cosmetics: Align codec declarations
[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     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     case CODEC_ID_VC1IMAGE:
95     case CODEC_ID_WMV3IMAGE:
96         s->h263_pred = 1;
97         s->msmpeg4_version=6;
98         avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
99         break;
100     case CODEC_ID_H263I:
101         break;
102     case CODEC_ID_FLV1:
103         s->h263_flv = 1;
104         break;
105     default:
106         return -1;
107     }
108     s->codec_id= avctx->codec->id;
109     avctx->hwaccel= ff_find_hwaccel(avctx->codec->id, avctx->pix_fmt);
110
111     /* for h263, we allocate the images after having read the header */
112     if (avctx->codec->id != CODEC_ID_H263 && avctx->codec->id != CODEC_ID_MPEG4)
113         if (ff_MPV_common_init(s) < 0)
114             return -1;
115
116         ff_h263_decode_init_vlc(s);
117
118     return 0;
119 }
120
121 av_cold int ff_h263_decode_end(AVCodecContext *avctx)
122 {
123     MpegEncContext *s = avctx->priv_data;
124
125     ff_MPV_common_end(s);
126     return 0;
127 }
128
129 /**
130  * Return the number of bytes consumed for building the current frame.
131  */
132 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
133     int pos= (get_bits_count(&s->gb)+7)>>3;
134
135     if(s->divx_packed || s->avctx->hwaccel){
136         //we would have to scan through the whole buf to handle the weird reordering ...
137         return buf_size;
138     }else if(s->flags&CODEC_FLAG_TRUNCATED){
139         pos -= s->parse_context.last_index;
140         if(pos<0) pos=0; // padding is not really read so this might be -1
141         return pos;
142     }else{
143         if(pos==0) pos=1; //avoid infinite loops (i doubt that is needed but ...)
144         if(pos+10>buf_size) pos=buf_size; // oops ;)
145
146         return pos;
147     }
148 }
149
150 static int decode_slice(MpegEncContext *s){
151     const int part_mask= s->partitioned_frame ? (ER_AC_END|ER_AC_ERROR) : 0x7F;
152     const int mb_size= 16>>s->avctx->lowres;
153     s->last_resync_gb= s->gb;
154     s->first_slice_line= 1;
155
156     s->resync_mb_x= s->mb_x;
157     s->resync_mb_y= s->mb_y;
158
159     ff_set_qscale(s, s->qscale);
160
161     if (s->avctx->hwaccel) {
162         const uint8_t *start= s->gb.buffer + get_bits_count(&s->gb)/8;
163         const uint8_t *end  = ff_h263_find_resync_marker(start + 1, s->gb.buffer_end);
164         skip_bits_long(&s->gb, 8*(end - start));
165         return s->avctx->hwaccel->decode_slice(s->avctx, start, end - start);
166     }
167
168     if(s->partitioned_frame){
169         const int qscale= s->qscale;
170
171         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
172             if(ff_mpeg4_decode_partitions(s) < 0)
173                 return -1;
174         }
175
176         /* restore variables which were modified */
177         s->first_slice_line=1;
178         s->mb_x= s->resync_mb_x;
179         s->mb_y= s->resync_mb_y;
180         ff_set_qscale(s, qscale);
181     }
182
183     for(; s->mb_y < s->mb_height; s->mb_y++) {
184         /* per-row end of slice checks */
185         if(s->msmpeg4_version){
186             if(s->resync_mb_y + s->slice_height == s->mb_y){
187                 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, ER_MB_END);
188
189                 return 0;
190             }
191         }
192
193         if(s->msmpeg4_version==1){
194             s->last_dc[0]=
195             s->last_dc[1]=
196             s->last_dc[2]= 128;
197         }
198
199         ff_init_block_index(s);
200         for(; s->mb_x < s->mb_width; s->mb_x++) {
201             int ret;
202
203             ff_update_block_index(s);
204
205             if(s->resync_mb_x == s->mb_x && s->resync_mb_y+1 == s->mb_y){
206                 s->first_slice_line=0;
207             }
208
209             /* DCT & quantize */
210
211             s->mv_dir = MV_DIR_FORWARD;
212             s->mv_type = MV_TYPE_16X16;
213 //            s->mb_skipped = 0;
214 //printf("%d %d %06X\n", ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
215             ret= s->decode_mb(s, s->block);
216
217             if (s->pict_type!=AV_PICTURE_TYPE_B)
218                 ff_h263_update_motion_val(s);
219
220             if(ret<0){
221                 const int xy= s->mb_x + s->mb_y*s->mb_stride;
222                 if(ret==SLICE_END){
223                     ff_MPV_decode_mb(s, s->block);
224                     if(s->loop_filter)
225                         ff_h263_loop_filter(s);
226
227 //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));
228                     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_END&part_mask);
229
230                     s->padding_bug_score--;
231
232                     if(++s->mb_x >= s->mb_width){
233                         s->mb_x=0;
234                         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
235                         ff_MPV_report_decode_progress(s);
236                         s->mb_y++;
237                     }
238                     return 0;
239                 }else if(ret==SLICE_NOEND){
240                     av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
241                     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);
242                     return -1;
243                 }
244                 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
245                 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_ERROR&part_mask);
246
247                 return -1;
248             }
249
250             ff_MPV_decode_mb(s, s->block);
251             if(s->loop_filter)
252                 ff_h263_loop_filter(s);
253         }
254
255         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
256         ff_MPV_report_decode_progress(s);
257
258         s->mb_x= 0;
259     }
260
261     assert(s->mb_x==0 && s->mb_y==s->mb_height);
262
263     if(s->codec_id==CODEC_ID_MPEG4
264        && (s->workaround_bugs&FF_BUG_AUTODETECT)
265        && get_bits_left(&s->gb) >= 48
266        && show_bits(&s->gb, 24)==0x4010
267        && !s->data_partitioning)
268         s->padding_bug_score+=32;
269
270     /* try to detect the padding bug */
271     if(      s->codec_id==CODEC_ID_MPEG4
272        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
273        &&    get_bits_left(&s->gb) >=0
274        &&    get_bits_left(&s->gb) < 48
275 //       &&   !s->resync_marker
276        &&   !s->data_partitioning){
277
278         const int bits_count= get_bits_count(&s->gb);
279         const int bits_left = s->gb.size_in_bits - bits_count;
280
281         if(bits_left==0){
282             s->padding_bug_score+=16;
283         } else if(bits_left != 1){
284             int v= show_bits(&s->gb, 8);
285             v|= 0x7F >> (7-(bits_count&7));
286
287             if(v==0x7F && bits_left<=8)
288                 s->padding_bug_score--;
289             else if(v==0x7F && ((get_bits_count(&s->gb)+8)&8) && bits_left<=16)
290                 s->padding_bug_score+= 4;
291             else
292                 s->padding_bug_score++;
293         }
294     }
295
296     if(s->workaround_bugs&FF_BUG_AUTODETECT){
297         if(s->padding_bug_score > -2 && !s->data_partitioning /*&& (s->divx_version>=0 || !s->resync_marker)*/)
298             s->workaround_bugs |=  FF_BUG_NO_PADDING;
299         else
300             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
301     }
302
303     // handle formats which don't have unique end markers
304     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
305         int left= get_bits_left(&s->gb);
306         int max_extra=7;
307
308         /* no markers in M$ crap */
309         if(s->msmpeg4_version && s->pict_type==AV_PICTURE_TYPE_I)
310             max_extra+= 17;
311
312         /* buggy padding but the frame should still end approximately at the bitstream end */
313         if((s->workaround_bugs&FF_BUG_NO_PADDING) && (s->err_recognition&AV_EF_BUFFER))
314             max_extra+= 48;
315         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
316             max_extra+= 256*256*256*64;
317
318         if(left>max_extra){
319             av_log(s->avctx, AV_LOG_ERROR, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
320         }
321         else if(left<0){
322             av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
323         }else
324             ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, ER_MB_END);
325
326         return 0;
327     }
328
329     av_log(s->avctx, AV_LOG_ERROR, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
330             get_bits_left(&s->gb),
331             show_bits(&s->gb, 24), s->padding_bug_score);
332
333     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_END&part_mask);
334
335     return -1;
336 }
337
338 int ff_h263_decode_frame(AVCodecContext *avctx,
339                              void *data, int *data_size,
340                              AVPacket *avpkt)
341 {
342     const uint8_t *buf = avpkt->data;
343     int buf_size = avpkt->size;
344     MpegEncContext *s = avctx->priv_data;
345     int ret;
346     AVFrame *pict = data;
347
348 #ifdef PRINT_FRAME_TIME
349 uint64_t time= rdtsc();
350 #endif
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             *pict = s->next_picture_ptr->f;
359             s->next_picture_ptr= NULL;
360
361             *data_size = sizeof(AVFrame);
362         }
363
364         return 0;
365     }
366
367     if(s->flags&CODEC_FLAG_TRUNCATED){
368         int next;
369
370         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
371             next= ff_mpeg4_find_frame_end(&s->parse_context, buf, buf_size);
372         }else if(CONFIG_H263_DECODER && s->codec_id==CODEC_ID_H263){
373             next= ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
374         }else{
375             av_log(s->avctx, AV_LOG_ERROR, "this codec does not support truncated bitstreams\n");
376             return -1;
377         }
378
379         if( ff_combine_frame(&s->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
380             return buf_size;
381     }
382
383
384 retry:
385
386     if(s->bitstream_buffer_size && (s->divx_packed || buf_size<20)){ //divx 5.01+/xvid frame reorder
387         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
388     }else
389         init_get_bits(&s->gb, buf, buf_size*8);
390     s->bitstream_buffer_size=0;
391
392     if (!s->context_initialized) {
393         if (ff_MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
394             return -1;
395     }
396
397     /* We need to set current_picture_ptr before reading the header,
398      * otherwise we cannot store anyting in there */
399     if (s->current_picture_ptr == NULL || s->current_picture_ptr->f.data[0]) {
400         int i= ff_find_unused_picture(s, 0);
401         if (i < 0)
402             return i;
403         s->current_picture_ptr= &s->picture[i];
404     }
405
406     /* let's go :-) */
407     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
408         ret= ff_wmv2_decode_picture_header(s);
409     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
410         ret = ff_msmpeg4_decode_picture_header(s);
411     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
412         if(s->avctx->extradata_size && s->picture_number==0){
413             GetBitContext gb;
414
415             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
416             ret = ff_mpeg4_decode_picture_header(s, &gb);
417         }
418         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
419     } else if (CONFIG_H263I_DECODER && s->codec_id == CODEC_ID_H263I) {
420         ret = ff_intel_h263_decode_picture_header(s);
421     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
422         ret = ff_flv_decode_picture_header(s);
423     } else {
424         ret = ff_h263_decode_picture_header(s);
425     }
426
427     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
428
429     /* skip if the header was thrashed */
430     if (ret < 0){
431         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
432         return -1;
433     }
434
435     avctx->has_b_frames= !s->low_delay;
436
437     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
438         if(s->stream_codec_tag == AV_RL32("XVID") ||
439            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
440            s->codec_tag == AV_RL32("RMP4") ||
441            s->codec_tag == AV_RL32("SIPP")
442            )
443             s->xvid_build= 0;
444 #if 0
445         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
446            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
447             s->xvid_build= 0;
448 #endif
449     }
450
451     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
452         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
453             s->divx_version= 400; //divx 4
454     }
455
456     if(s->xvid_build>=0 && s->divx_version>=0){
457         s->divx_version=
458         s->divx_build= -1;
459     }
460
461     if(s->workaround_bugs&FF_BUG_AUTODETECT){
462         if(s->codec_tag == AV_RL32("XVIX"))
463             s->workaround_bugs|= FF_BUG_XVID_ILACE;
464
465         if(s->codec_tag == AV_RL32("UMP4")){
466             s->workaround_bugs|= FF_BUG_UMP4;
467         }
468
469         if(s->divx_version>=500 && s->divx_build<1814){
470             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
471         }
472
473         if(s->divx_version>502 && s->divx_build<1814){
474             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
475         }
476
477         if(s->xvid_build<=3U)
478             s->padding_bug_score= 256*256*256*64;
479
480         if(s->xvid_build<=1U)
481             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
482
483         if(s->xvid_build<=12U)
484             s->workaround_bugs|= FF_BUG_EDGE;
485
486         if(s->xvid_build<=32U)
487             s->workaround_bugs|= FF_BUG_DC_CLIP;
488
489 #define SET_QPEL_FUNC(postfix1, postfix2) \
490     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
491     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
492     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
493
494         if(s->lavc_build<4653U)
495             s->workaround_bugs|= FF_BUG_STD_QPEL;
496
497         if(s->lavc_build<4655U)
498             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
499
500         if(s->lavc_build<4670U){
501             s->workaround_bugs|= FF_BUG_EDGE;
502         }
503
504         if(s->lavc_build<=4712U)
505             s->workaround_bugs|= FF_BUG_DC_CLIP;
506
507         if(s->divx_version>=0)
508             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
509 //printf("padding_bug_score: %d\n", s->padding_bug_score);
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==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 == 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 (   s->width  != avctx->coded_width
570         || s->height != avctx->coded_height) {
571         /* H.263 could change picture size any time */
572         ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
573
574         if (HAVE_THREADS && (s->avctx->active_thread_type&FF_THREAD_FRAME)) {
575             av_log_missing_feature(s->avctx, "Width/height/bit depth/chroma idc changing with threads is", 0);
576             return -1;   // width / height changed during parallelized decoding
577         }
578
579         s->parse_context.buffer=0;
580         ff_MPV_common_end(s);
581         s->parse_context= pc;
582     }
583     if (!s->context_initialized) {
584         avcodec_set_dimensions(avctx, s->width, s->height);
585
586         goto retry;
587     }
588
589     if((s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P || s->codec_id == CODEC_ID_H263I))
590         s->gob_index = ff_h263_get_gob_height(s);
591
592     // for skipping the frame
593     s->current_picture.f.pict_type = s->pict_type;
594     s->current_picture.f.key_frame = s->pict_type == AV_PICTURE_TYPE_I;
595
596     /* skip B-frames if we don't have reference frames */
597     if(s->last_picture_ptr==NULL && (s->pict_type==AV_PICTURE_TYPE_B || s->dropable)) return get_consumed_bytes(s, buf_size);
598     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==AV_PICTURE_TYPE_B)
599        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=AV_PICTURE_TYPE_I)
600        ||  avctx->skip_frame >= AVDISCARD_ALL)
601         return get_consumed_bytes(s, buf_size);
602
603     if(s->next_p_frame_damaged){
604         if(s->pict_type==AV_PICTURE_TYPE_B)
605             return get_consumed_bytes(s, buf_size);
606         else
607             s->next_p_frame_damaged=0;
608     }
609
610     if((s->avctx->flags2 & CODEC_FLAG2_FAST) && s->pict_type==AV_PICTURE_TYPE_B){
611         s->me.qpel_put= s->dsp.put_2tap_qpel_pixels_tab;
612         s->me.qpel_avg= s->dsp.avg_2tap_qpel_pixels_tab;
613     }else if((!s->no_rounding) || s->pict_type==AV_PICTURE_TYPE_B){
614         s->me.qpel_put= s->dsp.put_qpel_pixels_tab;
615         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
616     }else{
617         s->me.qpel_put= s->dsp.put_no_rnd_qpel_pixels_tab;
618         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
619     }
620
621     if(ff_MPV_frame_start(s, avctx) < 0)
622         return -1;
623
624     if (!s->divx_packed) ff_thread_finish_setup(avctx);
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 ff_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     ret = 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_left(&s->gb)<0)
654                 break;
655         }else{
656             int prev_x=s->mb_x, prev_y=s->mb_y;
657             if(ff_h263_resync(s)<0)
658                 break;
659             if (prev_y * s->mb_width + prev_x < s->mb_y * s->mb_width + s->mb_x)
660                 s->error_occurred = 1;
661         }
662
663         if(s->msmpeg4_version<4 && s->h263_pred)
664             ff_mpeg4_clean_buffers(s);
665
666         if (decode_slice(s) < 0) ret = AVERROR_INVALIDDATA;
667     }
668
669     if (s->msmpeg4_version && s->msmpeg4_version<4 && s->pict_type==AV_PICTURE_TYPE_I)
670         if(!CONFIG_MSMPEG4_DECODER || ff_msmpeg4_decode_ext_header(s, buf_size) < 0){
671             s->error_status_table[s->mb_num-1]= ER_MB_ERROR;
672         }
673
674     assert(s->bitstream_buffer_size==0);
675 frame_end:
676     /* divx 5.01+ bistream reorder stuff */
677     if(s->codec_id==CODEC_ID_MPEG4 && s->divx_packed){
678         int current_pos= get_bits_count(&s->gb)>>3;
679         int startcode_found=0;
680
681         if(buf_size - current_pos > 5){
682             int i;
683             for(i=current_pos; i<buf_size-3; i++){
684                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
685                     startcode_found=1;
686                     break;
687                 }
688             }
689         }
690         if(s->gb.buffer == s->bitstream_buffer && buf_size>7 && s->xvid_build>=0){ //xvid style
691             startcode_found=1;
692             current_pos=0;
693         }
694
695         if(startcode_found){
696             av_fast_malloc(
697                 &s->bitstream_buffer,
698                 &s->allocated_bitstream_buffer_size,
699                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
700             if (!s->bitstream_buffer)
701                 return AVERROR(ENOMEM);
702             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
703             s->bitstream_buffer_size= buf_size - current_pos;
704         }
705     }
706
707 intrax8_decoded:
708     ff_er_frame_end(s);
709
710     if (avctx->hwaccel) {
711         if (avctx->hwaccel->end_frame(avctx) < 0)
712             return -1;
713     }
714
715     ff_MPV_frame_end(s);
716
717     assert(s->current_picture.f.pict_type == s->current_picture_ptr->f.pict_type);
718     assert(s->current_picture.f.pict_type == s->pict_type);
719     if (s->pict_type == AV_PICTURE_TYPE_B || s->low_delay) {
720         *pict = s->current_picture_ptr->f;
721     } else if (s->last_picture_ptr != NULL) {
722         *pict = s->last_picture_ptr->f;
723     }
724
725     if(s->last_picture_ptr || s->low_delay){
726         *data_size = sizeof(AVFrame);
727         ff_print_debug_info(s, pict);
728     }
729
730 #ifdef PRINT_FRAME_TIME
731 av_log(avctx, AV_LOG_DEBUG, "%"PRId64"\n", rdtsc()-time);
732 #endif
733
734     return (ret && (avctx->err_recognition & AV_EF_EXPLODE))?ret:get_consumed_bytes(s, buf_size);
735 }
736
737 AVCodec ff_h263_decoder = {
738     .name           = "h263",
739     .type           = AVMEDIA_TYPE_VIDEO,
740     .id             = CODEC_ID_H263,
741     .priv_data_size = sizeof(MpegEncContext),
742     .init           = ff_h263_decode_init,
743     .close          = ff_h263_decode_end,
744     .decode         = ff_h263_decode_frame,
745     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 |
746                       CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
747     .flush          = ff_mpeg_flush,
748     .max_lowres     = 3,
749     .long_name      = NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
750     .pix_fmts       = ff_hwaccel_pixfmt_list_420,
751 };