mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
147 lines
5.6 KiB
147 lines
5.6 KiB
/* |
|
* 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 */
|
|
|