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   1 /*
   2  * ITU H.263 bitstream decoder
   3  * Copyright (c) 2000,2001 Fabrice Bellard
   4  * H.263+ support.
   5  * Copyright (c) 2001 Juan J. Sierralta P
   6  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
   7  *
   8  * This file is part of FFmpeg.
   9  *
  10  * FFmpeg is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2.1 of the License, or (at your option) any later version.
  14  *
  15  * FFmpeg is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public
  21  * License along with FFmpeg; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 /**
  26  * @file
  27  * H.263 decoder.
  28  */
  29
  30 #define UNCHECKED_BITSTREAM_READER 1
  31 #include <limits.h>
  32
  33 #include "libavutil/attributes.h"
  34 #include "libavutil/imgutils.h"
  35 #include "libavutil/internal.h"
  36 #include "libavutil/mathematics.h"
  37 #include "avcodec.h"
  38 #include "mpegvideo.h"
  39 #include "h263.h"
  40 #include "h263data.h"
  41 #include "internal.h"
  42 #include "mathops.h"
  43 #include "mpegutils.h"
  44 #include "unary.h"
  45 #include "flv.h"
  46 #include "rv10.h"
  47 #include "mpeg4video.h"
  48 #include "mpegvideodata.h"
  49
  50 // The defines below define the number of bits that are read at once for
  51 // reading vlc values. Changing these may improve speed and data cache needs
  52 // be aware though that decreasing them may need the number of stages that is
  53 // passed to get_vlc* to be increased.
  54 #define MV_VLC_BITS 9
  55 #define H263_MBTYPE_B_VLC_BITS 6
  56 #define CBPC_B_VLC_BITS 3
  57
  58 static const int h263_mb_type_b_map[15]= {
  59     MB_TYPE_DIRECT2 | MB_TYPE_L0L1,
  60     MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP,
  61     MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT,
  62                       MB_TYPE_L0                                 | MB_TYPE_16x16,
  63                       MB_TYPE_L0   | MB_TYPE_CBP                 | MB_TYPE_16x16,
  64                       MB_TYPE_L0   | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
  65                       MB_TYPE_L1                                 | MB_TYPE_16x16,
  66                       MB_TYPE_L1   | MB_TYPE_CBP                 | MB_TYPE_16x16,
  67                       MB_TYPE_L1   | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
  68                       MB_TYPE_L0L1                               | MB_TYPE_16x16,
  69                       MB_TYPE_L0L1 | MB_TYPE_CBP                 | MB_TYPE_16x16,
  70                       MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
  71     0, //stuffing
  72     MB_TYPE_INTRA4x4                | MB_TYPE_CBP,
  73     MB_TYPE_INTRA4x4                | MB_TYPE_CBP | MB_TYPE_QUANT,
  74 };
  75
  76 void ff_h263_show_pict_info(MpegEncContext *s){
  77     if(s->avctx->debug&FF_DEBUG_PICT_INFO){
  78     av_log(s->avctx, AV_LOG_DEBUG, "qp:%d %c size:%d rnd:%d%s%s%s%s%s%s%s%s%s %d/%d\n",
  79          s->qscale, av_get_picture_type_char(s->pict_type),
  80          s->gb.size_in_bits, 1-s->no_rounding,
  81          s->obmc ? " AP" : "",
  82          s->umvplus ? " UMV" : "",
  83          s->h263_long_vectors ? " LONG" : "",
  84          s->h263_plus ? " +" : "",
  85          s->h263_aic ? " AIC" : "",
  86          s->alt_inter_vlc ? " AIV" : "",
  87          s->modified_quant ? " MQ" : "",
  88          s->loop_filter ? " LOOP" : "",
  89          s->h263_slice_structured ? " SS" : "",
  90          s->avctx->framerate.num, s->avctx->framerate.den
  91     );
  92     }
  93 }
  94
  95 /***********************************************/
  96 /* decoding */
  97
  98 VLC ff_h263_intra_MCBPC_vlc;
  99 VLC ff_h263_inter_MCBPC_vlc;
 100 VLC ff_h263_cbpy_vlc;
 101 static VLC mv_vlc;
 102 static VLC h263_mbtype_b_vlc;
 103 static VLC cbpc_b_vlc;
 104
 105 /* init vlcs */
 106
 107 /* XXX: find a better solution to handle static init */
 108 av_cold void ff_h263_decode_init_vlc(void)
 109 {
 110     static volatile int done = 0;
 111
 112     if (!done) {
 113         INIT_VLC_STATIC(&ff_h263_intra_MCBPC_vlc, INTRA_MCBPC_VLC_BITS, 9,
 114                  ff_h263_intra_MCBPC_bits, 1, 1,
 115                  ff_h263_intra_MCBPC_code, 1, 1, 72);
 116         INIT_VLC_STATIC(&ff_h263_inter_MCBPC_vlc, INTER_MCBPC_VLC_BITS, 28,
 117                  ff_h263_inter_MCBPC_bits, 1, 1,
 118                  ff_h263_inter_MCBPC_code, 1, 1, 198);
 119         INIT_VLC_STATIC(&ff_h263_cbpy_vlc, CBPY_VLC_BITS, 16,
 120                  &ff_h263_cbpy_tab[0][1], 2, 1,
 121                  &ff_h263_cbpy_tab[0][0], 2, 1, 64);
 122         INIT_VLC_STATIC(&mv_vlc, MV_VLC_BITS, 33,
 123                  &ff_mvtab[0][1], 2, 1,
 124                  &ff_mvtab[0][0], 2, 1, 538);
 125         ff_rl_init(&ff_h263_rl_inter, ff_h263_static_rl_table_store[0]);
 126         ff_rl_init(&ff_rl_intra_aic, ff_h263_static_rl_table_store[1]);
 127         INIT_VLC_RL(ff_h263_rl_inter, 554);
 128         INIT_VLC_RL(ff_rl_intra_aic, 554);
 129         INIT_VLC_STATIC(&h263_mbtype_b_vlc, H263_MBTYPE_B_VLC_BITS, 15,
 130                  &ff_h263_mbtype_b_tab[0][1], 2, 1,
 131                  &ff_h263_mbtype_b_tab[0][0], 2, 1, 80);
 132         INIT_VLC_STATIC(&cbpc_b_vlc, CBPC_B_VLC_BITS, 4,
 133                  &ff_cbpc_b_tab[0][1], 2, 1,
 134                  &ff_cbpc_b_tab[0][0], 2, 1, 8);
 135         done = 1;
 136     }
 137 }
 138
 139 int ff_h263_decode_mba(MpegEncContext *s)
 140 {
 141     int i, mb_pos;
 142
 143     for (i = 0; i < 6; i++)
 144         if (s->mb_num - 1 <= ff_mba_max[i])
 145             break;
 146     mb_pos  = get_bits(&s->gb, ff_mba_length[i]);
 147     s->mb_x = mb_pos % s->mb_width;
 148     s->mb_y = mb_pos / s->mb_width;
 149
 150     return mb_pos;
 151 }
 152
 153 /**
 154  * Decode the group of blocks header or slice header.
 155  * @return <0 if an error occurred
 156  */
 157 static int h263_decode_gob_header(MpegEncContext *s)
 158 {
 159     unsigned int val, gob_number;
 160     int left;
 161
 162     /* Check for GOB Start Code */
 163     val = show_bits(&s->gb, 16);
 164     if(val)
 165         return -1;
 166
 167         /* We have a GBSC probably with GSTUFF */
 168     skip_bits(&s->gb, 16); /* Drop the zeros */
 169     left= get_bits_left(&s->gb);
 170     left = FFMIN(left, 32);
 171     //MN: we must check the bits left or we might end in an infinite loop (or segfault)
 172     for(;left>13; left--){
 173         if(get_bits1(&s->gb)) break; /* Seek the '1' bit */
 174     }
 175     if(left<=13)
 176         return -1;
 177
 178     if(s->h263_slice_structured){
 179         if(check_marker(s->avctx, &s->gb, "before MBA")==0)
 180             return -1;
 181
 182         ff_h263_decode_mba(s);
 183
 184         if(s->mb_num > 1583)
 185             if(check_marker(s->avctx, &s->gb, "after MBA")==0)
 186                 return -1;
 187
 188         s->qscale = get_bits(&s->gb, 5); /* SQUANT */
 189         if(check_marker(s->avctx, &s->gb, "after SQUANT")==0)
 190             return -1;
 191         skip_bits(&s->gb, 2); /* GFID */
 192     }else{
 193         gob_number = get_bits(&s->gb, 5); /* GN */
 194         s->mb_x= 0;
 195         s->mb_y= s->gob_index* gob_number;
 196         skip_bits(&s->gb, 2); /* GFID */
 197         s->qscale = get_bits(&s->gb, 5); /* GQUANT */
 198     }
 199
 200     if(s->mb_y >= s->mb_height)
 201         return -1;
 202
 203     if(s->qscale==0)
 204         return -1;
 205
 206     return 0;
 207 }
 208
 209 /**
 210  * Decode the group of blocks / video packet header.
 211  * @return bit position of the resync_marker, or <0 if none was found
 212  */
 213 int ff_h263_resync(MpegEncContext *s){
 214     int left, pos, ret;
 215
 216     if(s->codec_id==AV_CODEC_ID_MPEG4){
 217         skip_bits1(&s->gb);
 218         align_get_bits(&s->gb);
 219     }
 220
 221     if(show_bits(&s->gb, 16)==0){
 222         pos= get_bits_count(&s->gb);
 223         if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
 224             ret= ff_mpeg4_decode_video_packet_header(s->avctx->priv_data);
 225         else
 226             ret= h263_decode_gob_header(s);
 227         if(ret>=0)
 228             return pos;
 229     }
 230     //OK, it's not where it is supposed to be ...
 231     s->gb= s->last_resync_gb;
 232     align_get_bits(&s->gb);
 233     left= get_bits_left(&s->gb);
 234
 235     for(;left>16+1+5+5; left-=8){
 236         if(show_bits(&s->gb, 16)==0){
 237             GetBitContext bak= s->gb;
 238
 239             pos= get_bits_count(&s->gb);
 240             if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
 241                 ret= ff_mpeg4_decode_video_packet_header(s->avctx->priv_data);
 242             else
 243                 ret= h263_decode_gob_header(s);
 244             if(ret>=0)
 245                 return pos;
 246
 247             s->gb= bak;
 248         }
 249         skip_bits(&s->gb, 8);
 250     }
 251
 252     return -1;
 253 }
 254
 255 int ff_h263_decode_motion(MpegEncContext * s, int pred, int f_code)
 256 {
 257     int code, val, sign, shift;
 258     code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
 259
 260     if (code == 0)
 261         return pred;
 262     if (code < 0)
 263         return 0xffff;
 264
 265     sign = get_bits1(&s->gb);
 266     shift = f_code - 1;
 267     val = code;
 268     if (shift) {
 269         val = (val - 1) << shift;
 270         val |= get_bits(&s->gb, shift);
 271         val++;
 272     }
 273     if (sign)
 274         val = -val;
 275     val += pred;
 276
 277     /* modulo decoding */
 278     if (!s->h263_long_vectors) {
 279         val = sign_extend(val, 5 + f_code);
 280     } else {
 281         /* horrible H.263 long vector mode */
 282         if (pred < -31 && val < -63)
 283             val += 64;
 284         if (pred > 32 && val > 63)
 285             val -= 64;
 286
 287     }
 288     return val;
 289 }
 290
 291
 292 /* Decode RVLC of H.263+ UMV */
 293 static int h263p_decode_umotion(MpegEncContext * s, int pred)
 294 {
 295    int code = 0, sign;
 296
 297    if (get_bits1(&s->gb)) /* Motion difference = 0 */
 298       return pred;
 299
 300    code = 2 + get_bits1(&s->gb);
 301
 302    while (get_bits1(&s->gb))
 303    {
 304       code <<= 1;
 305       code += get_bits1(&s->gb);
 306    }
 307    sign = code & 1;
 308    code >>= 1;
 309
 310    code = (sign) ? (pred - code) : (pred + code);
 311    ff_tlog(s->avctx,"H.263+ UMV Motion = %d\n", code);
 312    return code;
 313
 314 }
 315
 316 /**
 317  * read the next MVs for OBMC. yes this is an ugly hack, feel free to send a patch :)
 318  */
 319 static void preview_obmc(MpegEncContext *s){
 320     GetBitContext gb= s->gb;
 321
 322     int cbpc, i, pred_x, pred_y, mx, my;
 323     int16_t *mot_val;
 324     const int xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
 325     const int stride= s->b8_stride*2;
 326
 327     for(i=0; i<4; i++)
 328         s->block_index[i]+= 2;
 329     for(i=4; i<6; i++)
 330         s->block_index[i]+= 1;
 331     s->mb_x++;
 332
 333     av_assert2(s->pict_type == AV_PICTURE_TYPE_P);
 334
 335     do{
 336         if (get_bits1(&s->gb)) {
 337             /* skip mb */
 338             mot_val = s->current_picture.motion_val[0][s->block_index[0]];
 339             mot_val[0       ]= mot_val[2       ]=
 340             mot_val[0+stride]= mot_val[2+stride]= 0;
 341             mot_val[1       ]= mot_val[3       ]=
 342             mot_val[1+stride]= mot_val[3+stride]= 0;
 343
 344             s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
 345             goto end;
 346         }
 347         cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
 348     }while(cbpc == 20);
 349
 350     if(cbpc & 4){
 351         s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
 352     }else{
 353         get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 354         if (cbpc & 8) {
 355             if(s->modified_quant){
 356                 if(get_bits1(&s->gb)) skip_bits(&s->gb, 1);
 357                 else                  skip_bits(&s->gb, 5);
 358             }else
 359                 skip_bits(&s->gb, 2);
 360         }
 361
 362         if ((cbpc & 16) == 0) {
 363                 s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
 364                 /* 16x16 motion prediction */
 365                 mot_val= ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
 366                 if (s->umvplus)
 367                     mx = h263p_decode_umotion(s, pred_x);
 368                 else
 369                     mx = ff_h263_decode_motion(s, pred_x, 1);
 370
 371                 if (s->umvplus)
 372                     my = h263p_decode_umotion(s, pred_y);
 373                 else
 374                     my = ff_h263_decode_motion(s, pred_y, 1);
 375
 376                 mot_val[0       ]= mot_val[2       ]=
 377                 mot_val[0+stride]= mot_val[2+stride]= mx;
 378                 mot_val[1       ]= mot_val[3       ]=
 379                 mot_val[1+stride]= mot_val[3+stride]= my;
 380         } else {
 381             s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
 382             for(i=0;i<4;i++) {
 383                 mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
 384                 if (s->umvplus)
 385                     mx = h263p_decode_umotion(s, pred_x);
 386                 else
 387                     mx = ff_h263_decode_motion(s, pred_x, 1);
 388
 389                 if (s->umvplus)
 390                     my = h263p_decode_umotion(s, pred_y);
 391                 else
 392                     my = ff_h263_decode_motion(s, pred_y, 1);
 393                 if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
 394                     skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
 395                 mot_val[0] = mx;
 396                 mot_val[1] = my;
 397             }
 398         }
 399     }
 400 end:
 401
 402     for(i=0; i<4; i++)
 403         s->block_index[i]-= 2;
 404     for(i=4; i<6; i++)
 405         s->block_index[i]-= 1;
 406     s->mb_x--;
 407
 408     s->gb= gb;
 409 }
 410
 411 static void h263_decode_dquant(MpegEncContext *s){
 412     static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
 413
 414     if(s->modified_quant){
 415         if(get_bits1(&s->gb))
 416             s->qscale= ff_modified_quant_tab[get_bits1(&s->gb)][ s->qscale ];
 417         else
 418             s->qscale= get_bits(&s->gb, 5);
 419     }else
 420         s->qscale += quant_tab[get_bits(&s->gb, 2)];
 421     ff_set_qscale(s, s->qscale);
 422 }
 423
 424 static int h263_decode_block(MpegEncContext * s, int16_t * block,
 425                              int n, int coded)
 426 {
 427     int level, i, j, run;
 428     RLTable *rl = &ff_h263_rl_inter;
 429     const uint8_t *scan_table;
 430     GetBitContext gb= s->gb;
 431
 432     scan_table = s->intra_scantable.permutated;
 433     if (s->h263_aic && s->mb_intra) {
 434         rl = &ff_rl_intra_aic;
 435         i = 0;
 436         if (s->ac_pred) {
 437             if (s->h263_aic_dir)
 438                 scan_table = s->intra_v_scantable.permutated; /* left */
 439             else
 440                 scan_table = s->intra_h_scantable.permutated; /* top */
 441         }
 442     } else if (s->mb_intra) {
 443         /* DC coef */
 444         if (CONFIG_RV10_DECODER && s->codec_id == AV_CODEC_ID_RV10) {
 445           if (s->rv10_version == 3 && s->pict_type == AV_PICTURE_TYPE_I) {
 446             int component, diff;
 447             component = (n <= 3 ? 0 : n - 4 + 1);
 448             level = s->last_dc[component];
 449             if (s->rv10_first_dc_coded[component]) {
 450                 diff = ff_rv_decode_dc(s, n);
 451                 if (diff == 0xffff)
 452                     return -1;
 453                 level += diff;
 454                 level = level & 0xff; /* handle wrap round */
 455                 s->last_dc[component] = level;
 456             } else {
 457                 s->rv10_first_dc_coded[component] = 1;
 458             }
 459           } else {
 460                 level = get_bits(&s->gb, 8);
 461                 if (level == 255)
 462                     level = 128;
 463           }
 464         }else{
 465             level = get_bits(&s->gb, 8);
 466             if((level&0x7F) == 0){
 467                 av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
 468                 if (s->avctx->err_recognition & (AV_EF_BITSTREAM|AV_EF_COMPLIANT))
 469                     return -1;
 470             }
 471             if (level == 255)
 472                 level = 128;
 473         }
 474         block[0] = level;
 475         i = 1;
 476     } else {
 477         i = 0;
 478     }
 479     if (!coded) {
 480         if (s->mb_intra && s->h263_aic)
 481             goto not_coded;
 482         s->block_last_index[n] = i - 1;
 483         return 0;
 484     }
 485 retry:
 486     {
 487     OPEN_READER(re, &s->gb);
 488     i--; // offset by -1 to allow direct indexing of scan_table
 489     for(;;) {
 490         UPDATE_CACHE(re, &s->gb);
 491         GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
 492         if (run == 66) {
 493             if (level){
 494                 CLOSE_READER(re, &s->gb);
 495                 av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
 496                 return -1;
 497             }
 498             /* escape */
 499             if (CONFIG_FLV_DECODER && s->h263_flv > 1) {
 500                 int is11 = SHOW_UBITS(re, &s->gb, 1);
 501                 SKIP_CACHE(re, &s->gb, 1);
 502                 run = SHOW_UBITS(re, &s->gb, 7) + 1;
 503                 if (is11) {
 504                     SKIP_COUNTER(re, &s->gb, 1 + 7);
 505                     UPDATE_CACHE(re, &s->gb);
 506                     level = SHOW_SBITS(re, &s->gb, 11);
 507                     SKIP_COUNTER(re, &s->gb, 11);
 508                 } else {
 509                     SKIP_CACHE(re, &s->gb, 7);
 510                     level = SHOW_SBITS(re, &s->gb, 7);
 511                     SKIP_COUNTER(re, &s->gb, 1 + 7 + 7);
 512                 }
 513             } else {
 514                 run = SHOW_UBITS(re, &s->gb, 7) + 1;
 515                 SKIP_CACHE(re, &s->gb, 7);
 516                 level = (int8_t)SHOW_UBITS(re, &s->gb, 8);
 517                 SKIP_COUNTER(re, &s->gb, 7 + 8);
 518                 if(level == -128){
 519                     UPDATE_CACHE(re, &s->gb);
 520                     if (s->codec_id == AV_CODEC_ID_RV10) {
 521                         /* XXX: should patch encoder too */
 522                         level = SHOW_SBITS(re, &s->gb, 12);
 523                         SKIP_COUNTER(re, &s->gb, 12);
 524                     }else{
 525                         level = SHOW_UBITS(re, &s->gb, 5);
 526                         SKIP_CACHE(re, &s->gb, 5);
 527                         level |= SHOW_SBITS(re, &s->gb, 6)<<5;
 528                         SKIP_COUNTER(re, &s->gb, 5 + 6);
 529                     }
 530                 }
 531             }
 532         } else {
 533             if (SHOW_UBITS(re, &s->gb, 1))
 534                 level = -level;
 535             SKIP_COUNTER(re, &s->gb, 1);
 536         }
 537         i += run;
 538         if (i >= 64){
 539             CLOSE_READER(re, &s->gb);
 540             // redo update without last flag, revert -1 offset
 541             i = i - run + ((run-1)&63) + 1;
 542             if (i < 64) {
 543                 // only last marker, no overrun
 544                 block[scan_table[i]] = level;
 545                 break;
 546             }
 547             if(s->alt_inter_vlc && rl == &ff_h263_rl_inter && !s->mb_intra){
 548                 //Looks like a hack but no, it's the way it is supposed to work ...
 549                 rl = &ff_rl_intra_aic;
 550                 i = 0;
 551                 s->gb= gb;
 552                 s->bdsp.clear_block(block);
 553                 goto retry;
 554             }
 555             av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
 556             return -1;
 557         }
 558         j = scan_table[i];
 559         block[j] = level;
 560     }
 561     }
 562 not_coded:
 563     if (s->mb_intra && s->h263_aic) {
 564         ff_h263_pred_acdc(s, block, n);
 565         i = 63;
 566     }
 567     s->block_last_index[n] = i;
 568     return 0;
 569 }
 570
 571 static int h263_skip_b_part(MpegEncContext *s, int cbp)
 572 {
 573     LOCAL_ALIGNED_16(int16_t, dblock, [64]);
 574     int i, mbi;
 575     int bli[6];
 576
 577     /* we have to set s->mb_intra to zero to decode B-part of PB-frame correctly
 578      * but real value should be restored in order to be used later (in OBMC condition)
 579      */
 580     mbi = s->mb_intra;
 581     memcpy(bli, s->block_last_index, sizeof(bli));
 582     s->mb_intra = 0;
 583     for (i = 0; i < 6; i++) {
 584         if (h263_decode_block(s, dblock, i, cbp&32) < 0)
 585             return -1;
 586         cbp+=cbp;
 587     }
 588     s->mb_intra = mbi;
 589     memcpy(s->block_last_index, bli, sizeof(bli));
 590     return 0;
 591 }
 592
 593 static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
 594 {
 595     int c, mv = 1;
 596
 597     if (pb_frame < 3) { // h.263 Annex G and i263 PB-frame
 598         c = get_bits1(gb);
 599         if (pb_frame == 2 && c)
 600             mv = !get_bits1(gb);
 601     } else { // h.263 Annex M improved PB-frame
 602         mv = get_unary(gb, 0, 4) + 1;
 603         c = mv & 1;
 604         mv = !!(mv & 2);
 605     }
 606     if(c)
 607         *cbpb = get_bits(gb, 6);
 608     return mv;
 609 }
 610
 611 int ff_h263_decode_mb(MpegEncContext *s,
 612                       int16_t block[6][64])
 613 {
 614     int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
 615     int16_t *mot_val;
 616     const int xy= s->mb_x + s->mb_y * s->mb_stride;
 617     int cbpb = 0, pb_mv_count = 0;
 618
 619     av_assert2(!s->h263_pred);
 620
 621     if (s->pict_type == AV_PICTURE_TYPE_P) {
 622         do{
 623             if (get_bits1(&s->gb)) {
 624                 /* skip mb */
 625                 s->mb_intra = 0;
 626                 for(i=0;i<6;i++)
 627                     s->block_last_index[i] = -1;
 628                 s->mv_dir = MV_DIR_FORWARD;
 629                 s->mv_type = MV_TYPE_16X16;
 630                 s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
 631                 s->mv[0][0][0] = 0;
 632                 s->mv[0][0][1] = 0;
 633                 s->mb_skipped = !(s->obmc | s->loop_filter);
 634                 goto end;
 635             }
 636             cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
 637             if (cbpc < 0){
 638                 av_log(s->avctx, AV_LOG_ERROR, "cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
 639                 return -1;
 640             }
 641         }while(cbpc == 20);
 642
 643         s->bdsp.clear_blocks(s->block[0]);
 644
 645         dquant = cbpc & 8;
 646         s->mb_intra = ((cbpc & 4) != 0);
 647         if (s->mb_intra) goto intra;
 648
 649         if(s->pb_frame && get_bits1(&s->gb))
 650             pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
 651         cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 652
 653         if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
 654             cbpy ^= 0xF;
 655
 656         cbp = (cbpc & 3) | (cbpy << 2);
 657         if (dquant) {
 658             h263_decode_dquant(s);
 659         }
 660
 661         s->mv_dir = MV_DIR_FORWARD;
 662         if ((cbpc & 16) == 0) {
 663             s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
 664             /* 16x16 motion prediction */
 665             s->mv_type = MV_TYPE_16X16;
 666             ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
 667             if (s->umvplus)
 668                mx = h263p_decode_umotion(s, pred_x);
 669             else
 670                mx = ff_h263_decode_motion(s, pred_x, 1);
 671
 672             if (mx >= 0xffff)
 673                 return -1;
 674
 675             if (s->umvplus)
 676                my = h263p_decode_umotion(s, pred_y);
 677             else
 678                my = ff_h263_decode_motion(s, pred_y, 1);
 679
 680             if (my >= 0xffff)
 681                 return -1;
 682             s->mv[0][0][0] = mx;
 683             s->mv[0][0][1] = my;
 684
 685             if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
 686                skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
 687         } else {
 688             s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
 689             s->mv_type = MV_TYPE_8X8;
 690             for(i=0;i<4;i++) {
 691                 mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
 692                 if (s->umvplus)
 693                     mx = h263p_decode_umotion(s, pred_x);
 694                 else
 695                     mx = ff_h263_decode_motion(s, pred_x, 1);
 696                 if (mx >= 0xffff)
 697                     return -1;
 698
 699                 if (s->umvplus)
 700                     my = h263p_decode_umotion(s, pred_y);
 701                 else
 702                     my = ff_h263_decode_motion(s, pred_y, 1);
 703                 if (my >= 0xffff)
 704                     return -1;
 705                 s->mv[0][i][0] = mx;
 706                 s->mv[0][i][1] = my;
 707                 if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
 708                   skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
 709                 mot_val[0] = mx;
 710                 mot_val[1] = my;
 711             }
 712         }
 713     } else if(s->pict_type==AV_PICTURE_TYPE_B) {
 714         int mb_type;
 715         const int stride= s->b8_stride;
 716         int16_t *mot_val0 = s->current_picture.motion_val[0][2 * (s->mb_x + s->mb_y * stride)];
 717         int16_t *mot_val1 = s->current_picture.motion_val[1][2 * (s->mb_x + s->mb_y * stride)];
 718 //        const int mv_xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
 719
 720         //FIXME ugly
 721         mot_val0[0       ]= mot_val0[2       ]= mot_val0[0+2*stride]= mot_val0[2+2*stride]=
 722         mot_val0[1       ]= mot_val0[3       ]= mot_val0[1+2*stride]= mot_val0[3+2*stride]=
 723         mot_val1[0       ]= mot_val1[2       ]= mot_val1[0+2*stride]= mot_val1[2+2*stride]=
 724         mot_val1[1       ]= mot_val1[3       ]= mot_val1[1+2*stride]= mot_val1[3+2*stride]= 0;
 725
 726         do{
 727             mb_type= get_vlc2(&s->gb, h263_mbtype_b_vlc.table, H263_MBTYPE_B_VLC_BITS, 2);
 728             if (mb_type < 0){
 729                 av_log(s->avctx, AV_LOG_ERROR, "b mb_type damaged at %d %d\n", s->mb_x, s->mb_y);
 730                 return -1;
 731             }
 732
 733             mb_type= h263_mb_type_b_map[ mb_type ];
 734         }while(!mb_type);
 735
 736         s->mb_intra = IS_INTRA(mb_type);
 737         if(HAS_CBP(mb_type)){
 738             s->bdsp.clear_blocks(s->block[0]);
 739             cbpc = get_vlc2(&s->gb, cbpc_b_vlc.table, CBPC_B_VLC_BITS, 1);
 740             if(s->mb_intra){
 741                 dquant = IS_QUANT(mb_type);
 742                 goto intra;
 743             }
 744
 745             cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 746
 747             if (cbpy < 0){
 748                 av_log(s->avctx, AV_LOG_ERROR, "b cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
 749                 return -1;
 750             }
 751
 752             if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
 753                 cbpy ^= 0xF;
 754
 755             cbp = (cbpc & 3) | (cbpy << 2);
 756         }else
 757             cbp=0;
 758
 759         av_assert2(!s->mb_intra);
 760
 761         if(IS_QUANT(mb_type)){
 762             h263_decode_dquant(s);
 763         }
 764
 765         if(IS_DIRECT(mb_type)){
 766             s->mv_dir = MV_DIR_FORWARD | MV_DIR_BACKWARD | MV_DIRECT;
 767             mb_type |= ff_mpeg4_set_direct_mv(s, 0, 0);
 768         }else{
 769             s->mv_dir = 0;
 770             s->mv_type= MV_TYPE_16X16;
 771 //FIXME UMV
 772
 773             if(USES_LIST(mb_type, 0)){
 774                 int16_t *mot_val= ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
 775                 s->mv_dir = MV_DIR_FORWARD;
 776
 777                 if (s->umvplus)
 778                     mx = h263p_decode_umotion(s, pred_x);
 779                 else
 780                     mx = ff_h263_decode_motion(s, pred_x, 1);
 781                 if (mx >= 0xffff)
 782                     return -1;
 783
 784                 if (s->umvplus)
 785                     my = h263p_decode_umotion(s, pred_y);
 786                 else
 787                     my = ff_h263_decode_motion(s, pred_y, 1);
 788                 if (my >= 0xffff)
 789                     return -1;
 790
 791                 if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
 792                     skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
 793
 794                 s->mv[0][0][0] = mx;
 795                 s->mv[0][0][1] = my;
 796                 mot_val[0       ]= mot_val[2       ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
 797                 mot_val[1       ]= mot_val[3       ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
 798             }
 799
 800             if(USES_LIST(mb_type, 1)){
 801                 int16_t *mot_val= ff_h263_pred_motion(s, 0, 1, &pred_x, &pred_y);
 802                 s->mv_dir |= MV_DIR_BACKWARD;
 803
 804                 if (s->umvplus)
 805                     mx = h263p_decode_umotion(s, pred_x);
 806                 else
 807                     mx = ff_h263_decode_motion(s, pred_x, 1);
 808                 if (mx >= 0xffff)
 809                     return -1;
 810
 811                 if (s->umvplus)
 812                     my = h263p_decode_umotion(s, pred_y);
 813                 else
 814                     my = ff_h263_decode_motion(s, pred_y, 1);
 815                 if (my >= 0xffff)
 816                     return -1;
 817
 818                 if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
 819                     skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
 820
 821                 s->mv[1][0][0] = mx;
 822                 s->mv[1][0][1] = my;
 823                 mot_val[0       ]= mot_val[2       ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
 824                 mot_val[1       ]= mot_val[3       ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
 825             }
 826         }
 827
 828         s->current_picture.mb_type[xy] = mb_type;
 829     } else { /* I-Frame */
 830         do{
 831             cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
 832             if (cbpc < 0){
 833                 av_log(s->avctx, AV_LOG_ERROR, "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
 834                 return -1;
 835             }
 836         }while(cbpc == 8);
 837
 838         s->bdsp.clear_blocks(s->block[0]);
 839
 840         dquant = cbpc & 4;
 841         s->mb_intra = 1;
 842 intra:
 843         s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
 844         if (s->h263_aic) {
 845             s->ac_pred = get_bits1(&s->gb);
 846             if(s->ac_pred){
 847                 s->current_picture.mb_type[xy] = MB_TYPE_INTRA | MB_TYPE_ACPRED;
 848
 849                 s->h263_aic_dir = get_bits1(&s->gb);
 850             }
 851         }else
 852             s->ac_pred = 0;
 853
 854         if(s->pb_frame && get_bits1(&s->gb))
 855             pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
 856         cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 857         if(cbpy<0){
 858             av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
 859             return -1;
 860         }
 861         cbp = (cbpc & 3) | (cbpy << 2);
 862         if (dquant) {
 863             h263_decode_dquant(s);
 864         }
 865
 866         pb_mv_count += !!s->pb_frame;
 867     }
 868
 869     while(pb_mv_count--){
 870         ff_h263_decode_motion(s, 0, 1);
 871         ff_h263_decode_motion(s, 0, 1);
 872     }
 873
 874     /* decode each block */
 875     for (i = 0; i < 6; i++) {
 876         if (h263_decode_block(s, block[i], i, cbp&32) < 0)
 877             return -1;
 878         cbp+=cbp;
 879     }
 880
 881     if(s->pb_frame && h263_skip_b_part(s, cbpb) < 0)
 882         return -1;
 883     if(s->obmc && !s->mb_intra){
 884         if(s->pict_type == AV_PICTURE_TYPE_P && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
 885             preview_obmc(s);
 886     }
 887 end:
 888
 889         /* per-MB end of slice check */
 890     {
 891         int v= show_bits(&s->gb, 16);
 892
 893         if (get_bits_left(&s->gb) < 16) {
 894             v >>= 16 - get_bits_left(&s->gb);
 895         }
 896
 897         if(v==0)
 898             return SLICE_END;
 899     }
 900
 901     return SLICE_OK;
 902 }
 903
 904 /* Most is hardcoded; should extend to handle all H.263 streams. */
 905 int ff_h263_decode_picture_header(MpegEncContext *s)
 906 {
 907     int format, width, height, i, ret;
 908     uint32_t startcode;
 909
 910     align_get_bits(&s->gb);
 911
 912     if (show_bits(&s->gb, 2) == 2 && s->avctx->frame_number == 0) {
 913          av_log(s->avctx, AV_LOG_WARNING, "Header looks like RTP instead of H.263\n");
 914     }
 915
 916     startcode= get_bits(&s->gb, 22-8);
 917
 918     for(i= get_bits_left(&s->gb); i>24; i-=8) {
 919         startcode = ((startcode << 8) | get_bits(&s->gb, 8)) & 0x003FFFFF;
 920
 921         if(startcode == 0x20)
 922             break;
 923     }
 924
 925     if (startcode != 0x20) {
 926         av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
 927         return -1;
 928     }
 929     /* temporal reference */
 930     i = get_bits(&s->gb, 8); /* picture timestamp */
 931     if( (s->picture_number&~0xFF)+i < s->picture_number)
 932         i+= 256;
 933     s->picture_number= (s->picture_number&~0xFF) + i;
 934
 935     /* PTYPE starts here */
 936     if (check_marker(s->avctx, &s->gb, "in PTYPE") != 1) {
 937         return -1;
 938     }
 939     if (get_bits1(&s->gb) != 0) {
 940         av_log(s->avctx, AV_LOG_ERROR, "Bad H.263 id\n");
 941         return -1;      /* H.263 id */
 942     }
 943     skip_bits1(&s->gb);         /* split screen off */
 944     skip_bits1(&s->gb);         /* camera  off */
 945     skip_bits1(&s->gb);         /* freeze picture release off */
 946
 947     format = get_bits(&s->gb, 3);
 948     /*
 949         0    forbidden
 950         1    sub-QCIF
 951         10   QCIF
 952         7       extended PTYPE (PLUSPTYPE)
 953     */
 954
 955     if (format != 7 && format != 6) {
 956         s->h263_plus = 0;
 957         /* H.263v1 */
 958         width = ff_h263_format[format][0];
 959         height = ff_h263_format[format][1];
 960         if (!width)
 961             return -1;
 962
 963         s->pict_type = AV_PICTURE_TYPE_I + get_bits1(&s->gb);
 964
 965         s->h263_long_vectors = get_bits1(&s->gb);
 966
 967         if (get_bits1(&s->gb) != 0) {
 968             av_log(s->avctx, AV_LOG_ERROR, "H.263 SAC not supported\n");
 969             return -1; /* SAC: off */
 970         }
 971         s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
 972         s->unrestricted_mv = s->h263_long_vectors || s->obmc;
 973
 974         s->pb_frame = get_bits1(&s->gb);
 975         s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
 976         skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
 977
 978         s->width = width;
 979         s->height = height;
 980         s->avctx->sample_aspect_ratio= (AVRational){12,11};
 981         s->avctx->framerate = (AVRational){ 30000, 1001 };
 982     } else {
 983         int ufep;
 984
 985         /* H.263v2 */
 986         s->h263_plus = 1;
 987         ufep = get_bits(&s->gb, 3); /* Update Full Extended PTYPE */
 988
 989         /* ufep other than 0 and 1 are reserved */
 990         if (ufep == 1) {
 991             /* OPPTYPE */
 992             format = get_bits(&s->gb, 3);
 993             ff_dlog(s->avctx, "ufep=1, format: %d\n", format);
 994             s->custom_pcf= get_bits1(&s->gb);
 995             s->umvplus = get_bits1(&s->gb); /* Unrestricted Motion Vector */
 996             if (get_bits1(&s->gb) != 0) {
 997                 av_log(s->avctx, AV_LOG_ERROR, "Syntax-based Arithmetic Coding (SAC) not supported\n");
 998             }
 999             s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
1000             s->h263_aic = get_bits1(&s->gb); /* Advanced Intra Coding (AIC) */
1001             s->loop_filter= get_bits1(&s->gb);
1002             s->unrestricted_mv = s->umvplus || s->obmc || s->loop_filter;
1003             if(s->avctx->lowres)
1004                 s->loop_filter = 0;
1005
1006             s->h263_slice_structured= get_bits1(&s->gb);
1007             if (get_bits1(&s->gb) != 0) {
1008                 av_log(s->avctx, AV_LOG_ERROR, "Reference Picture Selection not supported\n");
1009             }
1010             if (get_bits1(&s->gb) != 0) {
1011                 av_log(s->avctx, AV_LOG_ERROR, "Independent Segment Decoding not supported\n");
1012             }
1013             s->alt_inter_vlc= get_bits1(&s->gb);
1014             s->modified_quant= get_bits1(&s->gb);
1015             if(s->modified_quant)
1016                 s->chroma_qscale_table= ff_h263_chroma_qscale_table;
1017
1018             skip_bits(&s->gb, 1); /* Prevent start code emulation */
1019
1020             skip_bits(&s->gb, 3); /* Reserved */
1021         } else if (ufep != 0) {
1022             av_log(s->avctx, AV_LOG_ERROR, "Bad UFEP type (%d)\n", ufep);
1023             return -1;
1024         }
1025
1026         /* MPPTYPE */
1027         s->pict_type = get_bits(&s->gb, 3);
1028         switch(s->pict_type){
1029         case 0: s->pict_type= AV_PICTURE_TYPE_I;break;
1030         case 1: s->pict_type= AV_PICTURE_TYPE_P;break;
1031         case 2: s->pict_type= AV_PICTURE_TYPE_P;s->pb_frame = 3;break;
1032         case 3: s->pict_type= AV_PICTURE_TYPE_B;break;
1033         case 7: s->pict_type= AV_PICTURE_TYPE_I;break; //ZYGO
1034         default:
1035             return -1;
1036         }
1037         skip_bits(&s->gb, 2);
1038         s->no_rounding = get_bits1(&s->gb);
1039         skip_bits(&s->gb, 4);
1040
1041         /* Get the picture dimensions */
1042         if (ufep) {
1043             if (format == 6) {
1044                 /* Custom Picture Format (CPFMT) */
1045                 s->aspect_ratio_info = get_bits(&s->gb, 4);
1046                 ff_dlog(s->avctx, "aspect: %d\n", s->aspect_ratio_info);
1047                 /* aspect ratios:
1048                 0 - forbidden
1049                 1 - 1:1
1050                 2 - 12:11 (CIF 4:3)
1051                 3 - 10:11 (525-type 4:3)
1052                 4 - 16:11 (CIF 16:9)
1053                 5 - 40:33 (525-type 16:9)
1054                 6-14 - reserved
1055                 */
1056                 width = (get_bits(&s->gb, 9) + 1) * 4;
1057                 check_marker(s->avctx, &s->gb, "in dimensions");
1058                 height = get_bits(&s->gb, 9) * 4;
1059                 ff_dlog(s->avctx, "\nH.263+ Custom picture: %dx%d\n",width,height);
1060                 if (s->aspect_ratio_info == FF_ASPECT_EXTENDED) {
1061                     /* expected dimensions */
1062                     s->avctx->sample_aspect_ratio.num= get_bits(&s->gb, 8);
1063                     s->avctx->sample_aspect_ratio.den= get_bits(&s->gb, 8);
1064                 }else{
1065                     s->avctx->sample_aspect_ratio= ff_h263_pixel_aspect[s->aspect_ratio_info];
1066                 }
1067             } else {
1068                 width = ff_h263_format[format][0];
1069                 height = ff_h263_format[format][1];
1070                 s->avctx->sample_aspect_ratio= (AVRational){12,11};
1071             }
1072             s->avctx->sample_aspect_ratio.den <<= s->ehc_mode;
1073             if ((width == 0) || (height == 0))
1074                 return -1;
1075             s->width = width;
1076             s->height = height;
1077
1078             if(s->custom_pcf){
1079                 int gcd;
1080                 s->avctx->framerate.num  = 1800000;
1081                 s->avctx->framerate.den  = 1000 + get_bits1(&s->gb);
1082                 s->avctx->framerate.den *= get_bits(&s->gb, 7);
1083                 if(s->avctx->framerate.den == 0){
1084                     av_log(s, AV_LOG_ERROR, "zero framerate\n");
1085                     return -1;
1086                 }
1087                 gcd= av_gcd(s->avctx->framerate.den, s->avctx->framerate.num);
1088                 s->avctx->framerate.den /= gcd;
1089                 s->avctx->framerate.num /= gcd;
1090             }else{
1091                 s->avctx->framerate = (AVRational){ 30000, 1001 };
1092             }
1093         }
1094
1095         if(s->custom_pcf){
1096             skip_bits(&s->gb, 2); //extended Temporal reference
1097         }
1098
1099         if (ufep) {
1100             if (s->umvplus) {
1101                 if(get_bits1(&s->gb)==0) /* Unlimited Unrestricted Motion Vectors Indicator (UUI) */
1102                     skip_bits1(&s->gb);
1103             }
1104             if(s->h263_slice_structured){
1105                 if (get_bits1(&s->gb) != 0) {
1106                     av_log(s->avctx, AV_LOG_ERROR, "rectangular slices not supported\n");
1107                 }
1108                 if (get_bits1(&s->gb) != 0) {
1109                     av_log(s->avctx, AV_LOG_ERROR, "unordered slices not supported\n");
1110                 }
1111             }
1112             if (s->pict_type == AV_PICTURE_TYPE_B) {
1113                 skip_bits(&s->gb, 4); //ELNUM
1114                 if (ufep == 1) {
1115                     skip_bits(&s->gb, 4); // RLNUM
1116                 }
1117             }
1118         }
1119
1120         s->qscale = get_bits(&s->gb, 5);
1121     }
1122
1123     if ((ret = av_image_check_size(s->width, s->height, 0, s)) < 0)
1124         return ret;
1125
1126     s->mb_width = (s->width  + 15) / 16;
1127     s->mb_height = (s->height  + 15) / 16;
1128     s->mb_num = s->mb_width * s->mb_height;
1129
1130     if (s->pb_frame) {
1131         skip_bits(&s->gb, 3); /* Temporal reference for B-pictures */
1132         if (s->custom_pcf)
1133             skip_bits(&s->gb, 2); //extended Temporal reference
1134         skip_bits(&s->gb, 2); /* Quantization information for B-pictures */
1135     }
1136
1137     if (s->pict_type!=AV_PICTURE_TYPE_B) {
1138         s->time            = s->picture_number;
1139         s->pp_time         = s->time - s->last_non_b_time;
1140         s->last_non_b_time = s->time;
1141     }else{
1142         s->time    = s->picture_number;
1143         s->pb_time = s->pp_time - (s->last_non_b_time - s->time);
1144         if (s->pp_time <=s->pb_time ||
1145             s->pp_time <= s->pp_time - s->pb_time ||
1146             s->pp_time <= 0){
1147             s->pp_time = 2;
1148             s->pb_time = 1;
1149         }
1150         ff_mpeg4_init_direct_mv(s);
1151     }
1152
1153     /* PEI */
1154     if (skip_1stop_8data_bits(&s->gb) < 0)
1155         return AVERROR_INVALIDDATA;
1156
1157     if(s->h263_slice_structured){
1158         if (check_marker(s->avctx, &s->gb, "SEPB1") != 1) {
1159             return -1;
1160         }
1161
1162         ff_h263_decode_mba(s);
1163
1164         if (check_marker(s->avctx, &s->gb, "SEPB2") != 1) {
1165             return -1;
1166         }
1167     }
1168     s->f_code = 1;
1169
1170     if (s->pict_type == AV_PICTURE_TYPE_B)
1171         s->low_delay = 0;
1172
1173     if(s->h263_aic){
1174          s->y_dc_scale_table=
1175          s->c_dc_scale_table= ff_aic_dc_scale_table;
1176     }else{
1177         s->y_dc_scale_table=
1178         s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
1179     }
1180
1181         ff_h263_show_pict_info(s);
1182     if (s->pict_type == AV_PICTURE_TYPE_I && s->codec_tag == AV_RL32("ZYGO") && get_bits_left(&s->gb) >= 85 + 13*3*16 + 50){
1183         int i,j;
1184         for(i=0; i<85; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1185         av_log(s->avctx, AV_LOG_DEBUG, "\n");
1186         for(i=0; i<13; i++){
1187             for(j=0; j<3; j++){
1188                 int v= get_bits(&s->gb, 8);
1189                 v |= get_sbits(&s->gb, 8)<<8;
1190                 av_log(s->avctx, AV_LOG_DEBUG, " %5d", v);
1191             }
1192             av_log(s->avctx, AV_LOG_DEBUG, "\n");
1193         }
1194         for(i=0; i<50; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1195     }
1196
1197     return 0;
1198 }