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loasdec.c
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1 /*
2  * LOAS AudioSyncStream 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 "libavutil/intreadwrite.h"
23 #include "libavutil/internal.h"
24 #include "avformat.h"
25 #include "internal.h"
26 #include "rawdec.h"
27 
28 static int loas_probe(AVProbeData *p)
29 {
30  int max_frames = 0, first_frames = 0;
31  int fsize, frames;
32  const uint8_t *buf0 = p->buf;
33  const uint8_t *buf2;
34  const uint8_t *buf;
35  const uint8_t *end = buf0 + p->buf_size - 3;
36  buf = buf0;
37 
38  for(; buf < end; buf= buf2+1) {
39  buf2 = buf;
40 
41  for(frames = 0; buf2 < end; frames++) {
42  uint32_t header = AV_RB24(buf2);
43  if((header >> 13) != 0x2B7)
44  break;
45  fsize = (header & 0x1FFF) + 3;
46  if(fsize < 7)
47  break;
48  fsize = FFMIN(fsize, end - buf2);
49  buf2 += fsize;
50  }
51  max_frames = FFMAX(max_frames, frames);
52  if(buf == buf0)
53  first_frames= frames;
54  }
55  if (first_frames>=3) return AVPROBE_SCORE_EXTENSION+1;
56  else if(max_frames>100)return AVPROBE_SCORE_EXTENSION;
57  else if(max_frames>=3) return AVPROBE_SCORE_EXTENSION / 2;
58  else return 0;
59 }
60 
62 {
63  AVStream *st;
64 
65  st = avformat_new_stream(s, NULL);
66  if (!st)
67  return AVERROR(ENOMEM);
68 
72 
73  //LCM of all possible AAC sample rates
74  avpriv_set_pts_info(st, 64, 1, 28224000);
75 
76  return 0;
77 }
78 
80  .name = "loas",
81  .long_name = NULL_IF_CONFIG_SMALL("LOAS AudioSyncStream"),
82  .read_probe = loas_probe,
83  .read_header = loas_read_header,
84  .read_packet = ff_raw_read_partial_packet,
85  .flags= AVFMT_GENERIC_INDEX,
86  .raw_codec_id = AV_CODEC_ID_AAC_LATM,
87 };