/* * 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 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 unsigned int            UINTFLOAT;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                   UINTFLOAT;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 */