/*

  * 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 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

  * 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/float_dsp.h"

 #include "libavutil/lfg.h"

 #include "ac3.h"

 #include "ac3dsp.h"

 #include "get_bits.h"

 #include "dsputil.h"

 #include "fft.h"

 #include "fmtconvert.h"

 
 #define AC3_OUTPUT_LFEON  8
 

 #define SPX_MAX_BANDS    17

 /** Large enough for maximum possible frame size when the specification limit is ignored */
 #define AC3_FRAME_BUFFER_SIZE 32768
 

 typedef struct AC3DecodeContext {

     AVClass        *class;                  ///< class for AVOptions

     AVCodecContext *avctx;                  ///< parent context
     GetBitContext gbc;                      ///< bitstream reader
 

 ///@name 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_id;                       ///< bitstream id                           (bsid)

     int bitstream_mode;                     ///< bitstream mode                         (bsmod)

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

     int lfe_on;                             ///< lfe channel in use

     int channel_map;                        ///< custom channel map

     int preferred_downmix;                  ///< Preferred 2-channel downmix mode       (dmixmod)

     int center_mix_level;                   ///< Center mix level index

     int center_mix_level_ltrt;              ///< Center mix level index for Lt/Rt       (ltrtcmixlev)

     int surround_mix_level;                 ///< Surround mix level index

     int surround_mix_level_ltrt;            ///< Surround mix level index for Lt/Rt     (ltrtsurmixlev)
     int lfe_mix_level_exists;               ///< indicates if lfemixlevcod is specified (lfemixlevcode)
     int lfe_mix_level;                      ///< LFE mix level index                    (lfemixlevcod)

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

     int dolby_surround_mode;                ///< dolby surround mode                    (dsurmod)
     int dolby_surround_ex_mode;             ///< dolby surround ex mode                 (dsurexmod)
     int dolby_headphone_mode;               ///< dolby headphone mode                   (dheadphonmod)

 ///@}
 

     int preferred_stereo_downmix;
     float ltrt_center_mix_level;
     float ltrt_surround_mix_level;
     float loro_center_mix_level;
     float loro_surround_mix_level;
 

 ///@name 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)
  ///@}
 

 ///@name 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)

 ///@}

 ///@name 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)
 ///@}
 

 ///@name 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

 ///@}
 

 ///@name 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

 ///@}

 ///@name Dynamic range

     float dynamic_range[2];                 ///< dynamic range

     float drc_scale;                        ///< percentage of dynamic range compression to be applied

 ///@}
 

 ///@name Bandwidth

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

 ///@}

 ///@name Rematrixing

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

 ///@}
 

 ///@name 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)

 ///@}
 

 ///@name 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

 ///@}

 ///@name Zero-mantissa dithering

     int dither_flag[AC3_MAX_CHANNELS];      ///< dither flags                           (dithflg)

     AVLFG dith_state;                       ///< for dither generation

 ///@}

 ///@name 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

 ///@}
 

 ///@name Optimization

     DSPContext dsp;                         ///< for optimization

     AVFloatDSPContext fdsp;

     AC3DSPContext ac3dsp;

     FmtConvertContext fmt_conv;             ///< optimized conversion functions

 ///@}

     float *outptr[AC3_MAX_CHANNELS];
     float *xcfptr[AC3_MAX_CHANNELS];
     float *dlyptr[AC3_MAX_CHANNELS];
 

 ///@name Aligned arrays

     DECLARE_ALIGNED(16, int32_t, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS];     ///< fixed-point transform coefficients

     DECLARE_ALIGNED(32, float, transform_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS];   ///< transform coefficients
     DECLARE_ALIGNED(32, float, delay)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE];             ///< delay - added to the next block
     DECLARE_ALIGNED(32, float, window)[AC3_BLOCK_SIZE];                              ///< window coefficients
     DECLARE_ALIGNED(32, float, tmp_output)[AC3_BLOCK_SIZE];                          ///< temporary storage for output before windowing
     DECLARE_ALIGNED(32, float, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE];            ///< output after imdct transform and windowing

     DECLARE_ALIGNED(32, uint8_t, input_buffer)[AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE]; ///< temp buffer to prevent overread

 ///@}

 } 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);
 

 /**
  * 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 */