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/float_dsp.h" 54 #include "libavutil/fixed_dsp.h" 55 #include "libavutil/lfg.h" 56 #include "libavutil/mem_internal.h" 57 58 #include "ac3.h" 59 #include "ac3dsp.h" 60 #include "bswapdsp.h" 61 #include "get_bits.h" 62 #include "fft.h" 63 #include "fmtconvert.h" 64 65 #define AC3_OUTPUT_LFEON 8 66 67 #define SPX_MAX_BANDS 17 68 69 /** Large enough for maximum possible frame size when the specification limit is ignored */ 70 #define AC3_FRAME_BUFFER_SIZE 32768 71 72 typedef struct AC3DecodeContext { 73 AVClass *class; ///< class for AVOptions 74 AVCodecContext *avctx; ///< parent context 75 GetBitContext gbc; ///< bitstream reader 76 77 ///@name Bit stream information 78 ///@{ 79 int frame_type; ///< frame type (strmtyp) 80 int substreamid; ///< substream identification 81 int superframe_size; ///< current superframe size, in bytes 82 int frame_size; ///< current frame size, in bytes 83 int bit_rate; ///< stream bit rate, in bits-per-second 84 int sample_rate; ///< sample frequency, in Hz 85 int num_blocks; ///< number of audio blocks 86 int bitstream_id; ///< bitstream id (bsid) 87 int bitstream_mode; ///< bitstream mode (bsmod) 88 int channel_mode; ///< channel mode (acmod) 89 int lfe_on; ///< lfe channel in use 90 int dialog_normalization[2]; ///< dialog level in dBFS (dialnorm) 91 int compression_exists[2]; ///< compression field is valid for frame (compre) 92 int compression_gain[2]; ///< gain to apply for heavy compression (compr) 93 int channel_map; ///< custom channel map (chanmap) 94 int preferred_downmix; ///< Preferred 2-channel downmix mode (dmixmod) 95 int center_mix_level; ///< Center mix level index 96 int center_mix_level_ltrt; ///< Center mix level index for Lt/Rt (ltrtcmixlev) 97 int surround_mix_level; ///< Surround mix level index 98 int surround_mix_level_ltrt; ///< Surround mix level index for Lt/Rt (ltrtsurmixlev) 99 int lfe_mix_level_exists; ///< indicates if lfemixlevcod is specified (lfemixlevcode) 100 int lfe_mix_level; ///< LFE mix level index (lfemixlevcod) 101 int eac3; ///< indicates if current frame is E-AC-3 102 int eac3_frame_dependent_found; ///< bitstream has E-AC-3 dependent frame(s) 103 int eac3_subsbtreamid_found; ///< bitstream has E-AC-3 additional substream(s) 104 int dolby_surround_mode; ///< dolby surround mode (dsurmod) 105 int dolby_surround_ex_mode; ///< dolby surround ex mode (dsurexmod) 106 int dolby_headphone_mode; ///< dolby headphone mode (dheadphonmod) 107 ///@} 108 109 int preferred_stereo_downmix; 110 float ltrt_center_mix_level; 111 float ltrt_surround_mix_level; 112 float loro_center_mix_level; 113 float loro_surround_mix_level; 114 int target_level; ///< target level in dBFS 115 float level_gain[2]; 116 117 ///@name Frame syntax parameters 118 int snr_offset_strategy; ///< SNR offset strategy (snroffststr) 119 int block_switch_syntax; ///< block switch syntax enabled (blkswe) 120 int dither_flag_syntax; ///< dither flag syntax enabled (dithflage) 121 int bit_allocation_syntax; ///< bit allocation model syntax enabled (bamode) 122 int fast_gain_syntax; ///< fast gain codes enabled (frmfgaincode) 123 int dba_syntax; ///< delta bit allocation syntax enabled (dbaflde) 124 int skip_syntax; ///< skip field syntax enabled (skipflde) 125 ///@} 126 127 ///@name Standard coupling 128 int cpl_in_use[AC3_MAX_BLOCKS]; ///< coupling in use (cplinu) 129 int cpl_strategy_exists[AC3_MAX_BLOCKS];///< coupling strategy exists (cplstre) 130 int channel_in_cpl[AC3_MAX_CHANNELS]; ///< channel in coupling (chincpl) 131 int phase_flags_in_use; ///< phase flags in use (phsflginu) 132 int phase_flags[AC3_MAX_CPL_BANDS]; ///< phase flags (phsflg) 133 int num_cpl_bands; ///< number of coupling bands (ncplbnd) 134 uint8_t cpl_band_struct[AC3_MAX_CPL_BANDS]; 135 uint8_t cpl_band_sizes[AC3_MAX_CPL_BANDS]; ///< number of coeffs in each coupling band 136 int firstchincpl; ///< first channel in coupling 137 int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states (firstcplcos) 138 int cpl_coords[AC3_MAX_CHANNELS][AC3_MAX_CPL_BANDS]; ///< coupling coordinates (cplco) 139 ///@} 140 141 ///@name Spectral extension 142 ///@{ 143 int spx_in_use; ///< spectral extension in use (spxinu) 144 uint8_t channel_uses_spx[AC3_MAX_CHANNELS]; ///< channel uses spectral extension (chinspx) 145 int8_t spx_atten_code[AC3_MAX_CHANNELS]; ///< spx attenuation code (spxattencod) 146 int spx_src_start_freq; ///< spx start frequency bin 147 int spx_dst_end_freq; ///< spx end frequency bin 148 int spx_dst_start_freq; ///< spx starting frequency bin for copying (copystartmant) 149 ///< the copy region ends at the start of the spx region. 150 int num_spx_bands; ///< number of spx bands (nspxbnds) 151 uint8_t spx_band_struct[SPX_MAX_BANDS]; 152 uint8_t spx_band_sizes[SPX_MAX_BANDS]; ///< number of bins in each spx band 153 uint8_t first_spx_coords[AC3_MAX_CHANNELS]; ///< first spx coordinates states (firstspxcos) 154 INTFLOAT spx_noise_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS]; ///< spx noise blending factor (nblendfact) 155 INTFLOAT spx_signal_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS];///< spx signal blending factor (sblendfact) 156 ///@} 157 158 ///@name Adaptive hybrid transform 159 int channel_uses_aht[AC3_MAX_CHANNELS]; ///< channel AHT in use (chahtinu) 160 int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][AC3_MAX_BLOCKS]; ///< pre-IDCT mantissas 161 ///@} 162 163 ///@name Channel 164 int fbw_channels; ///< number of full-bandwidth channels 165 int channels; ///< number of total channels 166 int lfe_ch; ///< index of LFE channel 167 SHORTFLOAT *downmix_coeffs[2]; ///< stereo downmix coefficients 168 int downmixed; ///< indicates if coeffs are currently downmixed 169 int output_mode; ///< output channel configuration 170 int prev_output_mode; ///< output channel configuration for previous frame 171 int out_channels; ///< number of output channels 172 int prev_bit_rate; ///< stream bit rate, in bits-per-second for previous frame 173 ///@} 174 175 ///@name Dynamic range 176 INTFLOAT dynamic_range[2]; ///< dynamic range 177 INTFLOAT drc_scale; ///< percentage of dynamic range compression to be applied 178 int heavy_compression; ///< apply heavy compression 179 INTFLOAT heavy_dynamic_range[2]; ///< heavy dynamic range compression 180 ///@} 181 182 ///@name Bandwidth 183 int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin (strtmant) 184 int end_freq[AC3_MAX_CHANNELS]; ///< end frequency bin (endmant) 185 ///@} 186 187 ///@name Consistent noise generation 188 int consistent_noise_generation; ///< seed noise generation with AC-3 frame on decode 189 ///@} 190 191 ///@name Rematrixing 192 int num_rematrixing_bands; ///< number of rematrixing bands (nrematbnd) 193 int rematrixing_flags[4]; ///< rematrixing flags (rematflg) 194 ///@} 195 196 ///@name Exponents 197 int num_exp_groups[AC3_MAX_CHANNELS]; ///< Number of exponent groups (nexpgrp) 198 int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< decoded exponents 199 int exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies (expstr) 200 ///@} 201 202 ///@name Bit allocation 203 AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters 204 int first_cpl_leak; ///< first coupling leak state (firstcplleak) 205 int snr_offset[AC3_MAX_CHANNELS]; ///< signal-to-noise ratio offsets (snroffst) 206 int fast_gain[AC3_MAX_CHANNELS]; ///< fast gain values/SMR's (fgain) 207 uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< bit allocation pointers 208 int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< scaled exponents 209 int16_t band_psd[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< interpolated exponents 210 int16_t mask[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< masking curve values 211 int dba_mode[AC3_MAX_CHANNELS]; ///< delta bit allocation mode 212 int dba_nsegs[AC3_MAX_CHANNELS]; ///< number of delta segments 213 uint8_t dba_offsets[AC3_MAX_CHANNELS][8]; ///< delta segment offsets 214 uint8_t dba_lengths[AC3_MAX_CHANNELS][8]; ///< delta segment lengths 215 uint8_t dba_values[AC3_MAX_CHANNELS][8]; ///< delta values for each segment 216 ///@} 217 218 ///@name Zero-mantissa dithering 219 int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags (dithflg) 220 AVLFG dith_state; ///< for dither generation 221 ///@} 222 223 ///@name IMDCT 224 int block_switch[AC3_MAX_CHANNELS]; ///< block switch flags (blksw) 225 FFTContext imdct_512; ///< for 512 sample IMDCT 226 FFTContext imdct_256; ///< for 256 sample IMDCT 227 ///@} 228 229 ///@name Optimization 230 BswapDSPContext bdsp; 231 #if USE_FIXED 232 AVFixedDSPContext *fdsp; 233 #else 234 AVFloatDSPContext *fdsp; 235 #endif 236 AC3DSPContext ac3dsp; 237 FmtConvertContext fmt_conv; ///< optimized conversion functions 238 ///@} 239 240 SHORTFLOAT *outptr[AC3_MAX_CHANNELS]; 241 INTFLOAT *xcfptr[AC3_MAX_CHANNELS]; 242 INTFLOAT *dlyptr[AC3_MAX_CHANNELS]; 243 244 ///@name Aligned arrays 245 DECLARE_ALIGNED(16, int, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< fixed-point transform coefficients 246 DECLARE_ALIGNED(32, INTFLOAT, transform_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< transform coefficients 247 DECLARE_ALIGNED(32, INTFLOAT, delay)[EAC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< delay - added to the next block 248 DECLARE_ALIGNED(32, INTFLOAT, window)[AC3_BLOCK_SIZE]; ///< window coefficients 249 DECLARE_ALIGNED(32, INTFLOAT, tmp_output)[AC3_BLOCK_SIZE]; ///< temporary storage for output before windowing 250 DECLARE_ALIGNED(32, SHORTFLOAT, output)[EAC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< output after imdct transform and windowing 251 DECLARE_ALIGNED(32, uint8_t, input_buffer)[AC3_FRAME_BUFFER_SIZE + AV_INPUT_BUFFER_PADDING_SIZE]; ///< temp buffer to prevent overread 252 DECLARE_ALIGNED(32, SHORTFLOAT, output_buffer)[EAC3_MAX_CHANNELS][AC3_BLOCK_SIZE * 6]; ///< final output buffer 253 ///@} 254 } AC3DecodeContext; 255 256 /** 257 * Parse the E-AC-3 frame header. 258 * This parses both the bit stream info and audio frame header. 259 */ 260 static int ff_eac3_parse_header(AC3DecodeContext *s); 261 262 /** 263 * Decode mantissas in a single channel for the entire frame. 264 * This is used when AHT mode is enabled. 265 */ 266 static void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch); 267 268 /** 269 * Apply spectral extension to each channel by copying lower frequency 270 * coefficients to higher frequency bins and applying side information to 271 * approximate the original high frequency signal. 272 */ 273 static void ff_eac3_apply_spectral_extension(AC3DecodeContext *s); 274 275 #if (!USE_FIXED) 276 extern float ff_ac3_heavy_dynamic_range_tab[256]; 277 #endif 278 279 #endif /* AVCODEC_AC3DEC_H */ 280