mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-18 03:19:31 +02:00
ba87f0801d
Passing an explicit filename to this command is only necessary if the documentation in the @file block refers to a file different from the one the block resides in. Originally committed as revision 22921 to svn://svn.ffmpeg.org/ffmpeg/trunk
104 lines
3.1 KiB
C
104 lines
3.1 KiB
C
/*
|
|
* IIR filter
|
|
* Copyright (c) 2008 Konstantin Shishkov
|
|
*
|
|
* 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
|
|
* IIR filter interface
|
|
*/
|
|
|
|
#ifndef AVCODEC_IIRFILTER_H
|
|
#define AVCODEC_IIRFILTER_H
|
|
|
|
#include "avcodec.h"
|
|
|
|
struct FFIIRFilterCoeffs;
|
|
struct FFIIRFilterState;
|
|
|
|
enum IIRFilterType{
|
|
FF_FILTER_TYPE_BESSEL,
|
|
FF_FILTER_TYPE_BUTTERWORTH,
|
|
FF_FILTER_TYPE_CHEBYSHEV,
|
|
FF_FILTER_TYPE_ELLIPTIC,
|
|
};
|
|
|
|
enum IIRFilterMode{
|
|
FF_FILTER_MODE_LOWPASS,
|
|
FF_FILTER_MODE_HIGHPASS,
|
|
FF_FILTER_MODE_BANDPASS,
|
|
FF_FILTER_MODE_BANDSTOP,
|
|
};
|
|
|
|
/**
|
|
* Initialize filter coefficients.
|
|
*
|
|
* @param filt_type filter type (e.g. Butterworth)
|
|
* @param filt_mode filter mode (e.g. lowpass)
|
|
* @param order filter order
|
|
* @param cutoff_ratio cutoff to input frequency ratio
|
|
* @param stopband stopband to input frequency ratio (used by bandpass and bandstop filter modes)
|
|
* @param ripple ripple factor (used only in Chebyshev filters)
|
|
*
|
|
* @return pointer to filter coefficients structure or NULL if filter cannot be created
|
|
*/
|
|
struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(enum IIRFilterType filt_type,
|
|
enum IIRFilterMode filt_mode,
|
|
int order, float cutoff_ratio,
|
|
float stopband, float ripple);
|
|
|
|
/**
|
|
* Create new filter state.
|
|
*
|
|
* @param order filter order
|
|
*
|
|
* @return pointer to new filter state or NULL if state creation fails
|
|
*/
|
|
struct FFIIRFilterState* ff_iir_filter_init_state(int order);
|
|
|
|
/**
|
|
* Free filter coefficients.
|
|
*
|
|
* @param coeffs pointer allocated with ff_iir_filter_init_coeffs()
|
|
*/
|
|
void ff_iir_filter_free_coeffs(struct FFIIRFilterCoeffs *coeffs);
|
|
|
|
/**
|
|
* Free filter state.
|
|
*
|
|
* @param state pointer allocated with ff_iir_filter_init_state()
|
|
*/
|
|
void ff_iir_filter_free_state(struct FFIIRFilterState *state);
|
|
|
|
/**
|
|
* Perform lowpass filtering on input samples.
|
|
*
|
|
* @param coeffs pointer to filter coefficients
|
|
* @param state pointer to filter state
|
|
* @param size input length
|
|
* @param src source samples
|
|
* @param sstep source stride
|
|
* @param dst filtered samples (destination may be the same as input)
|
|
* @param dstep destination stride
|
|
*/
|
|
void ff_iir_filter(const struct FFIIRFilterCoeffs *coeffs, struct FFIIRFilterState *state,
|
|
int size, const int16_t *src, int sstep, int16_t *dst, int dstep);
|
|
|
|
#endif /* AVCODEC_IIRFILTER_H */
|