h263dec: Prevent dimension changes from leaking on errors in header parsing.
[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 #define UNCHECKED_BITSTREAM_READER 1
29
30 #include "libavutil/cpu.h"
31 #include "internal.h"
32 #include "avcodec.h"
33 #include "dsputil.h"
34 #include "mpegvideo.h"
35 #include "h263.h"
36 #include "h263_parser.h"
37 #include "mpeg4video_parser.h"
38 #include "msmpeg4.h"
39 #include "vdpau_internal.h"
40 #include "thread.h"
41 #include "flv.h"
42 #include "mpeg4video.h"
43
44 //#define DEBUG
45 //#define PRINT_FRAME_TIME
46
47 av_cold int ff_h263_decode_init(AVCodecContext *avctx)
48 {
49     MpegEncContext *s = avctx->priv_data;
50
51     s->avctx = avctx;
52     s->out_format = FMT_H263;
53
54     s->width  = avctx->coded_width;
55     s->height = avctx->coded_height;
56     s->workaround_bugs= avctx->workaround_bugs;
57
58     // set defaults
59     ff_MPV_decode_defaults(s);
60     s->quant_precision=5;
61     s->decode_mb= ff_h263_decode_mb;
62     s->low_delay= 1;
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 CODEC_ID_H263:
69         s->unrestricted_mv= 0;
70         avctx->chroma_sample_location = AVCHROMA_LOC_CENTER;
71         break;
72     case CODEC_ID_MPEG4:
73         break;
74     case CODEC_ID_MSMPEG4V1:
75         s->h263_pred = 1;
76         s->msmpeg4_version=1;
77         break;
78     case CODEC_ID_MSMPEG4V2:
79         s->h263_pred = 1;
80         s->msmpeg4_version=2;
81         break;
82     case CODEC_ID_MSMPEG4V3:
83         s->h263_pred = 1;
84         s->msmpeg4_version=3;
85         break;
86     case CODEC_ID_WMV1:
87         s->h263_pred = 1;
88         s->msmpeg4_version=4;
89         break;
90     case CODEC_ID_WMV2:
91         s->h263_pred = 1;
92         s->msmpeg4_version=5;
93         break;
94     case CODEC_ID_VC1:
95     case CODEC_ID_WMV3:
96     case CODEC_ID_VC1IMAGE:
97     case CODEC_ID_WMV3IMAGE:
98         s->h263_pred = 1;
99         s->msmpeg4_version=6;
100         avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
101         break;
102     case CODEC_ID_H263I:
103         break;
104     case CODEC_ID_FLV1:
105         s->h263_flv = 1;
106         break;
107     default:
108         return -1;
109     }
110     s->codec_id= avctx->codec->id;
111     avctx->hwaccel= ff_find_hwaccel(avctx->codec->id, avctx->pix_fmt);
112
113     /* for h263, we allocate the images after having read the header */
114     if (avctx->codec->id != CODEC_ID_H263 && avctx->codec->id != CODEC_ID_MPEG4)
115         if (ff_MPV_common_init(s) < 0)
116             return -1;
117
118         ff_h263_decode_init_vlc(s);
119
120     return 0;
121 }
122
123 av_cold int ff_h263_decode_end(AVCodecContext *avctx)
124 {
125     MpegEncContext *s = avctx->priv_data;
126
127     ff_MPV_common_end(s);
128     return 0;
129 }
130
131 /**
132  * Return the number of bytes consumed for building the current frame.
133  */
134 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
135     int pos= (get_bits_count(&s->gb)+7)>>3;
136
137     if(s->divx_packed || s->avctx->hwaccel){
138         //we would have to scan through the whole buf to handle the weird reordering ...
139         return buf_size;
140     }else if(s->flags&CODEC_FLAG_TRUNCATED){
141         pos -= s->parse_context.last_index;
142         if(pos<0) pos=0; // padding is not really read so this might be -1
143         return pos;
144     }else{
145         if(pos==0) pos=1; //avoid infinite loops (i doubt that is needed but ...)
146         if(pos+10>buf_size) pos=buf_size; // oops ;)
147
148         return pos;
149     }
150 }
151
152 static int decode_slice(MpegEncContext *s){
153     const int part_mask= s->partitioned_frame ? (ER_AC_END|ER_AC_ERROR) : 0x7F;
154     const int mb_size= 16>>s->avctx->lowres;
155     s->last_resync_gb= s->gb;
156     s->first_slice_line= 1;
157
158     s->resync_mb_x= s->mb_x;
159     s->resync_mb_y= s->mb_y;
160
161     ff_set_qscale(s, s->qscale);
162
163     if (s->avctx->hwaccel) {
164         const uint8_t *start= s->gb.buffer + get_bits_count(&s->gb)/8;
165         const uint8_t *end  = ff_h263_find_resync_marker(start + 1, s->gb.buffer_end);
166         skip_bits_long(&s->gb, 8*(end - start));
167         return s->avctx->hwaccel->decode_slice(s->avctx, start, end - start);
168     }
169
170     if(s->partitioned_frame){
171         const int qscale= s->qscale;
172
173         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
174             if(ff_mpeg4_decode_partitions(s) < 0)
175                 return -1;
176         }
177
178         /* restore variables which were modified */
179         s->first_slice_line=1;
180         s->mb_x= s->resync_mb_x;
181         s->mb_y= s->resync_mb_y;
182         ff_set_qscale(s, qscale);
183     }
184
185     for(; s->mb_y < s->mb_height; s->mb_y++) {
186         /* per-row end of slice checks */
187         if(s->msmpeg4_version){
188             if(s->resync_mb_y + s->slice_height == s->mb_y){
189                 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, ER_MB_END);
190
191                 return 0;
192             }
193         }
194
195         if(s->msmpeg4_version==1){
196             s->last_dc[0]=
197             s->last_dc[1]=
198             s->last_dc[2]= 128;
199         }
200
201         ff_init_block_index(s);
202         for(; s->mb_x < s->mb_width; s->mb_x++) {
203             int ret;
204
205             ff_update_block_index(s);
206
207             if(s->resync_mb_x == s->mb_x && s->resync_mb_y+1 == s->mb_y){
208                 s->first_slice_line=0;
209             }
210
211             /* DCT & quantize */
212
213             s->mv_dir = MV_DIR_FORWARD;
214             s->mv_type = MV_TYPE_16X16;
215 //            s->mb_skipped = 0;
216 //printf("%d %d %06X\n", ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
217             ret= s->decode_mb(s, s->block);
218
219             if (s->pict_type!=AV_PICTURE_TYPE_B)
220                 ff_h263_update_motion_val(s);
221
222             if(ret<0){
223                 const int xy= s->mb_x + s->mb_y*s->mb_stride;
224                 if(ret==SLICE_END){
225                     ff_MPV_decode_mb(s, s->block);
226                     if(s->loop_filter)
227                         ff_h263_loop_filter(s);
228
229 //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));
230                     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_END&part_mask);
231
232                     s->padding_bug_score--;
233
234                     if(++s->mb_x >= s->mb_width){
235                         s->mb_x=0;
236                         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
237                         ff_MPV_report_decode_progress(s);
238                         s->mb_y++;
239                     }
240                     return 0;
241                 }else if(ret==SLICE_NOEND){
242                     av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
243                     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x+1, s->mb_y, ER_MB_END&part_mask);
244                     return -1;
245                 }
246                 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
247                 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_ERROR&part_mask);
248
249                 return -1;
250             }
251
252             ff_MPV_decode_mb(s, s->block);
253             if(s->loop_filter)
254                 ff_h263_loop_filter(s);
255         }
256
257         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
258         ff_MPV_report_decode_progress(s);
259
260         s->mb_x= 0;
261     }
262
263     assert(s->mb_x==0 && s->mb_y==s->mb_height);
264
265     if(s->codec_id==CODEC_ID_MPEG4
266        && (s->workaround_bugs&FF_BUG_AUTODETECT)
267        && get_bits_left(&s->gb) >= 48
268        && show_bits(&s->gb, 24)==0x4010
269        && !s->data_partitioning)
270         s->padding_bug_score+=32;
271
272     /* try to detect the padding bug */
273     if(      s->codec_id==CODEC_ID_MPEG4
274        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
275        &&    get_bits_left(&s->gb) >=0
276        &&    get_bits_left(&s->gb) < 137
277 //       &&   !s->resync_marker
278        &&   !s->data_partitioning){
279
280         const int bits_count= get_bits_count(&s->gb);
281         const int bits_left = s->gb.size_in_bits - bits_count;
282
283         if(bits_left==0){
284             s->padding_bug_score+=16;
285         } else if(bits_left != 1){
286             int v= show_bits(&s->gb, 8);
287             v|= 0x7F >> (7-(bits_count&7));
288
289             if(v==0x7F && bits_left<=8)
290                 s->padding_bug_score--;
291             else if(v==0x7F && ((get_bits_count(&s->gb)+8)&8) && bits_left<=16)
292                 s->padding_bug_score+= 4;
293             else
294                 s->padding_bug_score++;
295         }
296     }
297
298     if(s->workaround_bugs&FF_BUG_AUTODETECT){
299         if(s->padding_bug_score > -2 && !s->data_partitioning /*&& (s->divx_version>=0 || !s->resync_marker)*/)
300             s->workaround_bugs |=  FF_BUG_NO_PADDING;
301         else
302             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
303     }
304
305     // handle formats which don't have unique end markers
306     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
307         int left= get_bits_left(&s->gb);
308         int max_extra=7;
309
310         /* no markers in M$ crap */
311         if(s->msmpeg4_version && s->pict_type==AV_PICTURE_TYPE_I)
312             max_extra+= 17;
313
314         /* buggy padding but the frame should still end approximately at the bitstream end */
315         if((s->workaround_bugs&FF_BUG_NO_PADDING) && (s->err_recognition&(AV_EF_BUFFER|AV_EF_AGGRESSIVE)))
316             max_extra+= 48;
317         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
318             max_extra+= 256*256*256*64;
319
320         if(left>max_extra){
321             av_log(s->avctx, AV_LOG_ERROR, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
322         }
323         else if(left<0){
324             av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
325         }else
326             ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, ER_MB_END);
327
328         return 0;
329     }
330
331     av_log(s->avctx, AV_LOG_ERROR, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
332             get_bits_left(&s->gb),
333             show_bits(&s->gb, 24), s->padding_bug_score);
334
335     ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, ER_MB_END&part_mask);
336
337     return -1;
338 }
339
340 int ff_h263_decode_frame(AVCodecContext *avctx,
341                              void *data, int *data_size,
342                              AVPacket *avpkt)
343 {
344     const uint8_t *buf = avpkt->data;
345     int buf_size = avpkt->size;
346     MpegEncContext *s = avctx->priv_data;
347     int ret;
348     AVFrame *pict = data;
349
350 #ifdef PRINT_FRAME_TIME
351 uint64_t time= rdtsc();
352 #endif
353     s->flags= avctx->flags;
354     s->flags2= avctx->flags2;
355
356     /* no supplementary picture */
357     if (buf_size == 0) {
358         /* special case for last picture */
359         if (s->low_delay==0 && s->next_picture_ptr) {
360             *pict = s->next_picture_ptr->f;
361             s->next_picture_ptr= NULL;
362
363             *data_size = sizeof(AVFrame);
364         }
365
366         return 0;
367     }
368
369     if(s->flags&CODEC_FLAG_TRUNCATED){
370         int next;
371
372         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
373             next= ff_mpeg4_find_frame_end(&s->parse_context, buf, buf_size);
374         }else if(CONFIG_H263_DECODER && s->codec_id==CODEC_ID_H263){
375             next= ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
376         }else{
377             av_log(s->avctx, AV_LOG_ERROR, "this codec does not support truncated bitstreams\n");
378             return -1;
379         }
380
381         if( ff_combine_frame(&s->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
382             return buf_size;
383     }
384
385
386 retry:
387     if(s->divx_packed && s->bitstream_buffer_size){
388         int i;
389         for(i=0; i<buf_size-3; i++){
390             if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1){
391                 if(buf[i+3]==0xB0){
392                     av_log(s->avctx, AV_LOG_WARNING, "Discarding excessive bitstream in packed xvid\n");
393                     s->bitstream_buffer_size=0;
394                 }
395                 break;
396             }
397         }
398     }
399
400     if(s->bitstream_buffer_size && (s->divx_packed || buf_size<20)){ //divx 5.01+/xvid frame reorder
401         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
402     }else
403         init_get_bits(&s->gb, buf, buf_size*8);
404     s->bitstream_buffer_size=0;
405
406     if (!s->context_initialized) {
407         if (ff_MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
408             return -1;
409     }
410
411     /* We need to set current_picture_ptr before reading the header,
412      * otherwise we cannot store anyting in there */
413     if (s->current_picture_ptr == NULL || s->current_picture_ptr->f.data[0]) {
414         int i= ff_find_unused_picture(s, 0);
415         if (i < 0)
416             return i;
417         s->current_picture_ptr= &s->picture[i];
418     }
419
420     /* let's go :-) */
421     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
422         ret= ff_wmv2_decode_picture_header(s);
423     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
424         ret = ff_msmpeg4_decode_picture_header(s);
425     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
426         if(s->avctx->extradata_size && s->picture_number==0){
427             GetBitContext gb;
428
429             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
430             ret = ff_mpeg4_decode_picture_header(s, &gb);
431         }
432         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
433     } else if (CONFIG_H263I_DECODER && s->codec_id == CODEC_ID_H263I) {
434         ret = ff_intel_h263_decode_picture_header(s);
435     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
436         ret = ff_flv_decode_picture_header(s);
437     } else {
438         ret = ff_h263_decode_picture_header(s);
439     }
440
441     if (HAVE_THREADS && (s->avctx->active_thread_type&FF_THREAD_FRAME) && ret < 0) {
442         if (   s->width  != avctx->coded_width
443             || s->height != avctx->coded_height) {
444                 av_log(s->avctx, AV_LOG_WARNING, "Reverting picture dimensions change due to header decoding failure\n");
445                 s->width = avctx->coded_width;
446                 s->height= avctx->coded_height;
447         }
448     }
449     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
450
451     /* skip if the header was thrashed */
452     if (ret < 0){
453         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
454         return -1;
455     }
456
457     avctx->has_b_frames= !s->low_delay;
458
459     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
460         if(s->stream_codec_tag == AV_RL32("XVID") ||
461            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
462            s->codec_tag == AV_RL32("RMP4") ||
463            s->codec_tag == AV_RL32("SIPP")
464            )
465             s->xvid_build= 0;
466 #if 0
467         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
468            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
469             s->xvid_build= 0;
470 #endif
471     }
472
473     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
474         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
475             s->divx_version= 400; //divx 4
476     }
477
478     if(s->xvid_build>=0 && s->divx_version>=0){
479         s->divx_version=
480         s->divx_build= -1;
481     }
482
483     if(s->workaround_bugs&FF_BUG_AUTODETECT){
484         if(s->codec_tag == AV_RL32("XVIX"))
485             s->workaround_bugs|= FF_BUG_XVID_ILACE;
486
487         if(s->codec_tag == AV_RL32("UMP4")){
488             s->workaround_bugs|= FF_BUG_UMP4;
489         }
490
491         if(s->divx_version>=500 && s->divx_build<1814){
492             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
493         }
494
495         if(s->divx_version>502 && s->divx_build<1814){
496             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
497         }
498
499         if(s->xvid_build<=3U)
500             s->padding_bug_score= 256*256*256*64;
501
502         if(s->xvid_build<=1U)
503             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
504
505         if(s->xvid_build<=12U)
506             s->workaround_bugs|= FF_BUG_EDGE;
507
508         if(s->xvid_build<=32U)
509             s->workaround_bugs|= FF_BUG_DC_CLIP;
510
511 #define SET_QPEL_FUNC(postfix1, postfix2) \
512     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
513     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
514     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
515
516         if(s->lavc_build<4653U)
517             s->workaround_bugs|= FF_BUG_STD_QPEL;
518
519         if(s->lavc_build<4655U)
520             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
521
522         if(s->lavc_build<4670U){
523             s->workaround_bugs|= FF_BUG_EDGE;
524         }
525
526         if(s->lavc_build<=4712U)
527             s->workaround_bugs|= FF_BUG_DC_CLIP;
528
529         if(s->divx_version>=0)
530             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
531 //printf("padding_bug_score: %d\n", s->padding_bug_score);
532         if(s->divx_version==501 && s->divx_build==20020416)
533             s->padding_bug_score= 256*256*256*64;
534
535         if(s->divx_version<500U){
536             s->workaround_bugs|= FF_BUG_EDGE;
537         }
538
539         if(s->divx_version>=0)
540             s->workaround_bugs|= FF_BUG_HPEL_CHROMA;
541 #if 0
542         if(s->divx_version==500)
543             s->padding_bug_score= 256*256*256*64;
544
545         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
546          * Let us hope this at least works.
547          */
548         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==-1
549            && s->codec_id==CODEC_ID_MPEG4 && s->vo_type==0)
550             s->workaround_bugs|= FF_BUG_NO_PADDING;
551
552         if(s->lavc_build<4609U) //FIXME not sure about the version num but a 4609 file seems ok
553             s->workaround_bugs|= FF_BUG_NO_PADDING;
554 #endif
555     }
556
557     if(s->workaround_bugs& FF_BUG_STD_QPEL){
558         SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
559         SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
560         SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
561         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
562         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
563         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
564
565         SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
566         SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
567         SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
568         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
569         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
570         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
571     }
572
573     if(avctx->debug & FF_DEBUG_BUGS)
574         av_log(s->avctx, AV_LOG_DEBUG, "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
575                s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
576                s->divx_packed ? "p" : "");
577
578 #if HAVE_MMX
579     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)) {
580         avctx->idct_algo= FF_IDCT_XVIDMMX;
581         ff_dct_common_init(s);
582     }
583 #endif
584
585         /* After H263 & mpeg4 header decode we have the height, width,*/
586         /* and other parameters. So then we could init the picture   */
587         /* FIXME: By the way H263 decoder is evolving it should have */
588         /* an H263EncContext                                         */
589
590     if (   s->width  != avctx->coded_width
591         || s->height != avctx->coded_height) {
592         /* H.263 could change picture size any time */
593         ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
594
595         if (HAVE_THREADS && (s->avctx->active_thread_type&FF_THREAD_FRAME)) {
596             av_log_missing_feature(s->avctx, "Width/height/bit depth/chroma idc changing with threads is", 0);
597             s->width = avctx->coded_width;
598             s->height= avctx->coded_height;
599             return -1;   // width / height changed during parallelized decoding
600         }
601
602         s->parse_context.buffer=0;
603         ff_MPV_common_end(s);
604         s->parse_context= pc;
605     }
606     if (!s->context_initialized) {
607         avcodec_set_dimensions(avctx, s->width, s->height);
608
609         goto retry;
610     }
611
612     if((s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P || s->codec_id == CODEC_ID_H263I))
613         s->gob_index = ff_h263_get_gob_height(s);
614
615     // for skipping the frame
616     s->current_picture.f.pict_type = s->pict_type;
617     s->current_picture.f.key_frame = s->pict_type == AV_PICTURE_TYPE_I;
618
619     /* skip B-frames if we don't have reference frames */
620     if(s->last_picture_ptr==NULL && (s->pict_type==AV_PICTURE_TYPE_B || s->dropable)) return get_consumed_bytes(s, buf_size);
621     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==AV_PICTURE_TYPE_B)
622        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=AV_PICTURE_TYPE_I)
623        ||  avctx->skip_frame >= AVDISCARD_ALL)
624         return get_consumed_bytes(s, buf_size);
625
626     if(s->next_p_frame_damaged){
627         if(s->pict_type==AV_PICTURE_TYPE_B)
628             return get_consumed_bytes(s, buf_size);
629         else
630             s->next_p_frame_damaged=0;
631     }
632
633     if((s->avctx->flags2 & CODEC_FLAG2_FAST) && s->pict_type==AV_PICTURE_TYPE_B){
634         s->me.qpel_put= s->dsp.put_2tap_qpel_pixels_tab;
635         s->me.qpel_avg= s->dsp.avg_2tap_qpel_pixels_tab;
636     }else if((!s->no_rounding) || s->pict_type==AV_PICTURE_TYPE_B){
637         s->me.qpel_put= s->dsp.put_qpel_pixels_tab;
638         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
639     }else{
640         s->me.qpel_put= s->dsp.put_no_rnd_qpel_pixels_tab;
641         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
642     }
643
644     if(ff_MPV_frame_start(s, avctx) < 0)
645         return -1;
646
647     if (!s->divx_packed) ff_thread_finish_setup(avctx);
648
649     if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
650         ff_vdpau_mpeg4_decode_picture(s, s->gb.buffer, s->gb.buffer_end - s->gb.buffer);
651         goto frame_end;
652     }
653
654     if (avctx->hwaccel) {
655         if (avctx->hwaccel->start_frame(avctx, s->gb.buffer, s->gb.buffer_end - s->gb.buffer) < 0)
656             return -1;
657     }
658
659     ff_er_frame_start(s);
660
661     //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
662     //which is not available before ff_MPV_frame_start()
663     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5){
664         ret = ff_wmv2_decode_secondary_picture_header(s);
665         if(ret<0) return ret;
666         if(ret==1) goto intrax8_decoded;
667     }
668
669     /* decode each macroblock */
670     s->mb_x=0;
671     s->mb_y=0;
672
673     ret = decode_slice(s);
674     while(s->mb_y<s->mb_height){
675         if(s->msmpeg4_version){
676             if(s->slice_height==0 || s->mb_x!=0 || (s->mb_y%s->slice_height)!=0 || get_bits_left(&s->gb)<0)
677                 break;
678         }else{
679             int prev_x=s->mb_x, prev_y=s->mb_y;
680             if(ff_h263_resync(s)<0)
681                 break;
682             if (prev_y * s->mb_width + prev_x < s->mb_y * s->mb_width + s->mb_x)
683                 s->error_occurred = 1;
684         }
685
686         if(s->msmpeg4_version<4 && s->h263_pred)
687             ff_mpeg4_clean_buffers(s);
688
689         if (decode_slice(s) < 0) ret = AVERROR_INVALIDDATA;
690     }
691
692     if (s->msmpeg4_version && s->msmpeg4_version<4 && s->pict_type==AV_PICTURE_TYPE_I)
693         if(!CONFIG_MSMPEG4_DECODER || ff_msmpeg4_decode_ext_header(s, buf_size) < 0){
694             s->error_status_table[s->mb_num-1]= ER_MB_ERROR;
695         }
696
697     assert(s->bitstream_buffer_size==0);
698 frame_end:
699     /* divx 5.01+ bistream reorder stuff */
700     if(s->codec_id==CODEC_ID_MPEG4 && s->divx_packed){
701         int current_pos= s->gb.buffer == s->bitstream_buffer ? 0 : (get_bits_count(&s->gb)>>3);
702         int startcode_found=0;
703
704         if(buf_size - current_pos > 7){
705             int i;
706             for(i=current_pos; i<buf_size-4; i++){
707                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
708                     startcode_found=!(buf[i+4]&0x40);
709                     break;
710                 }
711             }
712         }
713
714         if(startcode_found){
715             av_fast_malloc(
716                 &s->bitstream_buffer,
717                 &s->allocated_bitstream_buffer_size,
718                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
719             if (!s->bitstream_buffer)
720                 return AVERROR(ENOMEM);
721             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
722             s->bitstream_buffer_size= buf_size - current_pos;
723         }
724     }
725
726 intrax8_decoded:
727     ff_er_frame_end(s);
728
729     if (avctx->hwaccel) {
730         if (avctx->hwaccel->end_frame(avctx) < 0)
731             return -1;
732     }
733
734     ff_MPV_frame_end(s);
735
736     assert(s->current_picture.f.pict_type == s->current_picture_ptr->f.pict_type);
737     assert(s->current_picture.f.pict_type == s->pict_type);
738     if (s->pict_type == AV_PICTURE_TYPE_B || s->low_delay) {
739         *pict = s->current_picture_ptr->f;
740     } else if (s->last_picture_ptr != NULL) {
741         *pict = s->last_picture_ptr->f;
742     }
743
744     if(s->last_picture_ptr || s->low_delay){
745         *data_size = sizeof(AVFrame);
746         ff_print_debug_info(s, pict);
747     }
748
749 #ifdef PRINT_FRAME_TIME
750 av_log(avctx, AV_LOG_DEBUG, "%"PRId64"\n", rdtsc()-time);
751 #endif
752
753     return (ret && (avctx->err_recognition & AV_EF_EXPLODE))?ret:get_consumed_bytes(s, buf_size);
754 }
755
756 AVCodec ff_h263_decoder = {
757     .name           = "h263",
758     .type           = AVMEDIA_TYPE_VIDEO,
759     .id             = CODEC_ID_H263,
760     .priv_data_size = sizeof(MpegEncContext),
761     .init           = ff_h263_decode_init,
762     .close          = ff_h263_decode_end,
763     .decode         = ff_h263_decode_frame,
764     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 |
765                       CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
766     .flush          = ff_mpeg_flush,
767     .max_lowres     = 3,
768     .long_name      = NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
769     .pix_fmts       = ff_hwaccel_pixfmt_list_420,
770 };