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116 lines
3.6 KiB
116 lines
3.6 KiB
/* |
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* IIR filter |
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* Copyright (c) 2008 Konstantin Shishkov |
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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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* IIR filter interface |
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*/ |
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#ifndef AVCODEC_IIRFILTER_H |
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#define AVCODEC_IIRFILTER_H |
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#include <stddef.h> |
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struct FFIIRFilterCoeffs; |
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struct FFIIRFilterState; |
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enum IIRFilterType{ |
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FF_FILTER_TYPE_BESSEL, |
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FF_FILTER_TYPE_BIQUAD, |
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FF_FILTER_TYPE_BUTTERWORTH, |
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FF_FILTER_TYPE_CHEBYSHEV, |
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FF_FILTER_TYPE_ELLIPTIC, |
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}; |
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enum IIRFilterMode{ |
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FF_FILTER_MODE_LOWPASS, |
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FF_FILTER_MODE_HIGHPASS, |
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FF_FILTER_MODE_BANDPASS, |
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FF_FILTER_MODE_BANDSTOP, |
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}; |
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typedef struct FFIIRFilterContext { |
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/** |
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* Perform IIR filtering on floating-point input samples. |
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* |
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* @param coeffs pointer to filter coefficients |
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* @param state pointer to filter state |
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* @param size input length |
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* @param src source samples |
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* @param sstep source stride |
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* @param dst filtered samples (destination may be the same as input) |
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* @param dstep destination stride |
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*/ |
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void (*filter_flt)(const struct FFIIRFilterCoeffs *coeffs, |
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struct FFIIRFilterState *state, int size, |
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const float *src, ptrdiff_t sstep, float *dst, ptrdiff_t dstep); |
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} FFIIRFilterContext; |
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/** |
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* Initialize FFIIRFilterContext |
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*/ |
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void ff_iir_filter_init(FFIIRFilterContext *f); |
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void ff_iir_filter_init_mips(FFIIRFilterContext *f); |
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/** |
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* Initialize filter coefficients. |
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* |
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* @param avc a pointer to an arbitrary struct of which the first |
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* field is a pointer to an AVClass struct |
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* @param filt_type filter type (e.g. Butterworth) |
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* @param filt_mode filter mode (e.g. lowpass) |
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* @param order filter order |
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* @param cutoff_ratio cutoff to input frequency ratio |
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* @param stopband stopband to input frequency ratio (used by bandpass and bandstop filter modes) |
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* @param ripple ripple factor (used only in Chebyshev filters) |
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* |
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* @return pointer to filter coefficients structure or NULL if filter cannot be created |
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*/ |
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struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(void *avc, |
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enum IIRFilterType filt_type, |
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enum IIRFilterMode filt_mode, |
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int order, float cutoff_ratio, |
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float stopband, float ripple); |
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/** |
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* Create new filter state. |
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* |
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* @param order filter order |
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* |
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* @return pointer to new filter state or NULL if state creation fails |
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*/ |
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struct FFIIRFilterState* ff_iir_filter_init_state(int order); |
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/** |
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* Free filter coefficients. |
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* |
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* @param coeffs pointer allocated with ff_iir_filter_init_coeffs() |
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*/ |
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void ff_iir_filter_free_coeffsp(struct FFIIRFilterCoeffs **coeffs); |
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/** |
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* Free and zero filter state. |
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* |
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* @param state pointer to pointer allocated with ff_iir_filter_init_state() |
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*/ |
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void ff_iir_filter_free_statep(struct FFIIRFilterState **state); |
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#endif /* AVCODEC_IIRFILTER_H */
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