git.sesse.net Git - ffmpeg/blob - libavcodec/ituh263dec.c

   1 /*
   2  * ITU H263 bitstream decoder
   3  * Copyright (c) 2000,2001 Fabrice Bellard
   4  * H263+ 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  * h263 decoder.
  28  */
  29
  30 #define UNCHECKED_BITSTREAM_READER 1
  31 #include <limits.h>
  32
  33 #include "libavutil/attributes.h"
  34 #include "libavutil/internal.h"
  35 #include "libavutil/mathematics.h"
  36 #include "avcodec.h"
  37 #include "mpegvideo.h"
  38 #include "h263.h"
  39 #include "mathops.h"
  40 #include "mpegutils.h"
  41 #include "unary.h"
  42 #include "flv.h"
  43 #include "mpeg4video.h"
  44
  45 // The defines below define the number of bits that are read at once for
  46 // reading vlc values. Changing these may improve speed and data cache needs
  47 // be aware though that decreasing them may need the number of stages that is
  48 // passed to get_vlc* to be increased.
  49 #define MV_VLC_BITS 9
  50 #define H263_MBTYPE_B_VLC_BITS 6
  51 #define CBPC_B_VLC_BITS 3
  52
  53 static const int h263_mb_type_b_map[15]= {
  54     MB_TYPE_DIRECT2 | MB_TYPE_L0L1,
  55     MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP,
  56     MB_TYPE_DIRECT2 | MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT,
  57                       MB_TYPE_L0                                 | MB_TYPE_16x16,
  58                       MB_TYPE_L0   | MB_TYPE_CBP                 | MB_TYPE_16x16,
  59                       MB_TYPE_L0   | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
  60                       MB_TYPE_L1                                 | MB_TYPE_16x16,
  61                       MB_TYPE_L1   | MB_TYPE_CBP                 | MB_TYPE_16x16,
  62                       MB_TYPE_L1   | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
  63                       MB_TYPE_L0L1                               | MB_TYPE_16x16,
  64                       MB_TYPE_L0L1 | MB_TYPE_CBP                 | MB_TYPE_16x16,
  65                       MB_TYPE_L0L1 | MB_TYPE_CBP | MB_TYPE_QUANT | MB_TYPE_16x16,
  66     0, //stuffing
  67     MB_TYPE_INTRA4x4                | MB_TYPE_CBP,
  68     MB_TYPE_INTRA4x4                | MB_TYPE_CBP | MB_TYPE_QUANT,
  69 };
  70
  71 void ff_h263_show_pict_info(MpegEncContext *s){
  72     if(s->avctx->debug&FF_DEBUG_PICT_INFO){
  73     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",
  74          s->qscale, av_get_picture_type_char(s->pict_type),
  75          s->gb.size_in_bits, 1-s->no_rounding,
  76          s->obmc ? " AP" : "",
  77          s->umvplus ? " UMV" : "",
  78          s->h263_long_vectors ? " LONG" : "",
  79          s->h263_plus ? " +" : "",
  80          s->h263_aic ? " AIC" : "",
  81          s->alt_inter_vlc ? " AIV" : "",
  82          s->modified_quant ? " MQ" : "",
  83          s->loop_filter ? " LOOP" : "",
  84          s->h263_slice_structured ? " SS" : "",
  85          s->avctx->time_base.den, s->avctx->time_base.num
  86     );
  87     }
  88 }
  89
  90 /***********************************************/
  91 /* decoding */
  92
  93 VLC ff_h263_intra_MCBPC_vlc;
  94 VLC ff_h263_inter_MCBPC_vlc;
  95 VLC ff_h263_cbpy_vlc;
  96 static VLC mv_vlc;
  97 static VLC h263_mbtype_b_vlc;
  98 static VLC cbpc_b_vlc;
  99
 100 /* init vlcs */
 101
 102 /* XXX: find a better solution to handle static init */
 103 av_cold void ff_h263_decode_init_vlc(void)
 104 {
 105     static volatile int done = 0;
 106
 107     if (!done) {
 108         INIT_VLC_STATIC(&ff_h263_intra_MCBPC_vlc, INTRA_MCBPC_VLC_BITS, 9,
 109                  ff_h263_intra_MCBPC_bits, 1, 1,
 110                  ff_h263_intra_MCBPC_code, 1, 1, 72);
 111         INIT_VLC_STATIC(&ff_h263_inter_MCBPC_vlc, INTER_MCBPC_VLC_BITS, 28,
 112                  ff_h263_inter_MCBPC_bits, 1, 1,
 113                  ff_h263_inter_MCBPC_code, 1, 1, 198);
 114         INIT_VLC_STATIC(&ff_h263_cbpy_vlc, CBPY_VLC_BITS, 16,
 115                  &ff_h263_cbpy_tab[0][1], 2, 1,
 116                  &ff_h263_cbpy_tab[0][0], 2, 1, 64);
 117         INIT_VLC_STATIC(&mv_vlc, MV_VLC_BITS, 33,
 118                  &ff_mvtab[0][1], 2, 1,
 119                  &ff_mvtab[0][0], 2, 1, 538);
 120         ff_init_rl(&ff_h263_rl_inter, ff_h263_static_rl_table_store[0]);
 121         ff_init_rl(&ff_rl_intra_aic, ff_h263_static_rl_table_store[1]);
 122         INIT_VLC_RL(ff_h263_rl_inter, 554);
 123         INIT_VLC_RL(ff_rl_intra_aic, 554);
 124         INIT_VLC_STATIC(&h263_mbtype_b_vlc, H263_MBTYPE_B_VLC_BITS, 15,
 125                  &ff_h263_mbtype_b_tab[0][1], 2, 1,
 126                  &ff_h263_mbtype_b_tab[0][0], 2, 1, 80);
 127         INIT_VLC_STATIC(&cbpc_b_vlc, CBPC_B_VLC_BITS, 4,
 128                  &ff_cbpc_b_tab[0][1], 2, 1,
 129                  &ff_cbpc_b_tab[0][0], 2, 1, 8);
 130         done = 1;
 131     }
 132 }
 133
 134 int ff_h263_decode_mba(MpegEncContext *s)
 135 {
 136     int i, mb_pos;
 137
 138     for(i=0; i<6; i++){
 139         if(s->mb_num-1 <= ff_mba_max[i]) break;
 140     }
 141     mb_pos= get_bits(&s->gb, ff_mba_length[i]);
 142     s->mb_x= mb_pos % s->mb_width;
 143     s->mb_y= mb_pos / s->mb_width;
 144
 145     return mb_pos;
 146 }
 147
 148 /**
 149  * Decode the group of blocks header or slice header.
 150  * @return <0 if an error occurred
 151  */
 152 static int h263_decode_gob_header(MpegEncContext *s)
 153 {
 154     unsigned int val, gob_number;
 155     int left;
 156
 157     /* Check for GOB Start Code */
 158     val = show_bits(&s->gb, 16);
 159     if(val)
 160         return -1;
 161
 162         /* We have a GBSC probably with GSTUFF */
 163     skip_bits(&s->gb, 16); /* Drop the zeros */
 164     left= get_bits_left(&s->gb);
 165     //MN: we must check the bits left or we might end in a infinite loop (or segfault)
 166     for(;left>13; left--){
 167         if(get_bits1(&s->gb)) break; /* Seek the '1' bit */
 168     }
 169     if(left<=13)
 170         return -1;
 171
 172     if(s->h263_slice_structured){
 173         if(get_bits1(&s->gb)==0)
 174             return -1;
 175
 176         ff_h263_decode_mba(s);
 177
 178         if(s->mb_num > 1583)
 179             if(get_bits1(&s->gb)==0)
 180                 return -1;
 181
 182         s->qscale = get_bits(&s->gb, 5); /* SQUANT */
 183         if(get_bits1(&s->gb)==0)
 184             return -1;
 185         skip_bits(&s->gb, 2); /* GFID */
 186     }else{
 187         gob_number = get_bits(&s->gb, 5); /* GN */
 188         s->mb_x= 0;
 189         s->mb_y= s->gob_index* gob_number;
 190         skip_bits(&s->gb, 2); /* GFID */
 191         s->qscale = get_bits(&s->gb, 5); /* GQUANT */
 192     }
 193
 194     if(s->mb_y >= s->mb_height)
 195         return -1;
 196
 197     if(s->qscale==0)
 198         return -1;
 199
 200     return 0;
 201 }
 202
 203 /**
 204  * Decode the group of blocks / video packet header.
 205  * @return bit position of the resync_marker, or <0 if none was found
 206  */
 207 int ff_h263_resync(MpegEncContext *s){
 208     int left, pos, ret;
 209
 210     if(s->codec_id==AV_CODEC_ID_MPEG4){
 211         skip_bits1(&s->gb);
 212         align_get_bits(&s->gb);
 213     }
 214
 215     if(show_bits(&s->gb, 16)==0){
 216         pos= get_bits_count(&s->gb);
 217         if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
 218             ret= ff_mpeg4_decode_video_packet_header(s->avctx->priv_data);
 219         else
 220             ret= h263_decode_gob_header(s);
 221         if(ret>=0)
 222             return pos;
 223     }
 224     //OK, it's not where it is supposed to be ...
 225     s->gb= s->last_resync_gb;
 226     align_get_bits(&s->gb);
 227     left= get_bits_left(&s->gb);
 228
 229     for(;left>16+1+5+5; left-=8){
 230         if(show_bits(&s->gb, 16)==0){
 231             GetBitContext bak= s->gb;
 232
 233             pos= get_bits_count(&s->gb);
 234             if(CONFIG_MPEG4_DECODER && s->codec_id==AV_CODEC_ID_MPEG4)
 235                 ret= ff_mpeg4_decode_video_packet_header(s->avctx->priv_data);
 236             else
 237                 ret= h263_decode_gob_header(s);
 238             if(ret>=0)
 239                 return pos;
 240
 241             s->gb= bak;
 242         }
 243         skip_bits(&s->gb, 8);
 244     }
 245
 246     return -1;
 247 }
 248
 249 int ff_h263_decode_motion(MpegEncContext * s, int pred, int f_code)
 250 {
 251     int code, val, sign, shift;
 252     code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
 253
 254     if (code == 0)
 255         return pred;
 256     if (code < 0)
 257         return 0xffff;
 258
 259     sign = get_bits1(&s->gb);
 260     shift = f_code - 1;
 261     val = code;
 262     if (shift) {
 263         val = (val - 1) << shift;
 264         val |= get_bits(&s->gb, shift);
 265         val++;
 266     }
 267     if (sign)
 268         val = -val;
 269     val += pred;
 270
 271     /* modulo decoding */
 272     if (!s->h263_long_vectors) {
 273         val = sign_extend(val, 5 + f_code);
 274     } else {
 275         /* horrible h263 long vector mode */
 276         if (pred < -31 && val < -63)
 277             val += 64;
 278         if (pred > 32 && val > 63)
 279             val -= 64;
 280
 281     }
 282     return val;
 283 }
 284
 285
 286 /* Decode RVLC of H.263+ UMV */
 287 static int h263p_decode_umotion(MpegEncContext * s, int pred)
 288 {
 289    int code = 0, sign;
 290
 291    if (get_bits1(&s->gb)) /* Motion difference = 0 */
 292       return pred;
 293
 294    code = 2 + get_bits1(&s->gb);
 295
 296    while (get_bits1(&s->gb))
 297    {
 298       code <<= 1;
 299       code += get_bits1(&s->gb);
 300    }
 301    sign = code & 1;
 302    code >>= 1;
 303
 304    code = (sign) ? (pred - code) : (pred + code);
 305    av_dlog(s->avctx,"H.263+ UMV Motion = %d\n", code);
 306    return code;
 307
 308 }
 309
 310 /**
 311  * read the next MVs for OBMC. yes this is a ugly hack, feel free to send a patch :)
 312  */
 313 static void preview_obmc(MpegEncContext *s){
 314     GetBitContext gb= s->gb;
 315
 316     int cbpc, i, pred_x, pred_y, mx, my;
 317     int16_t *mot_val;
 318     const int xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
 319     const int stride= s->b8_stride*2;
 320
 321     for(i=0; i<4; i++)
 322         s->block_index[i]+= 2;
 323     for(i=4; i<6; i++)
 324         s->block_index[i]+= 1;
 325     s->mb_x++;
 326
 327     av_assert2(s->pict_type == AV_PICTURE_TYPE_P);
 328
 329     do{
 330         if (get_bits1(&s->gb)) {
 331             /* skip mb */
 332             mot_val = s->current_picture.motion_val[0][s->block_index[0]];
 333             mot_val[0       ]= mot_val[2       ]=
 334             mot_val[0+stride]= mot_val[2+stride]= 0;
 335             mot_val[1       ]= mot_val[3       ]=
 336             mot_val[1+stride]= mot_val[3+stride]= 0;
 337
 338             s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
 339             goto end;
 340         }
 341         cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
 342     }while(cbpc == 20);
 343
 344     if(cbpc & 4){
 345         s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
 346     }else{
 347         get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 348         if (cbpc & 8) {
 349             if(s->modified_quant){
 350                 if(get_bits1(&s->gb)) skip_bits(&s->gb, 1);
 351                 else                  skip_bits(&s->gb, 5);
 352             }else
 353                 skip_bits(&s->gb, 2);
 354         }
 355
 356         if ((cbpc & 16) == 0) {
 357                 s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
 358                 /* 16x16 motion prediction */
 359                 mot_val= ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
 360                 if (s->umvplus)
 361                    mx = h263p_decode_umotion(s, pred_x);
 362                 else
 363                    mx = ff_h263_decode_motion(s, pred_x, 1);
 364
 365                 if (s->umvplus)
 366                    my = h263p_decode_umotion(s, pred_y);
 367                 else
 368                    my = ff_h263_decode_motion(s, pred_y, 1);
 369
 370                 mot_val[0       ]= mot_val[2       ]=
 371                 mot_val[0+stride]= mot_val[2+stride]= mx;
 372                 mot_val[1       ]= mot_val[3       ]=
 373                 mot_val[1+stride]= mot_val[3+stride]= my;
 374         } else {
 375             s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
 376             for(i=0;i<4;i++) {
 377                 mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
 378                 if (s->umvplus)
 379                   mx = h263p_decode_umotion(s, pred_x);
 380                 else
 381                   mx = ff_h263_decode_motion(s, pred_x, 1);
 382
 383                 if (s->umvplus)
 384                   my = h263p_decode_umotion(s, pred_y);
 385                 else
 386                   my = ff_h263_decode_motion(s, pred_y, 1);
 387                 if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
 388                   skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
 389                 mot_val[0] = mx;
 390                 mot_val[1] = my;
 391             }
 392         }
 393     }
 394 end:
 395
 396     for(i=0; i<4; i++)
 397         s->block_index[i]-= 2;
 398     for(i=4; i<6; i++)
 399         s->block_index[i]-= 1;
 400     s->mb_x--;
 401
 402     s->gb= gb;
 403 }
 404
 405 static void h263_decode_dquant(MpegEncContext *s){
 406     static const int8_t quant_tab[4] = { -1, -2, 1, 2 };
 407
 408     if(s->modified_quant){
 409         if(get_bits1(&s->gb))
 410             s->qscale= ff_modified_quant_tab[get_bits1(&s->gb)][ s->qscale ];
 411         else
 412             s->qscale= get_bits(&s->gb, 5);
 413     }else
 414         s->qscale += quant_tab[get_bits(&s->gb, 2)];
 415     ff_set_qscale(s, s->qscale);
 416 }
 417
 418 static int h263_decode_block(MpegEncContext * s, int16_t * block,
 419                              int n, int coded)
 420 {
 421     int code, level, i, j, last, run;
 422     RLTable *rl = &ff_h263_rl_inter;
 423     const uint8_t *scan_table;
 424     GetBitContext gb= s->gb;
 425
 426     scan_table = s->intra_scantable.permutated;
 427     if (s->h263_aic && s->mb_intra) {
 428         rl = &ff_rl_intra_aic;
 429         i = 0;
 430         if (s->ac_pred) {
 431             if (s->h263_aic_dir)
 432                 scan_table = s->intra_v_scantable.permutated; /* left */
 433             else
 434                 scan_table = s->intra_h_scantable.permutated; /* top */
 435         }
 436     } else if (s->mb_intra) {
 437         /* DC coef */
 438         if(s->codec_id == AV_CODEC_ID_RV10){
 439 #if CONFIG_RV10_DECODER
 440           if (s->rv10_version == 3 && s->pict_type == AV_PICTURE_TYPE_I) {
 441             int component, diff;
 442             component = (n <= 3 ? 0 : n - 4 + 1);
 443             level = s->last_dc[component];
 444             if (s->rv10_first_dc_coded[component]) {
 445                 diff = ff_rv_decode_dc(s, n);
 446                 if (diff == 0xffff)
 447                     return -1;
 448                 level += diff;
 449                 level = level & 0xff; /* handle wrap round */
 450                 s->last_dc[component] = level;
 451             } else {
 452                 s->rv10_first_dc_coded[component] = 1;
 453             }
 454           } else {
 455                 level = get_bits(&s->gb, 8);
 456                 if (level == 255)
 457                     level = 128;
 458           }
 459 #endif
 460         }else{
 461             level = get_bits(&s->gb, 8);
 462             if((level&0x7F) == 0){
 463                 av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
 464                 if(s->err_recognition & (AV_EF_BITSTREAM|AV_EF_COMPLIANT))
 465                     return -1;
 466             }
 467             if (level == 255)
 468                 level = 128;
 469         }
 470         block[0] = level;
 471         i = 1;
 472     } else {
 473         i = 0;
 474     }
 475     if (!coded) {
 476         if (s->mb_intra && s->h263_aic)
 477             goto not_coded;
 478         s->block_last_index[n] = i - 1;
 479         return 0;
 480     }
 481 retry:
 482     for(;;) {
 483         code = get_vlc2(&s->gb, rl->vlc.table, TEX_VLC_BITS, 2);
 484         if (code < 0){
 485             av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
 486             return -1;
 487         }
 488         if (code == rl->n) {
 489             /* escape */
 490             if (CONFIG_FLV_DECODER && s->h263_flv > 1) {
 491                 ff_flv2_decode_ac_esc(&s->gb, &level, &run, &last);
 492             } else {
 493                 last = get_bits1(&s->gb);
 494                 run = get_bits(&s->gb, 6);
 495                 level = (int8_t)get_bits(&s->gb, 8);
 496                 if(level == -128){
 497                     if (s->codec_id == AV_CODEC_ID_RV10) {
 498                         /* XXX: should patch encoder too */
 499                         level = get_sbits(&s->gb, 12);
 500                     }else{
 501                         level = get_bits(&s->gb, 5);
 502                         level |= get_sbits(&s->gb, 6)<<5;
 503                     }
 504                 }
 505             }
 506         } else {
 507             run = rl->table_run[code];
 508             level = rl->table_level[code];
 509             last = code >= rl->last;
 510             if (get_bits1(&s->gb))
 511                 level = -level;
 512         }
 513         i += run;
 514         if (i >= 64){
 515             if(s->alt_inter_vlc && rl == &ff_h263_rl_inter && !s->mb_intra){
 516                 //Looks like a hack but no, it's the way it is supposed to work ...
 517                 rl = &ff_rl_intra_aic;
 518                 i = 0;
 519                 s->gb= gb;
 520                 s->bdsp.clear_block(block);
 521                 goto retry;
 522             }
 523             av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d i:%d\n", s->mb_x, s->mb_y, s->mb_intra);
 524             return -1;
 525         }
 526         j = scan_table[i];
 527         block[j] = level;
 528         if (last)
 529             break;
 530         i++;
 531     }
 532 not_coded:
 533     if (s->mb_intra && s->h263_aic) {
 534         ff_h263_pred_acdc(s, block, n);
 535         i = 63;
 536     }
 537     s->block_last_index[n] = i;
 538     return 0;
 539 }
 540
 541 static int h263_skip_b_part(MpegEncContext *s, int cbp)
 542 {
 543     LOCAL_ALIGNED_16(int16_t, dblock, [64]);
 544     int i, mbi;
 545     int bli[6];
 546
 547     /* we have to set s->mb_intra to zero to decode B-part of PB-frame correctly
 548      * but real value should be restored in order to be used later (in OBMC condition)
 549      */
 550     mbi = s->mb_intra;
 551     memcpy(bli, s->block_last_index, sizeof(bli));
 552     s->mb_intra = 0;
 553     for (i = 0; i < 6; i++) {
 554         if (h263_decode_block(s, dblock, i, cbp&32) < 0)
 555             return -1;
 556         cbp+=cbp;
 557     }
 558     s->mb_intra = mbi;
 559     memcpy(s->block_last_index, bli, sizeof(bli));
 560     return 0;
 561 }
 562
 563 static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
 564 {
 565     int c, mv = 1;
 566
 567     if (pb_frame < 3) { // h.263 Annex G and i263 PB-frame
 568         c = get_bits1(gb);
 569         if (pb_frame == 2 && c)
 570             mv = !get_bits1(gb);
 571     } else { // h.263 Annex M improved PB-frame
 572         mv = get_unary(gb, 0, 4) + 1;
 573         c = mv & 1;
 574         mv = !!(mv & 2);
 575     }
 576     if(c)
 577         *cbpb = get_bits(gb, 6);
 578     return mv;
 579 }
 580
 581 int ff_h263_decode_mb(MpegEncContext *s,
 582                       int16_t block[6][64])
 583 {
 584     int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
 585     int16_t *mot_val;
 586     const int xy= s->mb_x + s->mb_y * s->mb_stride;
 587     int cbpb = 0, pb_mv_count = 0;
 588
 589     av_assert2(!s->h263_pred);
 590
 591     if (s->pict_type == AV_PICTURE_TYPE_P) {
 592         do{
 593             if (get_bits1(&s->gb)) {
 594                 /* skip mb */
 595                 s->mb_intra = 0;
 596                 for(i=0;i<6;i++)
 597                     s->block_last_index[i] = -1;
 598                 s->mv_dir = MV_DIR_FORWARD;
 599                 s->mv_type = MV_TYPE_16X16;
 600                 s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
 601                 s->mv[0][0][0] = 0;
 602                 s->mv[0][0][1] = 0;
 603                 s->mb_skipped = !(s->obmc | s->loop_filter);
 604                 goto end;
 605             }
 606             cbpc = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc.table, INTER_MCBPC_VLC_BITS, 2);
 607             if (cbpc < 0){
 608                 av_log(s->avctx, AV_LOG_ERROR, "cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
 609                 return -1;
 610             }
 611         }while(cbpc == 20);
 612
 613         s->bdsp.clear_blocks(s->block[0]);
 614
 615         dquant = cbpc & 8;
 616         s->mb_intra = ((cbpc & 4) != 0);
 617         if (s->mb_intra) goto intra;
 618
 619         if(s->pb_frame && get_bits1(&s->gb))
 620             pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
 621         cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 622
 623         if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
 624             cbpy ^= 0xF;
 625
 626         cbp = (cbpc & 3) | (cbpy << 2);
 627         if (dquant) {
 628             h263_decode_dquant(s);
 629         }
 630
 631         s->mv_dir = MV_DIR_FORWARD;
 632         if ((cbpc & 16) == 0) {
 633             s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
 634             /* 16x16 motion prediction */
 635             s->mv_type = MV_TYPE_16X16;
 636             ff_h263_pred_motion(s, 0, 0, &pred_x, &pred_y);
 637             if (s->umvplus)
 638                mx = h263p_decode_umotion(s, pred_x);
 639             else
 640                mx = ff_h263_decode_motion(s, pred_x, 1);
 641
 642             if (mx >= 0xffff)
 643                 return -1;
 644
 645             if (s->umvplus)
 646                my = h263p_decode_umotion(s, pred_y);
 647             else
 648                my = ff_h263_decode_motion(s, pred_y, 1);
 649
 650             if (my >= 0xffff)
 651                 return -1;
 652             s->mv[0][0][0] = mx;
 653             s->mv[0][0][1] = my;
 654
 655             if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
 656                skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
 657         } else {
 658             s->current_picture.mb_type[xy] = MB_TYPE_8x8 | MB_TYPE_L0;
 659             s->mv_type = MV_TYPE_8X8;
 660             for(i=0;i<4;i++) {
 661                 mot_val = ff_h263_pred_motion(s, i, 0, &pred_x, &pred_y);
 662                 if (s->umvplus)
 663                   mx = h263p_decode_umotion(s, pred_x);
 664                 else
 665                   mx = ff_h263_decode_motion(s, pred_x, 1);
 666                 if (mx >= 0xffff)
 667                     return -1;
 668
 669                 if (s->umvplus)
 670                   my = h263p_decode_umotion(s, pred_y);
 671                 else
 672                   my = ff_h263_decode_motion(s, pred_y, 1);
 673                 if (my >= 0xffff)
 674                     return -1;
 675                 s->mv[0][i][0] = mx;
 676                 s->mv[0][i][1] = my;
 677                 if (s->umvplus && (mx - pred_x) == 1 && (my - pred_y) == 1)
 678                   skip_bits1(&s->gb); /* Bit stuffing to prevent PSC */
 679                 mot_val[0] = mx;
 680                 mot_val[1] = my;
 681             }
 682         }
 683     } else if(s->pict_type==AV_PICTURE_TYPE_B) {
 684         int mb_type;
 685         const int stride= s->b8_stride;
 686         int16_t *mot_val0 = s->current_picture.motion_val[0][2 * (s->mb_x + s->mb_y * stride)];
 687         int16_t *mot_val1 = s->current_picture.motion_val[1][2 * (s->mb_x + s->mb_y * stride)];
 688 //        const int mv_xy= s->mb_x + 1 + s->mb_y * s->mb_stride;
 689
 690         //FIXME ugly
 691         mot_val0[0       ]= mot_val0[2       ]= mot_val0[0+2*stride]= mot_val0[2+2*stride]=
 692         mot_val0[1       ]= mot_val0[3       ]= mot_val0[1+2*stride]= mot_val0[3+2*stride]=
 693         mot_val1[0       ]= mot_val1[2       ]= mot_val1[0+2*stride]= mot_val1[2+2*stride]=
 694         mot_val1[1       ]= mot_val1[3       ]= mot_val1[1+2*stride]= mot_val1[3+2*stride]= 0;
 695
 696         do{
 697             mb_type= get_vlc2(&s->gb, h263_mbtype_b_vlc.table, H263_MBTYPE_B_VLC_BITS, 2);
 698             if (mb_type < 0){
 699                 av_log(s->avctx, AV_LOG_ERROR, "b mb_type damaged at %d %d\n", s->mb_x, s->mb_y);
 700                 return -1;
 701             }
 702
 703             mb_type= h263_mb_type_b_map[ mb_type ];
 704         }while(!mb_type);
 705
 706         s->mb_intra = IS_INTRA(mb_type);
 707         if(HAS_CBP(mb_type)){
 708             s->bdsp.clear_blocks(s->block[0]);
 709             cbpc = get_vlc2(&s->gb, cbpc_b_vlc.table, CBPC_B_VLC_BITS, 1);
 710             if(s->mb_intra){
 711                 dquant = IS_QUANT(mb_type);
 712                 goto intra;
 713             }
 714
 715             cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 716
 717             if (cbpy < 0){
 718                 av_log(s->avctx, AV_LOG_ERROR, "b cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
 719                 return -1;
 720             }
 721
 722             if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
 723                 cbpy ^= 0xF;
 724
 725             cbp = (cbpc & 3) | (cbpy << 2);
 726         }else
 727             cbp=0;
 728
 729         av_assert2(!s->mb_intra);
 730
 731         if(IS_QUANT(mb_type)){
 732             h263_decode_dquant(s);
 733         }
 734
 735         if(IS_DIRECT(mb_type)){
 736             s->mv_dir = MV_DIR_FORWARD | MV_DIR_BACKWARD | MV_DIRECT;
 737             mb_type |= ff_mpeg4_set_direct_mv(s, 0, 0);
 738         }else{
 739             s->mv_dir = 0;
 740             s->mv_type= MV_TYPE_16X16;
 741 //FIXME UMV
 742
 743             if(USES_LIST(mb_type, 0)){
 744                 int16_t *mot_val= ff_h263_pred_motion(s, 0, 0, &mx, &my);
 745                 s->mv_dir = MV_DIR_FORWARD;
 746
 747                 mx = ff_h263_decode_motion(s, mx, 1);
 748                 my = ff_h263_decode_motion(s, my, 1);
 749
 750                 s->mv[0][0][0] = mx;
 751                 s->mv[0][0][1] = my;
 752                 mot_val[0       ]= mot_val[2       ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
 753                 mot_val[1       ]= mot_val[3       ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
 754             }
 755
 756             if(USES_LIST(mb_type, 1)){
 757                 int16_t *mot_val= ff_h263_pred_motion(s, 0, 1, &mx, &my);
 758                 s->mv_dir |= MV_DIR_BACKWARD;
 759
 760                 mx = ff_h263_decode_motion(s, mx, 1);
 761                 my = ff_h263_decode_motion(s, my, 1);
 762
 763                 s->mv[1][0][0] = mx;
 764                 s->mv[1][0][1] = my;
 765                 mot_val[0       ]= mot_val[2       ]= mot_val[0+2*stride]= mot_val[2+2*stride]= mx;
 766                 mot_val[1       ]= mot_val[3       ]= mot_val[1+2*stride]= mot_val[3+2*stride]= my;
 767             }
 768         }
 769
 770         s->current_picture.mb_type[xy] = mb_type;
 771     } else { /* I-Frame */
 772         do{
 773             cbpc = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc.table, INTRA_MCBPC_VLC_BITS, 2);
 774             if (cbpc < 0){
 775                 av_log(s->avctx, AV_LOG_ERROR, "I cbpc damaged at %d %d\n", s->mb_x, s->mb_y);
 776                 return -1;
 777             }
 778         }while(cbpc == 8);
 779
 780         s->bdsp.clear_blocks(s->block[0]);
 781
 782         dquant = cbpc & 4;
 783         s->mb_intra = 1;
 784 intra:
 785         s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
 786         if (s->h263_aic) {
 787             s->ac_pred = get_bits1(&s->gb);
 788             if(s->ac_pred){
 789                 s->current_picture.mb_type[xy] = MB_TYPE_INTRA | MB_TYPE_ACPRED;
 790
 791                 s->h263_aic_dir = get_bits1(&s->gb);
 792             }
 793         }else
 794             s->ac_pred = 0;
 795
 796         if(s->pb_frame && get_bits1(&s->gb))
 797             pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
 798         cbpy = get_vlc2(&s->gb, ff_h263_cbpy_vlc.table, CBPY_VLC_BITS, 1);
 799         if(cbpy<0){
 800             av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
 801             return -1;
 802         }
 803         cbp = (cbpc & 3) | (cbpy << 2);
 804         if (dquant) {
 805             h263_decode_dquant(s);
 806         }
 807
 808         pb_mv_count += !!s->pb_frame;
 809     }
 810
 811     while(pb_mv_count--){
 812         ff_h263_decode_motion(s, 0, 1);
 813         ff_h263_decode_motion(s, 0, 1);
 814     }
 815
 816     /* decode each block */
 817     for (i = 0; i < 6; i++) {
 818         if (h263_decode_block(s, block[i], i, cbp&32) < 0)
 819             return -1;
 820         cbp+=cbp;
 821     }
 822
 823     if(s->pb_frame && h263_skip_b_part(s, cbpb) < 0)
 824         return -1;
 825     if(s->obmc && !s->mb_intra){
 826         if(s->pict_type == AV_PICTURE_TYPE_P && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
 827             preview_obmc(s);
 828     }
 829 end:
 830
 831         /* per-MB end of slice check */
 832     {
 833         int v= show_bits(&s->gb, 16);
 834
 835         if (get_bits_left(&s->gb) < 16) {
 836             v >>= 16 - get_bits_left(&s->gb);
 837         }
 838
 839         if(v==0)
 840             return SLICE_END;
 841     }
 842
 843     return SLICE_OK;
 844 }
 845
 846 /* most is hardcoded. should extend to handle all h263 streams */
 847 int ff_h263_decode_picture_header(MpegEncContext *s)
 848 {
 849     int format, width, height, i;
 850     uint32_t startcode;
 851
 852     align_get_bits(&s->gb);
 853
 854     if (show_bits(&s->gb, 2) == 2 && s->avctx->frame_number == 0) {
 855          av_log(s->avctx, AV_LOG_WARNING, "Header looks like RTP instead of H.263\n");
 856     }
 857
 858     startcode= get_bits(&s->gb, 22-8);
 859
 860     for(i= get_bits_left(&s->gb); i>24; i-=8) {
 861         startcode = ((startcode << 8) | get_bits(&s->gb, 8)) & 0x003FFFFF;
 862
 863         if(startcode == 0x20)
 864             break;
 865     }
 866
 867     if (startcode != 0x20) {
 868         av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
 869         return -1;
 870     }
 871     /* temporal reference */
 872     i = get_bits(&s->gb, 8); /* picture timestamp */
 873     if( (s->picture_number&~0xFF)+i < s->picture_number)
 874         i+= 256;
 875     s->picture_number= (s->picture_number&~0xFF) + i;
 876
 877     /* PTYPE starts here */
 878     if (get_bits1(&s->gb) != 1) {
 879         /* marker */
 880         av_log(s->avctx, AV_LOG_ERROR, "Bad marker\n");
 881         return -1;
 882     }
 883     if (get_bits1(&s->gb) != 0) {
 884         av_log(s->avctx, AV_LOG_ERROR, "Bad H263 id\n");
 885         return -1;      /* h263 id */
 886     }
 887     skip_bits1(&s->gb);         /* split screen off */
 888     skip_bits1(&s->gb);         /* camera  off */
 889     skip_bits1(&s->gb);         /* freeze picture release off */
 890
 891     format = get_bits(&s->gb, 3);
 892     /*
 893         0    forbidden
 894         1    sub-QCIF
 895         10   QCIF
 896         7       extended PTYPE (PLUSPTYPE)
 897     */
 898
 899     if (format != 7 && format != 6) {
 900         s->h263_plus = 0;
 901         /* H.263v1 */
 902         width = ff_h263_format[format][0];
 903         height = ff_h263_format[format][1];
 904         if (!width)
 905             return -1;
 906
 907         s->pict_type = AV_PICTURE_TYPE_I + get_bits1(&s->gb);
 908
 909         s->h263_long_vectors = get_bits1(&s->gb);
 910
 911         if (get_bits1(&s->gb) != 0) {
 912             av_log(s->avctx, AV_LOG_ERROR, "H263 SAC not supported\n");
 913             return -1; /* SAC: off */
 914         }
 915         s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
 916         s->unrestricted_mv = s->h263_long_vectors || s->obmc;
 917
 918         s->pb_frame = get_bits1(&s->gb);
 919         s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
 920         skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
 921
 922         s->width = width;
 923         s->height = height;
 924         s->avctx->sample_aspect_ratio= (AVRational){12,11};
 925         s->avctx->time_base= (AVRational){1001, 30000};
 926     } else {
 927         int ufep;
 928
 929         /* H.263v2 */
 930         s->h263_plus = 1;
 931         ufep = get_bits(&s->gb, 3); /* Update Full Extended PTYPE */
 932
 933         /* ufep other than 0 and 1 are reserved */
 934         if (ufep == 1) {
 935             /* OPPTYPE */
 936             format = get_bits(&s->gb, 3);
 937             av_dlog(s->avctx, "ufep=1, format: %d\n", format);
 938             s->custom_pcf= get_bits1(&s->gb);
 939             s->umvplus = get_bits1(&s->gb); /* Unrestricted Motion Vector */
 940             if (get_bits1(&s->gb) != 0) {
 941                 av_log(s->avctx, AV_LOG_ERROR, "Syntax-based Arithmetic Coding (SAC) not supported\n");
 942             }
 943             s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
 944             s->h263_aic = get_bits1(&s->gb); /* Advanced Intra Coding (AIC) */
 945             s->loop_filter= get_bits1(&s->gb);
 946             s->unrestricted_mv = s->umvplus || s->obmc || s->loop_filter;
 947             if(s->avctx->lowres)
 948                 s->loop_filter = 0;
 949
 950             s->h263_slice_structured= get_bits1(&s->gb);
 951             if (get_bits1(&s->gb) != 0) {
 952                 av_log(s->avctx, AV_LOG_ERROR, "Reference Picture Selection not supported\n");
 953             }
 954             if (get_bits1(&s->gb) != 0) {
 955                 av_log(s->avctx, AV_LOG_ERROR, "Independent Segment Decoding not supported\n");
 956             }
 957             s->alt_inter_vlc= get_bits1(&s->gb);
 958             s->modified_quant= get_bits1(&s->gb);
 959             if(s->modified_quant)
 960                 s->chroma_qscale_table= ff_h263_chroma_qscale_table;
 961
 962             skip_bits(&s->gb, 1); /* Prevent start code emulation */
 963
 964             skip_bits(&s->gb, 3); /* Reserved */
 965         } else if (ufep != 0) {
 966             av_log(s->avctx, AV_LOG_ERROR, "Bad UFEP type (%d)\n", ufep);
 967             return -1;
 968         }
 969
 970         /* MPPTYPE */
 971         s->pict_type = get_bits(&s->gb, 3);
 972         switch(s->pict_type){
 973         case 0: s->pict_type= AV_PICTURE_TYPE_I;break;
 974         case 1: s->pict_type= AV_PICTURE_TYPE_P;break;
 975         case 2: s->pict_type= AV_PICTURE_TYPE_P;s->pb_frame = 3;break;
 976         case 3: s->pict_type= AV_PICTURE_TYPE_B;break;
 977         case 7: s->pict_type= AV_PICTURE_TYPE_I;break; //ZYGO
 978         default:
 979             return -1;
 980         }
 981         skip_bits(&s->gb, 2);
 982         s->no_rounding = get_bits1(&s->gb);
 983         skip_bits(&s->gb, 4);
 984
 985         /* Get the picture dimensions */
 986         if (ufep) {
 987             if (format == 6) {
 988                 /* Custom Picture Format (CPFMT) */
 989                 s->aspect_ratio_info = get_bits(&s->gb, 4);
 990                 av_dlog(s->avctx, "aspect: %d\n", s->aspect_ratio_info);
 991                 /* aspect ratios:
 992                 0 - forbidden
 993                 1 - 1:1
 994                 2 - 12:11 (CIF 4:3)
 995                 3 - 10:11 (525-type 4:3)
 996                 4 - 16:11 (CIF 16:9)
 997                 5 - 40:33 (525-type 16:9)
 998                 6-14 - reserved
 999                 */
1000                 width = (get_bits(&s->gb, 9) + 1) * 4;
1001                 skip_bits1(&s->gb);
1002                 height = get_bits(&s->gb, 9) * 4;
1003                 av_dlog(s->avctx, "\nH.263+ Custom picture: %dx%d\n",width,height);
1004                 if (s->aspect_ratio_info == FF_ASPECT_EXTENDED) {
1005                     /* aspected dimensions */
1006                     s->avctx->sample_aspect_ratio.num= get_bits(&s->gb, 8);
1007                     s->avctx->sample_aspect_ratio.den= get_bits(&s->gb, 8);
1008                 }else{
1009                     s->avctx->sample_aspect_ratio= ff_h263_pixel_aspect[s->aspect_ratio_info];
1010                 }
1011             } else {
1012                 width = ff_h263_format[format][0];
1013                 height = ff_h263_format[format][1];
1014                 s->avctx->sample_aspect_ratio= (AVRational){12,11};
1015             }
1016             s->avctx->sample_aspect_ratio.den <<= s->ehc_mode;
1017             if ((width == 0) || (height == 0))
1018                 return -1;
1019             s->width = width;
1020             s->height = height;
1021
1022             if(s->custom_pcf){
1023                 int gcd;
1024                 s->avctx->time_base.den= 1800000;
1025                 s->avctx->time_base.num= 1000 + get_bits1(&s->gb);
1026                 s->avctx->time_base.num*= get_bits(&s->gb, 7);
1027                 if(s->avctx->time_base.num == 0){
1028                     av_log(s, AV_LOG_ERROR, "zero framerate\n");
1029                     return -1;
1030                 }
1031                 gcd= av_gcd(s->avctx->time_base.den, s->avctx->time_base.num);
1032                 s->avctx->time_base.den /= gcd;
1033                 s->avctx->time_base.num /= gcd;
1034             }else{
1035                 s->avctx->time_base= (AVRational){1001, 30000};
1036             }
1037         }
1038
1039         if(s->custom_pcf){
1040             skip_bits(&s->gb, 2); //extended Temporal reference
1041         }
1042
1043         if (ufep) {
1044             if (s->umvplus) {
1045                 if(get_bits1(&s->gb)==0) /* Unlimited Unrestricted Motion Vectors Indicator (UUI) */
1046                     skip_bits1(&s->gb);
1047             }
1048             if(s->h263_slice_structured){
1049                 if (get_bits1(&s->gb) != 0) {
1050                     av_log(s->avctx, AV_LOG_ERROR, "rectangular slices not supported\n");
1051                 }
1052                 if (get_bits1(&s->gb) != 0) {
1053                     av_log(s->avctx, AV_LOG_ERROR, "unordered slices not supported\n");
1054                 }
1055             }
1056         }
1057
1058         s->qscale = get_bits(&s->gb, 5);
1059     }
1060
1061     if (s->width == 0 || s->height == 0) {
1062         av_log(s->avctx, AV_LOG_ERROR, "dimensions 0\n");
1063         return -1;
1064     }
1065     s->mb_width = (s->width  + 15) / 16;
1066     s->mb_height = (s->height  + 15) / 16;
1067     s->mb_num = s->mb_width * s->mb_height;
1068
1069     if (s->pb_frame) {
1070         skip_bits(&s->gb, 3); /* Temporal reference for B-pictures */
1071         if (s->custom_pcf)
1072             skip_bits(&s->gb, 2); //extended Temporal reference
1073         skip_bits(&s->gb, 2); /* Quantization information for B-pictures */
1074     }
1075
1076     if (s->pict_type!=AV_PICTURE_TYPE_B) {
1077         s->time            = s->picture_number;
1078         s->pp_time         = s->time - s->last_non_b_time;
1079         s->last_non_b_time = s->time;
1080     }else{
1081         s->time    = s->picture_number;
1082         s->pb_time = s->pp_time - (s->last_non_b_time - s->time);
1083         if (s->pp_time <=s->pb_time ||
1084             s->pp_time <= s->pp_time - s->pb_time ||
1085             s->pp_time <= 0){
1086             s->pp_time = 2;
1087             s->pb_time = 1;
1088         }
1089         ff_mpeg4_init_direct_mv(s);
1090     }
1091
1092     /* PEI */
1093     if (skip_1stop_8data_bits(&s->gb) < 0)
1094         return AVERROR_INVALIDDATA;
1095
1096     if(s->h263_slice_structured){
1097         if (get_bits1(&s->gb) != 1) {
1098             av_log(s->avctx, AV_LOG_ERROR, "SEPB1 marker missing\n");
1099             return -1;
1100         }
1101
1102         ff_h263_decode_mba(s);
1103
1104         if (get_bits1(&s->gb) != 1) {
1105             av_log(s->avctx, AV_LOG_ERROR, "SEPB2 marker missing\n");
1106             return -1;
1107         }
1108     }
1109     s->f_code = 1;
1110
1111     if(s->h263_aic){
1112          s->y_dc_scale_table=
1113          s->c_dc_scale_table= ff_aic_dc_scale_table;
1114     }else{
1115         s->y_dc_scale_table=
1116         s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
1117     }
1118
1119         ff_h263_show_pict_info(s);
1120     if (s->pict_type == AV_PICTURE_TYPE_I && s->codec_tag == AV_RL32("ZYGO") && get_bits_left(&s->gb) >= 85 + 13*3*16 + 50){
1121         int i,j;
1122         for(i=0; i<85; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1123         av_log(s->avctx, AV_LOG_DEBUG, "\n");
1124         for(i=0; i<13; i++){
1125             for(j=0; j<3; j++){
1126                 int v= get_bits(&s->gb, 8);
1127                 v |= get_sbits(&s->gb, 8)<<8;
1128                 av_log(s->avctx, AV_LOG_DEBUG, " %5d", v);
1129             }
1130             av_log(s->avctx, AV_LOG_DEBUG, "\n");
1131         }
1132         for(i=0; i<50; i++) av_log(s->avctx, AV_LOG_DEBUG, "%d", get_bits1(&s->gb));
1133     }
1134
1135     return 0;
1136 }