_version>=500 && s->divx_build<1814){
469             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
470         }
471
472         if(s->divx_version>502 && s->divx_build<1814){
473             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
474         }
475
476         if(s->xvid_build<=3U)
477             s->padding_bug_score= 256*256*256*64;
478
479         if(s->xvid_build<=1U)
480             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
481
482         if(s->xvid_build<=12U)
483             s->workaround_bugs|= FF_BUG_EDGE;
484
485         if(s->xvid_build<=32U)
486             s->workaround_bugs|= FF_BUG_DC_CLIP;
487
488 #define SET_QPEL_FUNC(postfix1, postfix2) \
489     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
490     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
491     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
492
493         if(s->lavc_build<4653U)
494             s->workaround_bugs|= FF_BUG_STD_QPEL;
495
496         if(s->lavc_build<4655U)
497             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
498
499         if(s->lavc_build<4670U){
500             s->workaround_bugs|= FF_BUG_EDGE;
501         }
502
503         if(s->lavc_build<=4712U)
504             s->workaround_bugs|= FF_BUG_DC_CLIP;
505
506         if(s->divx_version>=0)
507             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
508 //printf("padding_bug_score: %d\n", s->padding_bug_score);
509         if(s->divx_version==501 && s->divx_build==20020416)
510             s->padding_bug_score= 256*256*256*64;
511
512         if(s->divx_version<500U){
513             s->workaround_bugs|= FF_BUG_EDGE;
514         }
515
516         if(s->divx_version>=0)
517             s->workaround_bugs|= FF_BUG_HPEL_CHROMA;
518 #if 0
519         if(s->divx_version==500)
520             s->padding_bug_score= 256*256*256*64;
521
522         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
523          * Let us hope this at least works.
524          */
525         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==-1
526            && s->codec_id==CODEC_ID_MPEG4 && s->vo_type==0)
527             s->workaround_bugs|= FF_BUG_NO_PADDING;
528
529         if(s->lavc_build<4609U) //FIXME not sure about the version num but a 4609 file seems ok
530             s->workaround_bugs|= FF_BUG_NO_PADDING;
531 #endif
532     }
533
534     if(s->workaround_bugs& FF_BUG_STD_QPEL){
535         SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
536         SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
537         SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
538         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
539         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
540         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
541
542         SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
543         SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
544         SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
545         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
546         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
547         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
548     }
549
550     if(avctx->debug & FF_DEBUG_BUGS)
551         av_log(s->avctx, AV_LOG_DEBUG, "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
552                s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
553                s->divx_packed ? "p" : "");
554
555 #if 0 // dump bits per frame / qp / complexity
556 {
557     static FILE *f=NULL;
558     if(!f) f=fopen("rate_qp_cplx.txt", "w");
559     fprintf(f, "%d %d %f\n", buf_size, s->qscale, buf_size*(double)s->qscale);
560 }
561 #endif
562
563 #if HAVE_MMX
564     if (s->codec_id == CODEC_ID_MPEG4 && s->xvid_build>=0 && avctx->idct_algo == FF_IDCT_AUTO && (av_get_cpu_flags() & AV_CPU_FLAG_MMX)) {
565         avctx->idct_algo= FF_IDCT_XVIDMMX;
566         avctx->coded_width= 0; // force reinit
567 //        dsputil_init(&s->dsp, avctx);
568         s->picture_number=0;
569     }
570 #endif
571
572         /* After H263 & mpeg4 header decode we have the height, width,*/
573         /* and other parameters. So then we could init the picture   */
574         /* FIXME: By the way H263 decoder is evolving it should have */
575         /* an H263EncContext                                         */
576
577     if (   s->width  != avctx->coded_width
578         || s->height != avctx->coded_height) {
579         /* H.263 could change picture size any time */
580         ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
581         s->parse_context.buffer=0;
582         MPV_common_end(s);
583         s->parse_context= pc;
584     }
585     if (!s->context_initialized) {
586         avcodec_set_dimensions(avctx, s->width, s->height);
587
588         goto retry;
589     }
590
591     if((s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P || s->codec_id == CODEC_ID_H263I))
592         s->gob_index = ff_h263_get_gob_height(s);
593
594     // for skipping the frame
595     s->current_picture.pict_type= s->pict_type;
596     s->current_picture.key_frame= s->pict_type == FF_I_TYPE;
597
598     /* skip B-frames if we don't have reference frames */
599     if(s->last_picture_ptr==NULL && (s->pict_type==FF_B_TYPE || s->dropable)) return get_consumed_bytes(s, buf_size);
600     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==FF_B_TYPE)
601        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=FF_I_TYPE)
602        ||  avctx->skip_frame >= AVDISCARD_ALL)
603         return get_consumed_bytes(s, buf_size);
604
605     if(s->next_p_frame_damaged){
606         if(s->pict_type==FF_B_TYPE)
607             return get_consumed_bytes(s, buf_size);
608         else
609             s->next_p_frame_damaged=0;
610     }
611
612     if((s->avctx->flags2 & CODEC_FLAG2_FAST) && s->pict_type==FF_B_TYPE){
613         s->me.qpel_put= s->dsp.put_2tap_qpel_pixels_tab;
614         s->me.qpel_avg= s->dsp.avg_2tap_qpel_pixels_tab;
615     }else if((!s->no_rounding) || s->pict_type==FF_B_TYPE){
616         s->me.qpel_put= s->dsp.put_qpel_pixels_tab;
617         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
618     }else{
619         s->me.qpel_put= s->dsp.put_no_rnd_qpel_pixels_tab;
620         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
621     }
622
623     if(MPV_frame_start(s, avctx) < 0)
624         return -1;
625
626     if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
627         ff_vdpau_mpeg4_decode_picture(s, s->gb.buffer, s->gb.buffer_end - s->gb.buffer);
628         goto frame_end;
629     }
630
631     if (avctx->hwaccel) {
632         if (avctx->hwaccel->start_frame(avctx, s->gb.buffer, s->gb.buffer_end - s->gb.buffer) < 0)
633             return -1;
634     }
635
636     ff_er_frame_start(s);
637
638     //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
639     //which is not available before MPV_frame_start()
640     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5){
641         ret = ff_wmv2_decode_secondary_picture_header(s);
642         if(ret<0) return ret;
643         if(ret==1) goto intrax8_decoded;
644     }
645
646     /* decode each macroblock */
647     s->mb_x=0;
648     s->mb_y=0;
649
650     decode_slice(s);
651     while(s->mb_y<s->mb_height){
652         if(s->msmpeg4_version){
653             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)
654                 break;
655         }else{
656             if(ff_h263_resync(s)<0)
657                 break;
658         }
659
660         if(s->msmpeg4_version<4 && s->h263_pred)
661             ff_mpeg4_clean_buffers(s);
662
663         decode_slice(s);
664     }
665
666     if (s->h263_msmpeg4 && s->msmpeg4_version<4 && s->pict_type==FF_I_TYPE)
667         if(!CONFIG_MSMPEG4_DECODER || msmpeg4_decode_ext_header(s, buf_size) < 0){
668             s->error_status_table[s->mb_num-1]= AC_ERROR|DC_ERROR|MV_ERROR;
669         }
670
671     assert(s->bitstream_buffer_size==0);
672 frame_end:
673     /* divx 5.01+ bistream reorder stuff */
674     if(s->codec_id==CODEC_ID_MPEG4 && s->divx_packed){
675         int current_pos= get_bits_count(&s->gb)>>3;
676         int startcode_found=0;
677
678         if(buf_size - current_pos > 5){
679             int i;
680             for(i=current_pos; i<buf_size-3; i++){
681                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
682                     startcode_found=1;
683                     break;
684                 }
685             }
686         }
687         if(s->gb.buffer == s->bitstream_buffer && buf_size>7 && s->xvid_build>=0){ //xvid style
688             startcode_found=1;
689             current_pos=0;
690         }
691
692         if(startcode_found){
693             av_fast_malloc(
694                 &s->bitstream_buffer,
695                 &s->allocated_bitstream_buffer_size,
696                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
697             if (!s->bitstream_buffer)
698                 return AVERROR(ENOMEM);
699             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
700             s->bitstream_buffer_size= buf_size - current_pos;
701         }
702     }
703
704 intrax8_decoded:
705     ff_er_frame_end(s);
706
707     if (avctx->hwaccel) {
708         if (avctx->hwaccel->end_frame(avctx) < 0)
709             return -1;
710     }
711
712     MPV_frame_end(s);
713
714 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
715 assert(s->current_picture.pict_type == s->pict_type);
716     if (s->pict_type == FF_B_TYPE || s->low_delay) {
717         *pict= *(AVFrame*)s->current_picture_ptr;
718     } else if (s->last_picture_ptr != NULL) {
719         *pict= *(AVFrame*)s->last_picture_ptr;
720     }
721
722     if(s->last_picture_ptr || s->low_delay){
723         *data_size = sizeof(AVFrame);
724         ff_print_debug_info(s, pict);
725     }
726
727 #ifdef PRINT_FRAME_TIME
728 av_log(avctx, AV_LOG_DEBUG, "%"PRId64"\n", rdtsc()-time);
729 #endif
730
731     return get_consumed_bytes(s, buf_size);
732 }
733
734 AVCodec ff_h263_decoder = {
735     "h263",
736     AVMEDIA_TYPE_VIDEO,
737     CODEC_ID_H263,
738     sizeof(MpegEncContext),
739     ff_h263_decode_init,
740     NULL,
741     ff_h263_decode_end,
742     ff_h263_decode_frame,
743     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
744     .flush= ff_mpeg_flush,
745     .max_lowres= 3,
746     .long_name= NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
747     .pix_fmts= ff_hwaccel_pixfmt_list_420,
748 };