mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-25 16:52:31 +00:00
323e6fead0
This increases the accuracy of coefficients, leading to improved quality. Rescaling of the coefficients to full 25-bit accuracy is done rather than offsetting the exponent values. This requires coefficient scaling to be done before determining the rematrixing strategy. Also, the rematrixing strategy calculation must use 64-bit math to prevent overflow due to the higher precision coefficients.
62 lines
2.0 KiB
C
62 lines
2.0 KiB
C
/*
|
|
* The simplest AC-3 encoder
|
|
* Copyright (c) 2000 Fabrice Bellard
|
|
* Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
|
|
* Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
|
|
*
|
|
* 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
|
|
* fixed-point AC-3 encoder header.
|
|
*/
|
|
|
|
#ifndef AVCODEC_AC3ENC_FIXED_H
|
|
#define AVCODEC_AC3ENC_FIXED_H
|
|
|
|
#include <stdint.h>
|
|
|
|
|
|
typedef int16_t SampleType;
|
|
typedef int32_t CoefType;
|
|
typedef int64_t CoefSumType;
|
|
|
|
#define MAC_COEF(d,a,b) MAC64(d,a,b)
|
|
|
|
|
|
/**
|
|
* Compex number.
|
|
* Used in fixed-point MDCT calculation.
|
|
*/
|
|
typedef struct IComplex {
|
|
int16_t re,im;
|
|
} IComplex;
|
|
|
|
typedef struct AC3MDCTContext {
|
|
const int16_t *window; ///< MDCT window function
|
|
int nbits; ///< log2(transform size)
|
|
int16_t *costab; ///< FFT cos table
|
|
int16_t *sintab; ///< FFT sin table
|
|
int16_t *xcos1; ///< MDCT cos table
|
|
int16_t *xsin1; ///< MDCT sin table
|
|
int16_t *rot_tmp; ///< temp buffer for pre-rotated samples
|
|
IComplex *cplx_tmp; ///< temp buffer for complex pre-rotated samples
|
|
} AC3MDCTContext;
|
|
|
|
#endif /* AVCODEC_AC3ENC_FIXED_H */
|