FFmpeg/libavcodec/libac3/ac3.h

/* 
 *    ac3.h
 *
 *	Copyright (C) Aaron Holtzman - May 1999
 *
 *  This file is part of ac3dec, a free Dolby AC-3 stream decoder.
 *	
 *  ac3dec is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *   
 *  ac3dec 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 General Public License for more details.
 *   
 *  You should have received a copy of the GNU General Public License
 *  along with GNU Make; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 
 *
 *
 */

typedef struct ac3_ba_s {
    uint16_t fsnroffst;	// fine SNR offset
    uint16_t fgaincod;	// fast gain
    uint16_t deltbae;	// delta bit allocation exists
    int8_t deltba[50];	// per-band delta bit allocation
} ac3_ba_t;

typedef struct ac3_state_s {
    uint8_t fscod;		// sample rate
    uint8_t halfrate;		// halfrate factor
    uint8_t acmod;		// coded channels
    float clev;			// centre channel mix level
    float slev;			// surround channels mix level
    uint8_t lfeon;		// coded lfe channel

    int output;			// type of output
    float level;		// output level
    float bias;			// output bias

    uint16_t cplinu;		// coupling in use
    uint16_t chincpl[5];	// channel coupled
    uint16_t phsflginu;		// phase flags in use (stereo only)
    uint16_t cplbndstrc[18];	// coupling band structure
    uint16_t cplstrtmant;	// coupling channel start mantissa
    uint16_t cplendmant;	// coupling channel end mantissa
    float cplco[5][18];		// coupling coordinates

    // derived information
    uint16_t cplstrtbnd;	// coupling start band (for bit allocation)
    uint16_t ncplbnd;		// number of coupling bands

    uint16_t rematflg[4];	// stereo rematrixing

    uint16_t endmant[5];	// channel end mantissa

    uint8_t cpl_exp[256];	// decoded coupling channel exponents
    uint8_t fbw_exp[5][256];	// decoded channel exponents
    uint8_t lfe_exp[7];		// decoded lfe channel exponents

    uint16_t sdcycod;		// slow decay
    uint16_t fdcycod;		// fast decay
    uint16_t sgaincod;		// slow gain
    uint16_t dbpbcod;		// dB per bit - encodes the dbknee value
    uint16_t floorcod;		// masking floor

    uint16_t csnroffst;		// coarse SNR offset
    ac3_ba_t cplba;		// coupling bit allocation parameters
    ac3_ba_t ba[5];		// channel bit allocation parameters
    ac3_ba_t lfeba;		// lfe bit allocation parameters

    uint16_t cplfleak;		// coupling fast leak init
    uint16_t cplsleak;		// coupling slow leak init

    // derived bit allocation information
    int8_t fbw_bap[5][256];
    int8_t cpl_bap[256];
    int8_t lfe_bap[7];
} ac3_state_t;

/* samples work structure */
typedef float stream_samples_t[6][256];

#define AC3_CHANNEL 0
#define AC3_MONO 1
#define AC3_STEREO 2
#define AC3_3F 3
#define AC3_2F1R 4
#define AC3_3F1R 5
#define AC3_2F2R 6
#define AC3_3F2R 7
#define AC3_CHANNEL1 8
#define AC3_CHANNEL2 9
#define AC3_DOLBY 10
#define AC3_CHANNEL_MASK 15

#define AC3_LFE 16
#define AC3_ADJUST_LEVEL 32

void ac3_init (void);
int ac3_syncinfo (uint8_t * buf, int * flags,
		  int * sample_rate, int * bit_rate);
int ac3_frame (ac3_state_t * state, uint8_t * buf, int * flags,
	       float * level, float bias);
int ac3_block (ac3_state_t * state);