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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 libavcodec/h263dec.c
  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_parser.h"
  33 #include "mpeg4video_parser.h"
  34 #include "msmpeg4.h"
  35 #include "vdpau_internal.h"
  36 #include "flv.h"
  37 #include "mpeg4video.h"
  38
  39 //#define DEBUG
  40 //#define PRINT_FRAME_TIME
  41
  42 av_cold int ff_h263_decode_init(AVCodecContext *avctx)
  43 {
  44     MpegEncContext *s = avctx->priv_data;
  45
  46     s->avctx = avctx;
  47     s->out_format = FMT_H263;
  48
  49     s->width  = avctx->coded_width;
  50     s->height = avctx->coded_height;
  51     s->workaround_bugs= avctx->workaround_bugs;
  52
  53     // set defaults
  54     MPV_decode_defaults(s);
  55     s->quant_precision=5;
  56     s->decode_mb= ff_h263_decode_mb;
  57     s->low_delay= 1;
  58     avctx->pix_fmt= avctx->get_format(avctx, avctx->codec->pix_fmts);
  59     s->unrestricted_mv= 1;
  60
  61     /* select sub codec */
  62     switch(avctx->codec->id) {
  63     case CODEC_ID_H263:
  64         s->unrestricted_mv= 0;
  65         avctx->chroma_sample_location = AVCHROMA_LOC_CENTER;
  66         break;
  67     case CODEC_ID_MPEG4:
  68         break;
  69     case CODEC_ID_MSMPEG4V1:
  70         s->h263_msmpeg4 = 1;
  71         s->h263_pred = 1;
  72         s->msmpeg4_version=1;
  73         break;
  74     case CODEC_ID_MSMPEG4V2:
  75         s->h263_msmpeg4 = 1;
  76         s->h263_pred = 1;
  77         s->msmpeg4_version=2;
  78         break;
  79     case CODEC_ID_MSMPEG4V3:
  80         s->h263_msmpeg4 = 1;
  81         s->h263_pred = 1;
  82         s->msmpeg4_version=3;
  83         break;
  84     case CODEC_ID_WMV1:
  85         s->h263_msmpeg4 = 1;
  86         s->h263_pred = 1;
  87         s->msmpeg4_version=4;
  88         break;
  89     case CODEC_ID_WMV2:
  90         s->h263_msmpeg4 = 1;
  91         s->h263_pred = 1;
  92         s->msmpeg4_version=5;
  93         break;
  94     case CODEC_ID_VC1:
  95     case CODEC_ID_WMV3:
  96         s->h263_msmpeg4 = 1;
  97         s->h263_pred = 1;
  98         s->msmpeg4_version=6;
  99         avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
 100         break;
 101     case CODEC_ID_H263I:
 102         break;
 103     case CODEC_ID_FLV1:
 104         s->h263_flv = 1;
 105         break;
 106     default:
 107         return -1;
 108     }
 109     s->codec_id= avctx->codec->id;
 110     avctx->hwaccel= ff_find_hwaccel(avctx->codec->id, avctx->pix_fmt);
 111
 112     /* for h263, we allocate the images after having read the header */
 113     if (avctx->codec->id != CODEC_ID_H263 && avctx->codec->id != CODEC_ID_MPEG4)
 114         if (MPV_common_init(s) < 0)
 115             return -1;
 116
 117         h263_decode_init_vlc(s);
 118
 119     return 0;
 120 }
 121
 122 av_cold int ff_h263_decode_end(AVCodecContext *avctx)
 123 {
 124     MpegEncContext *s = avctx->priv_data;
 125
 126     MPV_common_end(s);
 127     return 0;
 128 }
 129
 130 /**
 131  * returns the number of bytes consumed for building the current frame
 132  */
 133 static int get_consumed_bytes(MpegEncContext *s, int buf_size){
 134     int pos= (get_bits_count(&s->gb)+7)>>3;
 135
 136     if(s->divx_packed || s->avctx->hwaccel){
 137         //we would have to scan through the whole buf to handle the weird reordering ...
 138         return buf_size;
 139     }else if(s->flags&CODEC_FLAG_TRUNCATED){
 140         pos -= s->parse_context.last_index;
 141         if(pos<0) pos=0; // padding is not really read so this might be -1
 142         return pos;
 143     }else{
 144         if(pos==0) pos=1; //avoid infinite loops (i doubt that is needed but ...)
 145         if(pos+10>buf_size) pos=buf_size; // oops ;)
 146
 147         return pos;
 148     }
 149 }
 150
 151 static int decode_slice(MpegEncContext *s){
 152     const int part_mask= s->partitioned_frame ? (AC_END|AC_ERROR) : 0x7F;
 153     const int mb_size= 16>>s->avctx->lowres;
 154     s->last_resync_gb= s->gb;
 155     s->first_slice_line= 1;
 156
 157     s->resync_mb_x= s->mb_x;
 158     s->resync_mb_y= s->mb_y;
 159
 160     ff_set_qscale(s, s->qscale);
 161
 162     if (s->avctx->hwaccel) {
 163         const uint8_t *start= s->gb.buffer + get_bits_count(&s->gb)/8;
 164         const uint8_t *end  = ff_h263_find_resync_marker(start + 1, s->gb.buffer_end);
 165         skip_bits_long(&s->gb, 8*(end - start));
 166         return s->avctx->hwaccel->decode_slice(s->avctx, start, end - start);
 167     }
 168
 169     if(s->partitioned_frame){
 170         const int qscale= s->qscale;
 171
 172         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
 173             if(ff_mpeg4_decode_partitions(s) < 0)
 174                 return -1;
 175         }
 176
 177         /* restore variables which were modified */
 178         s->first_slice_line=1;
 179         s->mb_x= s->resync_mb_x;
 180         s->mb_y= s->resync_mb_y;
 181         ff_set_qscale(s, qscale);
 182     }
 183
 184     for(; s->mb_y < s->mb_height; s->mb_y++) {
 185         /* per-row end of slice checks */
 186         if(s->msmpeg4_version){
 187             if(s->resync_mb_y + s->slice_height == s->mb_y){
 188                 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);
 189
 190                 return 0;
 191             }
 192         }
 193
 194         if(s->msmpeg4_version==1){
 195             s->last_dc[0]=
 196             s->last_dc[1]=
 197             s->last_dc[2]= 128;
 198         }
 199
 200         ff_init_block_index(s);
 201         for(; s->mb_x < s->mb_width; s->mb_x++) {
 202             int ret;
 203
 204             ff_update_block_index(s);
 205
 206             if(s->resync_mb_x == s->mb_x && s->resync_mb_y+1 == s->mb_y){
 207                 s->first_slice_line=0;
 208             }
 209
 210             /* DCT & quantize */
 211
 212             s->mv_dir = MV_DIR_FORWARD;
 213             s->mv_type = MV_TYPE_16X16;
 214 //            s->mb_skipped = 0;
 215 //printf("%d %d %06X\n", ret, get_bits_count(&s->gb), show_bits(&s->gb, 24));
 216             ret= s->decode_mb(s, s->block);
 217
 218             if (s->pict_type!=FF_B_TYPE)
 219                 ff_h263_update_motion_val(s);
 220
 221             if(ret<0){
 222                 const int xy= s->mb_x + s->mb_y*s->mb_stride;
 223                 if(ret==SLICE_END){
 224                     MPV_decode_mb(s, s->block);
 225                     if(s->loop_filter)
 226                         ff_h263_loop_filter(s);
 227
 228 //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));
 229                     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);
 230
 231                     s->padding_bug_score--;
 232
 233                     if(++s->mb_x >= s->mb_width){
 234                         s->mb_x=0;
 235                         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
 236                         s->mb_y++;
 237                     }
 238                     return 0;
 239                 }else if(ret==SLICE_NOEND){
 240                     av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
 241                     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);
 242                     return -1;
 243                 }
 244                 av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
 245                 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);
 246
 247                 return -1;
 248             }
 249
 250             MPV_decode_mb(s, s->block);
 251             if(s->loop_filter)
 252                 ff_h263_loop_filter(s);
 253         }
 254
 255         ff_draw_horiz_band(s, s->mb_y*mb_size, mb_size);
 256
 257         s->mb_x= 0;
 258     }
 259
 260     assert(s->mb_x==0 && s->mb_y==s->mb_height);
 261
 262     /* try to detect the padding bug */
 263     if(      s->codec_id==CODEC_ID_MPEG4
 264        &&   (s->workaround_bugs&FF_BUG_AUTODETECT)
 265        &&    get_bits_left(&s->gb) >=0
 266        &&    get_bits_left(&s->gb) < 48
 267 //       &&   !s->resync_marker
 268        &&   !s->data_partitioning){
 269
 270         const int bits_count= get_bits_count(&s->gb);
 271         const int bits_left = s->gb.size_in_bits - bits_count;
 272
 273         if(bits_left==0){
 274             s->padding_bug_score+=16;
 275         } else if(bits_left != 1){
 276             int v= show_bits(&s->gb, 8);
 277             v|= 0x7F >> (7-(bits_count&7));
 278
 279             if(v==0x7F && bits_left<=8)
 280                 s->padding_bug_score--;
 281             else if(v==0x7F && ((get_bits_count(&s->gb)+8)&8) && bits_left<=16)
 282                 s->padding_bug_score+= 4;
 283             else
 284                 s->padding_bug_score++;
 285         }
 286     }
 287
 288     if(s->workaround_bugs&FF_BUG_AUTODETECT){
 289         if(s->padding_bug_score > -2 && !s->data_partitioning /*&& (s->divx_version || !s->resync_marker)*/)
 290             s->workaround_bugs |=  FF_BUG_NO_PADDING;
 291         else
 292             s->workaround_bugs &= ~FF_BUG_NO_PADDING;
 293     }
 294
 295     // handle formats which don't have unique end markers
 296     if(s->msmpeg4_version || (s->workaround_bugs&FF_BUG_NO_PADDING)){ //FIXME perhaps solve this more cleanly
 297         int left= get_bits_left(&s->gb);
 298         int max_extra=7;
 299
 300         /* no markers in M$ crap */
 301         if(s->msmpeg4_version && s->pict_type==FF_I_TYPE)
 302             max_extra+= 17;
 303
 304         /* buggy padding but the frame should still end approximately at the bitstream end */
 305         if((s->workaround_bugs&FF_BUG_NO_PADDING) && s->error_recognition>=3)
 306             max_extra+= 48;
 307         else if((s->workaround_bugs&FF_BUG_NO_PADDING))
 308             max_extra+= 256*256*256*64;
 309
 310         if(left>max_extra){
 311             av_log(s->avctx, AV_LOG_ERROR, "discarding %d junk bits at end, next would be %X\n", left, show_bits(&s->gb, 24));
 312         }
 313         else if(left<0){
 314             av_log(s->avctx, AV_LOG_ERROR, "overreading %d bits\n", -left);
 315         }else
 316             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);
 317
 318         return 0;
 319     }
 320
 321     av_log(s->avctx, AV_LOG_ERROR, "slice end not reached but screenspace end (%d left %06X, score= %d)\n",
 322             get_bits_left(&s->gb),
 323             show_bits(&s->gb, 24), s->padding_bug_score);
 324
 325     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);
 326
 327     return -1;
 328 }
 329
 330 int ff_h263_decode_frame(AVCodecContext *avctx,
 331                              void *data, int *data_size,
 332                              AVPacket *avpkt)
 333 {
 334     const uint8_t *buf = avpkt->data;
 335     int buf_size = avpkt->size;
 336     MpegEncContext *s = avctx->priv_data;
 337     int ret;
 338     AVFrame *pict = data;
 339
 340 #ifdef PRINT_FRAME_TIME
 341 uint64_t time= rdtsc();
 342 #endif
 343     s->flags= avctx->flags;
 344     s->flags2= avctx->flags2;
 345
 346     /* no supplementary picture */
 347     if (buf_size == 0) {
 348         /* special case for last picture */
 349         if (s->low_delay==0 && s->next_picture_ptr) {
 350             *pict= *(AVFrame*)s->next_picture_ptr;
 351             s->next_picture_ptr= NULL;
 352
 353             *data_size = sizeof(AVFrame);
 354         }
 355
 356         return 0;
 357     }
 358
 359     if(s->flags&CODEC_FLAG_TRUNCATED){
 360         int next;
 361
 362         if(CONFIG_MPEG4_DECODER && s->codec_id==CODEC_ID_MPEG4){
 363             next= ff_mpeg4_find_frame_end(&s->parse_context, buf, buf_size);
 364         }else if(CONFIG_H263_DECODER && s->codec_id==CODEC_ID_H263){
 365             next= ff_h263_find_frame_end(&s->parse_context, buf, buf_size);
 366         }else{
 367             av_log(s->avctx, AV_LOG_ERROR, "this codec does not support truncated bitstreams\n");
 368             return -1;
 369         }
 370
 371         if( ff_combine_frame(&s->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
 372             return buf_size;
 373     }
 374
 375
 376 retry:
 377
 378     if(s->bitstream_buffer_size && (s->divx_packed || buf_size<20)){ //divx 5.01+/xvid frame reorder
 379         init_get_bits(&s->gb, s->bitstream_buffer, s->bitstream_buffer_size*8);
 380     }else
 381         init_get_bits(&s->gb, buf, buf_size*8);
 382     s->bitstream_buffer_size=0;
 383
 384     if (!s->context_initialized) {
 385         if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
 386             return -1;
 387     }
 388
 389     /* We need to set current_picture_ptr before reading the header,
 390      * otherwise we cannot store anyting in there */
 391     if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
 392         int i= ff_find_unused_picture(s, 0);
 393         s->current_picture_ptr= &s->picture[i];
 394     }
 395
 396     /* let's go :-) */
 397     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5) {
 398         ret= ff_wmv2_decode_picture_header(s);
 399     } else if (CONFIG_MSMPEG4_DECODER && s->msmpeg4_version) {
 400         ret = msmpeg4_decode_picture_header(s);
 401     } else if (CONFIG_MPEG4_DECODER && s->h263_pred) {
 402         if(s->avctx->extradata_size && s->picture_number==0){
 403             GetBitContext gb;
 404
 405             init_get_bits(&gb, s->avctx->extradata, s->avctx->extradata_size*8);
 406             ret = ff_mpeg4_decode_picture_header(s, &gb);
 407         }
 408         ret = ff_mpeg4_decode_picture_header(s, &s->gb);
 409     } else if (CONFIG_H263I_DECODER && s->codec_id == CODEC_ID_H263I) {
 410         ret = ff_intel_h263_decode_picture_header(s);
 411     } else if (CONFIG_FLV_DECODER && s->h263_flv) {
 412         ret = ff_flv_decode_picture_header(s);
 413     } else {
 414         ret = h263_decode_picture_header(s);
 415     }
 416
 417     if(ret==FRAME_SKIPPED) return get_consumed_bytes(s, buf_size);
 418
 419     /* skip if the header was thrashed */
 420     if (ret < 0){
 421         av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
 422         return -1;
 423     }
 424
 425     avctx->has_b_frames= !s->low_delay;
 426
 427     if(s->xvid_build==0 && s->divx_version==0 && s->lavc_build==0){
 428         if(s->stream_codec_tag == AV_RL32("XVID") ||
 429            s->codec_tag == AV_RL32("XVID") || s->codec_tag == AV_RL32("XVIX") ||
 430            s->codec_tag == AV_RL32("RMP4"))
 431             s->xvid_build= -1;
 432 #if 0
 433         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==1
 434            && s->padding_bug_score > 0 && s->low_delay) // XVID with modified fourcc
 435             s->xvid_build= -1;
 436 #endif
 437     }
 438
 439     if(s->xvid_build==0 && s->divx_version==0 && s->lavc_build==0){
 440         if(s->codec_tag == AV_RL32("DIVX") && s->vo_type==0 && s->vol_control_parameters==0)
 441             s->divx_version= 400; //divx 4
 442     }
 443
 444     if(s->xvid_build && s->divx_version){
 445         s->divx_version=
 446         s->divx_build= 0;
 447     }
 448
 449     if(s->workaround_bugs&FF_BUG_AUTODETECT){
 450         if(s->codec_tag == AV_RL32("XVIX"))
 451             s->workaround_bugs|= FF_BUG_XVID_ILACE;
 452
 453         if(s->codec_tag == AV_RL32("UMP4")){
 454             s->workaround_bugs|= FF_BUG_UMP4;
 455         }
 456
 457         if(s->divx_version>=500 && s->divx_build<1814){
 458             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 459         }
 460
 461         if(s->divx_version>502 && s->divx_build<1814){
 462             s->workaround_bugs|= FF_BUG_QPEL_CHROMA2;
 463         }
 464
 465         if(s->xvid_build && s->xvid_build<=3)
 466             s->padding_bug_score= 256*256*256*64;
 467
 468         if(s->xvid_build && s->xvid_build<=1)
 469             s->workaround_bugs|= FF_BUG_QPEL_CHROMA;
 470
 471         if(s->xvid_build && s->xvid_build<=12)
 472             s->workaround_bugs|= FF_BUG_EDGE;
 473
 474         if(s->xvid_build && s->xvid_build<=32)
 475             s->workaround_bugs|= FF_BUG_DC_CLIP;
 476
 477 #define SET_QPEL_FUNC(postfix1, postfix2) \
 478     s->dsp.put_ ## postfix1 = ff_put_ ## postfix2;\
 479     s->dsp.put_no_rnd_ ## postfix1 = ff_put_no_rnd_ ## postfix2;\
 480     s->dsp.avg_ ## postfix1 = ff_avg_ ## postfix2;
 481
 482         if(s->lavc_build && s->lavc_build<4653)
 483             s->workaround_bugs|= FF_BUG_STD_QPEL;
 484
 485         if(s->lavc_build && s->lavc_build<4655)
 486             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
 487
 488         if(s->lavc_build && s->lavc_build<4670){
 489             s->workaround_bugs|= FF_BUG_EDGE;
 490         }
 491
 492         if(s->lavc_build && s->lavc_build<=4712)
 493             s->workaround_bugs|= FF_BUG_DC_CLIP;
 494
 495         if(s->divx_version)
 496             s->workaround_bugs|= FF_BUG_DIRECT_BLOCKSIZE;
 497 //printf("padding_bug_score: %d\n", s->padding_bug_score);
 498         if(s->divx_version==501 && s->divx_build==20020416)
 499             s->padding_bug_score= 256*256*256*64;
 500
 501         if(s->divx_version && s->divx_version<500){
 502             s->workaround_bugs|= FF_BUG_EDGE;
 503         }
 504
 505         if(s->divx_version)
 506             s->workaround_bugs|= FF_BUG_HPEL_CHROMA;
 507 #if 0
 508         if(s->divx_version==500)
 509             s->padding_bug_score= 256*256*256*64;
 510
 511         /* very ugly XVID padding bug detection FIXME/XXX solve this differently
 512          * Let us hope this at least works.
 513          */
 514         if(   s->resync_marker==0 && s->data_partitioning==0 && s->divx_version==0
 515            && s->codec_id==CODEC_ID_MPEG4 && s->vo_type==0)
 516             s->workaround_bugs|= FF_BUG_NO_PADDING;
 517
 518         if(s->lavc_build && s->lavc_build<4609) //FIXME not sure about the version num but a 4609 file seems ok
 519             s->workaround_bugs|= FF_BUG_NO_PADDING;
 520 #endif
 521     }
 522
 523     if(s->workaround_bugs& FF_BUG_STD_QPEL){
 524         SET_QPEL_FUNC(qpel_pixels_tab[0][ 5], qpel16_mc11_old_c)
 525         SET_QPEL_FUNC(qpel_pixels_tab[0][ 7], qpel16_mc31_old_c)
 526         SET_QPEL_FUNC(qpel_pixels_tab[0][ 9], qpel16_mc12_old_c)
 527         SET_QPEL_FUNC(qpel_pixels_tab[0][11], qpel16_mc32_old_c)
 528         SET_QPEL_FUNC(qpel_pixels_tab[0][13], qpel16_mc13_old_c)
 529         SET_QPEL_FUNC(qpel_pixels_tab[0][15], qpel16_mc33_old_c)
 530
 531         SET_QPEL_FUNC(qpel_pixels_tab[1][ 5], qpel8_mc11_old_c)
 532         SET_QPEL_FUNC(qpel_pixels_tab[1][ 7], qpel8_mc31_old_c)
 533         SET_QPEL_FUNC(qpel_pixels_tab[1][ 9], qpel8_mc12_old_c)
 534         SET_QPEL_FUNC(qpel_pixels_tab[1][11], qpel8_mc32_old_c)
 535         SET_QPEL_FUNC(qpel_pixels_tab[1][13], qpel8_mc13_old_c)
 536         SET_QPEL_FUNC(qpel_pixels_tab[1][15], qpel8_mc33_old_c)
 537     }
 538
 539     if(avctx->debug & FF_DEBUG_BUGS)
 540         av_log(s->avctx, AV_LOG_DEBUG, "bugs: %X lavc_build:%d xvid_build:%d divx_version:%d divx_build:%d %s\n",
 541                s->workaround_bugs, s->lavc_build, s->xvid_build, s->divx_version, s->divx_build,
 542                s->divx_packed ? "p" : "");
 543
 544 #if 0 // dump bits per frame / qp / complexity
 545 {
 546     static FILE *f=NULL;
 547     if(!f) f=fopen("rate_qp_cplx.txt", "w");
 548     fprintf(f, "%d %d %f\n", buf_size, s->qscale, buf_size*(double)s->qscale);
 549 }
 550 #endif
 551
 552 #if HAVE_MMX
 553     if(s->codec_id == CODEC_ID_MPEG4 && s->xvid_build && avctx->idct_algo == FF_IDCT_AUTO && (mm_flags & FF_MM_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 hurry_up==5
 584     s->current_picture.pict_type= s->pict_type;
 585     s->current_picture.key_frame= s->pict_type == FF_I_TYPE;
 586
 587     /* skip B-frames if we don't have reference frames */
 588     if(s->last_picture_ptr==NULL && (s->pict_type==FF_B_TYPE || s->dropable)) return get_consumed_bytes(s, buf_size);
 589     /* skip b frames if we are in a hurry */
 590     if(avctx->hurry_up && s->pict_type==FF_B_TYPE) return get_consumed_bytes(s, buf_size);
 591     if(   (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==FF_B_TYPE)
 592        || (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=FF_I_TYPE)
 593        ||  avctx->skip_frame >= AVDISCARD_ALL)
 594         return get_consumed_bytes(s, buf_size);
 595     /* skip everything if we are in a hurry>=5 */
 596     if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
 597
 598     if(s->next_p_frame_damaged){
 599         if(s->pict_type==FF_B_TYPE)
 600             return get_consumed_bytes(s, buf_size);
 601         else
 602             s->next_p_frame_damaged=0;
 603     }
 604
 605     if((s->avctx->flags2 & CODEC_FLAG2_FAST) && s->pict_type==FF_B_TYPE){
 606         s->me.qpel_put= s->dsp.put_2tap_qpel_pixels_tab;
 607         s->me.qpel_avg= s->dsp.avg_2tap_qpel_pixels_tab;
 608     }else if((!s->no_rounding) || s->pict_type==FF_B_TYPE){
 609         s->me.qpel_put= s->dsp.put_qpel_pixels_tab;
 610         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
 611     }else{
 612         s->me.qpel_put= s->dsp.put_no_rnd_qpel_pixels_tab;
 613         s->me.qpel_avg= s->dsp.avg_qpel_pixels_tab;
 614     }
 615
 616     if(MPV_frame_start(s, avctx) < 0)
 617         return -1;
 618
 619     if (CONFIG_MPEG4_VDPAU_DECODER && (s->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)) {
 620         ff_vdpau_mpeg4_decode_picture(s, buf, buf_size);
 621         goto frame_end;
 622     }
 623
 624     if (avctx->hwaccel) {
 625         if (avctx->hwaccel->start_frame(avctx, buf, buf_size) < 0)
 626             return -1;
 627     }
 628
 629     ff_er_frame_start(s);
 630
 631     //the second part of the wmv2 header contains the MB skip bits which are stored in current_picture->mb_type
 632     //which is not available before MPV_frame_start()
 633     if (CONFIG_WMV2_DECODER && s->msmpeg4_version==5){
 634         ret = ff_wmv2_decode_secondary_picture_header(s);
 635         if(ret<0) return ret;
 636         if(ret==1) goto intrax8_decoded;
 637     }
 638
 639     /* decode each macroblock */
 640     s->mb_x=0;
 641     s->mb_y=0;
 642
 643     decode_slice(s);
 644     while(s->mb_y<s->mb_height){
 645         if(s->msmpeg4_version){
 646             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)
 647                 break;
 648         }else{
 649             if(ff_h263_resync(s)<0)
 650                 break;
 651         }
 652
 653         if(s->msmpeg4_version<4 && s->h263_pred)
 654             ff_mpeg4_clean_buffers(s);
 655
 656         decode_slice(s);
 657     }
 658
 659     if (s->h263_msmpeg4 && s->msmpeg4_version<4 && s->pict_type==FF_I_TYPE)
 660         if(!CONFIG_MSMPEG4_DECODER || msmpeg4_decode_ext_header(s, buf_size) < 0){
 661             s->error_status_table[s->mb_num-1]= AC_ERROR|DC_ERROR|MV_ERROR;
 662         }
 663
 664     assert(s->bitstream_buffer_size==0);
 665     /* divx 5.01+ bistream reorder stuff */
 666     if(s->codec_id==CODEC_ID_MPEG4 && s->divx_packed){
 667         int current_pos= get_bits_count(&s->gb)>>3;
 668         int startcode_found=0;
 669
 670         if(buf_size - current_pos > 5){
 671             int i;
 672             for(i=current_pos; i<buf_size-3; i++){
 673                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
 674                     startcode_found=1;
 675                     break;
 676                 }
 677             }
 678         }
 679         if(s->gb.buffer == s->bitstream_buffer && buf_size>7 && s->xvid_build){ //xvid style
 680             startcode_found=1;
 681             current_pos=0;
 682         }
 683
 684         if(startcode_found){
 685             av_fast_malloc(
 686                 &s->bitstream_buffer,
 687                 &s->allocated_bitstream_buffer_size,
 688                 buf_size - current_pos + FF_INPUT_BUFFER_PADDING_SIZE);
 689             if (!s->bitstream_buffer)
 690                 return AVERROR(ENOMEM);
 691             memcpy(s->bitstream_buffer, buf + current_pos, buf_size - current_pos);
 692             s->bitstream_buffer_size= buf_size - current_pos;
 693         }
 694     }
 695
 696 intrax8_decoded:
 697     ff_er_frame_end(s);
 698
 699 frame_end:
 700     if (avctx->hwaccel) {
 701         if (avctx->hwaccel->end_frame(avctx) < 0)
 702             return -1;
 703     }
 704
 705     MPV_frame_end(s);
 706
 707 assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
 708 assert(s->current_picture.pict_type == s->pict_type);
 709     if (s->pict_type == FF_B_TYPE || s->low_delay) {
 710         *pict= *(AVFrame*)s->current_picture_ptr;
 711     } else if (s->last_picture_ptr != NULL) {
 712         *pict= *(AVFrame*)s->last_picture_ptr;
 713     }
 714
 715     if(s->last_picture_ptr || s->low_delay){
 716         *data_size = sizeof(AVFrame);
 717         ff_print_debug_info(s, pict);
 718     }
 719
 720 #ifdef PRINT_FRAME_TIME
 721 av_log(avctx, AV_LOG_DEBUG, "%"PRId64"\n", rdtsc()-time);
 722 #endif
 723
 724     return get_consumed_bytes(s, buf_size);
 725 }
 726
 727 AVCodec h263_decoder = {
 728     "h263",
 729     CODEC_TYPE_VIDEO,
 730     CODEC_ID_H263,
 731     sizeof(MpegEncContext),
 732     ff_h263_decode_init,
 733     NULL,
 734     ff_h263_decode_end,
 735     ff_h263_decode_frame,
 736     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,
 737     .flush= ff_mpeg_flush,
 738     .long_name= NULL_IF_CONFIG_SMALL("H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2"),
 739     .pix_fmts= ff_hwaccel_pixfmt_list_420,
 740 };