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     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         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
 384     if(s->bitstream_buffer_size && (s->divx_packed || buf_size<20)){ //divx 5.01+/xvid frame reorder
 385         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
 386     }else
 387         init_get_bits(&s->gb, buf, buf_size*8);
 388     s->bitstream_buffer_size=0;
 389
 390     if (!s->context_initialized) {
 391         if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
 392             return -1;
 393     }
 394
 395     /* We need to set current_picture_ptr before reading the header,
 396      * otherwise we cannot store anyting in there */
 397     if (s->current_picture_ptr == NULL || s->current_picture_ptr->f.data[0]) {
 398         int i= ff_find_unused_picture(s, 0);
 399         s->current_picture_ptr= &s->picture[i];
 400     }
 401
 402     /* let's go :-) */
 403     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
 404         ret= ff_wmv2_decode_picture_header(s);
 405     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
 406         ret = msmpeg4_decode_picture_header(s);
 407     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
 408         if(s->avctx->extradata_size && s->picture_number==0){
 409             GetBitContext gb;
 410
 411             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
 412             ret = ff_mpeg4_decode_picture_header(s, &gb);
 413         }
 414         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
 415     } else if (CONFIG_H263I_DECODER && s->codec_id == CODEC_ID_H263I) {
 416         ret = ff_intel_h263_decode_picture_header(s);
 417     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
 418         ret = ff_flv_decode_picture_header(s);
 419     } else {
 420         ret = h263_decode_picture_header(s);
 421     }
 422
 423     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
 424
 425     /* skip if the header was thrashed */
 426     if (ret < 0){
 427         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
 428         return -1;
 429     }
 430
 431     avctx->has_b_frames= !s->low_delay;
 432
 433     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
 434         if(s->stream_codec_tag == AV_RL32("XVID") ||
 435            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
 436            s->codec_tag == AV_RL32("RMP4") ||
 437            s->codec_tag == AV_RL32("SIPP")
 438            )
 439             s->xvid_build= 0;
 440 #if 0
 441         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
 442            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
 443             s->xvid_build= 0;
 444 #endif
 445     }
 446
 447     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
 448         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
 449             s->divx_version= 400; //divx 4
 450     }
 451
 452     if(s->xvid_build>=0 && s->divx_version>=0){
 453         s->divx_version=
 454         s->divx_build= -1;
 455     }
 456
 457     if(s->workaround_bugs&FF_BUG_AUTODETECT){
 458         if(s->codec_tag == AV_RL32("XVIX"))
 459             s->workaround_bugs|= FF_BUG_XVID_ILACE;
 460
 461         if(s->codec_tag == AV_RL32("UMP4")){
 462             s->workaround_bugs|= FF_BUG_UMP4;
 463         }
 464
 465         if(s->divx_version>=500 && s->divx_build<1814){
 466             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 467         }
 468
 469         if(s->divx_version>502 && s->divx_build<1814){
 470             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
 471         }
 472
 473         if(s->xvid_build<=3U)
 474             s->padding_bug_score= 256*256*256*64;
 475
 476         if(s->xvid_build<=1U)
 477             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 478
 479         if(s->xvid_build<=12U)
 480             s->workaround_bugs|= FF_BUG_EDGE;
 481
 482         if(s->xvid_build<=32U)
 483             s->workaround_bugs|= FF_BUG_DC_CLIP;
 484
 485 #define SET_QPEL_FUNC(postfix1, postfix2) \
 486     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
 487     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
 488     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
 489
 490         if(s->lavc_build<4653U)
 491             s->workaround_bugs|= FF_BUG_STD_QPEL;
 492
 493         if(s->lavc_build<4655U)
 494             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
 495
 496         if(s->lavc_build<4670U){
 497             s->workaround_bugs|= FF_BUG_EDGE;
 498         }
 499
 500         if(s->lavc_build<=4712U)
 501             s->workaround_bugs|= FF_BUG_DC_CLIP;
 502
 503         if(s->divx_version>=0)
 504             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
 505 //printf("padding_bug_score: %d\n", s->padding_bug_score);
 506         if(s->divx_version==501 && s->divx_build==20020416)
 507             s->padding_bug_score= 256*256*256*64;
 508
 509         if(s->divx_version<500U){
 510             s->workaround_bugs|= FF_BUG_EDGE;
 511         }
 512
 513         if(s->divx_version>=0)
 514             s->workaround_bugs|= FF_BUG_HPEL_CHROMA;
 515 #if 0
 516         if(s->divx_version==500)
 517             s->padding_bug_score= 256*256*256*64;
 518
 519         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
 520          * Let us hope this at least works.
 521          */
 522         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==-1
 523            && s->codec_id==CODEC_ID_MPEG4 && s->vo_type==0)
 524             s->workaround_bugs|= FF_BUG_NO_PADDING;
 525
 526         if(s->lavc_build<4609U) //FIXME not sure about the version num but a 4609 file seems ok
 527             s->workaround_bugs|= FF_BUG_NO_PADDING;
 528 #endif
 529     }
 530
 531     if(s->workaround_bugs& FF_BUG_STD_QPEL){
 532         SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
 533         SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
 534         SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
 535         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
 536         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
 537         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
 538
 539         SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
 540         SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
 541         SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
 542         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
 543         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
 544         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
 545     }
 546
 547     if(avctx->debug & FF_DEBUG_BUGS)
 548         av_log(s->avctx, AV_LOG_DEBUG, "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
 549                s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
 550                s->divx_packed ? "p" : "");
 551
 552 #if HAVE_MMX
 553     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)) {
 554         avctx->idct_algo= FF_IDCT_XVIDMMX;
 555         avctx->coded_width= 0; // force reinit
 556 //        dsputil_init(&s->dsp, avctx);
 557         s->picture_number=0;
 558     }
 559 #endif
 560
 561         /* After H263 & mpeg4 header decode we have the height, width,*/
 562         /* and other parameters. So then we could init the picture   */
 563         /* FIXME: By the way H263 decoder is evolving it should have */
 564         /* an H263EncContext                                         */
 565
 566     if (   s->width  != avctx->coded_width
 567         || s->height != avctx->coded_height) {
 568         /* H.263 could change picture size any time */
 569         ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
 570         s->parse_context.buffer=0;
 571         MPV_common_end(s);
 572         s->parse_context= pc;
 573     }
 574     if (!s->context_initialized) {
 575         avcodec_set_dimensions(avctx, s->width, s->height);
 576
 577         goto retry;
 578     }
 579
 580     if((s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P || s->codec_id == CODEC_ID_H263I))
 581         s->gob_index = ff_h263_get_gob_height(s);
 582
 583     // for skipping the frame
 584     s->current_picture.f.pict_type = s->pict_type;
 585     s->current_picture.f.key_frame = s->pict_type == AV_PICTURE_TYPE_I;
 586
 587     /* skip B-frames if we don't have reference frames */
 588     if(s->last_picture_ptr==NULL && (s->pict_type==AV_PICTURE_TYPE_B || s->dropable)) return get_consumed_bytes(s, buf_size);
 589     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==AV_PICTURE_TYPE_B)
 590        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=AV_PICTURE_TYPE_I)
 591        ||  avctx->skip_frame >= AVDISCARD_ALL)
 592         return get_consumed_bytes(s, buf_size);
 593
 594     if(s->next_p_frame_damaged){
 595         if(s->pict_type==AV_PICTURE_TYPE_B)
 596             return get_consumed_bytes(s, buf_size);
 597         else
 598             s->next_p_frame_damaged=0;
 599     }
 600
 601     if((s->avctx->flags2 & CODEC_FLAG2_FAST) && s->pict_type==AV_PICTURE_TYPE_B){
 602         s->me.qpel_put= s->dsp.put_2tap_qpel_pixels_tab;
 603         s->me.qpel_avg= s->dsp.avg_2tap_qpel_pixels_tab;
 604     }else if((!s->no_rounding) || s->pict_type==AV_PICTURE_TYPE_B){
 605         s->me.qpel_put= s->dsp.put_qpel_pixels_tab;
 606         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
 607     }else{
 608         s->me.qpel_put= s->dsp.put_no_rnd_qpel_pixels_tab;
 609         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
 610     }
 611
 612     if(MPV_frame_start(s, avctx) < 0)
 613         return -1;
 614
 615     if (!s->divx_packed) ff_thread_finish_setup(avctx);
 616
 617     if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
 618         ff_vdpau_mpeg4_decode_picture(s, s->gb.buffer, s->gb.buffer_end - s->gb.buffer);
 619         goto frame_end;
 620     }
 621
 622     if (avctx->hwaccel) {
 623         if (avctx->hwaccel->start_frame(avctx, s->gb.buffer, s->gb.buffer_end - s->gb.buffer) < 0)
 624             return -1;
 625     }
 626
 627     ff_er_frame_start(s);
 628
 629     //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
 630     //which is not available before MPV_frame_start()
 631     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5){
 632         ret = ff_wmv2_decode_secondary_picture_header(s);
 633         if(ret<0) return ret;
 634         if(ret==1) goto intrax8_decoded;
 635     }
 636
 637     /* decode each macroblock */
 638     s->mb_x=0;
 639     s->mb_y=0;
 640
 641     ret = decode_slice(s);
 642     while(s->mb_y<s->mb_height){
 643         if(s->msmpeg4_version){
 644             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)
 645                 break;
 646         }else{
 647             int prev_x=s->mb_x, prev_y=s->mb_y;
 648             if(ff_h263_resync(s)<0)
 649                 break;
 650             if (prev_y * s->mb_width + prev_x < s->mb_y * s->mb_width + s->mb_x)
 651                 s->error_occurred = 1;
 652         }
 653
 654         if(s->msmpeg4_version<4 && s->h263_pred)
 655             ff_mpeg4_clean_buffers(s);
 656
 657         if (decode_slice(s) < 0) ret = AVERROR_INVALIDDATA;
 658     }
 659
 660     if (s->msmpeg4_version && s->msmpeg4_version<4 && s->pict_type==AV_PICTURE_TYPE_I)
 661         if(!CONFIG_MSMPEG4_DECODER || msmpeg4_decode_ext_header(s, buf_size) < 0){
 662             s->error_status_table[s->mb_num-1]= AC_ERROR|DC_ERROR|MV_ERROR;
 663         }
 664
 665     assert(s->bitstream_buffer_size==0);
 666 frame_end:
 667     /* divx 5.01+ bistream reorder stuff */
 668     if(s->codec_id==CODEC_ID_MPEG4 && s->divx_packed){
 669         int current_pos= get_bits_count(&s->gb)>>3;
 670         int startcode_found=0;
 671
 672         if(buf_size - current_pos > 5){
 673             int i;
 674             for(i=current_pos; i<buf_size-3; i++){
 675                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
 676                     startcode_found=1;
 677                     break;
 678                 }
 679             }
 680         }
 681         if(s->gb.buffer == s->bitstream_buffer && buf_size>7 && s->xvid_build>=0){ //xvid style
 682             startcode_found=1;
 683             current_pos=0;
 684         }
 685
 686         if(startcode_found){
 687             av_fast_malloc(
 688                 &s->bitstream_buffer,
 689                 &s->allocated_bitstream_buffer_size,
 690                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
 691             if (!s->bitstream_buffer)
 692                 return AVERROR(ENOMEM);
 693             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
 694             s->bitstream_buffer_size= buf_size - current_pos;
 695         }
 696     }
 697
 698 intrax8_decoded:
 699     ff_er_frame_end(s);
 700
 701     if (avctx->hwaccel) {
 702         if (avctx->hwaccel->end_frame(avctx) < 0)
 703             return -1;
 704     }
 705
 706     MPV_frame_end(s);
 707
 708 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
 709 assert(s->current_picture.pict_type == s->pict_type);
 710     if (s->pict_type == AV_PICTURE_TYPE_B || s->low_delay) {
 711         *pict= *(AVFrame*)s->current_picture_ptr;
 712     } else if (s->last_picture_ptr != NULL) {
 713         *pict= *(AVFrame*)s->last_picture_ptr;
 714     }
 715
 716     if(s->last_picture_ptr || s->low_delay){
 717         *data_size = sizeof(AVFrame);
 718         ff_print_debug_info(s, pict);
 719     }
 720
 721 #ifdef PRINT_FRAME_TIME
 722 av_log(avctx, AV_LOG_DEBUG, "%"PRId64"\n", rdtsc()-time);
 723 #endif
 724
 725     return (ret && avctx->error_recognition >= FF_ER_EXPLODE)?ret:get_consumed_bytes(s, buf_size);
 726 }
 727
 728 AVCodec ff_h263_decoder = {
 729     .name           = "h263",
 730     .type           = AVMEDIA_TYPE_VIDEO,
 731     .id             = CODEC_ID_H263,
 732     .priv_data_size = sizeof(MpegEncContext),
 733     .init           = ff_h263_decode_init,
 734     .close          = ff_h263_decode_end,
 735     .decode         = ff_h263_decode_frame,
 736     .capabilities   = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
 737     .flush= ff_mpeg_flush,
 738     .max_lowres= 3,
 739     .long_name= NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
 740     .pix_fmts= ff_hwaccel_pixfmt_list_420,
 741 };