014033fe1d0c079e3118bb0716043597b2763e05
[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 "error_resilience.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
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     ff_MPV_decode_defaults(s);
57     s->quant_precision=5;
58     s->decode_mb= ff_h263_decode_mb;
59     s->low_delay= 1;
60     if (avctx->codec->id == AV_CODEC_ID_MSS2)
61         avctx->pix_fmt = AV_PIX_FMT_YUV420P;
62     else
63         avctx->pix_fmt = avctx->get_format(avctx, avctx->codec->pix_fmts);
64     s->unrestricted_mv= 1;
65
66     /* select sub codec */
67     switch(avctx->codec->id) {
68     case AV_CODEC_ID_H263:
69         s->unrestricted_mv= 0;
70         avctx->chroma_sample_location = AVCHROMA_LOC_CENTER;
71         break;
72     case AV_CODEC_ID_MPEG4:
73         break;
74     case AV_CODEC_ID_MSMPEG4V1:
75         s->h263_pred = 1;
76         s->msmpeg4_version=1;
77         break;
78     case AV_CODEC_ID_MSMPEG4V2:
79         s->h263_pred = 1;
80         s->msmpeg4_version=2;
81         break;
82     case AV_CODEC_ID_MSMPEG4V3:
83         s->h263_pred = 1;
84         s->msmpeg4_version=3;
85         break;
86     case AV_CODEC_ID_WMV1:
87         s->h263_pred = 1;
88         s->msmpeg4_version=4;
89         break;
90     case AV_CODEC_ID_WMV2:
91         s->h263_pred = 1;
92         s->msmpeg4_version=5;
93         break;
94     case AV_CODEC_ID_VC1:
95     case AV_CODEC_ID_WMV3:
96     case AV_CODEC_ID_VC1IMAGE:
97     case AV_CODEC_ID_WMV3IMAGE:
98     case AV_CODEC_ID_MSS2:
99         s->h263_pred = 1;
100         s->msmpeg4_version=6;
101         avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
102         break;
103     case AV_CODEC_ID_H263I:
104         break;
105     case AV_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 != AV_CODEC_ID_H263 && avctx->codec->id != AV_CODEC_ID_MPEG4)
116         if (ff_MPV_common_init(s) < 0)
117             return -1;
118
119         ff_h263_decode_init_vlc();
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     ff_MPV_common_end(s);
129     return 0;
130 }
131
132 /**
133  * Return 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 ? (ER_AC_END|ER_AC_ERROR) : 0x7F;
155     const int mb_size = 16;
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==AV_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->er, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, ER_MB_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             av_dlog(s, "%d %d %06X\n",
218                     ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
219             ret= s->decode_mb(s, s->block);
220
221             if (s->pict_type!=AV_PICTURE_TYPE_B)
222                 ff_h263_update_motion_val(s);
223
224             if(ret<0){
225                 const int xy= s->mb_x + s->mb_y*s->mb_stride;
226                 if(ret==SLICE_END){
227                     ff_MPV_decode_mb(s, s->block);
228                     if(s->loop_filter)
229                         ff_h263_loop_filter(s);
230
231                     ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_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_mpeg_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
238                         ff_MPV_report_decode_progress(s);
239                         s->mb_y++;
240                     }
241                     return 0;
242                 }else if(ret==SLICE_NOEND){
243                     av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
244                     ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y, s->mb_x+1, s->mb_y, ER_MB_END&part_mask);
245                     return -1;
246                 }
247                 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
248                 ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_ERROR&part_mask);
249
250                 return -1;
251             }
252
253             ff_MPV_decode_mb(s, s->block);
254             if(s->loop_filter)
255                 ff_h263_loop_filter(s);
256         }
257
258         ff_mpeg_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
259         ff_MPV_report_decode_progress(s);
260
261         s->mb_x= 0;
262     }
263
264     assert(s->mb_x==0 && s->mb_y==s->mb_height);
265
266     if(s->codec_id==AV_CODEC_ID_MPEG4
267        && (s->workaround_bugs&FF_BUG_AUTODETECT)
268        && get_bits_left(&s->gb) >= 48
269        && show_bits(&s->gb, 24)==0x4010
270        && !s->data_partitioning)
271         s->padding_bug_score+=32;
272
273     /* try to detect the padding bug */
274     if(      s->codec_id==AV_CODEC_ID_MPEG4
275        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
276        &&    get_bits_left(&s->gb) >=0
277        &&    get_bits_left(&s->gb) < 48
278 //       &&   !s->resync_marker
279        &&   !s->data_partitioning){
280
281         const int bits_count= get_bits_count(&s->gb);
282         const int bits_left = s->gb.size_in_bits - bits_count;
283
284         if(bits_left==0){
285             s->padding_bug_score+=16;
286         } else if(bits_left != 1){
287             int v= show_bits(&s->gb, 8);
288             v|= 0x7F >> (7-(bits_count&7));
289
290             if(v==0x7F && bits_left<=8)
291                 s->padding_bug_score--;
292             else if(v==0x7F && ((get_bits_count(&s->gb)+8)&8) && bits_left<=16)
293                 s->padding_bug_score+= 4;
294             else
295                 s->padding_bug_score++;
296         }
297     }
298
299     if(s->workaround_bugs&FF_BUG_AUTODETECT){
300         if(s->padding_bug_score > -2 && !s->data_partitioning /*&& (s->divx_version>=0 || !s->resync_marker)*/)
301             s->workaround_bugs |=  FF_BUG_NO_PADDING;
302         else
303             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
304     }
305
306     // handle formats which don't have unique end markers
307     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
308         int left= get_bits_left(&s->gb);
309         int max_extra=7;
310
311         /* no markers in M$ crap */
312         if(s->msmpeg4_version && s->pict_type==AV_PICTURE_TYPE_I)
313             max_extra+= 17;
314
315         /* buggy padding but the frame should still end approximately at the bitstream end */
316         if((s->workaround_bugs&FF_BUG_NO_PADDING) && (s->err_recognition&AV_EF_BUFFER))
317             max_extra+= 48;
318         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
319             max_extra+= 256*256*256*64;
320
321         if(left>max_extra){
322             av_log(s->avctx, AV_LOG_ERROR, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
323         }
324         else if(left<0){
325             av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
326         }else
327             ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, ER_MB_END);
328
329         return 0;
330     }
331
332     av_log(s->avctx, AV_LOG_ERROR, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
333             get_bits_left(&s->gb),
334             show_bits(&s->gb, 24), s->padding_bug_score);
335
336     ff_er_add_slice(&s->er, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_END&part_mask);
337
338     return -1;
339 }
340
341 int ff_h263_decode_frame(AVCodecContext *avctx,
342                              void *data, int *got_frame,
343                              AVPacket *avpkt)
344 {
345     const uint8_t *buf = avpkt->data;
346     int buf_size = avpkt->size;
347     MpegEncContext *s = avctx->priv_data;
348     int ret;
349     AVFrame *pict = data;
350
351     s->flags= avctx->flags;
352     s->flags2= avctx->flags2;
353
354     /* no supplementary picture */
355     if (buf_size == 0) {
356         /* special case for last picture */
357         if (s->low_delay==0 && s->next_picture_ptr) {
358             if ((ret = av_frame_ref(pict, &s->next_picture_ptr->f)) < 0)
359                 return ret;
360             s->next_picture_ptr= NULL;
361
362             *got_frame = 1;
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==AV_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==AV_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 (ff_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->f.data[0]) {
401         int i= ff_find_unused_picture(s, 0);
402         if (i < 0)
403             return i;
404         s->current_picture_ptr= &s->picture[i];
405     }
406
407     /* let's go :-) */
408     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
409         ret= ff_wmv2_decode_picture_header(s);
410     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
411         ret = ff_msmpeg4_decode_picture_header(s);
412     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
413         if(s->avctx->extradata_size && s->picture_number==0){
414             GetBitContext gb;
415
416             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
417             ret = ff_mpeg4_decode_picture_header(s, &gb);
418         }
419         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
420     } else if (CONFIG_H263I_DECODER && s->codec_id == AV_CODEC_ID_H263I) {
421         ret = ff_intel_h263_decode_picture_header(s);
422     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
423         ret = ff_flv_decode_picture_header(s);
424     } else {
425         ret = ff_h263_decode_picture_header(s);
426     }
427
428     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
429
430     /* skip if the header was thrashed */
431     if (ret < 0){
432         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
433         return -1;
434     }
435
436     avctx->has_b_frames= !s->low_delay;
437
438     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
439         if(s->stream_codec_tag == AV_RL32("XVID") ||
440            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
441            s->codec_tag == AV_RL32("RMP4") || s->codec_tag == AV_RL32("ZMP4") ||
442            s->codec_tag == AV_RL32("SIPP")
443            )
444             s->xvid_build= 0;
445 #if 0
446         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
447            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
448             s->xvid_build= 0;
449 #endif
450     }
451
452     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
453         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
454             s->divx_version= 400; //divx 4
455     }
456
457     if(s->xvid_build>=0 && s->divx_version>=0){
458         s->divx_version=
459         s->divx_build= -1;
460     }
461
462     if(s->workaround_bugs&FF_BUG_AUTODETECT){
463         if(s->codec_tag == AV_RL32("XVIX"))
464             s->workaround_bugs|= FF_BUG_XVID_ILACE;
465
466         if(s->codec_tag == AV_RL32("UMP4")){
467             s->workaround_bugs|= FF_BUG_UMP4;
468         }
469
470         if(s->divx_version>=500 && s->divx_build<1814){
471             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
472         }
473
474         if(s->divx_version>502 && s->divx_build<1814){
475             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
476         }
477
478         if(s->xvid_build<=3U)
479             s->padding_bug_score= 256*256*256*64;
480
481         if(s->xvid_build<=1U)
482             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
483
484         if(s->xvid_build<=12U)
485             s->workaround_bugs|= FF_BUG_EDGE;
486
487         if(s->xvid_build<=32U)
488             s->workaround_bugs|= FF_BUG_DC_CLIP;
489
490 #define SET_QPEL_FUNC(postfix1, postfix2) \
491     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
492     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
493     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
494
495         if(s->lavc_build<4653U)
496             s->workaround_bugs|= FF_BUG_STD_QPEL;
497
498         if(s->lavc_build<4655U)
499             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
500
501         if(s->lavc_build<4670U){
502             s->workaround_bugs|= FF_BUG_EDGE;
503         }
504
505         if(s->lavc_build<=4712U)
506             s->workaround_bugs|= FF_BUG_DC_CLIP;
507
508         if(s->divx_version>=0)
509             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
510         if(s->divx_version==501 && s->divx_build==20020416)
511             s->padding_bug_score= 256*256*256*64;
512
513         if(s->divx_version<500U){
514             s->workaround_bugs|= FF_BUG_EDGE;
515         }
516
517         if(s->divx_version>=0)
518             s->workaround_bugs|= FF_BUG_HPEL_CHROMA;
519 #if 0
520         if(s->divx_version==500)
521             s->padding_bug_score= 256*256*256*64;
522
523         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
524          * Let us hope this at least works.
525          */
526         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==-1
527            && s->codec_id==AV_CODEC_ID_MPEG4 && s->vo_type==0)
528             s->workaround_bugs|= FF_BUG_NO_PADDING;
529
530         if(s->lavc_build<4609U) //FIXME not sure about the version num but a 4609 file seems ok
531             s->workaround_bugs|= FF_BUG_NO_PADDING;
532 #endif
533     }
534
535     if(s->workaround_bugs& FF_BUG_STD_QPEL){
536         SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
537         SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
538         SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
539         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
540         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
541         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
542
543         SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
544         SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
545         SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
546         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
547         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
548         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
549     }
550
551     if(avctx->debug & FF_DEBUG_BUGS)
552         av_log(s->avctx, AV_LOG_DEBUG, "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
553                s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
554                s->divx_packed ? "p" : "");
555
556 #if HAVE_MMX
557     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)) {
558         avctx->idct_algo= FF_IDCT_XVIDMMX;
559         ff_dct_common_init(s);
560         s->picture_number=0;
561     }
562 #endif
563
564         /* After H263 & mpeg4 header decode we have the height, width,*/
565         /* and other parameters. So then we could init the picture   */
566         /* FIXME: By the way H263 decoder is evolving it should have */
567         /* an H263EncContext                                         */
568
569     if (!avctx->coded_width || !avctx->coded_height) {
570         ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
571
572         s->parse_context.buffer=0;
573         ff_MPV_common_end(s);
574         s->parse_context= pc;
575         avcodec_set_dimensions(avctx, s->width, s->height);
576
577         goto retry;
578     }
579
580     if (s->width  != avctx->coded_width  ||
581         s->height != avctx->coded_height ||
582         s->context_reinit) {
583         /* H.263 could change picture size any time */
584         s->context_reinit = 0;
585
586         avcodec_set_dimensions(avctx, s->width, s->height);
587
588         if ((ret = ff_MPV_common_frame_size_change(s)))
589             return ret;
590     }
591
592     if((s->codec_id==AV_CODEC_ID_H263 || s->codec_id==AV_CODEC_ID_H263P || s->codec_id == AV_CODEC_ID_H263I))
593         s->gob_index = ff_h263_get_gob_height(s);
594
595     // for skipping the frame
596     s->current_picture.f.pict_type = s->pict_type;
597     s->current_picture.f.key_frame = s->pict_type == AV_PICTURE_TYPE_I;
598
599     /* skip B-frames if we don't have reference frames */
600     if (s->last_picture_ptr == NULL &&
601         (s->pict_type == AV_PICTURE_TYPE_B || s->droppable))
602         return get_consumed_bytes(s, buf_size);
603     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==AV_PICTURE_TYPE_B)
604        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=AV_PICTURE_TYPE_I)
605        ||  avctx->skip_frame >= AVDISCARD_ALL)
606         return get_consumed_bytes(s, buf_size);
607
608     if(s->next_p_frame_damaged){
609         if(s->pict_type==AV_PICTURE_TYPE_B)
610             return get_consumed_bytes(s, buf_size);
611         else
612             s->next_p_frame_damaged=0;
613     }
614
615     if((!s->no_rounding) || s->pict_type==AV_PICTURE_TYPE_B){
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(ff_MPV_frame_start(s, avctx) < 0)
624         return -1;
625
626     if (!s->divx_packed && !avctx->hwaccel)
627         ff_thread_finish_setup(avctx);
628
629     if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
630         ff_vdpau_mpeg4_decode_picture(s, s->gb.buffer, s->gb.buffer_end - s->gb.buffer);
631         goto frame_end;
632     }
633
634     if (avctx->hwaccel) {
635         if (avctx->hwaccel->start_frame(avctx, s->gb.buffer, s->gb.buffer_end - s->gb.buffer) < 0)
636             return -1;
637     }
638
639     ff_mpeg_er_frame_start(s);
640
641     //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
642     //which is not available before ff_MPV_frame_start()
643     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5){
644         ret = ff_wmv2_decode_secondary_picture_header(s);
645         if(ret<0) return ret;
646         if(ret==1) goto intrax8_decoded;
647     }
648
649     /* decode each macroblock */
650     s->mb_x=0;
651     s->mb_y=0;
652
653     ret = decode_slice(s);
654     while(s->mb_y<s->mb_height){
655         if(s->msmpeg4_version){
656             if(s->slice_height==0 || s->mb_x!=0 || (s->mb_y%s->slice_height)!=0 || get_bits_left(&s->gb)<0)
657                 break;
658         }else{
659             int prev_x=s->mb_x, prev_y=s->mb_y;
660             if(ff_h263_resync(s)<0)
661                 break;
662             if (prev_y * s->mb_width + prev_x < s->mb_y * s->mb_width + s->mb_x)
663                 s->er.error_occurred = 1;
664         }
665
666         if(s->msmpeg4_version<4 && s->h263_pred)
667             ff_mpeg4_clean_buffers(s);
668
669         if (decode_slice(s) < 0) ret = AVERROR_INVALIDDATA;
670     }
671
672     if (s->msmpeg4_version && s->msmpeg4_version<4 && s->pict_type==AV_PICTURE_TYPE_I)
673         if(!CONFIG_MSMPEG4_DECODER || ff_msmpeg4_decode_ext_header(s, buf_size) < 0){
674             s->er.error_status_table[s->mb_num - 1] = ER_MB_ERROR;
675         }
676
677     assert(s->bitstream_buffer_size==0);
678 frame_end:
679     /* divx 5.01+ bistream reorder stuff */
680     if(s->codec_id==AV_CODEC_ID_MPEG4 && s->divx_packed){
681         int current_pos= get_bits_count(&s->gb)>>3;
682         int startcode_found=0;
683
684         if(buf_size - current_pos > 5){
685             int i;
686             for(i=current_pos; i<buf_size-3; i++){
687                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
688                     startcode_found=1;
689                     break;
690                 }
691             }
692         }
693         if(s->gb.buffer == s->bitstream_buffer && buf_size>7 && s->xvid_build>=0){ //xvid style
694             startcode_found=1;
695             current_pos=0;
696         }
697
698         if(startcode_found){
699             av_fast_malloc(
700                 &s->bitstream_buffer,
701                 &s->allocated_bitstream_buffer_size,
702                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
703             if (!s->bitstream_buffer)
704                 return AVERROR(ENOMEM);
705             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
706             s->bitstream_buffer_size= buf_size - current_pos;
707         }
708     }
709
710 intrax8_decoded:
711     ff_er_frame_end(&s->er);
712
713     if (avctx->hwaccel) {
714         if (avctx->hwaccel->end_frame(avctx) < 0)
715             return -1;
716     }
717
718     ff_MPV_frame_end(s);
719
720     if (!s->divx_packed && avctx->hwaccel)
721         ff_thread_finish_setup(avctx);
722
723     assert(s->current_picture.f.pict_type == s->current_picture_ptr->f.pict_type);
724     assert(s->current_picture.f.pict_type == s->pict_type);
725     if (s->pict_type == AV_PICTURE_TYPE_B || s->low_delay) {
726         if ((ret = av_frame_ref(pict, &s->current_picture_ptr->f)) < 0)
727             return ret;
728         ff_print_debug_info(s, s->current_picture_ptr);
729     } else if (s->last_picture_ptr != NULL) {
730         if ((ret = av_frame_ref(pict, &s->last_picture_ptr->f)) < 0)
731             return ret;
732         ff_print_debug_info(s, s->last_picture_ptr);
733     }
734
735     if(s->last_picture_ptr || s->low_delay){
736         *got_frame = 1;
737     }
738
739     return (ret && (avctx->err_recognition & AV_EF_EXPLODE))?ret:get_consumed_bytes(s, buf_size);
740 }
741
742 const enum AVPixelFormat ff_h263_hwaccel_pixfmt_list_420[] = {
743 #if CONFIG_VAAPI
744     AV_PIX_FMT_VAAPI_VLD,
745 #endif
746 #if CONFIG_VDPAU
747     AV_PIX_FMT_VDPAU,
748 #endif
749     AV_PIX_FMT_YUV420P,
750     AV_PIX_FMT_NONE
751 };
752
753 AVCodec ff_h263_decoder = {
754     .name           = "h263",
755     .type           = AVMEDIA_TYPE_VIDEO,
756     .id             = AV_CODEC_ID_H263,
757     .priv_data_size = sizeof(MpegEncContext),
758     .init           = ff_h263_decode_init,
759     .close          = ff_h263_decode_end,
760     .decode         = ff_h263_decode_frame,
761     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 |
762                       CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
763     .flush          = ff_mpeg_flush,
764     .long_name      = NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
765     .pix_fmts       = ff_h263_hwaccel_pixfmt_list_420,
766 };