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  1. /*
  2.  * RAW H.263 video demuxer
  3.  * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. #include "avformat.h"
  23. #include "rawdec.h"
  24.  
  25. static int h263_probe(AVProbeData *p)
  26. {
  27.     uint64_t code= -1;
  28.     int i;
  29.     int valid_psc=0;
  30.     int invalid_psc=0;
  31.     int res_change=0;
  32.     int src_fmt, last_src_fmt=-1;
  33.     int last_gn=0;
  34.  
  35.     for(i=0; i<p->buf_size; i++){
  36.         code = (code<<8) + p->buf[i];
  37.         if ((code & 0xfffffc0000) == 0x800000) {
  38.             src_fmt= (code>>2)&3;
  39.             if(   src_fmt != last_src_fmt
  40.                && last_src_fmt>0 && last_src_fmt<6
  41.                && src_fmt<6)
  42.                 res_change++;
  43.  
  44.             if((code&0x300)==0x200 && src_fmt){
  45.                 valid_psc++;
  46.                 last_gn=0;
  47.             }else
  48.                 invalid_psc++;
  49.             last_src_fmt= src_fmt;
  50.         } else if((code & 0xffff800000) == 0x800000) {
  51.             int gn= (code>>(23-5)) & 0x1F;
  52.             if(gn<last_gn){
  53.                 invalid_psc++;
  54.             }else
  55.                 last_gn= gn;
  56.         }
  57.     }
  58.     if(valid_psc > 2*invalid_psc + 2*res_change + 3){
  59.         return AVPROBE_SCORE_EXTENSION;
  60.     }else if(valid_psc > 2*invalid_psc)
  61.         return AVPROBE_SCORE_EXTENSION / 2;
  62.     return 0;
  63. }
  64.  
  65. FF_DEF_RAWVIDEO_DEMUXER(h263, "raw H.263", h263_probe, NULL, AV_CODEC_ID_H263)
  66.