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