FFmpeg
h263dec.c
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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(const 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  int tr, last_tr = -1;
35 
36  for(i=0; i<p->buf_size; i++){
37  code = (code<<8) + p->buf[i];
38  if ((code & 0xfffffc000000) == 0x80000000) {
39  tr = (code >> 18) & 0xFF;
40  src_fmt= (code>>10)&7;
41  if( src_fmt != last_src_fmt
42  && last_src_fmt>0 && last_src_fmt<6
43  && src_fmt<6)
44  res_change++;
45 
46  if (tr == last_tr) {
47  invalid_psc++;
48  continue;
49  }
50 
51  if (src_fmt != 7 && !(code&(1<<9)) && (code&(1<<5))) {
52  invalid_psc++;
53  continue;
54  }
55 
56  if((code&0x30000)==0x20000 && src_fmt){
57  valid_psc++;
58  last_gn=0;
59  }else
60  invalid_psc++;
61  last_src_fmt= src_fmt;
62  last_tr = tr;
63  } else if((code & 0xffff80000000) == 0x80000000) {
64  int gn= (code>>(31-5)) & 0x1F;
65  if(gn<last_gn){
66  invalid_psc++;
67  }else
68  last_gn= gn;
69  }
70  }
71  if(valid_psc > 2*invalid_psc + 2*res_change + 3){
73  }else if(valid_psc > 2*invalid_psc)
74  return AVPROBE_SCORE_EXTENSION / 2;
75  return 0;
76 }
77 
#define NULL
Definition: coverity.c:32
#define FF_DEF_RAWVIDEO_DEMUXER(shortname, longname, probe, ext, id)
Definition: rawdec.h:86
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:449
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:448
if(ret)
static int h263_probe(const AVProbeData *p)
Definition: h263dec.c:25
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:456
This structure contains the data a format has to probe a file.
Definition: avformat.h:446
and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some it can consider them to be part of the FIFO and delay acknowledging a status change accordingly Example code
Main libavformat public API header.