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4349 | Serge | 1 | /* |
2 | * Common code between the AC-3 and E-AC-3 decoders |
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3 | * Copyright (c) 2007 Bartlomiej Wolowiec |
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4 | * |
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5 | * This file is part of FFmpeg. |
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6 | * |
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7 | * FFmpeg is free software; you can redistribute it and/or |
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8 | * modify it under the terms of the GNU Lesser General Public |
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9 | * License as published by the Free Software Foundation; either |
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10 | * version 2.1 of the License, or (at your option) any later version. |
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11 | * |
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12 | * FFmpeg is distributed in the hope that it will be useful, |
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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15 | * Lesser General Public License for more details. |
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16 | * |
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17 | * You should have received a copy of the GNU Lesser General Public |
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18 | * License along with FFmpeg; if not, write to the Free Software |
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19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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20 | */ |
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21 | |||
22 | /** |
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23 | * @file |
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24 | * Common code between the AC-3 and E-AC-3 decoders. |
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25 | * |
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26 | * Summary of MDCT Coefficient Grouping: |
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27 | * The individual MDCT coefficient indices are often referred to in the |
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28 | * (E-)AC-3 specification as frequency bins. These bins are grouped together |
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29 | * into subbands of 12 coefficients each. The subbands are grouped together |
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30 | * into bands as defined in the bitstream by the band structures, which |
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31 | * determine the number of bands and the size of each band. The full spectrum |
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32 | * of 256 frequency bins is divided into 1 DC bin + 21 subbands = 253 bins. |
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33 | * This system of grouping coefficients is used for channel bandwidth, stereo |
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34 | * rematrixing, channel coupling, enhanced coupling, and spectral extension. |
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35 | * |
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36 | * +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+ |
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37 | * |1| |12| | [12|12|12|12] | | | | | | | | | | | | |3| |
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38 | * +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+ |
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39 | * ~~~ ~~~~ ~~~~~~~~~~~~~ ~~~ |
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40 | * | | | | |
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41 | * | | | 3 unused frequency bins--+ |
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42 | * | | | |
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43 | * | | +--1 band containing 4 subbands |
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44 | * | | |
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45 | * | +--1 subband of 12 frequency bins |
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46 | * | |
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47 | * +--DC frequency bin |
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48 | */ |
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49 | |||
50 | #ifndef AVCODEC_AC3DEC_H |
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51 | #define AVCODEC_AC3DEC_H |
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52 | |||
53 | #include "libavutil/float_dsp.h" |
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54 | #include "libavutil/lfg.h" |
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55 | #include "ac3.h" |
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56 | #include "ac3dsp.h" |
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57 | #include "get_bits.h" |
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58 | #include "dsputil.h" |
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59 | #include "fft.h" |
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60 | #include "fmtconvert.h" |
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61 | |||
62 | #define AC3_OUTPUT_LFEON 8 |
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63 | |||
64 | #define SPX_MAX_BANDS 17 |
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65 | |||
66 | /** Large enough for maximum possible frame size when the specification limit is ignored */ |
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67 | #define AC3_FRAME_BUFFER_SIZE 32768 |
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68 | |||
69 | typedef struct AC3DecodeContext { |
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70 | AVClass *class; ///< class for AVOptions |
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71 | AVCodecContext *avctx; ///< parent context |
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72 | GetBitContext gbc; ///< bitstream reader |
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73 | |||
74 | ///@name Bit stream information |
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75 | ///@{ |
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76 | int frame_type; ///< frame type (strmtyp) |
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77 | int substreamid; ///< substream identification |
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78 | int frame_size; ///< current frame size, in bytes |
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79 | int bit_rate; ///< stream bit rate, in bits-per-second |
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80 | int sample_rate; ///< sample frequency, in Hz |
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81 | int num_blocks; ///< number of audio blocks |
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82 | int bitstream_mode; ///< bitstream mode (bsmod) |
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83 | int channel_mode; ///< channel mode (acmod) |
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84 | int channel_layout; ///< channel layout |
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85 | int lfe_on; ///< lfe channel in use |
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86 | int channel_map; ///< custom channel map |
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87 | int center_mix_level; ///< Center mix level index |
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88 | int surround_mix_level; ///< Surround mix level index |
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89 | int eac3; ///< indicates if current frame is E-AC-3 |
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90 | ///@} |
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91 | |||
92 | int preferred_stereo_downmix; |
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93 | float ltrt_center_mix_level; |
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94 | float ltrt_surround_mix_level; |
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95 | float loro_center_mix_level; |
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96 | float loro_surround_mix_level; |
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97 | |||
98 | ///@name Frame syntax parameters |
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99 | int snr_offset_strategy; ///< SNR offset strategy (snroffststr) |
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100 | int block_switch_syntax; ///< block switch syntax enabled (blkswe) |
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101 | int dither_flag_syntax; ///< dither flag syntax enabled (dithflage) |
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102 | int bit_allocation_syntax; ///< bit allocation model syntax enabled (bamode) |
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103 | int fast_gain_syntax; ///< fast gain codes enabled (frmfgaincode) |
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104 | int dba_syntax; ///< delta bit allocation syntax enabled (dbaflde) |
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105 | int skip_syntax; ///< skip field syntax enabled (skipflde) |
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106 | ///@} |
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107 | |||
108 | ///@name Standard coupling |
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109 | int cpl_in_use[AC3_MAX_BLOCKS]; ///< coupling in use (cplinu) |
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110 | int cpl_strategy_exists[AC3_MAX_BLOCKS];///< coupling strategy exists (cplstre) |
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111 | int channel_in_cpl[AC3_MAX_CHANNELS]; ///< channel in coupling (chincpl) |
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112 | int phase_flags_in_use; ///< phase flags in use (phsflginu) |
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113 | int phase_flags[AC3_MAX_CPL_BANDS]; ///< phase flags (phsflg) |
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114 | int num_cpl_bands; ///< number of coupling bands (ncplbnd) |
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115 | uint8_t cpl_band_sizes[AC3_MAX_CPL_BANDS]; ///< number of coeffs in each coupling band |
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116 | int firstchincpl; ///< first channel in coupling |
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117 | int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states (firstcplcos) |
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118 | int cpl_coords[AC3_MAX_CHANNELS][AC3_MAX_CPL_BANDS]; ///< coupling coordinates (cplco) |
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119 | ///@} |
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120 | |||
121 | ///@name Spectral extension |
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122 | ///@{ |
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123 | int spx_in_use; ///< spectral extension in use (spxinu) |
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124 | uint8_t channel_uses_spx[AC3_MAX_CHANNELS]; ///< channel uses spectral extension (chinspx) |
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125 | int8_t spx_atten_code[AC3_MAX_CHANNELS]; ///< spx attenuation code (spxattencod) |
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126 | int spx_src_start_freq; ///< spx start frequency bin |
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127 | int spx_dst_end_freq; ///< spx end frequency bin |
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128 | int spx_dst_start_freq; ///< spx starting frequency bin for copying (copystartmant) |
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129 | ///< the copy region ends at the start of the spx region. |
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130 | int num_spx_bands; ///< number of spx bands (nspxbnds) |
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131 | uint8_t spx_band_sizes[SPX_MAX_BANDS]; ///< number of bins in each spx band |
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132 | uint8_t first_spx_coords[AC3_MAX_CHANNELS]; ///< first spx coordinates states (firstspxcos) |
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133 | float spx_noise_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS]; ///< spx noise blending factor (nblendfact) |
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134 | float spx_signal_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS];///< spx signal blending factor (sblendfact) |
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135 | ///@} |
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136 | |||
137 | ///@name Adaptive hybrid transform |
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138 | int channel_uses_aht[AC3_MAX_CHANNELS]; ///< channel AHT in use (chahtinu) |
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139 | int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][AC3_MAX_BLOCKS]; ///< pre-IDCT mantissas |
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140 | ///@} |
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141 | |||
142 | ///@name Channel |
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143 | int fbw_channels; ///< number of full-bandwidth channels |
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144 | int channels; ///< number of total channels |
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145 | int lfe_ch; ///< index of LFE channel |
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146 | float downmix_coeffs[AC3_MAX_CHANNELS][2]; ///< stereo downmix coefficients |
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147 | int downmixed; ///< indicates if coeffs are currently downmixed |
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148 | int output_mode; ///< output channel configuration |
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149 | int out_channels; ///< number of output channels |
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150 | ///@} |
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151 | |||
152 | ///@name Dynamic range |
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153 | float dynamic_range[2]; ///< dynamic range |
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154 | float drc_scale; ///< percentage of dynamic range compression to be applied |
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155 | ///@} |
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156 | |||
157 | ///@name Bandwidth |
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158 | int start_freq[AC3_MAX_CHANNELS]; ///< start frequency bin (strtmant) |
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159 | int end_freq[AC3_MAX_CHANNELS]; ///< end frequency bin (endmant) |
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160 | ///@} |
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161 | |||
162 | ///@name Rematrixing |
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163 | int num_rematrixing_bands; ///< number of rematrixing bands (nrematbnd) |
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164 | int rematrixing_flags[4]; ///< rematrixing flags (rematflg) |
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165 | ///@} |
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166 | |||
167 | ///@name Exponents |
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168 | int num_exp_groups[AC3_MAX_CHANNELS]; ///< Number of exponent groups (nexpgrp) |
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169 | int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< decoded exponents |
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170 | int exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies (expstr) |
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171 | ///@} |
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172 | |||
173 | ///@name Bit allocation |
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174 | AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters |
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175 | int first_cpl_leak; ///< first coupling leak state (firstcplleak) |
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176 | int snr_offset[AC3_MAX_CHANNELS]; ///< signal-to-noise ratio offsets (snroffst) |
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177 | int fast_gain[AC3_MAX_CHANNELS]; ///< fast gain values/SMR's (fgain) |
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178 | uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< bit allocation pointers |
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179 | int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< scaled exponents |
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180 | int16_t band_psd[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< interpolated exponents |
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181 | int16_t mask[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< masking curve values |
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182 | int dba_mode[AC3_MAX_CHANNELS]; ///< delta bit allocation mode |
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183 | int dba_nsegs[AC3_MAX_CHANNELS]; ///< number of delta segments |
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184 | uint8_t dba_offsets[AC3_MAX_CHANNELS][8]; ///< delta segment offsets |
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185 | uint8_t dba_lengths[AC3_MAX_CHANNELS][8]; ///< delta segment lengths |
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186 | uint8_t dba_values[AC3_MAX_CHANNELS][8]; ///< delta values for each segment |
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187 | ///@} |
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188 | |||
189 | ///@name Zero-mantissa dithering |
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190 | int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags (dithflg) |
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191 | AVLFG dith_state; ///< for dither generation |
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192 | ///@} |
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193 | |||
194 | ///@name IMDCT |
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195 | int block_switch[AC3_MAX_CHANNELS]; ///< block switch flags (blksw) |
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196 | FFTContext imdct_512; ///< for 512 sample IMDCT |
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197 | FFTContext imdct_256; ///< for 256 sample IMDCT |
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198 | ///@} |
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199 | |||
200 | ///@name Optimization |
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201 | DSPContext dsp; ///< for optimization |
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202 | AVFloatDSPContext fdsp; |
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203 | AC3DSPContext ac3dsp; |
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204 | FmtConvertContext fmt_conv; ///< optimized conversion functions |
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205 | ///@} |
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206 | |||
207 | float *outptr[AC3_MAX_CHANNELS]; |
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208 | float *xcfptr[AC3_MAX_CHANNELS]; |
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209 | float *dlyptr[AC3_MAX_CHANNELS]; |
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210 | |||
211 | ///@name Aligned arrays |
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212 | DECLARE_ALIGNED(16, int32_t, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< fixed-point transform coefficients |
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213 | DECLARE_ALIGNED(32, float, transform_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS]; ///< transform coefficients |
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214 | DECLARE_ALIGNED(32, float, delay)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< delay - added to the next block |
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215 | DECLARE_ALIGNED(32, float, window)[AC3_BLOCK_SIZE]; ///< window coefficients |
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216 | DECLARE_ALIGNED(32, float, tmp_output)[AC3_BLOCK_SIZE]; ///< temporary storage for output before windowing |
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217 | DECLARE_ALIGNED(32, float, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE]; ///< output after imdct transform and windowing |
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218 | DECLARE_ALIGNED(32, uint8_t, input_buffer)[AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE]; ///< temp buffer to prevent overread |
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219 | ///@} |
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220 | } AC3DecodeContext; |
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221 | |||
222 | /** |
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223 | * Parse the E-AC-3 frame header. |
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224 | * This parses both the bit stream info and audio frame header. |
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225 | */ |
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226 | int ff_eac3_parse_header(AC3DecodeContext *s); |
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227 | |||
228 | /** |
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229 | * Decode mantissas in a single channel for the entire frame. |
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230 | * This is used when AHT mode is enabled. |
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231 | */ |
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232 | void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch); |
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233 | |||
234 | /** |
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235 | * Apply spectral extension to each channel by copying lower frequency |
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236 | * coefficients to higher frequency bins and applying side information to |
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237 | * approximate the original high frequency signal. |
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238 | */ |
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239 | void ff_eac3_apply_spectral_extension(AC3DecodeContext *s); |
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240 | |||
241 | #endif /* AVCODEC_AC3DEC_H */>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> |