hvirtual/quicktime/libavcodec/h263dec.c

   1 /*
   2  * H263 decoder
   3  * Copyright (c) 2001 Fabrice Bellard.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19 #include "avcodec.h"
  20 #include "dsputil.h"
  21 #include "mpegvideo.h"
  22
  23 #if 1
  24 #define PRINT_QP(a, b) {}
  25 #else
  26 #define PRINT_QP(a, b) printf(a, b)
  27 #endif
  28
  29 //#define DEBUG
  30 //#define PRINT_FRAME_TIME
  31 #ifdef PRINT_FRAME_TIME
  32 static inline long long rdtsc()
  33 {
  34         long long l;
  35         asm volatile(   "rdtsc\n\t"
  36                 : "=A" (l)
  37         );
  38 //      printf("%d\n", int(l/1000));
  39         return l;
  40 }
  41 #endif
  42
  43 static int h263_decode_init(AVCodecContext *avctx)
  44 {
  45     MpegEncContext *s = avctx->priv_data;
  46
  47     s->avctx = avctx;
  48     s->out_format = FMT_H263;
  49
  50     s->width = avctx->width;
  51     s->height = avctx->height;
  52     s->workaround_bugs= avctx->workaround_bugs;
  53
  54     // set defaults
  55     s->quant_precision=5;
  56     s->progressive_sequence=1;
  57     s->decode_mb= ff_h263_decode_mb;
  58     s->low_delay= 1;
  59
  60     /* select sub codec */
  61     switch(avctx->codec->id) {
  62     case CODEC_ID_H263:
  63         s->gob_number = 0;
  64         break;
  65     case CODEC_ID_MPEG4:
  66         s->time_increment_bits = 4; /* default value for broken headers */
  67         s->h263_pred = 1;
  68         s->low_delay = 0; //default, might be overriden in the vol header during header parsing
  69         break;
  70     case CODEC_ID_MSMPEG4V1:
  71         s->h263_msmpeg4 = 1;
  72         s->h263_pred = 1;
  73         s->msmpeg4_version=1;
  74         break;
  75     case CODEC_ID_MSMPEG4V2:
  76         s->h263_msmpeg4 = 1;
  77         s->h263_pred = 1;
  78         s->msmpeg4_version=2;
  79         break;
  80     case CODEC_ID_MSMPEG4V3:
  81         s->h263_msmpeg4 = 1;
  82         s->h263_pred = 1;
  83         s->msmpeg4_version=3;
  84         break;
  85     case CODEC_ID_WMV1:
  86         s->h263_msmpeg4 = 1;
  87         s->h263_pred = 1;
  88         s->msmpeg4_version=4;
  89         break;
  90     case CODEC_ID_WMV2:
  91         s->h263_msmpeg4 = 1;
  92         s->h263_pred = 1;
  93         s->msmpeg4_version=5;
  94         break;
  95     case CODEC_ID_H263I:
  96         s->h263_intel = 1;
  97         break;
  98     default:
  99         return -1;
 100     }
 101     s->codec_id= avctx->codec->id;
 102
 103     /* for h263, we allocate the images after having read the header */
 104     if (avctx->codec->id != CODEC_ID_H263 && avctx->codec->id != CODEC_ID_MPEG4)
 105         if (MPV_common_init(s) < 0)
 106             return -1;
 107
 108     if (s->h263_msmpeg4)
 109         ff_msmpeg4_decode_init(s);
 110     else
 111         h263_decode_init_vlc(s);
 112
 113     return 0;
 114 }
 115
 116 static int h263_decode_end(AVCodecContext *avctx)
 117 {
 118     MpegEncContext *s = avctx->priv_data;
 119
 120     MPV_common_end(s);
 121     return 0;
 122 }
 123
 124 /**
 125  * retunrs the number of bytes consumed for building the current frame
 126  */
 127 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
 128     int pos= (get_bits_count(&s->gb)+7)>>3;
 129
 130     if(s->divx_version>=500){
 131         //we would have to scan through the whole buf to handle the weird reordering ...
 132         return buf_size;
 133     }else if(s->flags&CODEC_FLAG_TRUNCATED){
 134         pos -= s->parse_context.last_index;
 135         if(pos<0) pos=0; // padding is not really read so this might be -1
 136         return pos;
 137     }else{
 138         if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
 139         if(pos+10>buf_size) pos=buf_size; // oops ;)
 140
 141         return pos;
 142     }
 143 }
 144
 145 static int decode_slice(MpegEncContext *s){
 146     s->last_resync_gb= s->gb;
 147     s->first_slice_line= 1;
 148
 149     s->resync_mb_x= s->mb_x;
 150     s->resync_mb_y= s->mb_y;
 151
 152     s->y_dc_scale= s->y_dc_scale_table[ s->qscale ];
 153     s->c_dc_scale= s->c_dc_scale_table[ s->qscale ];
 154
 155     if(s->partitioned_frame){
 156         const int qscale= s->qscale;
 157
 158         if(s->codec_id==CODEC_ID_MPEG4){
 159             if(ff_mpeg4_decode_partitions(s) < 0)
 160                 return -1;
 161         }
 162
 163         /* restore variables which where modified */
 164         s->first_slice_line=1;
 165         s->mb_x= s->resync_mb_x;
 166         s->mb_y= s->resync_mb_y;
 167         s->qscale= qscale;
 168         s->y_dc_scale= s->y_dc_scale_table[ s->qscale ];
 169         s->c_dc_scale= s->c_dc_scale_table[ s->qscale ];
 170     }
 171
 172     for(; s->mb_y < s->mb_height; s->mb_y++) {
 173         /* per-row end of slice checks */
 174         if(s->msmpeg4_version){
 175             if(s->resync_mb_y + s->slice_height == s->mb_y){
 176                 const int xy= s->mb_x + s->mb_y*s->mb_width;
 177                 s->error_status_table[xy-1]|= AC_END|DC_END|MV_END;
 178                 return 0;
 179             }
 180         }
 181
 182         if(s->msmpeg4_version==1){
 183             s->last_dc[0]=
 184             s->last_dc[1]=
 185             s->last_dc[2]= 128;
 186         }
 187
 188         ff_init_block_index(s);
 189         for(; s->mb_x < s->mb_width; s->mb_x++) {
 190             int ret;
 191
 192             ff_update_block_index(s);
 193
 194             if(s->resync_mb_x == s->mb_x && s->resync_mb_y+1 == s->mb_y){
 195                 s->first_slice_line=0;
 196             }
 197
 198             /* DCT & quantize */
 199             s->dsp.clear_blocks(s->block[0]);
 200
 201             s->mv_dir = MV_DIR_FORWARD;
 202             s->mv_type = MV_TYPE_16X16;
 203 //            s->mb_skiped = 0;
 204 //printf("%d %d %06X\n", ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
 205             ret= s->decode_mb(s, s->block);
 206
 207             PRINT_QP("%2d", s->qscale);
 208             MPV_decode_mb(s, s->block);
 209
 210             if(ret<0){
 211                 const int xy= s->mb_x + s->mb_y*s->mb_width;
 212                 if(ret==SLICE_END){
 213 //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));
 214                     s->error_status_table[xy]|= AC_END;
 215                     if(!s->partitioned_frame)
 216                         s->error_status_table[xy]|= MV_END|DC_END;
 217
 218                     s->padding_bug_score--;
 219
 220                     if(++s->mb_x >= s->mb_width){
 221                         s->mb_x=0;
 222                         ff_draw_horiz_band(s);
 223                         s->mb_y++;
 224                     }
 225                     return 0;
 226                 }else if(ret==SLICE_NOEND){
 227                     fprintf(stderr,"Slice mismatch at MB: %d\n", xy);
 228                     return -1;
 229                 }
 230                 fprintf(stderr,"Error at MB: %d\n", xy);
 231                 s->error_status_table[xy]|= AC_ERROR;
 232                 if(!s->partitioned_frame)
 233                     s->error_status_table[xy]|= DC_ERROR|MV_ERROR;
 234
 235                 return -1;
 236             }
 237         }
 238
 239         ff_draw_horiz_band(s);
 240
 241         PRINT_QP("%s", "\n");
 242
 243         s->mb_x= 0;
 244     }
 245
 246     assert(s->mb_x==0 && s->mb_y==s->mb_height);
 247
 248     /* try to detect the padding bug */
 249     if(      s->codec_id==CODEC_ID_MPEG4
 250        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
 251        &&    s->gb.size*8 - get_bits_count(&s->gb) >=0
 252        &&    s->gb.size*8 - get_bits_count(&s->gb) < 48
 253 //       &&   !s->resync_marker
 254        &&   !s->data_partitioning){
 255
 256         const int bits_count= get_bits_count(&s->gb);
 257         const int bits_left = s->gb.size*8 - bits_count;
 258
 259         if(bits_left==0 || bits_left>8){
 260             s->padding_bug_score++;
 261         } else if(bits_left != 1){
 262             int v= show_bits(&s->gb, 8);
 263             v|= 0x7F >> (7-(bits_count&7));
 264
 265             if(v==0x7F)
 266                 s->padding_bug_score--;
 267             else
 268                 s->padding_bug_score++;
 269         }
 270
 271         if(s->padding_bug_score > -2)
 272             s->workaround_bugs |=  FF_BUG_NO_PADDING;
 273         else
 274             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
 275     }
 276
 277     // handle formats which dont have unique end markers
 278     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
 279         int left= s->gb.size*8 - get_bits_count(&s->gb);
 280         int max_extra=7;
 281
 282         /* no markers in M$ crap */
 283         if(s->msmpeg4_version && s->pict_type==I_TYPE)
 284             max_extra+= 17;
 285
 286         /* buggy padding but the frame should still end approximately at the bitstream end */
 287         if((s->workaround_bugs&FF_BUG_NO_PADDING) && s->error_resilience>=3)
 288             max_extra+= 48;
 289         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
 290             max_extra+= 256*256*256*64;
 291
 292         if(left>max_extra){
 293             fprintf(stderr, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
 294         }
 295         else if(left<0){
 296             fprintf(stderr, "overreading %d bits\n", -left);
 297         }else
 298             s->error_status_table[s->mb_num-1]|= AC_END|MV_END|DC_END;
 299
 300         return 0;
 301     }
 302
 303     fprintf(stderr, "slice end not reached but screenspace end (%d left %06X)\n",
 304             s->gb.size*8 - get_bits_count(&s->gb),
 305             show_bits(&s->gb, 24));
 306     return -1;
 307 }
 308
 309 /**
 310  * finds the end of the current frame in the bitstream.
 311  * @return the position of the first byte of the next frame, or -1
 312  */
 313 static int mpeg4_find_frame_end(MpegEncContext *s, UINT8 *buf, int buf_size){
 314     ParseContext *pc= &s->parse_context;
 315     int vop_found, i;
 316     uint32_t state;
 317
 318     vop_found= pc->frame_start_found;
 319     state= pc->state;
 320
 321     i=0;
 322     if(!vop_found){
 323         for(i=0; i<buf_size; i++){
 324             state= (state<<8) | buf[i];
 325             if(state == 0x1B6){
 326                 i++;
 327                 vop_found=1;
 328                 break;
 329             }
 330         }
 331     }
 332
 333     for(; i<buf_size; i++){
 334         state= (state<<8) | buf[i];
 335         if((state&0xFFFFFF00) == 0x100){
 336             pc->frame_start_found=0;
 337             pc->state=-1;
 338             return i-3;
 339         }
 340     }
 341     pc->frame_start_found= vop_found;
 342     pc->state= state;
 343     return -1;
 344 }
 345
 346 static int h263_decode_frame(AVCodecContext *avctx,
 347                              void *data, int *data_size,
 348                              UINT8 *buf, int buf_size)
 349 {
 350     MpegEncContext *s = avctx->priv_data;
 351     int ret,i;
 352     AVFrame *pict = data;
 353     float new_aspect;
 354
 355
 356 //printf("h263_decode_frame 1\n");
 357
 358
 359 #ifdef PRINT_FRAME_TIME
 360 uint64_t time= rdtsc();
 361 #endif
 362 #ifdef DEBUG
 363     printf("*****frame %d size=%d\n", avctx->frame_number, buf_size);
 364     printf("bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
 365 #endif
 366     s->flags= avctx->flags;
 367
 368     *data_size = 0;
 369
 370    /* no supplementary picture */
 371     if (buf_size == 0) {
 372         return 0;
 373     }
 374
 375 //printf("h263_decode_frame 10\n");
 376
 377     if(s->flags&CODEC_FLAG_TRUNCATED){
 378         int next;
 379         ParseContext *pc= &s->parse_context;
 380
 381         pc->last_index= pc->index;
 382
 383         if(s->codec_id==CODEC_ID_MPEG4){
 384             next= mpeg4_find_frame_end(s, buf, buf_size);
 385         }else{
 386             fprintf(stderr, "this codec doesnt support truncated bitstreams\n");
 387             return -1;
 388         }
 389         if(next==-1){
 390             if(buf_size + FF_INPUT_BUFFER_PADDING_SIZE + pc->index > pc->buffer_size){
 391                 pc->buffer_size= buf_size + pc->index + 10*1024;
 392                 pc->buffer= realloc(pc->buffer, pc->buffer_size);
 393             }
 394
 395             memcpy(&pc->buffer[pc->index], buf, buf_size);
 396             pc->index += buf_size;
 397             return buf_size;
 398         }
 399
 400         if(pc->index){
 401             if(next + FF_INPUT_BUFFER_PADDING_SIZE + pc->index > pc->buffer_size){
 402                 pc->buffer_size= next + pc->index + 10*1024;
 403                 pc->buffer= realloc(pc->buffer, pc->buffer_size);
 404             }
 405
 406             memcpy(&pc->buffer[pc->index], buf, next + FF_INPUT_BUFFER_PADDING_SIZE );
 407             pc->index = 0;
 408             buf= pc->buffer;
 409             buf_size= pc->last_index + next;
 410         }
 411     }
 412 //printf("h263_decode_frame 20\n");
 413
 414
 415 retry:
 416
 417     if(s->bitstream_buffer_size && buf_size<20){ //divx 5.01+ frame reorder
 418         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size);
 419     }else
 420         init_get_bits(&s->gb, buf, buf_size);
 421     s->bitstream_buffer_size=0;
 422 //printf("h263_decode_frame 21\n");
 423
 424     if (!s->context_initialized) {
 425         if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
 426             return -1;
 427     }
 428 //printf("h263_decode_frame 22\n");
 429
 430     /* let's go :-) */
 431     if (s->h263_msmpeg4) {
 432         ret = msmpeg4_decode_picture_header(s);
 433     } else if (s->h263_pred) {
 434         if(s->avctx->extradata_size && s->picture_number==0){
 435             GetBitContext gb;
 436
 437             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size);
 438             ret = ff_mpeg4_decode_picture_header(s, &gb);
 439         }
 440         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
 441
 442         if(s->flags& CODEC_FLAG_LOW_DELAY)
 443             s->low_delay=1;
 444     } else if (s->h263_intel) {
 445         ret = intel_h263_decode_picture_header(s);
 446     } else {
 447         ret = h263_decode_picture_header(s);
 448     }
 449     avctx->has_b_frames= !s->low_delay;
 450 //printf("h263_decode_frame 23\n");
 451
 452     if(s->workaround_bugs&FF_BUG_AUTODETECT){
 453         if(s->avctx->fourcc == ff_get_fourcc("XVIX"))
 454             s->workaround_bugs|= FF_BUG_XVID_ILACE;
 455 #if 0
 456         if(s->avctx->fourcc == ff_get_fourcc("MP4S"))
 457             s->workaround_bugs|= FF_BUG_AC_VLC;
 458
 459         if(s->avctx->fourcc == ff_get_fourcc("M4S2"))
 460             s->workaround_bugs|= FF_BUG_AC_VLC;
 461 #endif
 462         if(s->avctx->fourcc == ff_get_fourcc("UMP4")){
 463             s->workaround_bugs|= FF_BUG_UMP4;
 464             s->workaround_bugs|= FF_BUG_AC_VLC;
 465         }
 466
 467         if(s->divx_version){
 468             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 469         }
 470
 471         if(s->avctx->fourcc == ff_get_fourcc("XVID") && s->xvid_build==0)
 472             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 473
 474         if(s->avctx->fourcc == ff_get_fourcc("XVID") && s->xvid_build==0)
 475             s->padding_bug_score= 256*256*256*64;
 476
 477         if(s->xvid_build && s->xvid_build<=1)
 478             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 479
 480 //printf("padding_bug_score: %d\n", s->padding_bug_score);
 481 #if 0
 482         if(s->divx_version==500)
 483             s->workaround_bugs|= FF_BUG_NO_PADDING;
 484
 485         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
 486          * lets hope this at least works
 487          */
 488         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==0
 489            && s->codec_id==CODEC_ID_MPEG4 && s->vo_type==0)
 490             s->workaround_bugs|= FF_BUG_NO_PADDING;
 491
 492         if(s->lavc_build && s->lavc_build<4609) //FIXME not sure about the version num but a 4609 file seems ok
 493             s->workaround_bugs|= FF_BUG_NO_PADDING;
 494 #endif
 495     }
 496 //printf("h263_decode_frame 24\n");
 497
 498
 499 #if 0 // dump bits per frame / qp / complexity
 500 {
 501     static FILE *f=NULL;
 502     if(!f) f=fopen("rate_qp_cplx.txt", "w");
 503     fprintf(f, "%d %d %f\n", buf_size, s->qscale, buf_size*(double)s->qscale);
 504 }
 505 #endif
 506
 507         /* After H263 & mpeg4 header decode we have the height, width,*/
 508         /* and other parameters. So then we could init the picture   */
 509         /* FIXME: By the way H263 decoder is evolving it should have */
 510         /* an H263EncContext                                         */
 511     if(s->aspected_height)
 512         new_aspect= s->aspected_width*s->width / (float)(s->height*s->aspected_height);
 513     else
 514         new_aspect=0;
 515
 516 //printf("h263_decode_frame 25\n");
 517     if (   s->width != avctx->width || s->height != avctx->height
 518         || ABS(new_aspect - avctx->aspect_ratio) > 0.001) {
 519         /* H.263 could change picture size any time */
 520         MPV_common_end(s);
 521         s->context_initialized=0;
 522     }
 523
 524 //printf("h263_decode_frame 26\n");
 525     if (!s->context_initialized) {
 526         avctx->width = s->width;
 527         avctx->height = s->height;
 528         avctx->aspect_ratio= new_aspect;
 529
 530         goto retry;
 531     }
 532
 533 //printf("h263_decode_frame 27\n");
 534     if((s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P))
 535         s->gob_index = ff_h263_get_gob_height(s);
 536
 537     if(ret==FRAME_SKIPED) return get_consumed_bytes(s, buf_size);
 538     /* skip if the header was thrashed */
 539     if (ret < 0){
 540         fprintf(stderr, "header damaged\n");
 541         return -1;
 542     }
 543 //printf("h263_decode_frame 28\n");
 544
 545     // for hurry_up==5
 546     s->current_picture.pict_type= s->pict_type;
 547     s->current_picture.key_frame= s->pict_type == I_TYPE;
 548
 549     /* skip b frames if we dont have reference frames */
 550     if(s->last_picture.data[0]==NULL && s->pict_type==B_TYPE) return get_consumed_bytes(s, buf_size);
 551     /* skip b frames if we are in a hurry */
 552     if(avctx->hurry_up && s->pict_type==B_TYPE) return get_consumed_bytes(s, buf_size);
 553     /* skip everything if we are in a hurry>=5 */
 554     if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
 555 //printf("h263_decode_frame 29\n");
 556
 557     if(s->next_p_frame_damaged){
 558         if(s->pict_type==B_TYPE)
 559             return get_consumed_bytes(s, buf_size);
 560         else
 561             s->next_p_frame_damaged=0;
 562     }
 563 //printf("h263_decode_frame 29\n");
 564
 565     if(MPV_frame_start(s, avctx) < 0)
 566         return -1;
 567 //printf("h263_decode_frame 29\n");
 568
 569 #ifdef DEBUG
 570     printf("qscale=%d\n", s->qscale);
 571 #endif
 572
 573     if(s->error_resilience)
 574         memset(s->error_status_table, MV_ERROR|AC_ERROR|DC_ERROR|VP_START|AC_END|DC_END|MV_END, s->mb_num*sizeof(UINT8));
 575 //printf("h263_decode_frame 30\n");
 576
 577
 578     /* decode each macroblock */
 579     s->block_wrap[0]=
 580     s->block_wrap[1]=
 581     s->block_wrap[2]=
 582     s->block_wrap[3]= s->mb_width*2 + 2;
 583     s->block_wrap[4]=
 584     s->block_wrap[5]= s->mb_width + 2;
 585     s->mb_x=0;
 586     s->mb_y=0;
 587
 588 //printf("h263_decode_frame 40\n");
 589
 590     decode_slice(s);
 591     s->error_status_table[0]|= VP_START;
 592     while(s->mb_y<s->mb_height && s->gb.size*8 - get_bits_count(&s->gb)>16){
 593         if(s->msmpeg4_version){
 594             if(s->mb_x!=0 || (s->mb_y%s->slice_height)!=0)
 595                 break;
 596         }else{
 597             if(ff_h263_resync(s)<0)
 598                 break;
 599         }
 600
 601         if(s->msmpeg4_version!=4 && s->h263_pred)
 602             ff_mpeg4_clean_buffers(s);
 603
 604         decode_slice(s);
 605
 606         s->error_status_table[s->resync_mb_x + s->resync_mb_y*s->mb_width]|= VP_START;
 607     }
 608
 609 //printf("h263_decode_frame 50\n");
 610
 611     if (s->h263_msmpeg4 && s->msmpeg4_version<4 && s->pict_type==I_TYPE)
 612         if(msmpeg4_decode_ext_header(s, buf_size) < 0){
 613             s->error_status_table[s->mb_num-1]= AC_ERROR|DC_ERROR|MV_ERROR;
 614         }
 615
 616     /* divx 5.01+ bistream reorder stuff */
 617     if(s->codec_id==CODEC_ID_MPEG4 && s->bitstream_buffer_size==0 && s->divx_version>=500){
 618         int current_pos= get_bits_count(&s->gb)>>3;
 619
 620         if(   buf_size - current_pos > 5
 621            && buf_size - current_pos < BITSTREAM_BUFFER_SIZE){
 622             int i;
 623             int startcode_found=0;
 624             for(i=current_pos; i<buf_size-3; i++){
 625                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
 626                     startcode_found=1;
 627                     break;
 628                 }
 629             }
 630             if(startcode_found){
 631                 memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
 632                 s->bitstream_buffer_size= buf_size - current_pos;
 633             }
 634         }
 635     }
 636
 637 //printf("h263_decode_frame 60\n");
 638
 639     if(s->error_resilience){
 640         int error=0, num_end_markers=0;
 641         for(i=0; i<s->mb_num; i++){
 642             int status= s->error_status_table[i];
 643 #if 0
 644             if(i%s->mb_width == 0) printf("\n");
 645             printf("%2X ", status);
 646 #endif
 647             if(status==0) continue;
 648
 649             if(status&(DC_ERROR|AC_ERROR|MV_ERROR))
 650                 error=1;
 651             if(status&VP_START){
 652                 if(num_end_markers)
 653                     error=1;
 654                 num_end_markers=3;
 655             }
 656             if(status&AC_END)
 657                 num_end_markers--;
 658             if(status&DC_END)
 659                 num_end_markers--;
 660             if(status&MV_END)
 661                 num_end_markers--;
 662         }
 663         if(num_end_markers || error){
 664             fprintf(stderr, "concealing errors\n");
 665 //printf("type:%d\n", s->pict_type);
 666             ff_error_resilience(s);
 667         }
 668     }
 669 //printf("h263_decode_frame 70\n");
 670
 671
 672     MPV_frame_end(s);
 673 #if 0 //dirty show MVs, we should export the MV tables and write a filter to show them
 674 {
 675   int mb_y;
 676   s->has_b_frames=1;
 677   for(mb_y=0; mb_y<s->mb_height; mb_y++){
 678     int mb_x;
 679     int y= mb_y*16 + 8;
 680     for(mb_x=0; mb_x<s->mb_width; mb_x++){
 681       int x= mb_x*16 + 8;
 682       uint8_t *ptr= s->last_picture.data[0];
 683       int xy= 1 + mb_x*2 + (mb_y*2 + 1)*(s->mb_width*2 + 2);
 684       int mx= (s->motion_val[xy][0]>>1) + x;
 685       int my= (s->motion_val[xy][1]>>1) + y;
 686       int i;
 687       int max;
 688
 689       if(mx<0) mx=0;
 690       if(my<0) my=0;
 691       if(mx>=s->width)  mx= s->width -1;
 692       if(my>=s->height) my= s->height-1;
 693       max= ABS(mx-x);
 694       if(ABS(my-y) > max) max= ABS(my-y);
 695       /* the ugliest linedrawing routine ... */
 696       for(i=0; i<max; i++){
 697         int x1= x + (mx-x)*i/max;
 698         int y1= y + (my-y)*i/max;
 699         ptr[y1*s->linesize + x1]+=100;
 700       }
 701       ptr[y*s->linesize + x]+=100;
 702       s->mbskip_table[mb_x + mb_y*s->mb_width]=0;
 703     }
 704   }
 705
 706 }
 707 #endif
 708
 709 //printf("h263_decode_frame 1\n");
 710     if(s->pict_type==B_TYPE || s->low_delay){
 711 //printf("h263_decode_frame 2\n");
 712         *pict= *(AVFrame*)&s->current_picture;
 713     } else {
 714 //printf("h263_decode_frame 3 %p\n", s->last_picture.data[0]);
 715         *pict= *(AVFrame*)&s->last_picture;
 716     }
 717
 718     if(avctx->debug&FF_DEBUG_QP){
 719         int8_t *qtab= pict->qscale_table;
 720         int x,y;
 721
 722         for(y=0; y<s->mb_height; y++){
 723             for(x=0; x<s->mb_width; x++){
 724                 printf("%2d ", qtab[x + y*s->mb_width]);
 725             }
 726             printf("\n");
 727         }
 728         printf("\n");
 729     }
 730 //printf("h263_decode_frame 80\n");
 731
 732
 733     /* Return the Picture timestamp as the frame number */
 734     /* we substract 1 because it is added on utils.c    */
 735     avctx->frame_number = s->picture_number - 1;
 736
 737     /* dont output the last pic after seeking */
 738     if(s->last_picture.data[0] || s->low_delay)
 739         *data_size = sizeof(AVFrame);
 740 #ifdef PRINT_FRAME_TIME
 741 printf("%Ld\n", rdtsc()-time);
 742 #endif
 743 //printf("h263_decode_frame 100\n");
 744     return get_consumed_bytes(s, buf_size);
 745 }
 746
 747 AVCodec mpeg4_decoder = {
 748     "mpeg4",
 749     CODEC_TYPE_VIDEO,
 750     CODEC_ID_MPEG4,
 751     sizeof(MpegEncContext),
 752     h263_decode_init,
 753     NULL,
 754     h263_decode_end,
 755     h263_decode_frame,
 756     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED,
 757 };
 758
 759 AVCodec h263_decoder = {
 760     "h263",
 761     CODEC_TYPE_VIDEO,
 762     CODEC_ID_H263,
 763     sizeof(MpegEncContext),
 764     h263_decode_init,
 765     NULL,
 766     h263_decode_end,
 767     h263_decode_frame,
 768     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
 769 };
 770
 771 AVCodec msmpeg4v1_decoder = {
 772     "msmpeg4v1",
 773     CODEC_TYPE_VIDEO,
 774     CODEC_ID_MSMPEG4V1,
 775     sizeof(MpegEncContext),
 776     h263_decode_init,
 777     NULL,
 778     h263_decode_end,
 779     h263_decode_frame,
 780     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
 781 };
 782
 783 AVCodec msmpeg4v2_decoder = {
 784     "msmpeg4v2",
 785     CODEC_TYPE_VIDEO,
 786     CODEC_ID_MSMPEG4V2,
 787     sizeof(MpegEncContext),
 788     h263_decode_init,
 789     NULL,
 790     h263_decode_end,
 791     h263_decode_frame,
 792     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
 793 };
 794
 795 AVCodec msmpeg4v3_decoder = {
 796     "msmpeg4",
 797     CODEC_TYPE_VIDEO,
 798     CODEC_ID_MSMPEG4V3,
 799     sizeof(MpegEncContext),
 800     h263_decode_init,
 801     NULL,
 802     h263_decode_end,
 803     h263_decode_frame,
 804     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
 805 };
 806
 807 AVCodec wmv1_decoder = {
 808     "wmv1",
 809     CODEC_TYPE_VIDEO,
 810     CODEC_ID_WMV1,
 811     sizeof(MpegEncContext),
 812     h263_decode_init,
 813     NULL,
 814     h263_decode_end,
 815     h263_decode_frame,
 816     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
 817 };
 818
 819 AVCodec wmv2_decoder = {
 820     "wmv2",
 821     CODEC_TYPE_VIDEO,
 822     CODEC_ID_WMV2,
 823     sizeof(MpegEncContext),
 824     h263_decode_init,
 825     NULL,
 826     h263_decode_end,
 827     h263_decode_frame,
 828     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
 829 };
 830
 831 AVCodec h263i_decoder = {
 832     "h263i",
 833     CODEC_TYPE_VIDEO,
 834     CODEC_ID_H263I,
 835     sizeof(MpegEncContext),
 836     h263_decode_init,
 837     NULL,
 838     h263_decode_end,
 839     h263_decode_frame,
 840     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,
 841 };
 842