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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 FFmpeg.
7  *
8  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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  const uint8_t *buf0 = p->buf;
35  const uint8_t *buf2;
36  const uint8_t *buf;
37  const 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  fsize = FFMIN(fsize, end - buf2);
52  buf2 += fsize;
53  }
54  max_frames = FFMAX(max_frames, frames);
55  if(buf == buf0)
56  first_frames= frames;
57  }
58  if (first_frames>=3) return AVPROBE_SCORE_MAX/2+1;
59  else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
60  else if(max_frames>=3) return AVPROBE_SCORE_MAX/4;
61  else if(max_frames>=1) return 1;
62  else return 0;
63 }
64 
66 {
67  AVStream *st;
68 
69  st = avformat_new_stream(s, NULL);
70  if (!st)
71  return AVERROR(ENOMEM);
72 
76 
77  ff_id3v1_read(s);
78 
79  //LCM of all possible ADTS sample rates
80  avpriv_set_pts_info(st, 64, 1, 28224000);
81 
82  return 0;
83 }
84 
86  .name = "aac",
87  .long_name = NULL_IF_CONFIG_SMALL("raw ADTS AAC (Advanced Audio Coding)"),
88  .read_probe = adts_aac_probe,
89  .read_header = adts_aac_read_header,
90  .read_packet = ff_raw_read_partial_packet,
91  .flags = AVFMT_GENERIC_INDEX,
92  .extensions = "aac",
93  .raw_codec_id = AV_CODEC_ID_AAC,
94 };