forked from KolibriOS/kolibrios
79 lines
2.4 KiB
C
79 lines
2.4 KiB
C
|
/*
|
||
|
|
* 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
|
||
|
|
*/
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @file
|
||
|
|
* MPEG Audio header decoder.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#ifndef AVCODEC_MPEGAUDIODECHEADER_H
|
||
|
|
#define AVCODEC_MPEGAUDIODECHEADER_H
|
||
|
|
|
||
|
|
#include "avcodec.h"
|
||
|
|
|
||
|
|
#define MP3_MASK 0xFFFE0CCF
|
||
|
|
|
||
|
|
#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;
|
||
|
|
|
||
|
|
typedef struct MPADecodeHeader {
|
||
|
|
MPA_DECODE_HEADER
|
||
|
|
} MPADecodeHeader;
|
||
|
|
|
||
|
|
/* 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);
|
||
|
|
|
||
|
|
int avpriv_mpa_decode_header2(uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bitrate, enum AVCodecID *codec_id);
|
||
|
|
|
||
|
|
/* 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;
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif /* AVCODEC_MPEGAUDIODECHEADER_H */
|