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   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 "flv.h"
  39 #include "mpeg4video.h"
  40
  41 //#define DEBUG
  42 //#define PRINT_FRAME_TIME
  43
  44 av_cold int ff_h263_decode_init(AVCodecContext *avctx)
  45 {
  46     MpegEncContext *s = avctx->priv_data;
  47
  48     s->avctx = avctx;
  49     s->out_format = FMT_H263;
  50
  51     s->width  = avctx->coded_width;
  52     s->height = avctx->coded_height;
  53     s->workaround_bugs= avctx->workaround_bugs;
  54
  55     // set defaults
  56     MPV_decode_defaults(s);
  57     s->quant_precision=5;
  58     s->decode_mb= ff_h263_decode_mb;
  59     s->low_delay= 1;
  60     avctx->pix_fmt= avctx->get_format(avctx, avctx->codec->pix_fmts);
  61     s->unrestricted_mv= 1;
  62
  63     /* select sub codec */
  64     switch(avctx->codec->id) {
  65     case CODEC_ID_H263:
  66         s->unrestricted_mv= 0;
  67         avctx->chroma_sample_location = AVCHROMA_LOC_CENTER;
  68         break;
  69     case CODEC_ID_MPEG4:
  70         break;
  71     case CODEC_ID_MSMPEG4V1:
  72         s->h263_pred = 1;
  73         s->msmpeg4_version=1;
  74         break;
  75     case CODEC_ID_MSMPEG4V2:
  76         s->h263_pred = 1;
  77         s->msmpeg4_version=2;
  78         break;
  79     case CODEC_ID_MSMPEG4V3:
  80         s->h263_pred = 1;
  81         s->msmpeg4_version=3;
  82         break;
  83     case CODEC_ID_WMV1:
  84         s->h263_pred = 1;
  85         s->msmpeg4_version=4;
  86         break;
  87     case CODEC_ID_WMV2:
  88         s->h263_pred = 1;
  89         s->msmpeg4_version=5;
  90         break;
  91     case CODEC_ID_VC1:
  92     case CODEC_ID_WMV3:
  93         s->h263_pred = 1;
  94         s->msmpeg4_version=6;
  95         avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
  96         break;
  97     case CODEC_ID_H263I:
  98         break;
  99     case CODEC_ID_FLV1:
 100         s->h263_flv = 1;
 101         break;
 102     default:
 103         return -1;
 104     }
 105     s->codec_id= avctx->codec->id;
 106     avctx->hwaccel= ff_find_hwaccel(avctx->codec->id, avctx->pix_fmt);
 107
 108     /* for h263, we allocate the images after having read the header */
 109     if (avctx->codec->id != CODEC_ID_H263 && avctx->codec->id != CODEC_ID_MPEG4)
 110         if (MPV_common_init(s) < 0)
 111             return -1;
 112
 113         h263_decode_init_vlc(s);
 114
 115     return 0;
 116 }
 117
 118 av_cold int ff_h263_decode_end(AVCodecContext *avctx)
 119 {
 120     MpegEncContext *s = avctx->priv_data;
 121
 122     MPV_common_end(s);
 123     return 0;
 124 }
 125
 126 /**
 127  * returns the number of bytes consumed for building the current frame
 128  */
 129 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
 130     int pos= (get_bits_count(&s->gb)+7)>>3;
 131
 132     if(s->divx_packed || s->avctx->hwaccel){
 133         //we would have to scan through the whole buf to handle the weird reordering ...
 134         return buf_size;
 135     }else if(s->flags&CODEC_FLAG_TRUNCATED){
 136         pos -= s->parse_context.last_index;
 137         if(pos<0) pos=0; // padding is not really read so this might be -1
 138         return pos;
 139     }else{
 140         if(pos==0) pos=1; //avoid infinite loops (i doubt that is needed but ...)
 141         if(pos+10>buf_size) pos=buf_size; // oops ;)
 142
 143         return pos;
 144     }
 145 }
 146
 147 static int decode_slice(MpegEncContext *s){
 148     const int part_mask= s->partitioned_frame ? (AC_END|AC_ERROR) : 0x7F;
 149     const int mb_size= 16>>s->avctx->lowres;
 150     s->last_resync_gb= s->gb;
 151     s->first_slice_line= 1;
 152
 153     s->resync_mb_x= s->mb_x;
 154     s->resync_mb_y= s->mb_y;
 155
 156     ff_set_qscale(s, s->qscale);
 157
 158     if (s->avctx->hwaccel) {
 159         const uint8_t *start= s->gb.buffer + get_bits_count(&s->gb)/8;
 160         const uint8_t *end  = ff_h263_find_resync_marker(start + 1, s->gb.buffer_end);
 161         skip_bits_long(&s->gb, 8*(end - start));
 162         return s->avctx->hwaccel->decode_slice(s->avctx, start, end - start);
 163     }
 164
 165     if(s->partitioned_frame){
 166         const int qscale= s->qscale;
 167
 168         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
 169             if(ff_mpeg4_decode_partitions(s) < 0)
 170                 return -1;
 171         }
 172
 173         /* restore variables which were modified */
 174         s->first_slice_line=1;
 175         s->mb_x= s->resync_mb_x;
 176         s->mb_y= s->resync_mb_y;
 177         ff_set_qscale(s, qscale);
 178     }
 179
 180     for(; s->mb_y < s->mb_height; s->mb_y++) {
 181         /* per-row end of slice checks */
 182         if(s->msmpeg4_version){
 183             if(s->resync_mb_y + s->slice_height == s->mb_y){
 184                 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);
 185
 186                 return 0;
 187             }
 188         }
 189
 190         if(s->msmpeg4_version==1){
 191             s->last_dc[0]=
 192             s->last_dc[1]=
 193             s->last_dc[2]= 128;
 194         }
 195
 196         ff_init_block_index(s);
 197         for(; s->mb_x < s->mb_width; s->mb_x++) {
 198             int ret;
 199
 200             ff_update_block_index(s);
 201
 202             if(s->resync_mb_x == s->mb_x && s->resync_mb_y+1 == s->mb_y){
 203                 s->first_slice_line=0;
 204             }
 205
 206             /* DCT & quantize */
 207
 208             s->mv_dir = MV_DIR_FORWARD;
 209             s->mv_type = MV_TYPE_16X16;
 210 //            s->mb_skipped = 0;
 211 //printf("%d %d %06X\n", ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
 212             ret= s->decode_mb(s, s->block);
 213
 214             if (s->pict_type!=AV_PICTURE_TYPE_B)
 215                 ff_h263_update_motion_val(s);
 216
 217             if(ret<0){
 218                 const int xy= s->mb_x + s->mb_y*s->mb_stride;
 219                 if(ret==SLICE_END){
 220                     MPV_decode_mb(s, s->block);
 221                     if(s->loop_filter)
 222                         ff_h263_loop_filter(s);
 223
 224 //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));
 225                     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);
 226
 227                     s->padding_bug_score--;
 228
 229                     if(++s->mb_x >= s->mb_width){
 230                         s->mb_x=0;
 231                         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
 232                         s->mb_y++;
 233                     }
 234                     return 0;
 235                 }else if(ret==SLICE_NOEND){
 236                     av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
 237                     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);
 238                     return -1;
 239                 }
 240                 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
 241                 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);
 242
 243                 return -1;
 244             }
 245
 246             MPV_decode_mb(s, s->block);
 247             if(s->loop_filter)
 248                 ff_h263_loop_filter(s);
 249         }
 250
 251         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
 252
 253         s->mb_x= 0;
 254     }
 255
 256     assert(s->mb_x==0 && s->mb_y==s->mb_height);
 257
 258     if(s->codec_id==CODEC_ID_MPEG4
 259        && (s->workaround_bugs&FF_BUG_AUTODETECT)
 260        && get_bits_left(&s->gb) >= 48
 261        && show_bits(&s->gb, 24)==0x4010
 262        && !s->data_partitioning)
 263         s->padding_bug_score+=32;
 264
 265     /* try to detect the padding bug */
 266     if(      s->codec_id==CODEC_ID_MPEG4
 267        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
 268        &&    get_bits_left(&s->gb) >=0
 269        &&    get_bits_left(&s->gb) < 48
 270 //       &&   !s->resync_marker
 271        &&   !s->data_partitioning){
 272
 273         const int bits_count= get_bits_count(&s->gb);
 274         const int bits_left = s->gb.size_in_bits - bits_count;
 275
 276         if(bits_left==0){
 277             s->padding_bug_score+=16;
 278         } else if(bits_left != 1){
 279             int v= show_bits(&s->gb, 8);
 280             v|= 0x7F >> (7-(bits_count&7));
 281
 282             if(v==0x7F && bits_left<=8)
 283                 s->padding_bug_score--;
 284             else if(v==0x7F && ((get_bits_count(&s->gb)+8)&8) && bits_left<=16)
 285                 s->padding_bug_score+= 4;
 286             else
 287                 s->padding_bug_score++;
 288         }
 289     }
 290
 291     if(s->workaround_bugs&FF_BUG_AUTODETECT){
 292         if(s->padding_bug_score > -2 && !s->data_partitioning /*&& (s->divx_version>=0 || !s->resync_marker)*/)
 293             s->workaround_bugs |=  FF_BUG_NO_PADDING;
 294         else
 295             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
 296     }
 297
 298     // handle formats which don't have unique end markers
 299     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
 300         int left= get_bits_left(&s->gb);
 301         int max_extra=7;
 302
 303         /* no markers in M$ crap */
 304         if(s->msmpeg4_version && s->pict_type==AV_PICTURE_TYPE_I)
 305             max_extra+= 17;
 306
 307         /* buggy padding but the frame should still end approximately at the bitstream end */
 308         if((s->workaround_bugs&FF_BUG_NO_PADDING) && s->error_recognition>=3)
 309             max_extra+= 48;
 310         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
 311             max_extra+= 256*256*256*64;
 312
 313         if(left>max_extra){
 314             av_log(s->avctx, AV_LOG_ERROR, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
 315         }
 316         else if(left<0){
 317             av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
 318         }else
 319             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);
 320
 321         return 0;
 322     }
 323
 324     av_log(s->avctx, AV_LOG_ERROR, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
 325             get_bits_left(&s->gb),
 326             show_bits(&s->gb, 24), s->padding_bug_score);
 327
 328     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);
 329
 330     return -1;
 331 }
 332
 333 int ff_h263_decode_frame(AVCodecContext *avctx,
 334                              void *data, int *data_size,
 335                              AVPacket *avpkt)
 336 {
 337     const uint8_t *buf = avpkt->data;
 338     int buf_size = avpkt->size;
 339     MpegEncContext *s = avctx->priv_data;
 340     int ret;
 341     AVFrame *pict = data;
 342
 343 #ifdef PRINT_FRAME_TIME
 344 uint64_t time= rdtsc();
 345 #endif
 346     s->flags= avctx->flags;
 347     s->flags2= avctx->flags2;
 348
 349     /* no supplementary picture */
 350     if (buf_size == 0) {
 351         /* special case for last picture */
 352         if (s->low_delay==0 && s->next_picture_ptr) {
 353             *pict= *(AVFrame*)s->next_picture_ptr;
 354             s->next_picture_ptr= NULL;
 355
 356             *data_size = sizeof(AVFrame);
 357         }
 358
 359         return 0;
 360     }
 361
 362     if(s->flags&CODEC_FLAG_TRUNCATED){
 363         int next;
 364
 365         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
 366             next= ff_mpeg4_find_frame_end(&s->parse_context, buf, buf_size);
 367         }else if(CONFIG_H263_DECODER && s->codec_id==CODEC_ID_H263){
 368             next= ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
 369         }else{
 370             av_log(s->avctx, AV_LOG_ERROR, "this codec does not support truncated bitstreams\n");
 371             return -1;
 372         }
 373
 374         if( ff_combine_frame(&s->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
 375             return buf_size;
 376     }
 377
 378
 379 retry:
 380
 381     if(s->bitstream_buffer_size && (s->divx_packed || buf_size<20)){ //divx 5.01+/xvid frame reorder
 382         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
 383     }else
 384         init_get_bits(&s->gb, buf, buf_size*8);
 385     s->bitstream_buffer_size=0;
 386
 387     if (!s->context_initialized) {
 388         if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
 389             return -1;
 390     }
 391
 392     /* We need to set current_picture_ptr before reading the header,
 393      * otherwise we cannot store anyting in there */
 394     if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
 395         int i= ff_find_unused_picture(s, 0);
 396         s->current_picture_ptr= &s->picture[i];
 397     }
 398
 399     /* let's go :-) */
 400     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
 401         ret= ff_wmv2_decode_picture_header(s);
 402     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
 403         ret = msmpeg4_decode_picture_header(s);
 404     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
 405         if(s->avctx->extradata_size && s->picture_number==0){
 406             GetBitContext gb;
 407
 408             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
 409             ret = ff_mpeg4_decode_picture_header(s, &gb);
 410         }
 411         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
 412     } else if (CONFIG_H263I_DECODER && s->codec_id == CODEC_ID_H263I) {
 413         ret = ff_intel_h263_decode_picture_header(s);
 414     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
 415         ret = ff_flv_decode_picture_header(s);
 416     } else {
 417         ret = h263_decode_picture_header(s);
 418     }
 419
 420     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
 421
 422     /* skip if the header was thrashed */
 423     if (ret < 0){
 424         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
 425         return -1;
 426     }
 427
 428     avctx->has_b_frames= !s->low_delay;
 429
 430     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
 431         if(s->stream_codec_tag == AV_RL32("XVID") ||
 432            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
 433            s->codec_tag == AV_RL32("RMP4") ||
 434            s->codec_tag == AV_RL32("SIPP")
 435            )
 436             s->xvid_build= 0;
 437 #if 0
 438         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
 439            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
 440             s->xvid_build= 0;
 441 #endif
 442     }
 443
 444     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
 445         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
 446             s->divx_version= 400; //divx 4
 447     }
 448
 449     if(s->xvid_build>=0 && s->divx_version>=0){
 450         s->divx_version=
 451         s->divx_build= -1;
 452     }
 453
 454     if(s->workaround_bugs&FF_BUG_AUTODETECT){
 455         if(s->codec_tag == AV_RL32("XVIX"))
 456             s->workaround_bugs|= FF_BUG_XVID_ILACE;
 457
 458         if(s->codec_tag == AV_RL32("UMP4")){
 459             s->workaround_bugs|= FF_BUG_UMP4;
 460         }
 461
 462         if(s->divx_version>=500 && s->divx_build<1814){
 463             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 464         }
 465
 466         if(s->divx_version>502 && s->divx_build<1814){
 467             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
 468         }
 469
 470         if(s->xvid_build<=3U)
 471             s->padding_bug_score= 256*256*256*64;
 472
 473         if(s->xvid_build<=1U)
 474             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 475
 476         if(s->xvid_build<=12U)
 477             s->workaround_bugs|= FF_BUG_EDGE;
 478
 479         if(s->xvid_build<=32U)
 480             s->workaround_bugs|= FF_BUG_DC_CLIP;
 481
 482 #define SET_QPEL_FUNC(postfix1, postfix2) \
 483     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
 484     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
 485     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
 486
 487         if(s->lavc_build<4653U)
 488             s->workaround_bugs|= FF_BUG_STD_QPEL;
 489
 490         if(s->lavc_build<4655U)
 491             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
 492
 493         if(s->lavc_build<4670U){
 494             s->workaround_bugs|= FF_BUG_EDGE;
 495         }
 496
 497         if(s->lavc_build<=4712U)
 498             s->workaround_bugs|= FF_BUG_DC_CLIP;
 499
 500         if(s->divx_version>=0)
 501             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
 502 //printf("padding_bug_score: %d\n", s->padding_bug_score);
 503         if(s->divx_version==501 && s->divx_build==20020416)
 504             s->padding_bug_score= 256*256*256*64;
 505
 506         if(s->divx_version<500U){
 507             s->workaround_bugs|= FF_BUG_EDGE;
 508         }
 509
 510         if(s->divx_version>=0)
 511             s->workaround_bugs|= FF_BUG_HPEL_CHROMA;
 512 #if 0
 513         if(s->divx_version==500)
 514             s->padding_bug_score= 256*256*256*64;
 515
 516         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
 517          * Let us hope this at least works.
 518          */
 519         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==-1
 520            && s->codec_id==CODEC_ID_MPEG4 && s->vo_type==0)
 521             s->workaround_bugs|= FF_BUG_NO_PADDING;
 522
 523         if(s->lavc_build<4609U) //FIXME not sure about the version num but a 4609 file seems ok
 524             s->workaround_bugs|= FF_BUG_NO_PADDING;
 525 #endif
 526     }
 527
 528     if(s->workaround_bugs& FF_BUG_STD_QPEL){
 529         SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
 530         SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
 531         SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
 532         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
 533         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
 534         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
 535
 536         SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
 537         SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
 538         SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
 539         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
 540         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
 541         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
 542     }
 543
 544     if(avctx->debug & FF_DEBUG_BUGS)
 545         av_log(s->avctx, AV_LOG_DEBUG, "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
 546                s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
 547                s->divx_packed ? "p" : "");
 548
 549 #if HAVE_MMX
 550     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)) {
 551         avctx->idct_algo= FF_IDCT_XVIDMMX;
 552         avctx->coded_width= 0; // force reinit
 553 //        dsputil_init(&s->dsp, avctx);
 554         s->picture_number=0;
 555     }
 556 #endif
 557
 558         /* After H263 & mpeg4 header decode we have the height, width,*/
 559         /* and other parameters. So then we could init the picture   */
 560         /* FIXME: By the way H263 decoder is evolving it should have */
 561         /* an H263EncContext                                         */
 562
 563     if (   s->width  != avctx->coded_width
 564         || s->height != avctx->coded_height) {
 565         /* H.263 could change picture size any time */
 566         ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
 567         s->parse_context.buffer=0;
 568         MPV_common_end(s);
 569         s->parse_context= pc;
 570     }
 571     if (!s->context_initialized) {
 572         avcodec_set_dimensions(avctx, s->width, s->height);
 573
 574         goto retry;
 575     }
 576
 577     if((s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P || s->codec_id == CODEC_ID_H263I))
 578         s->gob_index = ff_h263_get_gob_height(s);
 579
 580     // for skipping the frame
 581     s->current_picture.pict_type= s->pict_type;
 582     s->current_picture.key_frame= s->pict_type == AV_PICTURE_TYPE_I;
 583
 584     /* skip B-frames if we don't have reference frames */
 585     if(s->last_picture_ptr==NULL && (s->pict_type==AV_PICTURE_TYPE_B || s->dropable)) return get_consumed_bytes(s, buf_size);
 586     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==AV_PICTURE_TYPE_B)
 587        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=AV_PICTURE_TYPE_I)
 588        ||  avctx->skip_frame >= AVDISCARD_ALL)
 589         return get_consumed_bytes(s, buf_size);
 590
 591     if(s->next_p_frame_damaged){
 592         if(s->pict_type==AV_PICTURE_TYPE_B)
 593             return get_consumed_bytes(s, buf_size);
 594         else
 595             s->next_p_frame_damaged=0;
 596     }
 597
 598     if((s->avctx->flags2 & CODEC_FLAG2_FAST) && s->pict_type==AV_PICTURE_TYPE_B){
 599         s->me.qpel_put= s->dsp.put_2tap_qpel_pixels_tab;
 600         s->me.qpel_avg= s->dsp.avg_2tap_qpel_pixels_tab;
 601     }else if((!s->no_rounding) || s->pict_type==AV_PICTURE_TYPE_B){
 602         s->me.qpel_put= s->dsp.put_qpel_pixels_tab;
 603         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
 604     }else{
 605         s->me.qpel_put= s->dsp.put_no_rnd_qpel_pixels_tab;
 606         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
 607     }
 608
 609     if(MPV_frame_start(s, avctx) < 0)
 610         return -1;
 611
 612     if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
 613         ff_vdpau_mpeg4_decode_picture(s, s->gb.buffer, s->gb.buffer_end - s->gb.buffer);
 614         goto frame_end;
 615     }
 616
 617     if (avctx->hwaccel) {
 618         if (avctx->hwaccel->start_frame(avctx, s->gb.buffer, s->gb.buffer_end - s->gb.buffer) < 0)
 619             return -1;
 620     }
 621
 622     ff_er_frame_start(s);
 623
 624     //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
 625     //which is not available before MPV_frame_start()
 626     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5){
 627         ret = ff_wmv2_decode_secondary_picture_header(s);
 628         if(ret<0) return ret;
 629         if(ret==1) goto intrax8_decoded;
 630     }
 631
 632     /* decode each macroblock */
 633     s->mb_x=0;
 634     s->mb_y=0;
 635
 636     decode_slice(s);
 637     while(s->mb_y<s->mb_height){
 638         if(s->msmpeg4_version){
 639             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)
 640                 break;
 641         }else{
 642             if(ff_h263_resync(s)<0)
 643                 break;
 644         }
 645
 646         if(s->msmpeg4_version<4 && s->h263_pred)
 647             ff_mpeg4_clean_buffers(s);
 648
 649         decode_slice(s);
 650     }
 651
 652     if (s->msmpeg4_version && s->msmpeg4_version<4 && s->pict_type==AV_PICTURE_TYPE_I)
 653         if(!CONFIG_MSMPEG4_DECODER || msmpeg4_decode_ext_header(s, buf_size) < 0){
 654             s->error_status_table[s->mb_num-1]= AC_ERROR|DC_ERROR|MV_ERROR;
 655         }
 656
 657     assert(s->bitstream_buffer_size==0);
 658 frame_end:
 659     /* divx 5.01+ bistream reorder stuff */
 660     if(s->codec_id==CODEC_ID_MPEG4 && s->divx_packed){
 661         int current_pos= get_bits_count(&s->gb)>>3;
 662         int startcode_found=0;
 663
 664         if(buf_size - current_pos > 5){
 665             int i;
 666             for(i=current_pos; i<buf_size-3; i++){
 667                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
 668                     startcode_found=1;
 669                     break;
 670                 }
 671             }
 672         }
 673         if(s->gb.buffer == s->bitstream_buffer && buf_size>7 && s->xvid_build>=0){ //xvid style
 674             startcode_found=1;
 675             current_pos=0;
 676         }
 677
 678         if(startcode_found){
 679             av_fast_malloc(
 680                 &s->bitstream_buffer,
 681                 &s->allocated_bitstream_buffer_size,
 682                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
 683             if (!s->bitstream_buffer)
 684                 return AVERROR(ENOMEM);
 685             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
 686             s->bitstream_buffer_size= buf_size - current_pos;
 687         }
 688     }
 689
 690 intrax8_decoded:
 691     ff_er_frame_end(s);
 692
 693     if (avctx->hwaccel) {
 694         if (avctx->hwaccel->end_frame(avctx) < 0)
 695             return -1;
 696     }
 697
 698     MPV_frame_end(s);
 699
 700 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
 701 assert(s->current_picture.pict_type == s->pict_type);
 702     if (s->pict_type == AV_PICTURE_TYPE_B || s->low_delay) {
 703         *pict= *(AVFrame*)s->current_picture_ptr;
 704     } else if (s->last_picture_ptr != NULL) {
 705         *pict= *(AVFrame*)s->last_picture_ptr;
 706     }
 707
 708     if(s->last_picture_ptr || s->low_delay){
 709         *data_size = sizeof(AVFrame);
 710         ff_print_debug_info(s, pict);
 711     }
 712
 713 #ifdef PRINT_FRAME_TIME
 714 av_log(avctx, AV_LOG_DEBUG, "%"PRId64"\n", rdtsc()-time);
 715 #endif
 716
 717     return get_consumed_bytes(s, buf_size);
 718 }
 719
 720 AVCodec ff_h263_decoder = {
 721     "h263",
 722     AVMEDIA_TYPE_VIDEO,
 723     CODEC_ID_H263,
 724     sizeof(MpegEncContext),
 725     ff_h263_decode_init,
 726     NULL,
 727     ff_h263_decode_end,
 728     ff_h263_decode_frame,
 729     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
 730     .flush= ff_mpeg_flush,
 731     .max_lowres= 3,
 732     .long_name= NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
 733     .pix_fmts= ff_hwaccel_pixfmt_list_420,
 734 };