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 
30 {
31  int max_frames = 0, first_frames = 0;
32  int fsize, frames;
33  uint8_t *buf0 = p->buf;
34  uint8_t *buf2;
35  uint8_t *buf;
36  uint8_t *end = buf0 + p->buf_size - 7;
37 
38  buf = buf0;
39 
40  for (; buf < end; buf = buf2 + 1) {
41  buf2 = buf;
42 
43  for (frames = 0; buf2 < end; frames++) {
44  uint32_t header = AV_RB16(buf2);
45  if ((header & 0xFFF6) != 0xFFF0) {
46  if (buf != buf0) {
47  // Found something that isn't an ADTS header, starting
48  // from a position other than the start of the buffer.
49  // Discard the count we've accumulated so far since it
50  // probably was a false positive.
51  frames = 0;
52  }
53  break;
54  }
55  fsize = (AV_RB32(buf2 + 3) >> 13) & 0x1FFF;
56  if (fsize < 7)
57  break;
58  buf2 += fsize;
59  }
60  max_frames = FFMAX(max_frames, frames);
61  if (buf == buf0)
62  first_frames = frames;
63  }
64 
65  if (first_frames >= 3)
66  return AVPROBE_SCORE_EXTENSION + 1;
67  else if (max_frames > 100)
69  else if (max_frames >= 3)
70  return AVPROBE_SCORE_EXTENSION / 2;
71  else if (max_frames >= 1)
72  return 1;
73  else
74  return 0;
75 }
76 
78 {
79  AVStream *st;
80 
81  st = avformat_new_stream(s, NULL);
82  if (!st)
83  return AVERROR(ENOMEM);
84 
88 
89  ff_id3v1_read(s);
90 
91  // LCM of all possible ADTS sample rates
92  avpriv_set_pts_info(st, 64, 1, 28224000);
93 
94  return 0;
95 }
96 
98  .name = "aac",
99  .long_name = NULL_IF_CONFIG_SMALL("raw ADTS AAC (Advanced Audio Coding)"),
100  .read_probe = adts_aac_probe,
101  .read_header = adts_aac_read_header,
102  .read_packet = ff_raw_read_partial_packet,
103  .flags = AVFMT_GENERIC_INDEX,
104  .extensions = "aac",
105  .mime_type = "audio/aac,audio/aacp,audio/x-aac",
106  .raw_codec_id = AV_CODEC_ID_AAC,
107 };
#define FFMAX(a, b)
Definition: common.h:55
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:525
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:2821
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:718
void ff_id3v1_read(AVFormatContext *s)
Read an ID3v1 tag.
Definition: id3v1.c:227
Format I/O context.
Definition: avformat.h:922
#define AV_RB16(x)
Definition: intreadwrite.h:208
uint8_t
static int adts_aac_read_header(AVFormatContext *s)
Definition: aacdec.c:77
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:397
enum AVStreamParseType need_parsing
Definition: avformat.h:867
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:2518
#define AVERROR(e)
Definition: error.h:43
int ff_raw_read_partial_packet(AVFormatContext *s, AVPacket *pkt)
Definition: rawdec.c:34
AVInputFormat ff_aac_demuxer
Definition: aacdec.c:97
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:150
struct AVInputFormat * iformat
The input container format.
Definition: avformat.h:934
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:417
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:398
full parsing and repack
Definition: avformat.h:653
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:402
Stream structure.
Definition: avformat.h:699
NULL
Definition: eval.c:55
enum AVMediaType codec_type
Definition: avcodec.h:1058
enum AVCodecID codec_id
Definition: avcodec.h:1067
This structure contains the data a format has to probe a file.
Definition: avformat.h:395
int raw_codec_id
Raw demuxers store their codec ID here.
Definition: avformat.h:571
static int adts_aac_probe(AVProbeData *p)
Definition: aacdec.c:29
Main libavformat public API header.
#define AV_RB32(x)
Definition: intreadwrite.h:232