0,0 → 1,76 |
/* |
* MPEG Audio header decoder |
* Copyright (c) 2001, 2002 Fabrice Bellard |
* |
* This file is part of FFmpeg. |
* |
* FFmpeg is free software; you can redistribute it and/or |
* modify it under the terms of the GNU Lesser General Public |
* License as published by the Free Software Foundation; either |
* version 2.1 of the License, or (at your option) any later version. |
* |
* FFmpeg is distributed in the hope that it will be useful, |
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
* Lesser General Public License for more details. |
* |
* You should have received a copy of the GNU Lesser General Public |
* License along with FFmpeg; if not, write to the Free Software |
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
*/ |
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/** |
* @file |
* MPEG Audio header decoder. |
*/ |
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#ifndef AVCODEC_MPEGAUDIODECHEADER_H |
#define AVCODEC_MPEGAUDIODECHEADER_H |
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#include "avcodec.h" |
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#define MP3_MASK 0xFFFE0CCF |
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#define MPA_DECODE_HEADER \ |
int frame_size; \ |
int error_protection; \ |
int layer; \ |
int sample_rate; \ |
int sample_rate_index; /* between 0 and 8 */ \ |
int bit_rate; \ |
int nb_channels; \ |
int mode; \ |
int mode_ext; \ |
int lsf; |
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typedef struct MPADecodeHeader { |
MPA_DECODE_HEADER |
} MPADecodeHeader; |
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/* header decoding. MUST check the header before because no |
consistency check is done there. Return 1 if free format found and |
that the frame size must be computed externally */ |
int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header); |
|
/* useful helper to get mpeg audio stream infos. Return -1 if error in |
header, otherwise the coded frame size in bytes */ |
int avpriv_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bitrate); |
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/* fast header check for resync */ |
static inline int ff_mpa_check_header(uint32_t header){ |
/* header */ |
if ((header & 0xffe00000) != 0xffe00000) |
return -1; |
/* layer check */ |
if ((header & (3<<17)) == 0) |
return -1; |
/* bit rate */ |
if ((header & (0xf<<12)) == 0xf<<12) |
return -1; |
/* frequency */ |
if ((header & (3<<10)) == 3<<10) |
return -1; |
return 0; |
} |
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#endif /* AVCODEC_MPEGAUDIODECHEADER_H */ |