| 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|((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 | #define INTFLOAT int |
| 77 | #define SHORTFLOAT int16_t |
| 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) (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 | #define INTFLOAT float |
| 96 | #define SHORTFLOAT float |
| 97 | |
| 98 | #endif /* USE_FIXED */ |
| 99 | |
| 100 | #define AC3_LEVEL(x) ROUND15((x) * FIXR15(0.7071067811865476)) |
| 101 | |
| 102 | /* pre-defined gain values */ |
| 103 | #define LEVEL_PLUS_3DB 1.4142135623730950 |
| 104 | #define LEVEL_PLUS_1POINT5DB 1.1892071150027209 |
| 105 | #define LEVEL_MINUS_1POINT5DB 0.8408964152537145 |
| 106 | #define LEVEL_MINUS_3DB 0.7071067811865476 |
| 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 | #if AV_HAVE_INCOMPATIBLE_LIBAV_ABI |
| 194 | int dolby_surround_mode; |
| 195 | #endif |
| 196 | /** @} */ |
| 197 | |
| 198 | /** @name Derived values |
| 199 | * @{ |
| 200 | */ |
| 201 | uint8_t sr_shift; |
| 202 | uint16_t sample_rate; |
| 203 | uint32_t bit_rate; |
| 204 | uint8_t channels; |
| 205 | uint16_t frame_size; |
| 206 | uint64_t channel_layout; |
| 207 | /** @} */ |
| 208 | #if !AV_HAVE_INCOMPATIBLE_LIBAV_ABI |
| 209 | int dolby_surround_mode; |
| 210 | #endif |
| 211 | } AC3HeaderInfo; |
| 212 | |
| 213 | typedef enum { |
| 214 | EAC3_FRAME_TYPE_INDEPENDENT = 0, |
| 215 | EAC3_FRAME_TYPE_DEPENDENT, |
| 216 | EAC3_FRAME_TYPE_AC3_CONVERT, |
| 217 | EAC3_FRAME_TYPE_RESERVED |
| 218 | } EAC3FrameType; |
| 219 | |
| 220 | void ff_ac3_common_init(void); |
| 221 | |
| 222 | /** |
| 223 | * Calculate the log power-spectral density of the input signal. |
| 224 | * This gives a rough estimate of signal power in the frequency domain by using |
| 225 | * the spectral envelope (exponents). The psd is also separately grouped |
| 226 | * into critical bands for use in the calculating the masking curve. |
| 227 | * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters |
| 228 | * determines the reference level. |
| 229 | * |
| 230 | * @param[in] exp frequency coefficient exponents |
| 231 | * @param[in] start starting bin location |
| 232 | * @param[in] end ending bin location |
| 233 | * @param[out] psd signal power for each frequency bin |
| 234 | * @param[out] band_psd signal power for each critical band |
| 235 | */ |
| 236 | void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, |
| 237 | int16_t *band_psd); |
| 238 | |
| 239 | /** |
| 240 | * Calculate the masking curve. |
| 241 | * First, the excitation is calculated using parameters in s and the signal |
| 242 | * power in each critical band. The excitation is compared with a predefined |
| 243 | * hearing threshold table to produce the masking curve. If delta bit |
| 244 | * allocation information is provided, it is used for adjusting the masking |
| 245 | * curve, usually to give a closer match to a better psychoacoustic model. |
| 246 | * |
| 247 | * @param[in] s adjustable bit allocation parameters |
| 248 | * @param[in] band_psd signal power for each critical band |
| 249 | * @param[in] start starting bin location |
| 250 | * @param[in] end ending bin location |
| 251 | * @param[in] fast_gain fast gain (estimated signal-to-mask ratio) |
| 252 | * @param[in] is_lfe whether or not the channel being processed is the LFE |
| 253 | * @param[in] dba_mode delta bit allocation mode (none, reuse, or new) |
| 254 | * @param[in] dba_nsegs number of delta segments |
| 255 | * @param[in] dba_offsets location offsets for each segment |
| 256 | * @param[in] dba_lengths length of each segment |
| 257 | * @param[in] dba_values delta bit allocation for each segment |
| 258 | * @param[out] mask calculated masking curve |
| 259 | * @return returns 0 for success, non-zero for error |
| 260 | */ |
| 261 | int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd, |
| 262 | int start, int end, int fast_gain, int is_lfe, |
| 263 | int dba_mode, int dba_nsegs, uint8_t *dba_offsets, |
| 264 | uint8_t *dba_lengths, uint8_t *dba_values, |
| 265 | int16_t *mask); |
| 266 | |
| 267 | #endif /* AVCODEC_AC3_H */ |