FFmpeg
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 VOS_STARTCODE 0x1B0
26 #define USER_DATA_STARTCODE 0x1B2
27 #define GOP_STARTCODE 0x1B3
28 #define VISUAL_OBJ_STARTCODE 0x1B5
29 #define VOP_STARTCODE 0x1B6
30 #define SLICE_STARTCODE 0x1B7
31 #define EXT_STARTCODE 0x1B8
32 
33 static int mpeg4video_probe(const AVProbeData *probe_packet)
34 {
35  uint32_t temp_buffer = -1;
36  int VO = 0, VOL = 0, VOP = 0, VISO = 0, res = 0;
37  int res_main = 0;
38  int i;
39 
40  for (i = 0; i < probe_packet->buf_size; i++) {
41  temp_buffer = (temp_buffer << 8) + probe_packet->buf[i];
42  if (temp_buffer & 0xfffffe00)
43  continue;
44  if (temp_buffer < 2)
45  continue;
46 
47  if (temp_buffer == VOP_STARTCODE)
48  VOP++;
49  else if (temp_buffer == VISUAL_OBJ_STARTCODE)
50  VISO++;
51  else if (temp_buffer >= 0x100 && temp_buffer < 0x120)
52  VO++;
53  else if (temp_buffer >= 0x120 && temp_buffer < 0x130)
54  VOL++;
55  else if (temp_buffer == SLICE_STARTCODE || temp_buffer == EXT_STARTCODE)
56  res_main++;
57  else if (!(0x1AF < temp_buffer && temp_buffer < 0x1B7) &&
58  !(0x1B9 < temp_buffer && temp_buffer < 0x1C4))
59  res++;
60  }
61 
62  // res_main repesents the reserved codes within the "main" profile, they are
63  // added to the reserved ones if it appears that this is a "main" profile
64  // stream
65  if (res_main && 2*res_main < VOP)
66  res += res_main;
67 
68  if (VOP >= VISO && VOP >= VOL && VO >= VOL && VOL > 0 && res == 0)
69  return VOP+VO > 4 ? AVPROBE_SCORE_EXTENSION : AVPROBE_SCORE_EXTENSION/2;
70 
71  if (VOP >= VISO && VOP >= VOL && VO >= VOL && VOL > 0 && VOP+VO > 4)
72  return AVPROBE_SCORE_EXTENSION/10;
73  return 0;
74 }
75 
76 FF_DEF_RAWVIDEO_DEMUXER2(m4v, "raw MPEG-4 video", mpeg4video_probe, "m4v",
#define FF_DEF_RAWVIDEO_DEMUXER2(shortname, longname, probe, ext, id, flag)
Definition: rawdec.h:71
#define VISUAL_OBJ_STARTCODE
Definition: m4vdec.c:28
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
#define AVFMT_TS_DISCONT
Format allows timestamp discontinuities.
Definition: avformat.h:469
#define EXT_STARTCODE
Definition: m4vdec.c:31
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
#define SLICE_STARTCODE
Definition: m4vdec.c:30
if(ret)
#define VOP_STARTCODE
Definition: m4vdec.c:29
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:468
#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
Main libavformat public API header.
static int mpeg4video_probe(const AVProbeData *probe_packet)
Definition: m4vdec.c:33