/* * Common code between the AC-3 encoder and decoder * Copyright (c) 2000, 2001, 2002 Fabrice Bellard * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * Common code between the AC-3 encoder and decoder. */ #ifndef AVCODEC_AC3_H #define AVCODEC_AC3_H #include <math.h> #include <stdint.h> #include "ac3tab.h" #ifndef USE_FIXED #define USE_FIXED 0 #endif #if USE_FIXED #define FFT_FLOAT 0 #define FIXR(a) ((int)((a) * 0 + 0.5)) #define FIXR12(a) ((int)((a) * 4096 + 0.5)) #define FIXR15(a) ((int)((a) * 32768 + 0.5)) #define ROUND15(x) ((x) + 16384) >> 15 #define AC3_RENAME(x) x ## _fixed #define AC3_NORM(norm) (1<<24)/(norm) #define AC3_MUL(a,b) ((((int64_t) (a)) * (b))>>12) #define AC3_RANGE(x) ((x)|(((x)&128)<<1)) #define AC3_HEAVY_RANGE(x) ((x)<<1) #define AC3_DYNAMIC_RANGE(x) (x) #define AC3_SPX_BLEND(x) (x) #define AC3_DYNAMIC_RANGE1 0 typedef int INTFLOAT; typedef int16_t SHORTFLOAT; #else /* USE_FIXED */ #include "libavutil/libm.h" #define FIXR(x) ((float)(x)) #define FIXR12(x) ((float)(x)) #define FIXR15(x) ((float)(x)) #define ROUND15(x) (x) #define AC3_RENAME(x) x #define AC3_NORM(norm) (1.0f/(norm)) #define AC3_MUL(a,b) ((a) * (b)) #define AC3_RANGE(x) (dynamic_range_tab[(x)]) #define AC3_HEAVY_RANGE(x) (ff_ac3_heavy_dynamic_range_tab[(x)]) #define AC3_DYNAMIC_RANGE(x) (powf(x, s->drc_scale)) #define AC3_SPX_BLEND(x) (x)* (1.0f/32) #define AC3_DYNAMIC_RANGE1 1.0f typedef float INTFLOAT; typedef float SHORTFLOAT; #endif /* USE_FIXED */ #define AC3_LEVEL(x) ROUND15((x) * FIXR15(M_SQRT1_2)) /* pre-defined gain values */ #define LEVEL_PLUS_3DB M_SQRT2 #define LEVEL_PLUS_1POINT5DB 1.1892071150027209 #define LEVEL_MINUS_1POINT5DB 0.8408964152537145 #define LEVEL_MINUS_3DB M_SQRT1_2 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605 #define LEVEL_MINUS_6DB 0.5000000000000000 #define LEVEL_MINUS_9DB 0.3535533905932738 #define LEVEL_ZERO 0.0000000000000000 #define LEVEL_ONE 1.0000000000000000 typedef struct AC3BitAllocParameters { int sr_code; int sr_shift; int slow_gain, slow_decay, fast_decay, db_per_bit, floor; int cpl_fast_leak, cpl_slow_leak; } AC3BitAllocParameters; /** * Calculate the log power-spectral density of the input signal. * This gives a rough estimate of signal power in the frequency domain by using * the spectral envelope (exponents). The psd is also separately grouped * into critical bands for use in the calculating the masking curve. * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters * determines the reference level. * * @param[in] exp frequency coefficient exponents * @param[in] start starting bin location * @param[in] end ending bin location * @param[out] psd signal power for each frequency bin * @param[out] band_psd signal power for each critical band */ void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, int16_t *band_psd); /** * Calculate the masking curve. * First, the excitation is calculated using parameters in s and the signal * power in each critical band. The excitation is compared with a predefined * hearing threshold table to produce the masking curve. If delta bit * allocation information is provided, it is used for adjusting the masking * curve, usually to give a closer match to a better psychoacoustic model. * * @param[in] s adjustable bit allocation parameters * @param[in] band_psd signal power for each critical band * @param[in] start starting bin location * @param[in] end ending bin location * @param[in] fast_gain fast gain (estimated signal-to-mask ratio) * @param[in] is_lfe whether or not the channel being processed is the LFE * @param[in] dba_mode delta bit allocation mode (none, reuse, or new) * @param[in] dba_nsegs number of delta segments * @param[in] dba_offsets location offsets for each segment * @param[in] dba_lengths length of each segment * @param[in] dba_values delta bit allocation for each segment * @param[out] mask calculated masking curve * @return returns 0 for success, non-zero for error */ int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd, int start, int end, int fast_gain, int is_lfe, int dba_mode, int dba_nsegs, uint8_t *dba_offsets, uint8_t *dba_lengths, uint8_t *dba_values, int16_t *mask); #endif /* AVCODEC_AC3_H */