FFmpeg/libavcodec/ac3dec.h

/*
 * Common code between AC3 and E-AC3 decoder
 * Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
 *
 * 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 and E-AC3 decoder.
 */

#ifndef FFMPEG_AC3DEC_H
#define FFMPEG_AC3DEC_H

#include "libavutil/random.h"
#include "ac3tab.h"
#include "ac3.h"
#include "bitstream.h"
#include "dsputil.h"

/* override ac3.h to include coupling channel */
#undef AC3_MAX_CHANNELS
#define AC3_MAX_CHANNELS 7
#define CPL_CH 0

#define AC3_OUTPUT_LFEON  8

#define AC3_MAX_COEFS   256
#define AC3_BLOCK_SIZE  256

typedef struct {
    AVCodecContext *avctx;                  ///< parent context
    GetBitContext gbc;                      ///< bitstream reader
    uint8_t *input_buffer;                  ///< temp buffer to prevent overread

///@defgroup bsi bit stream information
///@{
    int frame_type;                         ///< frame type                             (strmtyp)
    int substreamid;                        ///< substream identification
    int frame_size;                         ///< current frame size, in bytes
    int bit_rate;                           ///< stream bit rate, in bits-per-second
    int sample_rate;                        ///< sample frequency, in Hz
    int num_blocks;                         ///< number of audio blocks
    int channel_mode;                       ///< channel mode                           (acmod)
    int lfe_on;                             ///< lfe channel in use
    int center_mix_level;                   ///< Center mix level index
    int surround_mix_level;                 ///< Surround mix level index
///@}

///@defgroup cpl standard coupling
    int cpl_in_use;                         ///< coupling in use                        (cplinu)
    int channel_in_cpl[AC3_MAX_CHANNELS];   ///< channel in coupling                    (chincpl)
    int phase_flags_in_use;                 ///< phase flags in use                     (phsflginu)
    int phase_flags[18];                    ///< phase flags                            (phsflg)
    int num_cpl_subbands;                   ///< number of coupling sub bands           (ncplsubnd)
    int num_cpl_bands;                      ///< number of coupling bands               (ncplbnd)
    int cpl_band_struct[18];                ///< coupling band structure                (cplbndstrc)
    int cpl_coords[AC3_MAX_CHANNELS][18];   ///< coupling coordinates                   (cplco)
///@}

///@defgroup channel channel
    int fbw_channels;                           ///< number of full-bandwidth channels
    int channels;                               ///< number of total channels
    int lfe_ch;                                 ///< index of LFE channel
    float downmix_coeffs[AC3_MAX_CHANNELS][2];  ///< stereo downmix coefficients
    float downmix_coeff_adjust[2];              ///< adjustment needed for each output channel when downmixing
    int downmixed;                              ///< indicates if coeffs are currently downmixed
    int output_mode;                            ///< output channel configuration
    int out_channels;                           ///< number of output channels
///@}

///@defgroup dynrng dynamic range
    float dynamic_range[2];                 ///< dynamic range
///@}

///@defgroup bandwidth bandwidth
    int start_freq[AC3_MAX_CHANNELS];       ///< start frequency bin                    (strtmant)
    int end_freq[AC3_MAX_CHANNELS];         ///< end frequency bin                      (endmant)
///@}

///@defgroup rematrixing rematrixing
    int num_rematrixing_bands;              ///< number of rematrixing bands            (nrematbnd)
    int rematrixing_flags[4];               ///< rematrixing flags                      (rematflg)
///@}

///@defgroup exponents exponents
    int num_exp_groups[AC3_MAX_CHANNELS];           ///< Number of exponent groups      (nexpgrp)
    int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS];  ///< decoded exponents
    int exp_strategy[AC3_MAX_CHANNELS];             ///< exponent strategies            (expstr)
///@}

///@defgroup bitalloc bit allocation
    AC3BitAllocParameters bit_alloc_params;         ///< bit allocation parameters
    int snr_offset[AC3_MAX_CHANNELS];               ///< signal-to-noise ratio offsets  (snroffst)
    int fast_gain[AC3_MAX_CHANNELS];                ///< fast gain values/SMR's         (fgain)
    uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS];   ///< bit allocation pointers
    int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS];   ///< scaled exponents
    int16_t band_psd[AC3_MAX_CHANNELS][50];         ///< interpolated exponents
    int16_t mask[AC3_MAX_CHANNELS][50];             ///< masking curve values
    int dba_mode[AC3_MAX_CHANNELS];                 ///< delta bit allocation mode
    int dba_nsegs[AC3_MAX_CHANNELS];                ///< number of delta segments
    uint8_t dba_offsets[AC3_MAX_CHANNELS][8];       ///< delta segment offsets
    uint8_t dba_lengths[AC3_MAX_CHANNELS][8];       ///< delta segment lengths
    uint8_t dba_values[AC3_MAX_CHANNELS][8];        ///< delta values for each segment
///@}

///@defgroup dithering zero-mantissa dithering
    int dither_all;                         ///< true if all channels are dithered
    int dither_flag[AC3_MAX_CHANNELS];      ///< dither flags                           (dithflg)
    AVRandomState dith_state;               ///< for dither generation
///@}

///@defgroup imdct IMDCT
    int block_switch[AC3_MAX_CHANNELS];     ///< block switch flags                     (blksw)
    MDCTContext imdct_512;                  ///< for 512 sample IMDCT
    MDCTContext imdct_256;                  ///< for 256 sample IMDCT
///@}

///@defgroup opt optimization
    DSPContext dsp;                         ///< for optimization
    float add_bias;                         ///< offset for float_to_int16 conversion
    float mul_bias;                         ///< scaling for float_to_int16 conversion
///@}

    int fixed_coeffs[AC3_MAX_CHANNELS][AC3_MAX_COEFS];  ///> fixed-point transform coefficients

///@defgroup arrays aligned arrays
    DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][AC3_MAX_COEFS]);   ///< transform coefficients
    DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]);             ///< delay - added to the next block
    DECLARE_ALIGNED_16(float, window[AC3_BLOCK_SIZE]);                              ///< window coefficients
    DECLARE_ALIGNED_16(float, tmp_output[AC3_BLOCK_SIZE*2]);                        ///< temporary storage for output before windowing
    DECLARE_ALIGNED_16(float, tmp_imdct[AC3_BLOCK_SIZE]);                           ///< temporary storage for imdct transform
    DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]);            ///< output after imdct transform and windowing
    DECLARE_ALIGNED_16(short, int_output[AC3_MAX_CHANNELS-1][AC3_BLOCK_SIZE]);      ///< final 16-bit integer output
///@}
} AC3DecodeContext;

#endif /* FFMPEG_AC3DEC_H */