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/*
* ac3_internal.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.
*
*/
#ifndef __GNUC__
#define inline
#endif
/* Exponent strategy constants */
#define EXP_REUSE (0)
#define EXP_D15 (1)
#define EXP_D25 (2)
#define EXP_D45 (3)
/* Delta bit allocation constants */
#define DELTA_BIT_REUSE (0)
#define DELTA_BIT_NEW (1)
#define DELTA_BIT_NONE (2)
#define DELTA_BIT_RESERVED (3)
/* samples work structure */
typedef float stream_samples_t[6][256];
/* global error flag */
extern uint32_t error_flag;
/* Everything you wanted to know about band structure */
/*
* The entire frequency domain is represented by 256 real
* floating point fourier coefficients. Only the lower 253
* coefficients are actually utilized however. We use arrays
* of 256 to be efficient in some cases.
*
* The 5 full bandwidth channels (fbw) can have their higher
* frequencies coupled together. These coupled channels then
* share their high frequency components.
*
* This coupling band is broken up into 18 sub-bands starting
* at mantissa number 37. Each sub-band is 12 bins wide.
*
* There are 50 bit allocation sub-bands which cover the entire
* frequency range. The sub-bands are of non-uniform width, and
* approximate a 1/6 octave scale.
*/
/* The following structures are filled in by their corresponding parse_*
* functions. See http://www.atsc.org/Standards/A52/a_52.pdf for
* full details on each field. Indented fields are used to denote
* conditional fields.
*/
typedef struct ac3_state_s {
int nfchans; // number of channels, derived from acmod
/* from syncinfo */
uint8_t fscod; // sample rate
/* from bsi */
uint8_t acmod; // coded channels
uint8_t cmixlev; // centre channel mix level
uint8_t surmixlev; // surround channels mix level
uint8_t lfeon; // coded lfe channel
} ac3_state_t;
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;
/* more pain */
typedef struct audblk_s {
uint32_t magic1;
// not reused between blocks
uint16_t blksw[5]; // imdct block transform switch
uint16_t dithflag[5]; // channel dither flag
uint16_t cplinu; // coupling in use
uint16_t chincpl[5]; // channel coupled
uint16_t phsflginu; // phase flags in use (stereo only)
uint16_t cplbegf; // coupling begin frequency code
uint16_t cplendf; // coupling end frequency code
uint16_t cplbndstrc[18]; // coupling band structure
// derived information
uint16_t cplstrtmant; // coupling channel start mantissa
uint16_t cplendmant; // coupling channel end mantissa
uint16_t ncplsubnd; // number of coupling sub-bands
uint16_t ncplbnd; // number of coupling bands
// should we simply have float cplco[5][18] instead of these 4 ?
uint8_t mstrcplco[5]; // per channel master coupling coordinate
uint8_t cplcoexp[5][18]; // per band coupling exponent
uint8_t cplcomant[5][18]; // per band coupling mantissa
uint8_t phsflg[18]; // per band phase flags for stereo
uint16_t rematflg[4]; // stereo rematrixing
uint16_t chbwcod[5]; // channel bandwidth for independant channels
uint32_t magic2;
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
/* coupling mantissas */
uint16_t cplmant[256];
/* -- Information not in the bitstream, but derived thereof -- */
/* End mantissa numbers of fbw channels */
uint16_t endmant[5];
/* Decoded exponent info */
uint8_t fbw_exp[5][256];
uint8_t cpl_exp[256];
uint8_t lfe_exp[7];
/* Bit allocation pointer results */
int8_t fbw_bap[5][256];
int8_t cpl_bap[256];
int8_t lfe_bap[7];
uint32_t magic3;
} audblk_t;
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