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libavformat
aacdec.c
Go to the documentation of this file.
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/*
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* raw ADTS AAC demuxer
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* Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
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* Copyright (c) 2009 Robert Swain ( rob opendot cl )
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
15
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "
libavutil/intreadwrite.h
"
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#include "
avformat.h
"
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#include "
internal.h
"
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#include "
rawdec.h
"
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#include "
id3v1.h
"
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#include "
apetag.h
"
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static
int
adts_aac_probe
(
AVProbeData
*p)
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{
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int
max_frames = 0, first_frames = 0;
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int
fsize, frames;
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const
uint8_t
*buf0 = p->
buf
;
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const
uint8_t
*buf2;
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const
uint8_t
*
buf
;
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const
uint8_t
*
end
= buf0 + p->
buf_size
- 7;
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buf = buf0;
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for
(; buf <
end
; buf = buf2 + 1) {
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buf2 =
buf
;
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for
(frames = 0; buf2 <
end
; frames++) {
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uint32_t
header
=
AV_RB16
(buf2);
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if
((header & 0xFFF6) != 0xFFF0) {
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if
(buf != buf0) {
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// Found something that isn't an ADTS header, starting
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// from a position other than the start of the buffer.
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// Discard the count we've accumulated so far since it
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// probably was a false positive.
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frames = 0;
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}
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break
;
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}
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fsize = (
AV_RB32
(buf2 + 3) >> 13) & 0x1FFF;
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if
(fsize < 7)
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break
;
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fsize =
FFMIN
(fsize, end - buf2);
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buf2 += fsize;
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}
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max_frames =
FFMAX
(max_frames, frames);
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if
(buf == buf0)
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first_frames = frames;
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}
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if
(first_frames >= 3)
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return
AVPROBE_SCORE_EXTENSION
+ 1;
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else
if
(max_frames > 100)
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return
AVPROBE_SCORE_EXTENSION
;
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else
if
(max_frames >= 3)
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return
AVPROBE_SCORE_EXTENSION
/ 2;
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else
if
(max_frames >= 1)
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return
1;
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else
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return
0;
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}
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static
int
adts_aac_read_header
(
AVFormatContext
*
s
)
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{
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AVStream
*st;
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st =
avformat_new_stream
(s,
NULL
);
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if
(!st)
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return
AVERROR
(ENOMEM);
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st->
codec
->
codec_type
=
AVMEDIA_TYPE_AUDIO
;
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st->
codec
->
codec_id
= s->
iformat
->
raw_codec_id
;
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st->
need_parsing
=
AVSTREAM_PARSE_FULL_RAW
;
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ff_id3v1_read
(s);
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if
(s->
pb
->
seekable
&&
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!
av_dict_get
(s->
metadata
,
""
,
NULL
,
AV_DICT_IGNORE_SUFFIX
)) {
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int64_t cur =
avio_tell
(s->
pb
);
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ff_ape_parse_tag
(s);
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avio_seek
(s->
pb
, cur, SEEK_SET);
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}
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// LCM of all possible ADTS sample rates
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avpriv_set_pts_info
(st, 64, 1, 28224000);
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return
0;
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}
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AVInputFormat
ff_aac_demuxer
= {
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.
name
=
"aac"
,
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.long_name =
NULL_IF_CONFIG_SMALL
(
"raw ADTS AAC (Advanced Audio Coding)"
),
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.read_probe =
adts_aac_probe
,
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.read_header =
adts_aac_read_header
,
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.read_packet =
ff_raw_read_partial_packet
,
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.flags =
AVFMT_GENERIC_INDEX
,
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.extensions =
"aac"
,
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.mime_type =
"audio/aac,audio/aacp,audio/x-aac"
,
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.raw_codec_id =
AV_CODEC_ID_AAC
,
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};
Generated on Sun Mar 8 2015 02:34:46 for FFmpeg by
1.8.2