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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 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 #include "internal.h"
  29 #include "avcodec.h"
  30 #include "dsputil.h"
  31 #include "mpegvideo.h"
  32 #include "h263.h"
  33 #include "h263_parser.h"
  34 #include "mpeg4video_parser.h"
  35 #include "msmpeg4.h"
  36 #include "vdpau_internal.h"
  37 #include "flv.h"
  38 #include "mpeg4video.h"
  39
  40 //#define DEBUG
  41 //#define PRINT_FRAME_TIME
  42
  43 av_cold int ff_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->coded_width;
  51     s->height = avctx->coded_height;
  52     s->workaround_bugs= avctx->workaround_bugs;
  53
  54     // set defaults
  55     MPV_decode_defaults(s);
  56     s->quant_precision=5;
  57     s->decode_mb= ff_h263_decode_mb;
  58     s->low_delay= 1;
  59     avctx->pix_fmt= avctx->get_format(avctx, avctx->codec->pix_fmts);
  60     s->unrestricted_mv= 1;
  61
  62     /* select sub codec */
  63     switch(avctx->codec->id) {
  64     case CODEC_ID_H263:
  65         s->unrestricted_mv= 0;
  66         avctx->chroma_sample_location = AVCHROMA_LOC_CENTER;
  67         break;
  68     case CODEC_ID_MPEG4:
  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_VC1:
  96     case CODEC_ID_WMV3:
  97         s->h263_msmpeg4 = 1;
  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 (MPV_common_init(s) < 0)
 116             return -1;
 117
 118         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     MPV_common_end(s);
 128     return 0;
 129 }
 130
 131 /**
 132  * returns 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 ? (AC_END|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, AC_END|DC_END|MV_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!=FF_B_TYPE)
 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                     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, (AC_END|DC_END|MV_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                         s->mb_y++;
 238                     }
 239                     return 0;
 240                 }else if(ret==SLICE_NOEND){
 241                     av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
 242                     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);
 243                     return -1;
 244                 }
 245                 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
 246                 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);
 247
 248                 return -1;
 249             }
 250
 251             MPV_decode_mb(s, s->block);
 252             if(s->loop_filter)
 253                 ff_h263_loop_filter(s);
 254         }
 255
 256         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
 257
 258         s->mb_x= 0;
 259     }
 260
 261     assert(s->mb_x==0 && s->mb_y==s->mb_height);
 262
 263     /* try to detect the padding bug */
 264     if(      s->codec_id==CODEC_ID_MPEG4
 265        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
 266        &&    get_bits_left(&s->gb) >=0
 267        &&    get_bits_left(&s->gb) < 48
 268 //       &&   !s->resync_marker
 269        &&   !s->data_partitioning){
 270
 271         const int bits_count= get_bits_count(&s->gb);
 272         const int bits_left = s->gb.size_in_bits - bits_count;
 273
 274         if(bits_left==0){
 275             s->padding_bug_score+=16;
 276         } else if(bits_left != 1){
 277             int v= show_bits(&s->gb, 8);
 278             v|= 0x7F >> (7-(bits_count&7));
 279
 280             if(v==0x7F && bits_left<=8)
 281                 s->padding_bug_score--;
 282             else if(v==0x7F && ((get_bits_count(&s->gb)+8)&8) && bits_left<=16)
 283                 s->padding_bug_score+= 4;
 284             else
 285                 s->padding_bug_score++;
 286         }
 287     }
 288
 289     if(s->workaround_bugs&FF_BUG_AUTODETECT){
 290         if(s->padding_bug_score > -2 && !s->data_partitioning /*&& (s->divx_version>=0 || !s->resync_marker)*/)
 291             s->workaround_bugs |=  FF_BUG_NO_PADDING;
 292         else
 293             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
 294     }
 295
 296     // handle formats which don't have unique end markers
 297     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
 298         int left= get_bits_left(&s->gb);
 299         int max_extra=7;
 300
 301         /* no markers in M$ crap */
 302         if(s->msmpeg4_version && s->pict_type==FF_I_TYPE)
 303             max_extra+= 17;
 304
 305         /* buggy padding but the frame should still end approximately at the bitstream end */
 306         if((s->workaround_bugs&FF_BUG_NO_PADDING) && s->error_recognition>=3)
 307             max_extra+= 48;
 308         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
 309             max_extra+= 256*256*256*64;
 310
 311         if(left>max_extra){
 312             av_log(s->avctx, AV_LOG_ERROR, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
 313         }
 314         else if(left<0){
 315             av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
 316         }else
 317             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);
 318
 319         return 0;
 320     }
 321
 322     av_log(s->avctx, AV_LOG_ERROR, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
 323             get_bits_left(&s->gb),
 324             show_bits(&s->gb, 24), s->padding_bug_score);
 325
 326     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);
 327
 328     return -1;
 329 }
 330
 331 int ff_h263_decode_frame(AVCodecContext *avctx,
 332                              void *data, int *data_size,
 333                              AVPacket *avpkt)
 334 {
 335     const uint8_t *buf = avpkt->data;
 336     int buf_size = avpkt->size;
 337     MpegEncContext *s = avctx->priv_data;
 338     int ret;
 339     AVFrame *pict = data;
 340
 341 #ifdef PRINT_FRAME_TIME
 342 uint64_t time= rdtsc();
 343 #endif
 344     s->flags= avctx->flags;
 345     s->flags2= avctx->flags2;
 346
 347     /* no supplementary picture */
 348     if (buf_size == 0) {
 349         /* special case for last picture */
 350         if (s->low_delay==0 && s->next_picture_ptr) {
 351             *pict= *(AVFrame*)s->next_picture_ptr;
 352             s->next_picture_ptr= NULL;
 353
 354             *data_size = sizeof(AVFrame);
 355         }
 356
 357         return 0;
 358     }
 359
 360     if(s->flags&CODEC_FLAG_TRUNCATED){
 361         int next;
 362
 363         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
 364             next= ff_mpeg4_find_frame_end(&s->parse_context, buf, buf_size);
 365         }else if(CONFIG_H263_DECODER && s->codec_id==CODEC_ID_H263){
 366             next= ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
 367         }else{
 368             av_log(s->avctx, AV_LOG_ERROR, "this codec does not support truncated bitstreams\n");
 369             return -1;
 370         }
 371
 372         if( ff_combine_frame(&s->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
 373             return buf_size;
 374     }
 375
 376
 377 retry:
 378
 379     if(s->bitstream_buffer_size && (s->divx_packed || buf_size<20)){ //divx 5.01+/xvid frame reorder
 380         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
 381     }else
 382         init_get_bits(&s->gb, buf, buf_size*8);
 383     s->bitstream_buffer_size=0;
 384
 385     if (!s->context_initialized) {
 386         if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
 387             return -1;
 388     }
 389
 390     /* We need to set current_picture_ptr before reading the header,
 391      * otherwise we cannot store anyting in there */
 392     if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
 393         int i= ff_find_unused_picture(s, 0);
 394         s->current_picture_ptr= &s->picture[i];
 395     }
 396
 397     /* let's go :-) */
 398     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
 399         ret= ff_wmv2_decode_picture_header(s);
 400     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
 401         ret = msmpeg4_decode_picture_header(s);
 402     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
 403         if(s->avctx->extradata_size && s->picture_number==0){
 404             GetBitContext gb;
 405
 406             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
 407             ret = ff_mpeg4_decode_picture_header(s, &gb);
 408         }
 409         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
 410     } else if (CONFIG_H263I_DECODER && s->codec_id == CODEC_ID_H263I) {
 411         ret = ff_intel_h263_decode_picture_header(s);
 412     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
 413         ret = ff_flv_decode_picture_header(s);
 414     } else {
 415         ret = h263_decode_picture_header(s);
 416     }
 417
 418     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
 419
 420     /* skip if the header was thrashed */
 421     if (ret < 0){
 422         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
 423         return -1;
 424     }
 425
 426     avctx->has_b_frames= !s->low_delay;
 427
 428     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
 429         if(s->stream_codec_tag == AV_RL32("XVID") ||
 430            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
 431            s->codec_tag == AV_RL32("RMP4") ||
 432            s->codec_tag == AV_RL32("SIPP")
 433            )
 434             s->xvid_build= 0;
 435 #if 0
 436         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
 437            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
 438             s->xvid_build= 0;
 439 #endif
 440     }
 441
 442     if(s->xvid_build==-1 && s->divx_version==-1 && s->lavc_build==-1){
 443         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
 444             s->divx_version= 400; //divx 4
 445     }
 446
 447     if(s->xvid_build>=0 && s->divx_version>=0){
 448         s->divx_version=
 449         s->divx_build= -1;
 450     }
 451
 452     if(s->workaround_bugs&FF_BUG_AUTODETECT){
 453         if(s->codec_tag == AV_RL32("XVIX"))
 454             s->workaround_bugs|= FF_BUG_XVID_ILACE;
 455
 456         if(s->codec_tag == AV_RL32("UMP4")){
 457             s->workaround_bugs|= FF_BUG_UMP4;
 458         }
 459
 460         if(s->divx_version>=500 && s->divx_build<1814){
 461             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 462         }
 463
 464         if(s->divx_version>502 && s->divx_build<1814){
 465             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
 466         }
 467
 468         if(s->xvid_build<=3U)
 469             s->padding_bug_score= 256*256*256*64;
 470
 471         if(s->xvid_build<=1U)
 472             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 473
 474         if(s->xvid_build<=12U)
 475             s->workaround_bugs|= FF_BUG_EDGE;
 476
 477         if(s->xvid_build<=32U)
 478             s->workaround_bugs|= FF_BUG_DC_CLIP;
 479
 480 #define SET_QPEL_FUNC(postfix1, postfix2) \
 481     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
 482     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
 483     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
 484
 485         if(s->lavc_build<4653U)
 486             s->workaround_bugs|= FF_BUG_STD_QPEL;
 487
 488         if(s->lavc_build<4655U)
 489             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
 490
 491         if(s->lavc_build<4670U){
 492             s->workaround_bugs|= FF_BUG_EDGE;
 493         }
 494
 495         if(s->lavc_build<=4712U)
 496             s->workaround_bugs|= FF_BUG_DC_CLIP;
 497
 498         if(s->divx_version>=0)
 499             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
 500 //printf("padding_bug_score: %d\n", s->padding_bug_score);
 501         if(s->divx_version==501 && s->divx_build==20020416)
 502             s->padding_bug_score= 256*256*256*64;
 503
 504         if(s->divx_version<500U){
 505             s->workaround_bugs|= FF_BUG_EDGE;
 506         }
 507
 508         if(s->divx_version>=0)
 509             s->workaround_bugs|= FF_BUG_HPEL_CHROMA;
 510 #if 0
 511         if(s->divx_version==500)
 512             s->padding_bug_score= 256*256*256*64;
 513
 514         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
 515          * Let us hope this at least works.
 516          */
 517         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==-1
 518            && s->codec_id==CODEC_ID_MPEG4 && s->vo_type==0)
 519             s->workaround_bugs|= FF_BUG_NO_PADDING;
 520
 521         if(s->lavc_build<4609U) //FIXME not sure about the version num but a 4609 file seems ok
 522             s->workaround_bugs|= FF_BUG_NO_PADDING;
 523 #endif
 524     }
 525
 526     if(s->workaround_bugs& FF_BUG_STD_QPEL){
 527         SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
 528         SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
 529         SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
 530         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
 531         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
 532         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
 533
 534         SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
 535         SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
 536         SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
 537         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
 538         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
 539         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
 540     }
 541
 542     if(avctx->debug & FF_DEBUG_BUGS)
 543         av_log(s->avctx, AV_LOG_DEBUG, "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
 544                s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
 545                s->divx_packed ? "p" : "");
 546
 547 #if 0 // dump bits per frame / qp / complexity
 548 {
 549     static FILE *f=NULL;
 550     if(!f) f=fopen("rate_qp_cplx.txt", "w");
 551     fprintf(f, "%d %d %f\n", buf_size, s->qscale, buf_size*(double)s->qscale);
 552 }
 553 #endif
 554
 555 #if HAVE_MMX
 556     if(s->codec_id == CODEC_ID_MPEG4 && s->xvid_build>=0 && avctx->idct_algo == FF_IDCT_AUTO && (mm_flags & FF_MM_MMX)){
 557         avctx->idct_algo= FF_IDCT_XVIDMMX;
 558         avctx->coded_width= 0; // force reinit
 559 //        dsputil_init(&s->dsp, avctx);
 560         s->picture_number=0;
 561     }
 562 #endif
 563
 564         /* After H263 & mpeg4 header decode we have the height, width,*/
 565         /* and other parameters. So then we could init the picture   */
 566         /* FIXME: By the way H263 decoder is evolving it should have */
 567         /* an H263EncContext                                         */
 568
 569     if (   s->width  != avctx->coded_width
 570         || s->height != avctx->coded_height) {
 571         /* H.263 could change picture size any time */
 572         ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
 573         s->parse_context.buffer=0;
 574         MPV_common_end(s);
 575         s->parse_context= pc;
 576     }
 577     if (!s->context_initialized) {
 578         avcodec_set_dimensions(avctx, s->width, s->height);
 579
 580         goto retry;
 581     }
 582
 583     if((s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P || s->codec_id == CODEC_ID_H263I))
 584         s->gob_index = ff_h263_get_gob_height(s);
 585
 586     // for hurry_up==5
 587     s->current_picture.pict_type= s->pict_type;
 588     s->current_picture.key_frame= s->pict_type == FF_I_TYPE;
 589
 590     /* skip B-frames if we don't have reference frames */
 591     if(s->last_picture_ptr==NULL && (s->pict_type==FF_B_TYPE || s->dropable)) return get_consumed_bytes(s, buf_size);
 592     /* skip b frames if we are in a hurry */
 593     if(avctx->hurry_up && s->pict_type==FF_B_TYPE) return get_consumed_bytes(s, buf_size);
 594     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==FF_B_TYPE)
 595        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=FF_I_TYPE)
 596        ||  avctx->skip_frame >= AVDISCARD_ALL)
 597         return get_consumed_bytes(s, buf_size);
 598     /* skip everything if we are in a hurry>=5 */
 599     if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
 600
 601     if(s->next_p_frame_damaged){
 602         if(s->pict_type==FF_B_TYPE)
 603             return get_consumed_bytes(s, buf_size);
 604         else
 605             s->next_p_frame_damaged=0;
 606     }
 607
 608     if((s->avctx->flags2 & CODEC_FLAG2_FAST) && s->pict_type==FF_B_TYPE){
 609         s->me.qpel_put= s->dsp.put_2tap_qpel_pixels_tab;
 610         s->me.qpel_avg= s->dsp.avg_2tap_qpel_pixels_tab;
 611     }else if((!s->no_rounding) || s->pict_type==FF_B_TYPE){
 612         s->me.qpel_put= s->dsp.put_qpel_pixels_tab;
 613         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
 614     }else{
 615         s->me.qpel_put= s->dsp.put_no_rnd_qpel_pixels_tab;
 616         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
 617     }
 618
 619     if(MPV_frame_start(s, avctx) < 0)
 620         return -1;
 621
 622     if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
 623         ff_vdpau_mpeg4_decode_picture(s, s->gb.buffer, s->gb.buffer_end - s->gb.buffer);
 624         goto frame_end;
 625     }
 626
 627     if (avctx->hwaccel) {
 628         if (avctx->hwaccel->start_frame(avctx, s->gb.buffer, s->gb.buffer_end - s->gb.buffer) < 0)
 629             return -1;
 630     }
 631
 632     ff_er_frame_start(s);
 633
 634     //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
 635     //which is not available before MPV_frame_start()
 636     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5){
 637         ret = ff_wmv2_decode_secondary_picture_header(s);
 638         if(ret<0) return ret;
 639         if(ret==1) goto intrax8_decoded;
 640     }
 641
 642     /* decode each macroblock */
 643     s->mb_x=0;
 644     s->mb_y=0;
 645
 646     decode_slice(s);
 647     while(s->mb_y<s->mb_height){
 648         if(s->msmpeg4_version){
 649             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)
 650                 break;
 651         }else{
 652             if(ff_h263_resync(s)<0)
 653                 break;
 654         }
 655
 656         if(s->msmpeg4_version<4 && s->h263_pred)
 657             ff_mpeg4_clean_buffers(s);
 658
 659         decode_slice(s);
 660     }
 661
 662     if (s->h263_msmpeg4 && s->msmpeg4_version<4 && s->pict_type==FF_I_TYPE)
 663         if(!CONFIG_MSMPEG4_DECODER || msmpeg4_decode_ext_header(s, buf_size) < 0){
 664             s->error_status_table[s->mb_num-1]= AC_ERROR|DC_ERROR|MV_ERROR;
 665         }
 666
 667     assert(s->bitstream_buffer_size==0);
 668 frame_end:
 669     /* divx 5.01+ bistream reorder stuff */
 670     if(s->codec_id==CODEC_ID_MPEG4 && s->divx_packed){
 671         int current_pos= get_bits_count(&s->gb)>>3;
 672         int startcode_found=0;
 673
 674         if(buf_size - current_pos > 5){
 675             int i;
 676             for(i=current_pos; i<buf_size-3; i++){
 677                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
 678                     startcode_found=1;
 679                     break;
 680                 }
 681             }
 682         }
 683         if(s->gb.buffer == s->bitstream_buffer && buf_size>7 && s->xvid_build>=0){ //xvid style
 684             startcode_found=1;
 685             current_pos=0;
 686         }
 687
 688         if(startcode_found){
 689             av_fast_malloc(
 690                 &s->bitstream_buffer,
 691                 &s->allocated_bitstream_buffer_size,
 692                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
 693             if (!s->bitstream_buffer)
 694                 return AVERROR(ENOMEM);
 695             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
 696             s->bitstream_buffer_size= buf_size - current_pos;
 697         }
 698     }
 699
 700 intrax8_decoded:
 701     ff_er_frame_end(s);
 702
 703     if (avctx->hwaccel) {
 704         if (avctx->hwaccel->end_frame(avctx) < 0)
 705             return -1;
 706     }
 707
 708     MPV_frame_end(s);
 709
 710 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
 711 assert(s->current_picture.pict_type == s->pict_type);
 712     if (s->pict_type == FF_B_TYPE || s->low_delay) {
 713         *pict= *(AVFrame*)s->current_picture_ptr;
 714     } else if (s->last_picture_ptr != NULL) {
 715         *pict= *(AVFrame*)s->last_picture_ptr;
 716     }
 717
 718     if(s->last_picture_ptr || s->low_delay){
 719         *data_size = sizeof(AVFrame);
 720         ff_print_debug_info(s, pict);
 721     }
 722
 723 #ifdef PRINT_FRAME_TIME
 724 av_log(avctx, AV_LOG_DEBUG, "%"PRId64"\n", rdtsc()-time);
 725 #endif
 726
 727     return get_consumed_bytes(s, buf_size);
 728 }
 729
 730 AVCodec h263_decoder = {
 731     "h263",
 732     AVMEDIA_TYPE_VIDEO,
 733     CODEC_ID_H263,
 734     sizeof(MpegEncContext),
 735     ff_h263_decode_init,
 736     NULL,
 737     ff_h263_decode_end,
 738     ff_h263_decode_frame,
 739     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
 740     .flush= ff_mpeg_flush,
 741     .max_lowres= 3,
 742     .long_name= NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
 743     .pix_fmts= ff_hwaccel_pixfmt_list_420,
 744 };