PeerStreamer

/*

 * Common code between the AC-3 and E-AC-3 decoders

 * Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>

 *

 * This file is part of Libav.

 *

 * Libav 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.

 *

 * Libav 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 Libav; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * Common code between the AC-3 and E-AC-3 decoders.

 *

 * Summary of MDCT Coefficient Grouping:

 * The individual MDCT coefficient indices are often referred to in the

 * (E-)AC-3 specification as frequency bins.  These bins are grouped together

 * into subbands of 12 coefficients each.  The subbands are grouped together

 * into bands as defined in the bitstream by the band structures, which

 * determine the number of bands and the size of each band.  The full spectrum

 * of 256 frequency bins is divided into 1 DC bin + 21 subbands = 253 bins.

 * This system of grouping coefficients is used for channel bandwidth, stereo

 * rematrixing, channel coupling, enhanced coupling, and spectral extension.

 *

 * +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+

 * |1|  |12|  |  [12|12|12|12]  |  |  |  |  |  |  |  |  |  |  |  |  |3|

 * +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+

 * ~~~  ~~~~     ~~~~~~~~~~~~~                                      ~~~

 *  |     |            |                                             |

 *  |     |            |                    3 unused frequency bins--+

 *  |     |            |

 *  |     |            +--1 band containing 4 subbands

 *  |     |

 *  |     +--1 subband of 12 frequency bins

 *  |

 *  +--DC frequency bin

 */

#ifndef AVCODEC_AC3DEC_H

#define AVCODEC_AC3DEC_H

#include "libavutil/lfg.h"

#include "ac3.h"

#include "get_bits.h"

#include "dsputil.h"

#include "fft.h"

#include "fmtconvert.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 SPX_MAX_BANDS    17

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 bitstream_mode;                     ///< bitstream mode                         (bsmod)

    int channel_mode;                       ///< channel mode                           (acmod)

    int channel_layout;                     ///< channel layout

    int lfe_on;                             ///< lfe channel in use

    int channel_map;                        ///< custom channel map

    int center_mix_level;                   ///< Center mix level index

    int surround_mix_level;                 ///< Surround mix level index

    int eac3;                               ///< indicates if current frame is E-AC-3

///@}

///@defgroup audfrm frame syntax parameters

    int snr_offset_strategy;                ///< SNR offset strategy                    (snroffststr)

    int block_switch_syntax;                ///< block switch syntax enabled            (blkswe)

    int dither_flag_syntax;                 ///< dither flag syntax enabled             (dithflage)

    int bit_allocation_syntax;              ///< bit allocation model syntax enabled    (bamode)

    int fast_gain_syntax;                   ///< fast gain codes enabled                (frmfgaincode)

    int dba_syntax;                         ///< delta bit allocation syntax enabled    (dbaflde)

    int skip_syntax;                        ///< skip field syntax enabled              (skipflde)

 ///@}

///@defgroup cpl standard coupling

    int cpl_in_use[AC3_MAX_BLOCKS];         ///< coupling in use                        (cplinu)

    int cpl_strategy_exists[AC3_MAX_BLOCKS];///< coupling strategy exists               (cplstre)

    int channel_in_cpl[AC3_MAX_CHANNELS];   ///< channel in coupling                    (chincpl)

    int phase_flags_in_use;                 ///< phase flags in use                     (phsflginu)

    int phase_flags[AC3_MAX_CPL_BANDS];     ///< phase flags                            (phsflg)

    int num_cpl_bands;                      ///< number of coupling bands               (ncplbnd)

    uint8_t cpl_band_sizes[AC3_MAX_CPL_BANDS]; ///< number of coeffs in each coupling band

    int firstchincpl;                       ///< first channel in coupling

    int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states      (firstcplcos)

    int cpl_coords[AC3_MAX_CHANNELS][AC3_MAX_CPL_BANDS]; ///< coupling coordinates      (cplco)

///@}

///@defgroup spx spectral extension

///@{

    int spx_in_use;                             ///< spectral extension in use              (spxinu)

    uint8_t channel_uses_spx[AC3_MAX_CHANNELS]; ///< channel uses spectral extension        (chinspx)

    int8_t spx_atten_code[AC3_MAX_CHANNELS];    ///< spx attenuation code                   (spxattencod)

    int spx_src_start_freq;                     ///< spx start frequency bin

    int spx_dst_end_freq;                       ///< spx end frequency bin

    int spx_dst_start_freq;                     ///< spx starting frequency bin for copying (copystartmant)

                                                ///< the copy region ends at the start of the spx region.

    int num_spx_bands;                          ///< number of spx bands                    (nspxbnds)

    uint8_t spx_band_sizes[SPX_MAX_BANDS];      ///< number of bins in each spx band

    uint8_t first_spx_coords[AC3_MAX_CHANNELS]; ///< first spx coordinates states           (firstspxcos)

    float spx_noise_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS]; ///< spx noise blending factor  (nblendfact)

    float spx_signal_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS];///< spx signal blending factor (sblendfact)

///@}

///@defgroup aht adaptive hybrid transform

    int channel_uses_aht[AC3_MAX_CHANNELS];                         ///< channel AHT in use (chahtinu)

    int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][AC3_MAX_BLOCKS];  ///< pre-IDCT mantissas

///@}

///@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

    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_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies        (expstr)

///@}

///@defgroup bitalloc bit allocation

    AC3BitAllocParameters bit_alloc_params;         ///< bit allocation parameters

    int first_cpl_leak;                             ///< first coupling leak state      (firstcplleak)

    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][AC3_CRITICAL_BANDS]; ///< interpolated exponents

    int16_t mask[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS];     ///< 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_flag[AC3_MAX_CHANNELS];      ///< dither flags                           (dithflg)

    AVLFG dith_state;                       ///< for dither generation

///@}

///@defgroup imdct IMDCT

    int block_switch[AC3_MAX_CHANNELS];     ///< block switch flags                     (blksw)

    FFTContext imdct_512;                   ///< for 512 sample IMDCT

    FFTContext imdct_256;                   ///< for 256 sample IMDCT

///@}

///@defgroup opt optimization

    DSPContext dsp;                         ///< for optimization

    FmtConvertContext fmt_conv;             ///< optimized conversion functions

    float mul_bias;                         ///< scaling for float_to_int16 conversion

///@}

///@defgroup arrays aligned arrays

    DECLARE_ALIGNED(16, int,   fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS];       ///> fixed-point transform coefficients

    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];                          ///< temporary storage for output before windowing

    DECLARE_ALIGNED(16, float, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE];            ///< output after imdct transform and windowing

///@}

} AC3DecodeContext;

/**

 * Parse the E-AC-3 frame header.

 * This parses both the bit stream info and audio frame header.

 */

int ff_eac3_parse_header(AC3DecodeContext *s);

/**

 * Decode mantissas in a single channel for the entire frame.

 * This is used when AHT mode is enabled.

 */

void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch);

void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2],

                      int out_ch, int in_ch, int len);

/**

 * Apply spectral extension to each channel by copying lower frequency

 * coefficients to higher frequency bins and applying side information to

 * approximate the original high frequency signal.

 */

void ff_eac3_apply_spectral_extension(AC3DecodeContext *s);

#endif /* AVCODEC_AC3DEC_H */