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83 lines
2.5 KiB
83 lines
2.5 KiB
/* |
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* Lowpass 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 lowpass.h |
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* lowpass filter interface |
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*/ |
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#ifndef FFMPEG_LOWPASS_H |
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#define FFMPEG_LOWPASS_H |
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#include "avcodec.h" |
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struct FFLPFilterCoeffs; |
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struct FFLPFilterState; |
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/** |
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* Initialize filter coefficients. |
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* |
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* @param order filter order |
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* @param cutoff_ratio cutoff to input frequency ratio |
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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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const struct FFLPFilterCoeffs* ff_lowpass_filter_init_coeffs(int order, float cutoff_ratio); |
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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 FFLPFilterState* ff_lowpass_filter_init_state(int order); |
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#if 0 //enable with arbitrary order filter implementation, use av_free() for filter state only for now |
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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_lowpass_filter_init_coeffs() |
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*/ |
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void ff_lowpass_filter_free_coeffs(struct FFLPFilterCoeffs *coeffs); |
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/** |
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* Free filter state. |
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* |
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* @param state pointer allocated with ff_lowpass_filter_init_state() |
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*/ |
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void ff_lowpass_filter_free_state(struct FFLPFilterState *state); |
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#endif |
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/** |
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* Perform lowpass filtering on 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 ff_lowpass_filter(const struct FFLPFilterCoeffs *coeffs, struct FFLPFilterState *state, int size, int16_t *src, int sstep, int16_t *dst, int dstep); |
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#endif /* FFMPEG_LOWPASS_H */
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