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/lfg.h"
  31 #include "ac3.h"
  32 #include "get_bits.h"
  33 #include "dsputil.h"
  34
  35 /* override ac3.h to include coupling channel */
  36 #undef AC3_MAX_CHANNELS
  37 #define AC3_MAX_CHANNELS 7
  38 #define CPL_CH 0
  39
  40 #define AC3_OUTPUT_LFEON  8
  41
  42 #define AC3_MAX_COEFS   256
  43 #define AC3_BLOCK_SIZE  256
  44 #define MAX_BLOCKS        6
  45
  46 typedef struct {
  47     AVCodecContext *avctx;                  ///< parent context
  48     GetBitContext gbc;                      ///< bitstream reader
  49     uint8_t *input_buffer;                  ///< temp buffer to prevent overread
  50
  51 ///@defgroup bsi bit stream information
  52 ///@{
  53     int frame_type;                         ///< frame type                             (strmtyp)
  54     int substreamid;                        ///< substream identification
  55     int frame_size;                         ///< current frame size, in bytes
  56     int bit_rate;                           ///< stream bit rate, in bits-per-second
  57     int sample_rate;                        ///< sample frequency, in Hz
  58     int num_blocks;                         ///< number of audio blocks
  59     int channel_mode;                       ///< channel mode                           (acmod)
  60     int channel_layout;                     ///< channel layout
  61     int lfe_on;                             ///< lfe channel in use
  62     int channel_map;                        ///< custom channel map
  63     int center_mix_level;                   ///< Center mix level index
  64     int surround_mix_level;                 ///< Surround mix level index
  65     int eac3;                               ///< indicates if current frame is E-AC-3
  66 ///@}
  67
  68 ///@defgroup audfrm frame syntax parameters
  69     int snr_offset_strategy;                ///< SNR offset strategy                    (snroffststr)
  70     int block_switch_syntax;                ///< block switch syntax enabled            (blkswe)
  71     int dither_flag_syntax;                 ///< dither flag syntax enabled             (dithflage)
  72     int bit_allocation_syntax;              ///< bit allocation model syntax enabled    (bamode)
  73     int fast_gain_syntax;                   ///< fast gain codes enabled                (frmfgaincode)
  74     int dba_syntax;                         ///< delta bit allocation syntax enabled    (dbaflde)
  75     int skip_syntax;                        ///< skip field syntax enabled              (skipflde)
  76  ///@}
  77
  78 ///@defgroup cpl standard coupling
  79     int cpl_in_use[MAX_BLOCKS];             ///< coupling in use                        (cplinu)
  80     int cpl_strategy_exists[MAX_BLOCKS];    ///< coupling strategy exists               (cplstre)
  81     int channel_in_cpl[AC3_MAX_CHANNELS];   ///< channel in coupling                    (chincpl)
  82     int phase_flags_in_use;                 ///< phase flags in use                     (phsflginu)
  83     int phase_flags[18];                    ///< phase flags                            (phsflg)
  84     int num_cpl_bands;                      ///< number of coupling bands               (ncplbnd)
  85     uint8_t cpl_band_sizes[18];             ///< number of coeffs in each coupling band
  86     int firstchincpl;                       ///< first channel in coupling
  87     int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states      (firstcplcos)
  88     int cpl_coords[AC3_MAX_CHANNELS][18];   ///< coupling coordinates                   (cplco)
  89 ///@}
  90
  91 ///@defgroup aht adaptive hybrid transform
  92     int channel_uses_aht[AC3_MAX_CHANNELS];                         ///< channel AHT in use (chahtinu)
  93     int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][MAX_BLOCKS];  ///< pre-IDCT mantissas
  94 ///@}
  95
  96 ///@defgroup channel channel
  97     int fbw_channels;                           ///< number of full-bandwidth channels
  98     int channels;                               ///< number of total channels
  99     int lfe_ch;                                 ///< index of LFE channel
 100     float downmix_coeffs[AC3_MAX_CHANNELS][2];  ///< stereo downmix coefficients
 101     int downmixed;                              ///< indicates if coeffs are currently downmixed
 102     int output_mode;                            ///< output channel configuration
 103     int out_channels;                           ///< number of output channels
 104 ///@}
 105
 106 ///@defgroup dynrng dynamic range
 107     float dynamic_range[2];                 ///< dynamic range
 108 ///@}
 109
 110 ///@defgroup bandwidth bandwidth
 111     int start_freq[AC3_MAX_CHANNELS];       ///< start frequency bin                    (strtmant)
 112     int end_freq[AC3_MAX_CHANNELS];         ///< end frequency bin                      (endmant)
 113 ///@}
 114
 115 ///@defgroup rematrixing rematrixing
 116     int num_rematrixing_bands;              ///< number of rematrixing bands            (nrematbnd)
 117     int rematrixing_flags[4];               ///< rematrixing flags                      (rematflg)
 118 ///@}
 119
 120 ///@defgroup exponents exponents
 121     int num_exp_groups[AC3_MAX_CHANNELS];           ///< Number of exponent groups      (nexpgrp)
 122     int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS];  ///< decoded exponents
 123     int exp_strategy[MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies            (expstr)
 124 ///@}
 125
 126 ///@defgroup bitalloc bit allocation
 127     AC3BitAllocParameters bit_alloc_params;         ///< bit allocation parameters
 128     int first_cpl_leak;                             ///< first coupling leak state      (firstcplleak)
 129     int snr_offset[AC3_MAX_CHANNELS];               ///< signal-to-noise ratio offsets  (snroffst)
 130     int fast_gain[AC3_MAX_CHANNELS];                ///< fast gain values/SMR's         (fgain)
 131     uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS];   ///< bit allocation pointers
 132     int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS];   ///< scaled exponents
 133     int16_t band_psd[AC3_MAX_CHANNELS][50];         ///< interpolated exponents
 134     int16_t mask[AC3_MAX_CHANNELS][50];             ///< masking curve values
 135     int dba_mode[AC3_MAX_CHANNELS];                 ///< delta bit allocation mode
 136     int dba_nsegs[AC3_MAX_CHANNELS];                ///< number of delta segments
 137     uint8_t dba_offsets[AC3_MAX_CHANNELS][8];       ///< delta segment offsets
 138     uint8_t dba_lengths[AC3_MAX_CHANNELS][8];       ///< delta segment lengths
 139     uint8_t dba_values[AC3_MAX_CHANNELS][8];        ///< delta values for each segment
 140 ///@}
 141
 142 ///@defgroup dithering zero-mantissa dithering
 143     int dither_flag[AC3_MAX_CHANNELS];      ///< dither flags                           (dithflg)
 144     AVLFG dith_state;                       ///< for dither generation
 145 ///@}
 146
 147 ///@defgroup imdct IMDCT
 148     int block_switch[AC3_MAX_CHANNELS];     ///< block switch flags                     (blksw)
 149     MDCTContext imdct_512;                  ///< for 512 sample IMDCT
 150     MDCTContext imdct_256;                  ///< for 256 sample IMDCT
 151 ///@}
 152
 153 ///@defgroup opt optimization
 154     DSPContext dsp;                         ///< for optimization
 155     float add_bias;                         ///< offset for float_to_int16 conversion
 156     float mul_bias;                         ///< scaling for float_to_int16 conversion
 157 ///@}
 158
 159 ///@defgroup arrays aligned arrays
 160     DECLARE_ALIGNED_16(int,   fixed_coeffs[AC3_MAX_CHANNELS][AC3_MAX_COEFS]);       ///> fixed-point transform coefficients
 161     DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][AC3_MAX_COEFS]);   ///< transform coefficients
 162     DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]);             ///< delay - added to the next block
 163     DECLARE_ALIGNED_16(float, window[AC3_BLOCK_SIZE]);                              ///< window coefficients
 164     DECLARE_ALIGNED_16(float, tmp_output[AC3_BLOCK_SIZE]);                          ///< temporary storage for output before windowing
 165     DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]);            ///< output after imdct transform and windowing
 166 ///@}
 167 } AC3DecodeContext;
 168
 169 /**
 170  * Parse the E-AC-3 frame header.
 171  * This parses both the bit stream info and audio frame header.
 172  */
 173 int ff_eac3_parse_header(AC3DecodeContext *s);
 174
 175 /**
 176  * Decode mantissas in a single channel for the entire frame.
 177  * This is used when AHT mode is enabled.
 178  */
 179 void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch);
 180
 181 #endif /* AVCODEC_AC3DEC_H */