FFmpeg
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
h264dec.c
Go to the documentation of this file.
1 /*
2  * RAW H.264 video demuxer
3  * Copyright (c) 2008 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 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)