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#include <math.h> 31#include <stdint.h> 32 33#include "ac3tab.h" 34 35#ifndef USE_FIXED 36#define USE_FIXED 0 37#endif 38 39#if USE_FIXED 40 41#define FFT_FLOAT 0 42 43#define FIXR(a) ((int)((a) * 0 + 0.5)) 44#define FIXR12(a) ((int)((a) * 4096 + 0.5)) 45#define FIXR15(a) ((int)((a) * 32768 + 0.5)) 46#define ROUND15(x) ((x) + 16384) >> 15 47 48#define AC3_RENAME(x) x ## _fixed 49#define AC3_NORM(norm) (1<<24)/(norm) 50#define AC3_MUL(a,b) ((((int64_t) (a)) * (b))>>12) 51#define AC3_RANGE(x) ((x)|(((x)&128)<<1)) 52#define AC3_HEAVY_RANGE(x) ((x)<<1) 53#define AC3_DYNAMIC_RANGE(x) (x) 54#define AC3_SPX_BLEND(x) (x) 55#define AC3_DYNAMIC_RANGE1 0 56 57typedef int INTFLOAT; 58typedef unsigned int UINTFLOAT; 59typedef int16_t SHORTFLOAT; 60 61#else /* USE_FIXED */ 62#include "libavutil/libm.h" 63 64#define FIXR(x) ((float)(x)) 65#define FIXR12(x) ((float)(x)) 66#define FIXR15(x) ((float)(x)) 67#define ROUND15(x) (x) 68 69#define AC3_RENAME(x) x 70#define AC3_NORM(norm) (1.0f/(norm)) 71#define AC3_MUL(a,b) ((a) * (b)) 72#define AC3_RANGE(x) (dynamic_range_tab[(x)]) 73#define AC3_HEAVY_RANGE(x) (ff_ac3_heavy_dynamic_range_tab[(x)]) 74#define AC3_DYNAMIC_RANGE(x) (powf(x, s->drc_scale)) 75#define AC3_SPX_BLEND(x) (x)* (1.0f/32) 76#define AC3_DYNAMIC_RANGE1 1.0f 77 78typedef float INTFLOAT; 79typedef float UINTFLOAT; 80typedef float SHORTFLOAT; 81 82#endif /* USE_FIXED */ 83 84#define AC3_LEVEL(x) ROUND15((x) * FIXR15(M_SQRT1_2)) 85 86/* pre-defined gain values */ 87#define LEVEL_PLUS_3DB M_SQRT2 88#define LEVEL_PLUS_1POINT5DB 1.1892071150027209 89#define LEVEL_MINUS_1POINT5DB 0.8408964152537145 90#define LEVEL_MINUS_3DB M_SQRT1_2 91#define LEVEL_MINUS_4POINT5DB 0.5946035575013605 92#define LEVEL_MINUS_6DB 0.5000000000000000 93#define LEVEL_MINUS_9DB 0.3535533905932738 94#define LEVEL_ZERO 0.0000000000000000 95#define LEVEL_ONE 1.0000000000000000 96 97typedef struct AC3BitAllocParameters { 98 int sr_code; 99 int sr_shift; 100 int slow_gain, slow_decay, fast_decay, db_per_bit, floor; 101 int cpl_fast_leak, cpl_slow_leak; 102} AC3BitAllocParameters; 103 104/** 105 * Calculate the log power-spectral density of the input signal. 106 * This gives a rough estimate of signal power in the frequency domain by using 107 * the spectral envelope (exponents). The psd is also separately grouped 108 * into critical bands for use in the calculating the masking curve. 109 * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters 110 * determines the reference level. 111 * 112 * @param[in] exp frequency coefficient exponents 113 * @param[in] start starting bin location 114 * @param[in] end ending bin location 115 * @param[out] psd signal power for each frequency bin 116 * @param[out] band_psd signal power for each critical band 117 */ 118void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, 119 int16_t *band_psd); 120 121/** 122 * Calculate the masking curve. 123 * First, the excitation is calculated using parameters in s and the signal 124 * power in each critical band. The excitation is compared with a predefined 125 * hearing threshold table to produce the masking curve. If delta bit 126 * allocation information is provided, it is used for adjusting the masking 127 * curve, usually to give a closer match to a better psychoacoustic model. 128 * 129 * @param[in] s adjustable bit allocation parameters 130 * @param[in] band_psd signal power for each critical band 131 * @param[in] start starting bin location 132 * @param[in] end ending bin location 133 * @param[in] fast_gain fast gain (estimated signal-to-mask ratio) 134 * @param[in] is_lfe whether or not the channel being processed is the LFE 135 * @param[in] dba_mode delta bit allocation mode (none, reuse, or new) 136 * @param[in] dba_nsegs number of delta segments 137 * @param[in] dba_offsets location offsets for each segment 138 * @param[in] dba_lengths length of each segment 139 * @param[in] dba_values delta bit allocation for each segment 140 * @param[out] mask calculated masking curve 141 * @return returns 0 for success, non-zero for error 142 */ 143int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd, 144 int start, int end, int fast_gain, int is_lfe, 145 int dba_mode, int dba_nsegs, uint8_t *dba_offsets, 146 uint8_t *dba_lengths, uint8_t *dba_values, 147 int16_t *mask); 148 149#endif /* AVCODEC_AC3_H */ 150