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 AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */ 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) 71#define AC3_DYNAMIC_RANGE(x) (x) 72#define AC3_SPX_BLEND(x) (x) 73#define AC3_DYNAMIC_RANGE1 0 74 75#define INTFLOAT int 76#define SHORTFLOAT int16_t 77 78#else /* USE_FIXED */ 79 80#define FIXR(x) ((float)(x)) 81#define FIXR12(x) ((float)(x)) 82#define FIXR15(x) ((float)(x)) 83#define ROUND15(x) (x) 84 85#define AC3_RENAME(x) x 86#define AC3_NORM(norm) (1.0f/(norm)) 87#define AC3_MUL(a,b) ((a) * (b)) 88#define AC3_RANGE(x) (dynamic_range_tab[(x)]) 89#define AC3_DYNAMIC_RANGE(x) (powf(x, s->drc_scale)) 90#define AC3_SPX_BLEND(x) (x)* (1.0f/32) 91#define AC3_DYNAMIC_RANGE1 1.0f 92 93#define INTFLOAT float 94#define SHORTFLOAT float 95 96#endif /* USE_FIXED */ 97 98#define AC3_LEVEL(x) ROUND15((x) * FIXR15(0.7071067811865476)) 99 100/* pre-defined gain values */ 101#define LEVEL_PLUS_3DB 1.4142135623730950 102#define LEVEL_PLUS_1POINT5DB 1.1892071150027209 103#define LEVEL_MINUS_1POINT5DB 0.8408964152537145 104#define LEVEL_MINUS_3DB 0.7071067811865476 105#define LEVEL_MINUS_4POINT5DB 0.5946035575013605 106#define LEVEL_MINUS_6DB 0.5000000000000000 107#define LEVEL_MINUS_9DB 0.3535533905932738 108#define LEVEL_ZERO 0.0000000000000000 109#define LEVEL_ONE 1.0000000000000000 110 111/** Delta bit allocation strategy */ 112typedef enum { 113 DBA_REUSE = 0, 114 DBA_NEW, 115 DBA_NONE, 116 DBA_RESERVED 117} AC3DeltaStrategy; 118 119/** Channel mode (audio coding mode) */ 120typedef enum { 121 AC3_CHMODE_DUALMONO = 0, 122 AC3_CHMODE_MONO, 123 AC3_CHMODE_STEREO, 124 AC3_CHMODE_3F, 125 AC3_CHMODE_2F1R, 126 AC3_CHMODE_3F1R, 127 AC3_CHMODE_2F2R, 128 AC3_CHMODE_3F2R 129} AC3ChannelMode; 130 131/** Dolby Surround mode */ 132typedef enum AC3DolbySurroundMode { 133 AC3_DSURMOD_NOTINDICATED = 0, 134 AC3_DSURMOD_OFF, 135 AC3_DSURMOD_ON, 136 AC3_DSURMOD_RESERVED 137} AC3DolbySurroundMode; 138 139/** Dolby Surround EX mode */ 140typedef enum AC3DolbySurroundEXMode { 141 AC3_DSUREXMOD_NOTINDICATED = 0, 142 AC3_DSUREXMOD_OFF, 143 AC3_DSUREXMOD_ON, 144 AC3_DSUREXMOD_PLIIZ 145} AC3DolbySurroundEXMode; 146 147/** Dolby Headphone mode */ 148typedef enum AC3DolbyHeadphoneMode { 149 AC3_DHEADPHONMOD_NOTINDICATED = 0, 150 AC3_DHEADPHONMOD_OFF, 151 AC3_DHEADPHONMOD_ON, 152 AC3_DHEADPHONMOD_RESERVED 153} AC3DolbyHeadphoneMode; 154 155/** Preferred Stereo Downmix mode */ 156typedef enum AC3PreferredStereoDownmixMode { 157 AC3_DMIXMOD_NOTINDICATED = 0, 158 AC3_DMIXMOD_LTRT, 159 AC3_DMIXMOD_LORO, 160 AC3_DMIXMOD_DPLII // reserved value in A/52, but used by encoders to indicate DPL2 161} AC3PreferredStereoDownmixMode; 162 163typedef struct AC3BitAllocParameters { 164 int sr_code; 165 int sr_shift; 166 int slow_gain, slow_decay, fast_decay, db_per_bit, floor; 167 int cpl_fast_leak, cpl_slow_leak; 168} AC3BitAllocParameters; 169 170/** 171 * @struct AC3HeaderInfo 172 * Coded AC-3 header values up to the lfeon element, plus derived values. 173 */ 174typedef struct AC3HeaderInfo { 175 /** @name Coded elements 176 * @{ 177 */ 178 uint16_t sync_word; 179 uint16_t crc1; 180 uint8_t sr_code; 181 uint8_t bitstream_id; 182 uint8_t bitstream_mode; 183 uint8_t channel_mode; 184 uint8_t lfe_on; 185 uint8_t frame_type; 186 int substreamid; ///< substream identification 187 int center_mix_level; ///< Center mix level index 188 int surround_mix_level; ///< Surround mix level index 189 uint16_t channel_map; 190 int num_blocks; ///< number of audio blocks 191#if AV_HAVE_INCOMPATIBLE_LIBAV_ABI 192 int dolby_surround_mode; 193#endif 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#if !AV_HAVE_INCOMPATIBLE_LIBAV_ABI 207 int dolby_surround_mode; 208#endif 209} AC3HeaderInfo; 210 211typedef enum { 212 EAC3_FRAME_TYPE_INDEPENDENT = 0, 213 EAC3_FRAME_TYPE_DEPENDENT, 214 EAC3_FRAME_TYPE_AC3_CONVERT, 215 EAC3_FRAME_TYPE_RESERVED 216} EAC3FrameType; 217 218void ff_ac3_common_init(void); 219 220/** 221 * Calculate the log power-spectral density of the input signal. 222 * This gives a rough estimate of signal power in the frequency domain by using 223 * the spectral envelope (exponents). The psd is also separately grouped 224 * into critical bands for use in the calculating the masking curve. 225 * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters 226 * determines the reference level. 227 * 228 * @param[in] exp frequency coefficient exponents 229 * @param[in] start starting bin location 230 * @param[in] end ending bin location 231 * @param[out] psd signal power for each frequency bin 232 * @param[out] band_psd signal power for each critical band 233 */ 234void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, 235 int16_t *band_psd); 236 237/** 238 * Calculate the masking curve. 239 * First, the excitation is calculated using parameters in s and the signal 240 * power in each critical band. The excitation is compared with a predefined 241 * hearing threshold table to produce the masking curve. If delta bit 242 * allocation information is provided, it is used for adjusting the masking 243 * curve, usually to give a closer match to a better psychoacoustic model. 244 * 245 * @param[in] s adjustable bit allocation parameters 246 * @param[in] band_psd signal power for each critical band 247 * @param[in] start starting bin location 248 * @param[in] end ending bin location 249 * @param[in] fast_gain fast gain (estimated signal-to-mask ratio) 250 * @param[in] is_lfe whether or not the channel being processed is the LFE 251 * @param[in] dba_mode delta bit allocation mode (none, reuse, or new) 252 * @param[in] dba_nsegs number of delta segments 253 * @param[in] dba_offsets location offsets for each segment 254 * @param[in] dba_lengths length of each segment 255 * @param[in] dba_values delta bit allocation for each segment 256 * @param[out] mask calculated masking curve 257 * @return returns 0 for success, non-zero for error 258 */ 259int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd, 260 int start, int end, int fast_gain, int is_lfe, 261 int dba_mode, int dba_nsegs, uint8_t *dba_offsets, 262 uint8_t *dba_lengths, uint8_t *dba_values, 263 int16_t *mask); 264 265#endif /* AVCODEC_AC3_H */ 266