Details | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4349 | Serge | 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 | /* pre-defined gain values */ |
||
| 55 | #define LEVEL_PLUS_3DB 1.4142135623730950 |
||
| 56 | #define LEVEL_PLUS_1POINT5DB 1.1892071150027209 |
||
| 57 | #define LEVEL_MINUS_1POINT5DB 0.8408964152537145 |
||
| 58 | #define LEVEL_MINUS_3DB 0.7071067811865476 |
||
| 59 | #define LEVEL_MINUS_4POINT5DB 0.5946035575013605 |
||
| 60 | #define LEVEL_MINUS_6DB 0.5000000000000000 |
||
| 61 | #define LEVEL_MINUS_9DB 0.3535533905932738 |
||
| 62 | #define LEVEL_ZERO 0.0000000000000000 |
||
| 63 | #define LEVEL_ONE 1.0000000000000000 |
||
| 64 | |||
| 65 | /** Delta bit allocation strategy */ |
||
| 66 | typedef enum { |
||
| 67 | DBA_REUSE = 0, |
||
| 68 | DBA_NEW, |
||
| 69 | DBA_NONE, |
||
| 70 | DBA_RESERVED |
||
| 71 | } AC3DeltaStrategy; |
||
| 72 | |||
| 73 | /** Channel mode (audio coding mode) */ |
||
| 74 | typedef enum { |
||
| 75 | AC3_CHMODE_DUALMONO = 0, |
||
| 76 | AC3_CHMODE_MONO, |
||
| 77 | AC3_CHMODE_STEREO, |
||
| 78 | AC3_CHMODE_3F, |
||
| 79 | AC3_CHMODE_2F1R, |
||
| 80 | AC3_CHMODE_3F1R, |
||
| 81 | AC3_CHMODE_2F2R, |
||
| 82 | AC3_CHMODE_3F2R |
||
| 83 | } AC3ChannelMode; |
||
| 84 | |||
| 85 | typedef struct AC3BitAllocParameters { |
||
| 86 | int sr_code; |
||
| 87 | int sr_shift; |
||
| 88 | int slow_gain, slow_decay, fast_decay, db_per_bit, floor; |
||
| 89 | int cpl_fast_leak, cpl_slow_leak; |
||
| 90 | } AC3BitAllocParameters; |
||
| 91 | |||
| 92 | /** |
||
| 93 | * @struct AC3HeaderInfo |
||
| 94 | * Coded AC-3 header values up to the lfeon element, plus derived values. |
||
| 95 | */ |
||
| 96 | typedef struct AC3HeaderInfo { |
||
| 97 | /** @name Coded elements |
||
| 98 | * @{ |
||
| 99 | */ |
||
| 100 | uint16_t sync_word; |
||
| 101 | uint16_t crc1; |
||
| 102 | uint8_t sr_code; |
||
| 103 | uint8_t bitstream_id; |
||
| 104 | uint8_t bitstream_mode; |
||
| 105 | uint8_t channel_mode; |
||
| 106 | uint8_t lfe_on; |
||
| 107 | uint8_t frame_type; |
||
| 108 | int substreamid; ///< substream identification |
||
| 109 | int center_mix_level; ///< Center mix level index |
||
| 110 | int surround_mix_level; ///< Surround mix level index |
||
| 111 | uint16_t channel_map; |
||
| 112 | int num_blocks; ///< number of audio blocks |
||
| 113 | /** @} */ |
||
| 114 | |||
| 115 | /** @name Derived values |
||
| 116 | * @{ |
||
| 117 | */ |
||
| 118 | uint8_t sr_shift; |
||
| 119 | uint16_t sample_rate; |
||
| 120 | uint32_t bit_rate; |
||
| 121 | uint8_t channels; |
||
| 122 | uint16_t frame_size; |
||
| 123 | uint64_t channel_layout; |
||
| 124 | /** @} */ |
||
| 125 | } AC3HeaderInfo; |
||
| 126 | |||
| 127 | typedef enum { |
||
| 128 | EAC3_FRAME_TYPE_INDEPENDENT = 0, |
||
| 129 | EAC3_FRAME_TYPE_DEPENDENT, |
||
| 130 | EAC3_FRAME_TYPE_AC3_CONVERT, |
||
| 131 | EAC3_FRAME_TYPE_RESERVED |
||
| 132 | } EAC3FrameType; |
||
| 133 | |||
| 134 | void ff_ac3_common_init(void); |
||
| 135 | |||
| 136 | /** |
||
| 137 | * Calculate the log power-spectral density of the input signal. |
||
| 138 | * This gives a rough estimate of signal power in the frequency domain by using |
||
| 139 | * the spectral envelope (exponents). The psd is also separately grouped |
||
| 140 | * into critical bands for use in the calculating the masking curve. |
||
| 141 | * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters |
||
| 142 | * determines the reference level. |
||
| 143 | * |
||
| 144 | * @param[in] exp frequency coefficient exponents |
||
| 145 | * @param[in] start starting bin location |
||
| 146 | * @param[in] end ending bin location |
||
| 147 | * @param[out] psd signal power for each frequency bin |
||
| 148 | * @param[out] band_psd signal power for each critical band |
||
| 149 | */ |
||
| 150 | void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, |
||
| 151 | int16_t *band_psd); |
||
| 152 | |||
| 153 | /** |
||
| 154 | * Calculate the masking curve. |
||
| 155 | * First, the excitation is calculated using parameters in s and the signal |
||
| 156 | * power in each critical band. The excitation is compared with a predefined |
||
| 157 | * hearing threshold table to produce the masking curve. If delta bit |
||
| 158 | * allocation information is provided, it is used for adjusting the masking |
||
| 159 | * curve, usually to give a closer match to a better psychoacoustic model. |
||
| 160 | * |
||
| 161 | * @param[in] s adjustable bit allocation parameters |
||
| 162 | * @param[in] band_psd signal power for each critical band |
||
| 163 | * @param[in] start starting bin location |
||
| 164 | * @param[in] end ending bin location |
||
| 165 | * @param[in] fast_gain fast gain (estimated signal-to-mask ratio) |
||
| 166 | * @param[in] is_lfe whether or not the channel being processed is the LFE |
||
| 167 | * @param[in] dba_mode delta bit allocation mode (none, reuse, or new) |
||
| 168 | * @param[in] dba_nsegs number of delta segments |
||
| 169 | * @param[in] dba_offsets location offsets for each segment |
||
| 170 | * @param[in] dba_lengths length of each segment |
||
| 171 | * @param[in] dba_values delta bit allocation for each segment |
||
| 172 | * @param[out] mask calculated masking curve |
||
| 173 | * @return returns 0 for success, non-zero for error |
||
| 174 | */ |
||
| 175 | int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd, |
||
| 176 | int start, int end, int fast_gain, int is_lfe, |
||
| 177 | int dba_mode, int dba_nsegs, uint8_t *dba_offsets, |
||
| 178 | uint8_t *dba_lengths, uint8_t *dba_values, |
||
| 179 | int16_t *mask); |
||
| 180 | |||
| 181 | #endif /* AVCODEC_AC3_H */ |