libavcodec/ac3dec.h

   1 /*
   2  * Common code between the AC-3 and E-AC-3 decoders
   3  * Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file libavcodec/ac3.h
  24  * Common code between the AC-3 and E-AC-3 decoders.
  25  */
  26
  27 #ifndef AVCODEC_AC3DEC_H
  28 #define AVCODEC_AC3DEC_H
  29
  30 #include "libavutil/internal.h"
  31 #include "libavutil/lfg.h"
  32 #include "ac3.h"
  33 #include "get_bits.h"
  34 #include "dsputil.h"
  35
  36 /* override ac3.h to include coupling channel */
  37 #undef AC3_MAX_CHANNELS
  38 #define AC3_MAX_CHANNELS 7
  39 #define CPL_CH 0
  40
  41 #define AC3_OUTPUT_LFEON  8
  42
  43 #define AC3_MAX_COEFS   256
  44 #define AC3_BLOCK_SIZE  256
  45 #define MAX_BLOCKS        6
  46
  47 typedef struct {
  48     AVCodecContext *avctx;                  ///< parent context
  49     GetBitContext gbc;                      ///< bitstream reader
  50     uint8_t *input_buffer;                  ///< temp buffer to prevent overread
  51
  52 ///@defgroup bsi bit stream information
  53 ///@{
  54     int frame_type;                         ///< frame type                             (strmtyp)
  55     int substreamid;                        ///< substream identification
  56     int frame_size;                         ///< current frame size, in bytes
  57     int bit_rate;                           ///< stream bit rate, in bits-per-second
  58     int sample_rate;                        ///< sample frequency, in Hz
  59     int num_blocks;                         ///< number of audio blocks
  60     int channel_mode;                       ///< channel mode                           (acmod)
  61     int channel_layout;                     ///< channel layout
  62     int lfe_on;                             ///< lfe channel in use
  63     int channel_map;                        ///< custom channel map
  64     int center_mix_level;                   ///< Center mix level index
  65     int surround_mix_level;                 ///< Surround mix level index
  66     int eac3;                               ///< indicates if current frame is E-AC-3
  67 ///@}
  68
  69 ///@defgroup audfrm frame syntax parameters
  70     int snr_offset_strategy;                ///< SNR offset strategy                    (snroffststr)
  71     int block_switch_syntax;                ///< block switch syntax enabled            (blkswe)
  72     int dither_flag_syntax;                 ///< dither flag syntax enabled             (dithflage)
  73     int bit_allocation_syntax;              ///< bit allocation model syntax enabled    (bamode)
  74     int fast_gain_syntax;                   ///< fast gain codes enabled                (frmfgaincode)
  75     int dba_syntax;                         ///< delta bit allocation syntax enabled    (dbaflde)
  76     int skip_syntax;                        ///< skip field syntax enabled              (skipflde)
  77  ///@}
  78
  79 ///@defgroup cpl standard coupling
  80     int cpl_in_use[MAX_BLOCKS];             ///< coupling in use                        (cplinu)
  81     int cpl_strategy_exists[MAX_BLOCKS];    ///< coupling strategy exists               (cplstre)
  82     int channel_in_cpl[AC3_MAX_CHANNELS];   ///< channel in coupling                    (chincpl)
  83     int phase_flags_in_use;                 ///< phase flags in use                     (phsflginu)
  84     int phase_flags[18];                    ///< phase flags                            (phsflg)
  85     int num_cpl_bands;                      ///< number of coupling bands               (ncplbnd)
  86     uint8_t cpl_band_struct[18];            ///< coupling band structure                (cplbndstrc)
  87     int firstchincpl;                       ///< first channel in coupling
  88     int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states      (firstcplcos)
  89     int cpl_coords[AC3_MAX_CHANNELS][18];   ///< coupling coordinates                   (cplco)
  90 ///@}
  91
  92 ///@defgroup aht adaptive hybrid transform
  93     int channel_uses_aht[AC3_MAX_CHANNELS];                         ///< channel AHT in use (chahtinu)
  94     int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][MAX_BLOCKS];  ///< pre-IDCT mantissas
  95 ///@}
  96
  97 ///@defgroup channel channel
  98     int fbw_channels;                           ///< number of full-bandwidth channels
  99     int channels;                               ///< number of total channels
 100     int lfe_ch;                                 ///< index of LFE channel
 101     float downmix_coeffs[AC3_MAX_CHANNELS][2];  ///< stereo downmix coefficients
 102     int downmixed;                              ///< indicates if coeffs are currently downmixed
 103     int output_mode;                            ///< output channel configuration
 104     int out_channels;                           ///< number of output channels
 105 ///@}
 106
 107 ///@defgroup dynrng dynamic range
 108     float dynamic_range[2];                 ///< dynamic range
 109 ///@}
 110
 111 ///@defgroup bandwidth bandwidth
 112     int start_freq[AC3_MAX_CHANNELS];       ///< start frequency bin                    (strtmant)
 113     int end_freq[AC3_MAX_CHANNELS];         ///< end frequency bin                      (endmant)
 114 ///@}
 115
 116 ///@defgroup rematrixing rematrixing
 117     int num_rematrixing_bands;              ///< number of rematrixing bands            (nrematbnd)
 118     int rematrixing_flags[4];               ///< rematrixing flags                      (rematflg)
 119 ///@}
 120
 121 ///@defgroup exponents exponents
 122     int num_exp_groups[AC3_MAX_CHANNELS];           ///< Number of exponent groups      (nexpgrp)
 123     int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS];  ///< decoded exponents
 124     int exp_strategy[MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies            (expstr)
 125 ///@}
 126
 127 ///@defgroup bitalloc bit allocation
 128     AC3BitAllocParameters bit_alloc_params;         ///< bit allocation parameters
 129     int first_cpl_leak;                             ///< first coupling leak state      (firstcplleak)
 130     int snr_offset[AC3_MAX_CHANNELS];               ///< signal-to-noise ratio offsets  (snroffst)
 131     int fast_gain[AC3_MAX_CHANNELS];                ///< fast gain values/SMR's         (fgain)
 132     uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS];   ///< bit allocation pointers
 133     int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS];   ///< scaled exponents
 134     int16_t band_psd[AC3_MAX_CHANNELS][50];         ///< interpolated exponents
 135     int16_t mask[AC3_MAX_CHANNELS][50];             ///< masking curve values
 136     int dba_mode[AC3_MAX_CHANNELS];                 ///< delta bit allocation mode
 137     int dba_nsegs[AC3_MAX_CHANNELS];                ///< number of delta segments
 138     uint8_t dba_offsets[AC3_MAX_CHANNELS][8];       ///< delta segment offsets
 139     uint8_t dba_lengths[AC3_MAX_CHANNELS][8];       ///< delta segment lengths
 140     uint8_t dba_values[AC3_MAX_CHANNELS][8];        ///< delta values for each segment
 141 ///@}
 142
 143 ///@defgroup dithering zero-mantissa dithering
 144     int dither_flag[AC3_MAX_CHANNELS];      ///< dither flags                           (dithflg)
 145     AVLFG dith_state;                       ///< for dither generation
 146 ///@}
 147
 148 ///@defgroup imdct IMDCT
 149     int block_switch[AC3_MAX_CHANNELS];     ///< block switch flags                     (blksw)
 150     MDCTContext imdct_512;                  ///< for 512 sample IMDCT
 151     MDCTContext imdct_256;                  ///< for 256 sample IMDCT
 152 ///@}
 153
 154 ///@defgroup opt optimization
 155     DSPContext dsp;                         ///< for optimization
 156     float add_bias;                         ///< offset for float_to_int16 conversion
 157     float mul_bias;                         ///< scaling for float_to_int16 conversion
 158 ///@}
 159
 160     DECLARE_ALIGNED_16(int, fixed_coeffs[AC3_MAX_CHANNELS][AC3_MAX_COEFS]);  ///> fixed-point transform coefficients
 161
 162 ///@defgroup arrays aligned arrays
 163     DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][AC3_MAX_COEFS]);   ///< transform coefficients
 164     DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]);             ///< delay - added to the next block
 165     DECLARE_ALIGNED_16(float, window[AC3_BLOCK_SIZE]);                              ///< window coefficients
 166     DECLARE_ALIGNED_16(float, tmp_output[AC3_BLOCK_SIZE]);                          ///< temporary storage for output before windowing
 167     DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]);            ///< output after imdct transform and windowing
 168 ///@}
 169 } AC3DecodeContext;
 170
 171 /**
 172  * Parse the E-AC-3 frame header.
 173  * This parses both the bit stream info and audio frame header.
 174  */
 175 int ff_eac3_parse_header(AC3DecodeContext *s);
 176
 177 /**
 178  * Decode mantissas in a single channel for the entire frame.
 179  * This is used when AHT mode is enabled.
 180  */
 181 void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch);
 182
 183 #endif /* AVCODEC_AC3DEC_H */