FFmpeg
libavcodec
mpegaudiodecheader.h
Go to the documentation of this file.
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/*
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* MPEG Audio header decoder
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* Copyright (c) 2001, 2002 Fabrice Bellard
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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
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* 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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/**
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* @file
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* MPEG Audio header decoder.
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*/
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#ifndef AVCODEC_MPEGAUDIODECHEADER_H
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#define AVCODEC_MPEGAUDIODECHEADER_H
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#include <stdint.h>
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#include "
codec_id.h
"
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#define MP3_MASK 0xFFFE0CCF
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#define MPA_DECODE_HEADER \
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int frame_size; \
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int error_protection; \
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int layer; \
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int sample_rate; \
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int sample_rate_index;
/* between 0 and 8 */
\
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int bit_rate; \
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int nb_channels; \
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int mode; \
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int mode_ext; \
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int lsf;
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typedef
struct
MPADecodeHeader
{
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MPA_DECODE_HEADER
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}
MPADecodeHeader
;
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/* header decoding. MUST check the header before because no
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consistency check is done there. Return 1 if free format found and
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that the frame size must be computed externally */
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int
avpriv_mpegaudio_decode_header
(
MPADecodeHeader
*
s
, uint32_t
header
);
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/* useful helper to get MPEG audio stream info. Return -1 if error in
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header, otherwise the coded frame size in bytes */
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int
ff_mpa_decode_header
(uint32_t head,
int
*sample_rate,
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int
*
channels
,
int
*
frame_size
,
int
*
bitrate
,
enum
AVCodecID
*
codec_id
);
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/* fast header check for resync */
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static
inline
int
ff_mpa_check_header
(uint32_t
header
){
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/* header */
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if
((
header
& 0xffe00000) != 0xffe00000)
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return
-1;
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/* version check */
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if
((
header
& (3<<19)) == 1<<19)
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return
-1;
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/* layer check */
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if
((
header
& (3<<17)) == 0)
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return
-1;
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/* bit rate */
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if
((
header
& (0
xf
<<12)) == 0
xf
<<12)
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return
-1;
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/* frequency */
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if
((
header
& (3<<10)) == 3<<10)
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return
-1;
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return
0;
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}
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#endif
/* AVCODEC_MPEGAUDIODECHEADER_H */
MPADecodeHeader
Definition:
mpegaudiodecheader.h:47
codec_id.h
s
#define s(width, name)
Definition:
cbs_vp9.c:198
bitrate
int64_t bitrate
Definition:
av1_levels.c:47
frame_size
int frame_size
Definition:
mxfenc.c:2429
channels
channels
Definition:
aptx.h:31
codec_id
enum AVCodecID codec_id
Definition:
vaapi_decode.c:410
AVCodecID
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition:
codec_id.h:49
ff_mpa_check_header
static int ff_mpa_check_header(uint32_t header)
Definition:
mpegaudiodecheader.h:62
header
static const uint8_t header[24]
Definition:
sdr2.c:68
MPA_DECODE_HEADER
#define MPA_DECODE_HEADER
Definition:
mpegaudiodecheader.h:35
ff_mpa_decode_header
int ff_mpa_decode_header(uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bitrate, enum AVCodecID *codec_id)
Definition:
mpegaudiodecheader.c:120
xf
#define xf(width, name, var, range_min, range_max, subs,...)
Definition:
cbs_av1.c:598
avpriv_mpegaudio_decode_header
int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header)
Definition:
mpegaudiodecheader.c:34
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