mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
109 lines
3.5 KiB
109 lines
3.5 KiB
/* |
|
* 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 const 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);
|
|
|