Blame view

ffmpeg-4.2.2/libavformat/h263dec.c 2.38 KB
aac5773f   hucm   功能基本完成,接口待打磨
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
  /*
   * RAW H.263 video demuxer
   * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "avformat.h"
  #include "rawdec.h"
  
  static int h263_probe(const AVProbeData *p)
  {
      uint64_t code= -1;
      int i;
      int valid_psc=0;
      int invalid_psc=0;
      int res_change=0;
      int src_fmt, last_src_fmt=-1;
      int last_gn=0;
      int tr, last_tr = -1;
  
      for(i=0; i<p->buf_size; i++){
          code = (code<<8) + p->buf[i];
          if ((code & 0xfffffc000000) == 0x80000000) {
              tr = (code >> 18) & 0xFF;
              src_fmt= (code>>10)&7;
              if(   src_fmt != last_src_fmt
                 && last_src_fmt>0 && last_src_fmt<6
                 && src_fmt<6)
                  res_change++;
  
              if (tr == last_tr) {
                  invalid_psc++;
                  continue;
              }
  
              if (src_fmt != 7 && !(code&(1<<9)) && (code&(1<<5))) {
                  invalid_psc++;
                  continue;
              }
  
              if((code&0x30000)==0x20000 && src_fmt){
                  valid_psc++;
                  last_gn=0;
              }else
                  invalid_psc++;
              last_src_fmt= src_fmt;
              last_tr = tr;
          } else if((code & 0xffff80000000) == 0x80000000) {
              int gn= (code>>(31-5)) & 0x1F;
              if(gn<last_gn){
                  invalid_psc++;
              }else
                  last_gn= gn;
          }
      }
      if(valid_psc > 2*invalid_psc + 2*res_change + 3){
          return AVPROBE_SCORE_EXTENSION;
      }else if(valid_psc > 2*invalid_psc)
          return AVPROBE_SCORE_EXTENSION / 2;
      return 0;
  }
  
  FF_DEF_RAWVIDEO_DEMUXER(h263, "raw H.263", h263_probe, NULL, AV_CODEC_ID_H263)