110 lines
3.4 KiB
C
110 lines
3.4 KiB
C
/*
|
|
* Common code between AC3 encoder and decoder
|
|
* Copyright (c) 2000, 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 ac3.h
|
|
* Common code between AC3 encoder and decoder.
|
|
*/
|
|
|
|
#define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */
|
|
#define AC3_MAX_CHANNELS 6 /* including LFE channel */
|
|
|
|
#define NB_BLOCKS 6 /* number of PCM blocks inside an AC3 frame */
|
|
#define AC3_FRAME_SIZE (NB_BLOCKS * 256)
|
|
|
|
/* exponent encoding strategy */
|
|
#define EXP_REUSE 0
|
|
#define EXP_NEW 1
|
|
|
|
#define EXP_D15 1
|
|
#define EXP_D25 2
|
|
#define EXP_D45 3
|
|
|
|
typedef struct AC3BitAllocParameters {
|
|
int fscod; /* frequency */
|
|
int halfratecod;
|
|
int sgain, sdecay, fdecay, dbknee, floor;
|
|
int cplfleak, cplsleak;
|
|
} AC3BitAllocParameters;
|
|
|
|
/**
|
|
* @struct AC3HeaderInfo
|
|
* Coded AC-3 header values up to the lfeon element, plus derived values.
|
|
*/
|
|
typedef struct {
|
|
/** @defgroup coded Coded elements
|
|
* @{
|
|
*/
|
|
uint16_t sync_word;
|
|
uint16_t crc1;
|
|
uint8_t fscod;
|
|
uint8_t frmsizecod;
|
|
uint8_t bsid;
|
|
uint8_t bsmod;
|
|
uint8_t acmod;
|
|
uint8_t cmixlev;
|
|
uint8_t surmixlev;
|
|
uint8_t dsurmod;
|
|
uint8_t lfeon;
|
|
/** @} */
|
|
|
|
/** @defgroup derived Derived values
|
|
* @{
|
|
*/
|
|
uint8_t halfratecod;
|
|
uint16_t sample_rate;
|
|
uint32_t bit_rate;
|
|
uint8_t channels;
|
|
uint16_t frame_size;
|
|
/** @} */
|
|
} AC3HeaderInfo;
|
|
|
|
/**
|
|
* Parses AC-3 frame header.
|
|
* Parses the header up to the lfeon element, which is the first 52 or 54 bits
|
|
* depending on the audio coding mode.
|
|
* @param buf[in] Array containing the first 7 bytes of the frame.
|
|
* @param hdr[out] Pointer to struct where header info is written.
|
|
* @return Returns 0 on success, -1 if there is a sync word mismatch,
|
|
* -2 if the bsid (version) element is invalid, -3 if the fscod (sample rate)
|
|
* element is invalid, or -4 if the frmsizecod (bit rate) element is invalid.
|
|
*/
|
|
int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr);
|
|
|
|
extern uint16_t ff_ac3_frame_sizes[38][3];
|
|
extern const uint8_t ff_ac3_channels[8];
|
|
extern const uint16_t ff_ac3_freqs[3];
|
|
extern const uint16_t ff_ac3_bitratetab[19];
|
|
extern const int16_t ff_ac3_window[256];
|
|
extern const uint8_t ff_sdecaytab[4];
|
|
extern const uint8_t ff_fdecaytab[4];
|
|
extern const uint16_t ff_sgaintab[4];
|
|
extern const uint16_t ff_dbkneetab[4];
|
|
extern const int16_t ff_floortab[8];
|
|
extern const uint16_t ff_fgaintab[8];
|
|
|
|
void ac3_common_init(void);
|
|
void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap,
|
|
int8_t *exp, int start, int end,
|
|
int snroffset, int fgain, int is_lfe,
|
|
int deltbae,int deltnseg,
|
|
uint8_t *deltoffst, uint8_t *deltlen, uint8_t *deltba);
|