| /* |
| * 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 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 */ |
