libavformat/h264dec.c

   1 /*
   2  * RAW H.264 video demuxer
   3  * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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 h264_probe(AVProbeData *p)
  26 {
  27     uint32_t code= -1;
  28     int sps=0, pps=0, idr=0, res=0, sli=0;
  29     int i;
  30
  31     for(i=0; i<p->buf_size; i++){
  32         code = (code<<8) + p->buf[i];
  33         if ((code & 0xffffff00) == 0x100) {
  34             int ref_idc= (code>>5)&3;
  35             int type   = code & 0x1F;
  36             static const int8_t ref_zero[32]={
  37                 2, 0, 0, 0, 0,-1, 1,-1,
  38                -1, 1, 1, 1, 1,-1, 2, 2,
  39                 2, 2, 2, 0, 2, 2, 2, 2,
  40                 2, 2, 2, 2, 2, 2, 2, 2
  41             };
  42
  43             if(code & 0x80) //forbidden bit
  44                 return 0;
  45
  46             if(ref_zero[type] == 1 && ref_idc)
  47                 return 0;
  48             if(ref_zero[type] ==-1 && !ref_idc)
  49                 return 0;
  50             if(ref_zero[type] == 2)
  51                 res++;
  52
  53             switch(type){
  54             case     1:   sli++; break;
  55             case     5:   idr++; break;
  56             case     7:
  57                 if (p->buf[i + 2] & 0x03)
  58                     return 0;
  59                 sps++;
  60                 break;
  61             case     8:   pps++; break;
  62             }
  63         }
  64     }
  65     if(sps && pps && (idr||sli>3) && res<(sps+pps+idr))
  66         return AVPROBE_SCORE_MAX/2+1; // +1 for .mpg
  67     return 0;
  68 }
  69
  70 FF_DEF_RAWVIDEO_DEMUXER(h264 , "raw H.264 video", h264_probe, "h26l,h264,264", AV_CODEC_ID_H264)