1 /* 2 * Common code between the AC-3 encoder and decoder 3 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard 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 encoder and decoder. 25 */ 26 27 #ifndef AVCODEC_AC3_H 28 #define AVCODEC_AC3_H 29 30 #define EAC3_MAX_CHANNELS 16 /**< maximum number of channels in EAC3 */ 31 #define AC3_MAX_CHANNELS 7 /**< maximum number of channels, including coupling channel */ 32 #define CPL_CH 0 /**< coupling channel index */ 33 34 #define AC3_MAX_COEFS 256 35 #define AC3_BLOCK_SIZE 256 36 #define AC3_MAX_BLOCKS 6 37 #define AC3_FRAME_SIZE (AC3_MAX_BLOCKS * 256) 38 #define AC3_WINDOW_SIZE (AC3_BLOCK_SIZE * 2) 39 #define AC3_CRITICAL_BANDS 50 40 #define AC3_MAX_CPL_BANDS 18 41 42 #include "libavutil/opt.h" 43 #include "avcodec.h" 44 #include "ac3tab.h" 45 46 /* exponent encoding strategy */ 47 #define EXP_REUSE 0 48 #define EXP_NEW 1 49 50 #define EXP_D15 1 51 #define EXP_D25 2 52 #define EXP_D45 3 53 54 #ifndef USE_FIXED 55 #define USE_FIXED 0 56 #endif 57 58 #if USE_FIXED 59 60 #define FFT_FLOAT 0 61 62 #define FIXR(a) ((int)((a) * 0 + 0.5)) 63 #define FIXR12(a) ((int)((a) * 4096 + 0.5)) 64 #define FIXR15(a) ((int)((a) * 32768 + 0.5)) 65 #define ROUND15(x) ((x) + 16384) >> 15 66 67 #define AC3_RENAME(x) x ## _fixed 68 #define AC3_NORM(norm) (1<<24)/(norm) 69 #define AC3_MUL(a,b) ((((int64_t) (a)) * (b))>>12) 70 #define AC3_RANGE(x) ((x)|(((x)&128)<<1)) 71 #define AC3_HEAVY_RANGE(x) ((x)<<1) 72 #define AC3_DYNAMIC_RANGE(x) (x) 73 #define AC3_SPX_BLEND(x) (x) 74 #define AC3_DYNAMIC_RANGE1 0 75 76 typedef int INTFLOAT; 77 typedef int16_t SHORTFLOAT; 78 79 #else /* USE_FIXED */ 80 81 #define FIXR(x) ((float)(x)) 82 #define FIXR12(x) ((float)(x)) 83 #define FIXR15(x) ((float)(x)) 84 #define ROUND15(x) (x) 85 86 #define AC3_RENAME(x) x 87 #define AC3_NORM(norm) (1.0f/(norm)) 88 #define AC3_MUL(a,b) ((a) * (b)) 89 #define AC3_RANGE(x) (dynamic_range_tab[(x)]) 90 #define AC3_HEAVY_RANGE(x) (ff_ac3_heavy_dynamic_range_tab[(x)]) 91 #define AC3_DYNAMIC_RANGE(x) (powf(x, s->drc_scale)) 92 #define AC3_SPX_BLEND(x) (x)* (1.0f/32) 93 #define AC3_DYNAMIC_RANGE1 1.0f 94 95 typedef float INTFLOAT; 96 typedef float SHORTFLOAT; 97 98 #endif /* USE_FIXED */ 99 100 #define AC3_LEVEL(x) ROUND15((x) * FIXR15(M_SQRT1_2)) 101 102 /* pre-defined gain values */ 103 #define LEVEL_PLUS_3DB M_SQRT2 104 #define LEVEL_PLUS_1POINT5DB 1.1892071150027209 105 #define LEVEL_MINUS_1POINT5DB 0.8408964152537145 106 #define LEVEL_MINUS_3DB M_SQRT1_2 107 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605 108 #define LEVEL_MINUS_6DB 0.5000000000000000 109 #define LEVEL_MINUS_9DB 0.3535533905932738 110 #define LEVEL_ZERO 0.0000000000000000 111 #define LEVEL_ONE 1.0000000000000000 112 113 /** Delta bit allocation strategy */ 114 typedef enum { 115 DBA_REUSE = 0, 116 DBA_NEW, 117 DBA_NONE, 118 DBA_RESERVED 119 } AC3DeltaStrategy; 120 121 /** Channel mode (audio coding mode) */ 122 typedef enum { 123 AC3_CHMODE_DUALMONO = 0, 124 AC3_CHMODE_MONO, 125 AC3_CHMODE_STEREO, 126 AC3_CHMODE_3F, 127 AC3_CHMODE_2F1R, 128 AC3_CHMODE_3F1R, 129 AC3_CHMODE_2F2R, 130 AC3_CHMODE_3F2R 131 } AC3ChannelMode; 132 133 /** Dolby Surround mode */ 134 typedef enum AC3DolbySurroundMode { 135 AC3_DSURMOD_NOTINDICATED = 0, 136 AC3_DSURMOD_OFF, 137 AC3_DSURMOD_ON, 138 AC3_DSURMOD_RESERVED 139 } AC3DolbySurroundMode; 140 141 /** Dolby Surround EX mode */ 142 typedef enum AC3DolbySurroundEXMode { 143 AC3_DSUREXMOD_NOTINDICATED = 0, 144 AC3_DSUREXMOD_OFF, 145 AC3_DSUREXMOD_ON, 146 AC3_DSUREXMOD_PLIIZ 147 } AC3DolbySurroundEXMode; 148 149 /** Dolby Headphone mode */ 150 typedef enum AC3DolbyHeadphoneMode { 151 AC3_DHEADPHONMOD_NOTINDICATED = 0, 152 AC3_DHEADPHONMOD_OFF, 153 AC3_DHEADPHONMOD_ON, 154 AC3_DHEADPHONMOD_RESERVED 155 } AC3DolbyHeadphoneMode; 156 157 /** Preferred Stereo Downmix mode */ 158 typedef enum AC3PreferredStereoDownmixMode { 159 AC3_DMIXMOD_NOTINDICATED = 0, 160 AC3_DMIXMOD_LTRT, 161 AC3_DMIXMOD_LORO, 162 AC3_DMIXMOD_DPLII // reserved value in A/52, but used by encoders to indicate DPL2 163 } AC3PreferredStereoDownmixMode; 164 165 typedef struct AC3BitAllocParameters { 166 int sr_code; 167 int sr_shift; 168 int slow_gain, slow_decay, fast_decay, db_per_bit, floor; 169 int cpl_fast_leak, cpl_slow_leak; 170 } AC3BitAllocParameters; 171 172 /** 173 * @struct AC3HeaderInfo 174 * Coded AC-3 header values up to the lfeon element, plus derived values. 175 */ 176 typedef struct AC3HeaderInfo { 177 /** @name Coded elements 178 * @{ 179 */ 180 uint16_t sync_word; 181 uint16_t crc1; 182 uint8_t sr_code; 183 uint8_t bitstream_id; 184 uint8_t bitstream_mode; 185 uint8_t channel_mode; 186 uint8_t lfe_on; 187 uint8_t frame_type; 188 int substreamid; ///< substream identification 189 int center_mix_level; ///< Center mix level index 190 int surround_mix_level; ///< Surround mix level index 191 uint16_t channel_map; 192 int num_blocks; ///< number of audio blocks 193 int dolby_surround_mode; 194 /** @} */ 195 196 /** @name Derived values 197 * @{ 198 */ 199 uint8_t sr_shift; 200 uint16_t sample_rate; 201 uint32_t bit_rate; 202 uint8_t channels; 203 uint16_t frame_size; 204 uint64_t channel_layout; 205 /** @} */ 206 } AC3HeaderInfo; 207 208 typedef enum { 209 EAC3_FRAME_TYPE_INDEPENDENT = 0, 210 EAC3_FRAME_TYPE_DEPENDENT, 211 EAC3_FRAME_TYPE_AC3_CONVERT, 212 EAC3_FRAME_TYPE_RESERVED 213 } EAC3FrameType; 214 215 void ff_ac3_common_init(void); 216 217 /** 218 * Calculate the log power-spectral density of the input signal. 219 * This gives a rough estimate of signal power in the frequency domain by using 220 * the spectral envelope (exponents). The psd is also separately grouped 221 * into critical bands for use in the calculating the masking curve. 222 * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters 223 * determines the reference level. 224 * 225 * @param[in] exp frequency coefficient exponents 226 * @param[in] start starting bin location 227 * @param[in] end ending bin location 228 * @param[out] psd signal power for each frequency bin 229 * @param[out] band_psd signal power for each critical band 230 */ 231 void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, 232 int16_t *band_psd); 233 234 /** 235 * Calculate the masking curve. 236 * First, the excitation is calculated using parameters in s and the signal 237 * power in each critical band. The excitation is compared with a predefined 238 * hearing threshold table to produce the masking curve. If delta bit 239 * allocation information is provided, it is used for adjusting the masking 240 * curve, usually to give a closer match to a better psychoacoustic model. 241 * 242 * @param[in] s adjustable bit allocation parameters 243 * @param[in] band_psd signal power for each critical band 244 * @param[in] start starting bin location 245 * @param[in] end ending bin location 246 * @param[in] fast_gain fast gain (estimated signal-to-mask ratio) 247 * @param[in] is_lfe whether or not the channel being processed is the LFE 248 * @param[in] dba_mode delta bit allocation mode (none, reuse, or new) 249 * @param[in] dba_nsegs number of delta segments 250 * @param[in] dba_offsets location offsets for each segment 251 * @param[in] dba_lengths length of each segment 252 * @param[in] dba_values delta bit allocation for each segment 253 * @param[out] mask calculated masking curve 254 * @return returns 0 for success, non-zero for error 255 */ 256 int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd, 257 int start, int end, int fast_gain, int is_lfe, 258 int dba_mode, int dba_nsegs, uint8_t *dba_offsets, 259 uint8_t *dba_lengths, uint8_t *dba_values, 260 int16_t *mask); 261 262 #endif /* AVCODEC_AC3_H */ 263