lavc: support ZenoXVID custom tag
[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 "thread.h"
39 #include "flv.h"
40 #include "mpeg4video.h"
41
42 //#define DEBUG
43 //#define PRINT_FRAME_TIME
44
45 av_cold int ff_h263_decode_init(AVCodecContext *avctx)
46 {
47     MpegEncContext *s = avctx->priv_data;
48
49     s->avctx = avctx;
50     s->out_format = FMT_H263;
51
52     s->width  = avctx->coded_width;
53     s->height = avctx->coded_height;
54     s->workaround_bugs= avctx->workaround_bugs;
55
56     // set defaults
57     ff_MPV_decode_defaults(s);
58     s->quant_precision=5;
59     s->decode_mb= ff_h263_decode_mb;
60     s->low_delay= 1;
61     if (avctx->codec->id == AV_CODEC_ID_MSS2)
62         avctx->pix_fmt = AV_PIX_FMT_YUV420P;
63     else
64         avctx->pix_fmt = avctx->get_format(avctx, avctx->codec->pix_fmts);
65     s->unrestricted_mv= 1;
66
67     /* select sub codec */
68     switch(avctx->codec->id) {
69     case AV_CODEC_ID_H263:
70         s->unrestricted_mv= 0;
71         avctx->chroma_sample_location = AVCHROMA_LOC_CENTER;
72         break;
73     case AV_CODEC_ID_MPEG4:
74         break;
75     case AV_CODEC_ID_MSMPEG4V1:
76         s->h263_pred = 1;
77         s->msmpeg4_version=1;
78         break;
79     case AV_CODEC_ID_MSMPEG4V2:
80         s->h263_pred = 1;
81         s->msmpeg4_version=2;
82         break;
83     case AV_CODEC_ID_MSMPEG4V3:
84         s->h263_pred = 1;
85         s->msmpeg4_version=3;
86         break;
87     case AV_CODEC_ID_WMV1:
88         s->h263_pred = 1;
89         s->msmpeg4_version=4;
90         break;
91     case AV_CODEC_ID_WMV2:
92         s->h263_pred = 1;
93         s->msmpeg4_version=5;
94         break;
95     case AV_CODEC_ID_VC1:
96     case AV_CODEC_ID_WMV3:
97     case AV_CODEC_ID_VC1IMAGE:
98     case AV_CODEC_ID_WMV3IMAGE:
99     case AV_CODEC_ID_MSS2:
100         s->h263_pred = 1;
101         s->msmpeg4_version=6;
102         avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
103         break;
104     case AV_CODEC_ID_H263I:
105         break;
106     case AV_CODEC_ID_FLV1:
107         s->h263_flv = 1;
108         break;
109     default:
110         return -1;
111     }
112     s->codec_id= avctx->codec->id;
113     avctx->hwaccel= ff_find_hwaccel(avctx->codec->id, avctx->pix_fmt);
114
115     /* for h263, we allocate the images after having read the header */
116     if (avctx->codec->id != AV_CODEC_ID_H263 && avctx->codec->id != AV_CODEC_ID_MPEG4)
117         if (ff_MPV_common_init(s) < 0)
118             return -1;
119
120         ff_h263_decode_init_vlc(s);
121
122     return 0;
123 }
124
125 av_cold int ff_h263_decode_end(AVCodecContext *avctx)
126 {
127     MpegEncContext *s = avctx->priv_data;
128
129     ff_MPV_common_end(s);
130     return 0;
131 }
132
133 /**
134  * Return the number of bytes consumed for building the current frame.
135  */
136 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
137     int pos= (get_bits_count(&s->gb)+7)>>3;
138
139     if(s->divx_packed || s->avctx->hwaccel){
140         //we would have to scan through the whole buf to handle the weird reordering ...
141         return buf_size;
142     }else if(s->flags&CODEC_FLAG_TRUNCATED){
143         pos -= s->parse_context.last_index;
144         if(pos<0) pos=0; // padding is not really read so this might be -1
145         return pos;
146     }else{
147         if(pos==0) pos=1; //avoid infinite loops (i doubt that is needed but ...)
148         if(pos+10>buf_size) pos=buf_size; // oops ;)
149
150         return pos;
151     }
152 }
153
154 static int decode_slice(MpegEncContext *s){
155     const int part_mask= s->partitioned_frame ? (ER_AC_END|ER_AC_ERROR) : 0x7F;
156     const int mb_size = 16;
157     s->last_resync_gb= s->gb;
158     s->first_slice_line= 1;
159
160     s->resync_mb_x= s->mb_x;
161     s->resync_mb_y= s->mb_y;
162
163     ff_set_qscale(s, s->qscale);
164
165     if (s->avctx->hwaccel) {
166         const uint8_t *start= s->gb.buffer + get_bits_count(&s->gb)/8;
167         const uint8_t *end  = ff_h263_find_resync_marker(start + 1, s->gb.buffer_end);
168         skip_bits_long(&s->gb, 8*(end - start));
169         return s->avctx->hwaccel->decode_slice(s->avctx, start, end - start);
170     }
171
172     if(s->partitioned_frame){
173         const int qscale= s->qscale;
174
175         if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4){
176             if(ff_mpeg4_decode_partitions(s) < 0)
177                 return -1;
178         }
179
180         /* restore variables which were modified */
181         s->first_slice_line=1;
182         s->mb_x= s->resync_mb_x;
183         s->mb_y= s->resync_mb_y;
184         ff_set_qscale(s, qscale);
185     }
186
187     for(; s->mb_y < s->mb_height; s->mb_y++) {
188         /* per-row end of slice checks */
189         if(s->msmpeg4_version){
190             if(s->resync_mb_y + s->slice_height == s->mb_y){
191                 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, ER_MB_END);
192
193                 return 0;
194             }
195         }
196
197         if(s->msmpeg4_version==1){
198             s->last_dc[0]=
199             s->last_dc[1]=
200             s->last_dc[2]= 128;
201         }
202
203         ff_init_block_index(s);
204         for(; s->mb_x < s->mb_width; s->mb_x++) {
205             int ret;
206
207             ff_update_block_index(s);
208
209             if(s->resync_mb_x == s->mb_x && s->resync_mb_y+1 == s->mb_y){
210                 s->first_slice_line=0;
211             }
212
213             /* DCT & quantize */
214
215             s->mv_dir = MV_DIR_FORWARD;
216             s->mv_type = MV_TYPE_16X16;
217 //            s->mb_skipped = 0;
218             av_dlog(s, "%d %d %06X\n",
219                     ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
220             ret= s->decode_mb(s, s->block);
221
222             if (s->pict_type!=AV_PICTURE_TYPE_B)
223                 ff_h263_update_motion_val(s);
224
225             if(ret<0){
226                 const int xy= s->mb_x + s->mb_y*s->mb_stride;
227                 if(ret==SLICE_END){
228                     ff_MPV_decode_mb(s, s->block);
229                     if(s->loop_filter)
230                         ff_h263_loop_filter(s);
231
232                     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_END&part_mask);
233
234                     s->padding_bug_score--;
235
236                     if(++s->mb_x >= s->mb_width){
237                         s->mb_x=0;
238                         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
239                         ff_MPV_report_decode_progress(s);
240                         s->mb_y++;
241                     }
242                     return 0;
243                 }else if(ret==SLICE_NOEND){
244                     av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
245                     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x+1, s->mb_y, ER_MB_END&part_mask);
246                     return -1;
247                 }
248                 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
249                 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_ERROR&part_mask);
250
251                 return -1;
252             }
253
254             ff_MPV_decode_mb(s, s->block);
255             if(s->loop_filter)
256                 ff_h263_loop_filter(s);
257         }
258
259         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
260         ff_MPV_report_decode_progress(s);
261
262         s->mb_x= 0;
263     }
264
265     assert(s->mb_x==0 && s->mb_y==s->mb_height);
266
267     if(s->codec_id==AV_CODEC_ID_MPEG4
268        && (s->workaround_bugs&FF_BUG_AUTODETECT)
269        && get_bits_left(&s->gb) >= 48
270        && show_bits(&s->gb, 24)==0x4010
271        && !s->data_partitioning)
272         s->padding_bug_score+=32;
273
274     /* try to detect the padding bug */
275     if(      s->codec_id==AV_CODEC_ID_MPEG4
276        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
277        &&    get_bits_left(&s->gb) >=0
278        &&    get_bits_left(&s->gb) < 48
279 //       &&   !s->resync_marker
280        &&   !s->data_partitioning){
281
282         const int bits_count= get_bits_count(&s->gb);
283         const int bits_left = s->gb.size_in_bits - bits_count;
284
285         if(bits_left==0){
286             s->padding_bug_score+=16;
287         } else if(bits_left != 1){
288             int v= show_bits(&s->gb, 8);
289             v|= 0x7F >> (7-(bits_count&7));
290
291             if(v==0x7F && bits_left<=8)
292                 s->padding_bug_score--;
293             else if(v==0x7F && ((get_bits_count(&s->gb)+8)&8) && bits_left<=16)
294                 s->padding_bug_score+= 4;
295             else
296                 s->padding_bug_score++;
297         }
298     }
299
300     if(s->workaround_bugs&FF_BUG_AUTODETECT){
301         if(s->padding_bug_score > -2 && !s->data_partitioning /*&& (s->divx_version>=0 || !s->resync_marker)*/)
302             s->workaround_bugs |=  FF_BUG_NO_PADDING;
303         else
304             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
305     }
306
307     // handle formats which don't have unique end markers
308     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
309         int left= get_bits_left(&s->gb);
310         int max_extra=7;
311
312         /* no markers in M$ crap */
313         if(s->msmpeg4_version && s->pict_type==AV_PICTURE_TYPE_I)
314             max_extra+= 17;
315
316         /* buggy padding but the frame should still end approximately at the bitstream end */
317         if((s->workaround_bugs&FF_BUG_NO_PADDING) && (s->err_recognition&AV_EF_BUFFER))
318             max_extra+= 48;
319         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
320             max_extra+= 256*256*256*64;
321
322         if(left>max_extra){
323             av_log(s->avctx, AV_LOG_ERROR, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
324         }
325         else if(left<0){
326             av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
327         }else
328             ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, ER_MB_END);
329
330         return 0;
331     }
332
333     av_log(s->avctx, AV_LOG_ERROR, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
334             get_bits_left(&s->gb),
335             show_bits(&s->gb, 24), s->padding_bug_score);
336
337     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_END&part_mask);
338
339     return -1;
340 }
341
342 int ff_h263_decode_frame(AVCodecContext *avctx,
343                              void *data, int *got_frame,
344                              AVPacket *avpkt)
345 {
346     const uint8_t *buf = avpkt->data;
347     int buf_size = avpkt->size;
348     MpegEncContext *s = avctx->priv_data;
349     int ret;
350     AVFrame *pict = data;
351
352 #ifdef PRINT_FRAME_TIME
353 uint64_t time= rdtsc();
354 #endif
355     s->flags= avctx->flags;
356     s->flags2= avctx->flags2;
357
358     /* no supplementary picture */
359     if (buf_size == 0) {
360         /* special case for last picture */
361         if (s->low_delay==0 && s->next_picture_ptr) {
362             *pict = s->next_picture_ptr->f;
363             s->next_picture_ptr= NULL;
364
365             *got_frame = 1;
366         }
367
368         return 0;
369     }
370
371     if(s->flags&CODEC_FLAG_TRUNCATED){
372         int next;
373
374         if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4){
375             next= ff_mpeg4_find_frame_end(&s->parse_context, buf, buf_size);
376         }else if(CONFIG_H263_DECODER && s->codec_id==AV_CODEC_ID_H263){
377             next= ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
378         }else{
379             av_log(s->avctx, AV_LOG_ERROR, "this codec does not support truncated bitstreams\n");
380             return -1;
381         }
382
383         if( ff_combine_frame(&s->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
384             return buf_size;
385     }
386
387
388 retry:
389
390     if(s->bitstream_buffer_size && (s->divx_packed || buf_size<20)){ //divx 5.01+/xvid frame reorder
391         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
392     }else
393         init_get_bits(&s->gb, buf, buf_size*8);
394     s->bitstream_buffer_size=0;
395
396     if (!s->context_initialized) {
397         if (ff_MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
398             return -1;
399     }
400
401     /* We need to set current_picture_ptr before reading the header,
402      * otherwise we cannot store anyting in there */
403     if (s->current_picture_ptr == NULL || s->current_picture_ptr->f.data[0]) {
404         int i= ff_find_unused_picture(s, 0);
405         if (i < 0)
406             return i;
407         s->current_picture_ptr= &s->picture[i];
408     }
409
410     /* let's go :-) */
411     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
412         ret= ff_wmv2_decode_picture_header(s);
413     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
414         ret = ff_msmpeg4_decode_picture_header(s);
415     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
416         if(s->avctx->extradata_size && s->picture_number==0){
417             GetBitContext gb;
418
419             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
420             ret = ff_mpeg4_decode_picture_header(s, &gb);
421         }
422         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
423     } else if (CONFIG_H263I_DECODER && s->codec_id == AV_CODEC_ID_H263I) {
424         ret = ff_intel_h263_decode_picture_header(s);
425     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
426         ret = ff_flv_decode_picture_header(s);
427     } else {
428         ret = ff_h263_decode_picture_header(s);
429     }
430
431     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
432
433     /* skip if the header was thrashed */
434     if (ret < 0){
435         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
436         return -1;
437     }
438
439     avctx->has_b_frames= !s->low_delay;
440
441     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
442         if(s->stream_codec_tag == AV_RL32("XVID") ||
443            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
444            s->codec_tag == AV_RL32("RMP4") || s->codec_tag == AV_RL32("ZMP4") ||
445            s->codec_tag == AV_RL32("SIPP")
446            )
447             s->xvid_build= 0;
448 #if 0
449         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
450            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
451             s->xvid_build= 0;
452 #endif
453     }
454
455     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
456         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
457             s->divx_version= 400; //divx 4
458     }
459
460     if(s->xvid_build>=0 && s->divx_version>=0){
461         s->divx_version=
462         s->divx_build= -1;
463     }
464
465     if(s->workaround_bugs&FF_BUG_AUTODETECT){
466         if(s->codec_tag == AV_RL32("XVIX"))
467             s->workaround_bugs|= FF_BUG_XVID_ILACE;
468
469         if(s->codec_tag == AV_RL32("UMP4")){
470             s->workaround_bugs|= FF_BUG_UMP4;
471         }
472
473         if(s->divx_version>=500 && s->divx_build<1814){
474             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
475         }
476
477         if(s->divx_version>502 && s->divx_build<1814){
478             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
479         }
480
481         if(s->xvid_build<=3U)
482             s->padding_bug_score= 256*256*256*64;
483
484         if(s->xvid_build<=1U)
485             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
486
487         if(s->xvid_build<=12U)
488             s->workaround_bugs|= FF_BUG_EDGE;
489
490         if(s->xvid_build<=32U)
491             s->workaround_bugs|= FF_BUG_DC_CLIP;
492
493 #define SET_QPEL_FUNC(postfix1, postfix2) \
494     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
495     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
496     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
497
498         if(s->lavc_build<4653U)
499             s->workaround_bugs|= FF_BUG_STD_QPEL;
500
501         if(s->lavc_build<4655U)
502             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
503
504         if(s->lavc_build<4670U){
505             s->workaround_bugs|= FF_BUG_EDGE;
506         }
507
508         if(s->lavc_build<=4712U)
509             s->workaround_bugs|= FF_BUG_DC_CLIP;
510
511         if(s->divx_version>=0)
512             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
513         if(s->divx_version==501 && s->divx_build==20020416)
514             s->padding_bug_score= 256*256*256*64;
515
516         if(s->divx_version<500U){
517             s->workaround_bugs|= FF_BUG_EDGE;
518         }
519
520         if(s->divx_version>=0)
521             s->workaround_bugs|= FF_BUG_HPEL_CHROMA;
522 #if 0
523         if(s->divx_version==500)
524             s->padding_bug_score= 256*256*256*64;
525
526         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
527          * Let us hope this at least works.
528          */
529         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==-1
530            && s->codec_id==AV_CODEC_ID_MPEG4 && s->vo_type==0)
531             s->workaround_bugs|= FF_BUG_NO_PADDING;
532
533         if(s->lavc_build<4609U) //FIXME not sure about the version num but a 4609 file seems ok
534             s->workaround_bugs|= FF_BUG_NO_PADDING;
535 #endif
536     }
537
538     if(s->workaround_bugs& FF_BUG_STD_QPEL){
539         SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
540         SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
541         SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
542         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
543         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
544         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
545
546         SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
547         SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
548         SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
549         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
550         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
551         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
552     }
553
554     if(avctx->debug & FF_DEBUG_BUGS)
555         av_log(s->avctx, AV_LOG_DEBUG, "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
556                s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
557                s->divx_packed ? "p" : "");
558
559 #if HAVE_MMX
560     if (s->codec_id == AV_CODEC_ID_MPEG4 && s->xvid_build>=0 && avctx->idct_algo == FF_IDCT_AUTO && (av_get_cpu_flags() & AV_CPU_FLAG_MMX)) {
561         avctx->idct_algo= FF_IDCT_XVIDMMX;
562         ff_dct_common_init(s);
563         s->picture_number=0;
564     }
565 #endif
566
567         /* After H263 & mpeg4 header decode we have the height, width,*/
568         /* and other parameters. So then we could init the picture   */
569         /* FIXME: By the way H263 decoder is evolving it should have */
570         /* an H263EncContext                                         */
571
572     if (!avctx->coded_width || !avctx->coded_height) {
573         ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
574
575         s->parse_context.buffer=0;
576         ff_MPV_common_end(s);
577         s->parse_context= pc;
578         avcodec_set_dimensions(avctx, s->width, s->height);
579
580         goto retry;
581     }
582
583     if (s->width  != avctx->coded_width  ||
584         s->height != avctx->coded_height ||
585         s->context_reinit) {
586         /* H.263 could change picture size any time */
587         s->context_reinit = 0;
588
589         avcodec_set_dimensions(avctx, s->width, s->height);
590
591         if ((ret = ff_MPV_common_frame_size_change(s)))
592             return ret;
593     }
594
595     if((s->codec_id==AV_CODEC_ID_H263 || s->codec_id==AV_CODEC_ID_H263P || s->codec_id == AV_CODEC_ID_H263I))
596         s->gob_index = ff_h263_get_gob_height(s);
597
598     // for skipping the frame
599     s->current_picture.f.pict_type = s->pict_type;
600     s->current_picture.f.key_frame = s->pict_type == AV_PICTURE_TYPE_I;
601
602     /* skip B-frames if we don't have reference frames */
603     if (s->last_picture_ptr == NULL &&
604         (s->pict_type == AV_PICTURE_TYPE_B || s->droppable))
605         return get_consumed_bytes(s, buf_size);
606     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==AV_PICTURE_TYPE_B)
607        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=AV_PICTURE_TYPE_I)
608        ||  avctx->skip_frame >= AVDISCARD_ALL)
609         return get_consumed_bytes(s, buf_size);
610
611     if(s->next_p_frame_damaged){
612         if(s->pict_type==AV_PICTURE_TYPE_B)
613             return get_consumed_bytes(s, buf_size);
614         else
615             s->next_p_frame_damaged=0;
616     }
617
618     if((s->avctx->flags2 & CODEC_FLAG2_FAST) && s->pict_type==AV_PICTURE_TYPE_B){
619         s->me.qpel_put= s->dsp.put_2tap_qpel_pixels_tab;
620         s->me.qpel_avg= s->dsp.avg_2tap_qpel_pixels_tab;
621     }else if((!s->no_rounding) || s->pict_type==AV_PICTURE_TYPE_B){
622         s->me.qpel_put= s->dsp.put_qpel_pixels_tab;
623         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
624     }else{
625         s->me.qpel_put= s->dsp.put_no_rnd_qpel_pixels_tab;
626         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
627     }
628
629     if(ff_MPV_frame_start(s, avctx) < 0)
630         return -1;
631
632     if (!s->divx_packed) ff_thread_finish_setup(avctx);
633
634     if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
635         ff_vdpau_mpeg4_decode_picture(s, s->gb.buffer, s->gb.buffer_end - s->gb.buffer);
636         goto frame_end;
637     }
638
639     if (avctx->hwaccel) {
640         if (avctx->hwaccel->start_frame(avctx, s->gb.buffer, s->gb.buffer_end - s->gb.buffer) < 0)
641             return -1;
642     }
643
644     ff_er_frame_start(s);
645
646     //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
647     //which is not available before ff_MPV_frame_start()
648     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5){
649         ret = ff_wmv2_decode_secondary_picture_header(s);
650         if(ret<0) return ret;
651         if(ret==1) goto intrax8_decoded;
652     }
653
654     /* decode each macroblock */
655     s->mb_x=0;
656     s->mb_y=0;
657
658     ret = decode_slice(s);
659     while(s->mb_y<s->mb_height){
660         if(s->msmpeg4_version){
661             if(s->slice_height==0 || s->mb_x!=0 || (s->mb_y%s->slice_height)!=0 || get_bits_left(&s->gb)<0)
662                 break;
663         }else{
664             int prev_x=s->mb_x, prev_y=s->mb_y;
665             if(ff_h263_resync(s)<0)
666                 break;
667             if (prev_y * s->mb_width + prev_x < s->mb_y * s->mb_width + s->mb_x)
668                 s->error_occurred = 1;
669         }
670
671         if(s->msmpeg4_version<4 && s->h263_pred)
672             ff_mpeg4_clean_buffers(s);
673
674         if (decode_slice(s) < 0) ret = AVERROR_INVALIDDATA;
675     }
676
677     if (s->msmpeg4_version && s->msmpeg4_version<4 && s->pict_type==AV_PICTURE_TYPE_I)
678         if(!CONFIG_MSMPEG4_DECODER || ff_msmpeg4_decode_ext_header(s, buf_size) < 0){
679             s->error_status_table[s->mb_num-1]= ER_MB_ERROR;
680         }
681
682     assert(s->bitstream_buffer_size==0);
683 frame_end:
684     /* divx 5.01+ bistream reorder stuff */
685     if(s->codec_id==AV_CODEC_ID_MPEG4 && s->divx_packed){
686         int current_pos= get_bits_count(&s->gb)>>3;
687         int startcode_found=0;
688
689         if(buf_size - current_pos > 5){
690             int i;
691             for(i=current_pos; i<buf_size-3; i++){
692                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
693                     startcode_found=1;
694                     break;
695                 }
696             }
697         }
698         if(s->gb.buffer == s->bitstream_buffer && buf_size>7 && s->xvid_build>=0){ //xvid style
699             startcode_found=1;
700             current_pos=0;
701         }
702
703         if(startcode_found){
704             av_fast_malloc(
705                 &s->bitstream_buffer,
706                 &s->allocated_bitstream_buffer_size,
707                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
708             if (!s->bitstream_buffer)
709                 return AVERROR(ENOMEM);
710             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
711             s->bitstream_buffer_size= buf_size - current_pos;
712         }
713     }
714
715 intrax8_decoded:
716     ff_er_frame_end(s);
717
718     if (avctx->hwaccel) {
719         if (avctx->hwaccel->end_frame(avctx) < 0)
720             return -1;
721     }
722
723     ff_MPV_frame_end(s);
724
725     assert(s->current_picture.f.pict_type == s->current_picture_ptr->f.pict_type);
726     assert(s->current_picture.f.pict_type == s->pict_type);
727     if (s->pict_type == AV_PICTURE_TYPE_B || s->low_delay) {
728         *pict = s->current_picture_ptr->f;
729     } else if (s->last_picture_ptr != NULL) {
730         *pict = s->last_picture_ptr->f;
731     }
732
733     if(s->last_picture_ptr || s->low_delay){
734         *got_frame = 1;
735         ff_print_debug_info(s, pict);
736     }
737
738 #ifdef PRINT_FRAME_TIME
739 av_log(avctx, AV_LOG_DEBUG, "%"PRId64"\n", rdtsc()-time);
740 #endif
741
742     return (ret && (avctx->err_recognition & AV_EF_EXPLODE))?ret:get_consumed_bytes(s, buf_size);
743 }
744
745 AVCodec ff_h263_decoder = {
746     .name           = "h263",
747     .type           = AVMEDIA_TYPE_VIDEO,
748     .id             = AV_CODEC_ID_H263,
749     .priv_data_size = sizeof(MpegEncContext),
750     .init           = ff_h263_decode_init,
751     .close          = ff_h263_decode_end,
752     .decode         = ff_h263_decode_frame,
753     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 |
754                       CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
755     .flush          = ff_mpeg_flush,
756     .long_name      = NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
757     .pix_fmts       = ff_hwaccel_pixfmt_list_420,
758 };