Merge commit 'aa45b90804ab21175b8c116bd8e5eb4b4e85fbcb' into release/0.8
[ffmpeg: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
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     MPV_decode_defaults(s);
58     s->quant_precision=5;
59     s->decode_mb= ff_h263_decode_mb;
60     s->low_delay= 1;
61     avctx->pix_fmt= avctx->get_format(avctx, avctx->codec->pix_fmts);
62     s->unrestricted_mv= 1;
63
64     /* select sub codec */
65     switch(avctx->codec->id) {
66     case CODEC_ID_H263:
67         s->unrestricted_mv= 0;
68         avctx->chroma_sample_location = AVCHROMA_LOC_CENTER;
69         break;
70     case CODEC_ID_MPEG4:
71         break;
72     case CODEC_ID_MSMPEG4V1:
73         s->h263_pred = 1;
74         s->msmpeg4_version=1;
75         break;
76     case CODEC_ID_MSMPEG4V2:
77         s->h263_pred = 1;
78         s->msmpeg4_version=2;
79         break;
80     case CODEC_ID_MSMPEG4V3:
81         s->h263_pred = 1;
82         s->msmpeg4_version=3;
83         break;
84     case CODEC_ID_WMV1:
85         s->h263_pred = 1;
86         s->msmpeg4_version=4;
87         break;
88     case CODEC_ID_WMV2:
89         s->h263_pred = 1;
90         s->msmpeg4_version=5;
91         break;
92     case CODEC_ID_VC1:
93     case CODEC_ID_WMV3:
94         s->h263_pred = 1;
95         s->msmpeg4_version=6;
96         avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
97         break;
98     case CODEC_ID_H263I:
99         break;
100     case CODEC_ID_FLV1:
101         s->h263_flv = 1;
102         break;
103     default:
104         return -1;
105     }
106     s->codec_id= avctx->codec->id;
107     avctx->hwaccel= ff_find_hwaccel(avctx->codec->id, avctx->pix_fmt);
108
109     /* for h263, we allocate the images after having read the header */
110     if (avctx->codec->id != CODEC_ID_H263 && avctx->codec->id != CODEC_ID_MPEG4)
111         if (MPV_common_init(s) < 0)
112             return -1;
113
114         ff_h263_decode_init_vlc(s);
115
116     return 0;
117 }
118
119 av_cold int ff_h263_decode_end(AVCodecContext *avctx)
120 {
121     MpegEncContext *s = avctx->priv_data;
122
123     MPV_common_end(s);
124     return 0;
125 }
126
127 /**
128  * returns the number of bytes consumed for building the current frame
129  */
130 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
131     int pos= (get_bits_count(&s->gb)+7)>>3;
132
133     if(s->divx_packed || s->avctx->hwaccel){
134         //we would have to scan through the whole buf to handle the weird reordering ...
135         return buf_size;
136     }else if(s->flags&CODEC_FLAG_TRUNCATED){
137         pos -= s->parse_context.last_index;
138         if(pos<0) pos=0; // padding is not really read so this might be -1
139         return pos;
140     }else{
141         if(pos==0) pos=1; //avoid infinite loops (i doubt that is needed but ...)
142         if(pos+10>buf_size) pos=buf_size; // oops ;)
143
144         return pos;
145     }
146 }
147
148 static int decode_slice(MpegEncContext *s){
149     const int part_mask= s->partitioned_frame ? (AC_END|AC_ERROR) : 0x7F;
150     const int mb_size= 16>>s->avctx->lowres;
151     s->last_resync_gb= s->gb;
152     s->first_slice_line= 1;
153
154     s->resync_mb_x= s->mb_x;
155     s->resync_mb_y= s->mb_y;
156
157     ff_set_qscale(s, s->qscale);
158
159     if (s->avctx->hwaccel) {
160         const uint8_t *start= s->gb.buffer + get_bits_count(&s->gb)/8;
161         const uint8_t *end  = ff_h263_find_resync_marker(start + 1, s->gb.buffer_end);
162         skip_bits_long(&s->gb, 8*(end - start));
163         return s->avctx->hwaccel->decode_slice(s->avctx, start, end - start);
164     }
165
166     if(s->partitioned_frame){
167         const int qscale= s->qscale;
168
169         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
170             if(ff_mpeg4_decode_partitions(s) < 0)
171                 return -1;
172         }
173
174         /* restore variables which were modified */
175         s->first_slice_line=1;
176         s->mb_x= s->resync_mb_x;
177         s->mb_y= s->resync_mb_y;
178         ff_set_qscale(s, qscale);
179     }
180
181     for(; s->mb_y < s->mb_height; s->mb_y++) {
182         /* per-row end of slice checks */
183         if(s->msmpeg4_version){
184             if(s->resync_mb_y + s->slice_height == s->mb_y){
185                 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);
186
187                 return 0;
188             }
189         }
190
191         if(s->msmpeg4_version==1){
192             s->last_dc[0]=
193             s->last_dc[1]=
194             s->last_dc[2]= 128;
195         }
196
197         ff_init_block_index(s);
198         for(; s->mb_x < s->mb_width; s->mb_x++) {
199             int ret;
200
201             ff_update_block_index(s);
202
203             if(s->resync_mb_x == s->mb_x && s->resync_mb_y+1 == s->mb_y){
204                 s->first_slice_line=0;
205             }
206
207             /* DCT & quantize */
208
209             s->mv_dir = MV_DIR_FORWARD;
210             s->mv_type = MV_TYPE_16X16;
211 //            s->mb_skipped = 0;
212 //printf("%d %d %06X\n", ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
213             ret= s->decode_mb(s, s->block);
214
215             if (s->pict_type!=AV_PICTURE_TYPE_B)
216                 ff_h263_update_motion_val(s);
217
218             if(ret<0){
219                 const int xy= s->mb_x + s->mb_y*s->mb_stride;
220                 if(ret==SLICE_END){
221                     MPV_decode_mb(s, s->block);
222                     if(s->loop_filter)
223                         ff_h263_loop_filter(s);
224
225 //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));
226                     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);
227
228                     s->padding_bug_score--;
229
230                     if(++s->mb_x >= s->mb_width){
231                         s->mb_x=0;
232                         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
233                         MPV_report_decode_progress(s);
234                         s->mb_y++;
235                     }
236                     return 0;
237                 }else if(ret==SLICE_NOEND){
238                     av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
239                     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);
240                     return -1;
241                 }
242                 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
243                 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);
244
245                 return -1;
246             }
247
248             MPV_decode_mb(s, s->block);
249             if(s->loop_filter)
250                 ff_h263_loop_filter(s);
251         }
252
253         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
254         MPV_report_decode_progress(s);
255
256         s->mb_x= 0;
257     }
258
259     assert(s->mb_x==0 && s->mb_y==s->mb_height);
260
261     if(s->codec_id==CODEC_ID_MPEG4
262        && (s->workaround_bugs&FF_BUG_AUTODETECT)
263        && get_bits_left(&s->gb) >= 48
264        && show_bits(&s->gb, 24)==0x4010
265        && !s->data_partitioning)
266         s->padding_bug_score+=32;
267
268     /* try to detect the padding bug */
269     if(      s->codec_id==CODEC_ID_MPEG4
270        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
271        &&    get_bits_left(&s->gb) >=0
272        &&    get_bits_left(&s->gb) < 48
273 //       &&   !s->resync_marker
274        &&   !s->data_partitioning){
275
276         const int bits_count= get_bits_count(&s->gb);
277         const int bits_left = s->gb.size_in_bits - bits_count;
278
279         if(bits_left==0){
280             s->padding_bug_score+=16;
281         } else if(bits_left != 1){
282             int v= show_bits(&s->gb, 8);
283             v|= 0x7F >> (7-(bits_count&7));
284
285             if(v==0x7F && bits_left<=8)
286                 s->padding_bug_score--;
287             else if(v==0x7F && ((get_bits_count(&s->gb)+8)&8) && bits_left<=16)
288                 s->padding_bug_score+= 4;
289             else
290                 s->padding_bug_score++;
291         }
292     }
293
294     if(s->workaround_bugs&FF_BUG_AUTODETECT){
295         if(s->padding_bug_score > -2 && !s->data_partitioning /*&& (s->divx_version>=0 || !s->resync_marker)*/)
296             s->workaround_bugs |=  FF_BUG_NO_PADDING;
297         else
298             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
299     }
300
301     // handle formats which don't have unique end markers
302     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
303         int left= get_bits_left(&s->gb);
304         int max_extra=7;
305
306         /* no markers in M$ crap */
307         if(s->msmpeg4_version && s->pict_type==AV_PICTURE_TYPE_I)
308             max_extra+= 17;
309
310         /* buggy padding but the frame should still end approximately at the bitstream end */
311         if((s->workaround_bugs&FF_BUG_NO_PADDING) && s->error_recognition>=3)
312             max_extra+= 48;
313         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
314             max_extra+= 256*256*256*64;
315
316         if(left>max_extra){
317             av_log(s->avctx, AV_LOG_ERROR, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
318         }
319         else if(left<0){
320             av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
321         }else
322             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);
323
324         return 0;
325     }
326
327     av_log(s->avctx, AV_LOG_ERROR, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
328             get_bits_left(&s->gb),
329             show_bits(&s->gb, 24), s->padding_bug_score);
330
331     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);
332
333     return -1;
334 }
335
336 int ff_h263_decode_frame(AVCodecContext *avctx,
337                              void *data, int *data_size,
338                              AVPacket *avpkt)
339 {
340     const uint8_t *buf = avpkt->data;
341     int buf_size = avpkt->size;
342     MpegEncContext *s = avctx->priv_data;
343     int ret;
344     AVFrame *pict = data;
345
346 #ifdef PRINT_FRAME_TIME
347 uint64_t time= rdtsc();
348 #endif
349     s->flags= avctx->flags;
350     s->flags2= avctx->flags2;
351
352     /* no supplementary picture */
353     if (buf_size == 0) {
354         /* special case for last picture */
355         if (s->low_delay==0 && s->next_picture_ptr) {
356             *pict= *(AVFrame*)s->next_picture_ptr;
357             s->next_picture_ptr= NULL;
358
359             *data_size = sizeof(AVFrame);
360         }
361
362         return 0;
363     }
364
365     if(s->flags&CODEC_FLAG_TRUNCATED){
366         int next;
367
368         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
369             next= ff_mpeg4_find_frame_end(&s->parse_context, buf, buf_size);
370         }else if(CONFIG_H263_DECODER && s->codec_id==CODEC_ID_H263){
371             next= ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
372         }else{
373             av_log(s->avctx, AV_LOG_ERROR, "this codec does not support truncated bitstreams\n");
374             return -1;
375         }
376
377         if( ff_combine_frame(&s->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
378             return buf_size;
379     }
380
381
382 retry:
383     if(s->divx_packed && s->bitstream_buffer_size){
384         int i;
385         for(i=0; i<buf_size-3; i++){
386             if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1){
387                 if(buf[i+3]==0xB0){
388                     av_log(s->avctx, AV_LOG_WARNING, "Discarding excessive bitstream in packed xvid\n");
389                     s->bitstream_buffer_size=0;
390                 }
391                 break;
392             }
393         }
394     }
395
396     if(s->bitstream_buffer_size && (s->divx_packed || buf_size<20)){ //divx 5.01+/xvid frame reorder
397         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
398     }else
399         init_get_bits(&s->gb, buf, buf_size*8);
400     s->bitstream_buffer_size=0;
401
402     if (!s->context_initialized) {
403         if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
404             return -1;
405     }
406
407     /* We need to set current_picture_ptr before reading the header,
408      * otherwise we cannot store anyting in there */
409     if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
410         int i= ff_find_unused_picture(s, 0);
411         s->current_picture_ptr= &s->picture[i];
412     }
413
414     /* let's go :-) */
415     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
416         ret= ff_wmv2_decode_picture_header(s);
417     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
418         ret = msmpeg4_decode_picture_header(s);
419     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
420         if(s->avctx->extradata_size && s->picture_number==0){
421             GetBitContext gb;
422
423             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
424             ret = ff_mpeg4_decode_picture_header(s, &gb);
425         }
426         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
427     } else if (CONFIG_H263I_DECODER && s->codec_id == CODEC_ID_H263I) {
428         ret = ff_intel_h263_decode_picture_header(s);
429     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
430         ret = ff_flv_decode_picture_header(s);
431     } else {
432         ret = ff_h263_decode_picture_header(s);
433     }
434
435     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
436
437     /* skip if the header was thrashed */
438     if (ret < 0){
439         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
440         return -1;
441     } else if ((s->width  != avctx->coded_width  ||
442                 s->height != avctx->coded_height ||
443                 (s->width  + 15) >> 4 != s->mb_width ||
444                 (s->height + 15) >> 4 != s->mb_height) &&
445                (HAVE_THREADS && (s->avctx->active_thread_type & FF_THREAD_FRAME))) {
446         av_log_missing_feature(s->avctx, "Width/height/bit depth/chroma idc changing with threads is", 0);
447         return AVERROR_PATCHWELCOME;   // width / height changed during parallelized decoding
448     }
449
450     avctx->has_b_frames= !s->low_delay;
451
452     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
453         if(s->stream_codec_tag == AV_RL32("XVID") ||
454            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
455            s->codec_tag == AV_RL32("RMP4") ||
456            s->codec_tag == AV_RL32("SIPP")
457            )
458             s->xvid_build= 0;
459 #if 0
460         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
461            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
462             s->xvid_build= 0;
463 #endif
464     }
465
466     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
467         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
468             s->divx_version= 400; //divx 4
469     }
470
471     if(s->xvid_build>=0 && s->divx_version>=0){
472         s->divx_version=
473         s->divx_build= -1;
474     }
475
476     if(s->workaround_bugs&FF_BUG_AUTODETECT){
477         if(s->codec_tag == AV_RL32("XVIX"))
478             s->workaround_bugs|= FF_BUG_XVID_ILACE;
479
480         if(s->codec_tag == AV_RL32("UMP4")){
481             s->workaround_bugs|= FF_BUG_UMP4;
482         }
483
484         if(s->divx_version>=500 && s->divx_build<1814){
485             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
486         }
487
488         if(s->divx_version>502 && s->divx_build<1814){
489             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
490         }
491
492         if(s->xvid_build<=3U)
493             s->padding_bug_score= 256*256*256*64;
494
495         if(s->xvid_build<=1U)
496             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
497
498         if(s->xvid_build<=12U)
499             s->workaround_bugs|= FF_BUG_EDGE;
500
501         if(s->xvid_build<=32U)
502             s->workaround_bugs|= FF_BUG_DC_CLIP;
503
504 #define SET_QPEL_FUNC(postfix1, postfix2) \
505     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
506     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
507     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
508
509         if(s->lavc_build<4653U)
510             s->workaround_bugs|= FF_BUG_STD_QPEL;
511
512         if(s->lavc_build<4655U)
513             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
514
515         if(s->lavc_build<4670U){
516             s->workaround_bugs|= FF_BUG_EDGE;
517         }
518
519         if(s->lavc_build<=4712U)
520             s->workaround_bugs|= FF_BUG_DC_CLIP;
521
522         if(s->divx_version>=0)
523             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
524 //printf("padding_bug_score: %d\n", s->padding_bug_score);
525         if(s->divx_version==501 && s->divx_build==20020416)
526             s->padding_bug_score= 256*256*256*64;
527
528         if(s->divx_version<500U){
529             s->workaround_bugs|= FF_BUG_EDGE;
530         }
531
532         if(s->divx_version>=0)
533             s->workaround_bugs|= FF_BUG_HPEL_CHROMA;
534 #if 0
535         if(s->divx_version==500)
536             s->padding_bug_score= 256*256*256*64;
537
538         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
539          * Let us hope this at least works.
540          */
541         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==-1
542            && s->codec_id==CODEC_ID_MPEG4 && s->vo_type==0)
543             s->workaround_bugs|= FF_BUG_NO_PADDING;
544
545         if(s->lavc_build<4609U) //FIXME not sure about the version num but a 4609 file seems ok
546             s->workaround_bugs|= FF_BUG_NO_PADDING;
547 #endif
548     }
549
550     if(s->workaround_bugs& FF_BUG_STD_QPEL){
551         SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
552         SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
553         SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
554         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
555         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
556         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
557
558         SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
559         SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
560         SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
561         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
562         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
563         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
564     }
565
566     if(avctx->debug & FF_DEBUG_BUGS)
567         av_log(s->avctx, AV_LOG_DEBUG, "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
568                s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
569                s->divx_packed ? "p" : "");
570
571 #if HAVE_MMX
572     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)) {
573         avctx->idct_algo= FF_IDCT_XVIDMMX;
574         ff_dct_common_init(s);
575         s->picture_number=0;
576     }
577 #endif
578
579         /* After H263 & mpeg4 header decode we have the height, width,*/
580         /* and other parameters. So then we could init the picture   */
581         /* FIXME: By the way H263 decoder is evolving it should have */
582         /* an H263EncContext                                         */
583
584     if (   s->width  != avctx->coded_width
585         || s->height != avctx->coded_height) {
586         /* H.263 could change picture size any time */
587         ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
588
589         if (HAVE_THREADS && (s->avctx->active_thread_type&FF_THREAD_FRAME)) {
590             av_log_missing_feature(s->avctx, "Width/height/bit depth/chroma idc changing with threads is", 0);
591             return -1;   // width / height changed during parallelized decoding
592         }
593
594         s->parse_context.buffer=0;
595         MPV_common_end(s);
596         s->parse_context= pc;
597     }
598     if (!s->context_initialized) {
599         avcodec_set_dimensions(avctx, s->width, s->height);
600
601         goto retry;
602     }
603
604     if((s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P || s->codec_id == CODEC_ID_H263I))
605         s->gob_index = ff_h263_get_gob_height(s);
606
607     // for skipping the frame
608     s->current_picture.pict_type= s->pict_type;
609     s->current_picture.key_frame= s->pict_type == AV_PICTURE_TYPE_I;
610
611     /* skip B-frames if we don't have reference frames */
612     if(s->last_picture_ptr==NULL && (s->pict_type==AV_PICTURE_TYPE_B || s->dropable)) return get_consumed_bytes(s, buf_size);
613     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==AV_PICTURE_TYPE_B)
614        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=AV_PICTURE_TYPE_I)
615        ||  avctx->skip_frame >= AVDISCARD_ALL)
616         return get_consumed_bytes(s, buf_size);
617
618     if(s->next_p_frame_damaged){
619         if(s->pict_type==AV_PICTURE_TYPE_B)
620             return get_consumed_bytes(s, buf_size);
621         else
622             s->next_p_frame_damaged=0;
623     }
624
625     if((s->avctx->flags2 & CODEC_FLAG2_FAST) && s->pict_type==AV_PICTURE_TYPE_B){
626         s->me.qpel_put= s->dsp.put_2tap_qpel_pixels_tab;
627         s->me.qpel_avg= s->dsp.avg_2tap_qpel_pixels_tab;
628     }else if((!s->no_rounding) || s->pict_type==AV_PICTURE_TYPE_B){
629         s->me.qpel_put= s->dsp.put_qpel_pixels_tab;
630         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
631     }else{
632         s->me.qpel_put= s->dsp.put_no_rnd_qpel_pixels_tab;
633         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
634     }
635
636     if(MPV_frame_start(s, avctx) < 0)
637         return -1;
638
639     if (!s->divx_packed) ff_thread_finish_setup(avctx);
640
641     if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
642         ff_vdpau_mpeg4_decode_picture(s, s->gb.buffer, s->gb.buffer_end - s->gb.buffer);
643         goto frame_end;
644     }
645
646     if (avctx->hwaccel) {
647         if (avctx->hwaccel->start_frame(avctx, s->gb.buffer, s->gb.buffer_end - s->gb.buffer) < 0)
648             return -1;
649     }
650
651     ff_er_frame_start(s);
652
653     //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
654     //which is not available before MPV_frame_start()
655     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5){
656         ret = ff_wmv2_decode_secondary_picture_header(s);
657         if(ret<0) return ret;
658         if(ret==1) goto intrax8_decoded;
659     }
660
661     /* decode each macroblock */
662     s->mb_x=0;
663     s->mb_y=0;
664
665     decode_slice(s);
666     while(s->mb_y<s->mb_height){
667         if(s->msmpeg4_version){
668             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)
669                 break;
670         }else{
671             int prev_x=s->mb_x, prev_y=s->mb_y;
672             if(ff_h263_resync(s)<0)
673                 break;
674             if (prev_y * s->mb_width + prev_x < s->mb_y * s->mb_width + s->mb_x)
675                 s->error_occurred = 1;
676         }
677
678         if(s->msmpeg4_version<4 && s->h263_pred)
679             ff_mpeg4_clean_buffers(s);
680
681         decode_slice(s);
682     }
683
684     if (s->msmpeg4_version && s->msmpeg4_version<4 && s->pict_type==AV_PICTURE_TYPE_I)
685         if(!CONFIG_MSMPEG4_DECODER || msmpeg4_decode_ext_header(s, buf_size) < 0){
686             s->error_status_table[s->mb_num-1]= AC_ERROR|DC_ERROR|MV_ERROR;
687         }
688
689     assert(s->bitstream_buffer_size==0);
690 frame_end:
691     /* divx 5.01+ bistream reorder stuff */
692     if(s->codec_id==CODEC_ID_MPEG4 && s->divx_packed){
693         int current_pos= s->gb.buffer == s->bitstream_buffer ? 0 : (get_bits_count(&s->gb)>>3);
694         int startcode_found=0;
695
696         if(buf_size - current_pos > 7){
697             int i;
698             for(i=current_pos; i<buf_size-4; i++){
699                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
700                     startcode_found=!(buf[i+4]&0x40);
701                     break;
702                 }
703             }
704         }
705
706         if(startcode_found){
707             av_fast_malloc(
708                 &s->bitstream_buffer,
709                 &s->allocated_bitstream_buffer_size,
710                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
711             if (!s->bitstream_buffer)
712                 return AVERROR(ENOMEM);
713             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
714             s->bitstream_buffer_size= buf_size - current_pos;
715         }
716     }
717
718 intrax8_decoded:
719     ff_er_frame_end(s);
720
721     if (avctx->hwaccel) {
722         if (avctx->hwaccel->end_frame(avctx) < 0)
723             return -1;
724     }
725
726     MPV_frame_end(s);
727
728 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
729 assert(s->current_picture.pict_type == s->pict_type);
730     if (s->pict_type == AV_PICTURE_TYPE_B || s->low_delay) {
731         *pict= *(AVFrame*)s->current_picture_ptr;
732     } else if (s->last_picture_ptr != NULL) {
733         *pict= *(AVFrame*)s->last_picture_ptr;
734     }
735
736     if(s->last_picture_ptr || s->low_delay){
737         *data_size = sizeof(AVFrame);
738         ff_print_debug_info(s, pict);
739     }
740
741 #ifdef PRINT_FRAME_TIME
742 av_log(avctx, AV_LOG_DEBUG, "%"PRId64"\n", rdtsc()-time);
743 #endif
744
745     return get_consumed_bytes(s, buf_size);
746 }
747
748 AVCodec ff_h263_decoder = {
749     "h263",
750     AVMEDIA_TYPE_VIDEO,
751     CODEC_ID_H263,
752     sizeof(MpegEncContext),
753     ff_h263_decode_init,
754     NULL,
755     ff_h263_decode_end,
756     ff_h263_decode_frame,
757     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
758     .flush= ff_mpeg_flush,
759     .max_lowres= 3,
760     .long_name= NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
761     .pix_fmts= ff_hwaccel_pixfmt_list_420,
762 };