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.
103 lines
3.2 KiB
103 lines
3.2 KiB
/* |
|
* 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 libavcodec/iirfilter.h |
|
* 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 */
|
|
|