FFmpeg
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m4vdec.c
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1 /*
2  * RAW MPEG-4 video demuxer
3  * Copyright (c) 2006 Thijs Vermeir <thijs.vermeir@barco.com>
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 #define VISUAL_OBJECT_START_CODE 0x000001b5
26 #define VOP_START_CODE 0x000001b6
27 
28 static int mpeg4video_probe(AVProbeData *probe_packet)
29 {
30  uint32_t temp_buffer= -1;
31  int VO=0, VOL=0, VOP = 0, VISO = 0, res=0;
32  int i;
33 
34  for(i=0; i<probe_packet->buf_size; i++){
35  temp_buffer = (temp_buffer<<8) + probe_packet->buf[i];
36  if ((temp_buffer & 0xffffff00) != 0x100)
37  continue;
38 
39  if (temp_buffer == VOP_START_CODE) VOP++;
40  else if (temp_buffer == VISUAL_OBJECT_START_CODE) VISO++;
41  else if (temp_buffer < 0x120) VO++;
42  else if (temp_buffer < 0x130) VOL++;
43  else if ( !(0x1AF < temp_buffer && temp_buffer < 0x1B7)
44  && !(0x1B9 < temp_buffer && temp_buffer < 0x1C4)) res++;
45  }
46 
47  if (VOP >= VISO && VOP >= VOL && VO >= VOL && VOL > 0 && res==0)
48  return VOP+VO > 3 ? AVPROBE_SCORE_EXTENSION : AVPROBE_SCORE_EXTENSION/2;
49  return 0;
50 }
51 
52 FF_DEF_RAWVIDEO_DEMUXER(m4v, "raw MPEG-4 video", mpeg4video_probe, "m4v", AV_CODEC_ID_MPEG4)