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 24 * Common code between the AC-3 and E-AC-3 decoders. 25 * 26 * Summary of MDCT Coefficient Grouping: 27 * The individual MDCT coefficient indices are often referred to in the 28 * (E-)AC-3 specification as frequency bins. These bins are grouped together 29 * into subbands of 12 coefficients each. The subbands are grouped together 30 * into bands as defined in the bitstream by the band structures, which 31 * determine the number of bands and the size of each band. The full spectrum 32 * of 256 frequency bins is divided into 1 DC bin + 21 subbands = 253 bins. 33 * This system of grouping coefficients is used for channel bandwidth, stereo 34 * rematrixing, channel coupling, enhanced coupling, and spectral extension. 35 * 36 * +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+ 37 * |1| |12| | [12|12|12|12] | | | | | | | | | | | | |3| 38 * +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+ 39 * ~~~ ~~~~ ~~~~~~~~~~~~~ ~~~ 40 * | | | | 41 * | | | 3 unused frequency bins--+ 42 * | | | 43 * | | +--1 band containing 4 subbands 44 * | | 45 * | +--1 subband of 12 frequency bins 46 * | 47 * +--DC frequency bin 48 */ 49 50#ifndef AVCODEC_AC3DEC_H 51#define AVCODEC_AC3DEC_H 52 53#include "libavutil/lfg.h" 54#include "ac3.h" 55#include "get_bits.h" 56#include "dsputil.h" 57#include "fft.h" 58 59/* override ac3.h to include coupling channel */ 60#undef AC3_MAX_CHANNELS 61#define AC3_MAX_CHANNELS 7 62#define CPL_CH 0 63 64#define AC3_OUTPUT_LFEON 8 65 66#define AC3_MAX_COEFS 256 67#define AC3_BLOCK_SIZE 256 68#define MAX_BLOCKS 6 69#define SPX_MAX_BANDS 17 70 71typedef struct { 72 AVCodecContext *avctx; ///< parent context 73 GetBitContext gbc; ///< bitstream reader 74 uint8_t *input_buffer; ///< temp buffer to prevent overread 75 76///@defgroup bsi bit stream information 77///@{ 78 int frame_type; ///< frame type (strmtyp) 79 int substreamid; ///< substream identification 80 int frame_size; ///< current frame size, in bytes 81 int bit_rate; ///< stream bit rate, in bits-per-second 82 int sample_rate; ///< sample frequency, in Hz 83 int num_blocks; ///< number of audio blocks 84 int channel_mode; ///< channel mode (acmod) 85 int channel_layout; ///< channel layout 86 int lfe_on; ///< lfe channel in use 87 int channel_map; ///< custom channel map 88 int center_mix_level; ///< Center mix level index 89 int surround_mix_level; ///< Surround mix level index 90 int eac3; ///< indicates if current frame is E-AC-3 91///@} 92 93///@defgroup audfrm frame syntax parameters 94 int snr_offset_strategy; ///< SNR offset strategy (snroffststr) 95 int block_switch_syntax; ///< block switch syntax enabled (blkswe) 96 int dither_flag_syntax; ///< dither flag syntax enabled (dithflage) 97 int bit_allocation_syntax; ///< bit allocation model syntax enabled (bamode) 98 int fast_gain_syntax; ///< fast gain codes enabled (frmfgaincode) 99 int dba_syntax; ///< delta bit allocation syntax enabled (dbaflde) 100 int skip_syntax; ///< skip field syntax enabled (skipflde) 101 ///@} 102 103///@defgroup cpl standard coupling 104 int cpl_in_use[MAX_BLOCKS]; ///< coupling in use (cplinu) 105 int cpl_strategy_exists[MAX_BLOCKS]; ///< coupling strategy exists (cplstre) 106 int channel_in_cpl[AC3_MAX_CHANNELS]; ///< channel in coupling (chincpl) 107 int phase_flags_in_use; ///< phase flags in use (phsflginu) 108 int phase_flags[18]; ///< phase flags (phsflg) 109 int num_cpl_bands; ///< number of coupling bands (ncplbnd) 110 uint8_t cpl_band_sizes[18]; ///< number of coeffs in each coupling band 111 int firstchincpl; ///< first channel in coupling 112 int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states (firstcplcos) 113 int cpl_coords[AC3_MAX_CHANNELS][18]; ///< coupling coordinates (cplco) 114///@} 115 116///@defgroup spx spectral extension 117///@{ 118 int spx_in_use; ///< spectral extension in use (spxinu) 119 uint8_t channel_uses_spx[AC3_MAX_CHANNELS]; ///< channel uses spectral extension (chinspx) 120 int8_t spx_atten_code[AC3_MAX_CHANNELS]; ///< spx attenuation code (spxattencod) 121 int spx_src_start_freq; ///< spx start frequency bin 122 int spx_dst_end_freq; ///< spx end frequency bin 123 int spx_dst_start_freq; ///< spx starting frequency bin for copying (copystartmant) 124 ///< the copy region ends at the start of the spx region. 125 int num_spx_bands; ///< number of spx bands (nspxbnds) 126 uint8_t spx_band_sizes[SPX_MAX_BANDS]; ///< number of bins in each spx band 127 uint8_t first_spx_coords[AC3_MAX_CHANNELS]; ///< first spx coordinates states (firstspxcos) 128 float spx_noise_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS]; ///< spx noise blending factor (nblendfact) 129 float spx_signal_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS];///< spx signal blending factor (sblendfact) 130///@} 131 132///@defgroup aht adaptive hybrid transform 133 int channel_uses_aht[AC3_MAX_CHANNELS]; ///< channel AHT in use (chahtinu) 134 int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][MAX_BLOCKS]; ///< pre-IDCT mantissas 135///@} 136 137///@defgroup channel channel 138 int fbw_channels; ///< number of full-bandwidth channels 139 int channels; ///< number of total channels 140 int lfe_ch; ///< index of LFE channel 141 float downmix_coeffs[AC3_MAX_CHANNELS][2]; ///< stereo downmix coefficients 142 int downmixed; ///< indicates if coeffs are currently downmixed 143 int output_mode; ///< output channel configuration 144 int out_channels; ///< number of output channels 145///@} 146 147///@defgroup dynrng dynamic range 148 float dynamic_range[2]; ///< dynamic range 149///@} 150 151///@defgroup bandwidth bandwidth 152 int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin (strtmant) 153 int end_freq[AC3_MAX_CHANNELS]; ///< end frequency bin (endmant) 154///@} 155 156///@defgroup rematrixing rematrixing 157 int num_rematrixing_bands; ///< number of rematrixing bands (nrematbnd) 158 int rematrixing_flags[4]; ///< rematrixing flags (rematflg) 159///@} 160 161///@defgroup exponents exponents 162 int num_exp_groups[AC3_MAX_CHANNELS]; ///< Number of exponent groups (nexpgrp) 163 int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< decoded exponents 164 int exp_strategy[MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies (expstr) 165///@} 166 167///@defgroup bitalloc bit allocation 168 AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters 169 int first_cpl_leak; ///< first coupling leak state (firstcplleak) 170 int snr_offset[AC3_MAX_CHANNELS]; ///< signal-to-noise ratio offsets (snroffst) 171 int fast_gain[AC3_MAX_CHANNELS]; ///< fast gain values/SMR's (fgain) 172 uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< bit allocation pointers 173 int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< scaled exponents 174 int16_t band_psd[AC3_MAX_CHANNELS][50]; ///< interpolated exponents 175 int16_t mask[AC3_MAX_CHANNELS][50]; ///< masking curve values 176 int dba_mode[AC3_MAX_CHANNELS]; ///< delta bit allocation mode 177 int dba_nsegs[AC3_MAX_CHANNELS]; ///< number of delta segments 178 uint8_t dba_offsets[AC3_MAX_CHANNELS][8]; ///< delta segment offsets 179 uint8_t dba_lengths[AC3_MAX_CHANNELS][8]; ///< delta segment lengths 180 uint8_t dba_values[AC3_MAX_CHANNELS][8]; ///< delta values for each segment 181///@} 182 183///@defgroup dithering zero-mantissa dithering 184 int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags (dithflg) 185 AVLFG dith_state; ///< for dither generation 186///@} 187 188///@defgroup imdct IMDCT 189 int block_switch[AC3_MAX_CHANNELS]; ///< block switch flags (blksw) 190 FFTContext imdct_512; ///< for 512 sample IMDCT 191 FFTContext imdct_256; ///< for 256 sample IMDCT 192///@} 193 194///@defgroup opt optimization 195 DSPContext dsp; ///< for optimization 196 float add_bias; ///< offset for float_to_int16 conversion 197 float mul_bias; ///< scaling for float_to_int16 conversion 198///@} 199 200///@defgroup arrays aligned arrays 201 DECLARE_ALIGNED(16, int, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///> fixed-point transform coefficients 202 DECLARE_ALIGNED(16, float, transform_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< transform coefficients 203 DECLARE_ALIGNED(16, float, delay)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< delay - added to the next block 204 DECLARE_ALIGNED(16, float, window)[AC3_BLOCK_SIZE]; ///< window coefficients 205 DECLARE_ALIGNED(16, float, tmp_output)[AC3_BLOCK_SIZE]; ///< temporary storage for output before windowing 206 DECLARE_ALIGNED(16, float, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< output after imdct transform and windowing 207///@} 208} AC3DecodeContext; 209 210/** 211 * Parse the E-AC-3 frame header. 212 * This parses both the bit stream info and audio frame header. 213 */ 214int ff_eac3_parse_header(AC3DecodeContext *s); 215 216/** 217 * Decode mantissas in a single channel for the entire frame. 218 * This is used when AHT mode is enabled. 219 */ 220void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch); 221 222void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], 223 int out_ch, int in_ch, int len); 224 225/** 226 * Apply spectral extension to each channel by copying lower frequency 227 * coefficients to higher frequency bins and applying side information to 228 * approximate the original high frequency signal. 229 */ 230void ff_eac3_apply_spectral_extension(AC3DecodeContext *s); 231 232#endif /* AVCODEC_AC3DEC_H */ 233