Libav
aacdec.c
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1 /*
2  * raw ADTS AAC demuxer
3  * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
4  * Copyright (c) 2009 Robert Swain ( rob opendot cl )
5  *
6  * This file is part of Libav.
7  *
8  * Libav is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * Libav is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with Libav; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include "libavutil/intreadwrite.h"
24 #include "avformat.h"
25 #include "internal.h"
26 #include "rawdec.h"
27 #include "id3v1.h"
28 
29 
31 {
32  int max_frames = 0, first_frames = 0;
33  int fsize, frames;
34  uint8_t *buf0 = p->buf;
35  uint8_t *buf2;
36  uint8_t *buf;
37  uint8_t *end = buf0 + p->buf_size - 7;
38 
39  buf = buf0;
40 
41  for(; buf < end; buf= buf2+1) {
42  buf2 = buf;
43 
44  for(frames = 0; buf2 < end; frames++) {
45  uint32_t header = AV_RB16(buf2);
46  if((header&0xFFF6) != 0xFFF0)
47  break;
48  fsize = (AV_RB32(buf2 + 3) >> 13) & 0x1FFF;
49  if(fsize < 7)
50  break;
51  buf2 += fsize;
52  }
53  max_frames = FFMAX(max_frames, frames);
54  if(buf == buf0)
55  first_frames= frames;
56  }
57  if (first_frames>=3) return AVPROBE_SCORE_EXTENSION + 1;
58  else if(max_frames>500)return AVPROBE_SCORE_EXTENSION;
59  else if(max_frames>=3) return AVPROBE_SCORE_EXTENSION / 2;
60  else if(max_frames>=1) return 1;
61  else return 0;
62 }
63 
65 {
66  AVStream *st;
67 
68  st = avformat_new_stream(s, NULL);
69  if (!st)
70  return AVERROR(ENOMEM);
71 
75 
76  ff_id3v1_read(s);
77 
78  //LCM of all possible ADTS sample rates
79  avpriv_set_pts_info(st, 64, 1, 28224000);
80 
81  return 0;
82 }
83 
85  .name = "aac",
86  .long_name = NULL_IF_CONFIG_SMALL("raw ADTS AAC (Advanced Audio Coding)"),
87  .read_probe = adts_aac_probe,
88  .read_header = adts_aac_read_header,
89  .read_packet = ff_raw_read_partial_packet,
90  .flags = AVFMT_GENERIC_INDEX,
91  .extensions = "aac",
92  .raw_codec_id = AV_CODEC_ID_AAC,
93 };