75 lines
2.1 KiB
C
75 lines
2.1 KiB
C
/*
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Copyright (C) 2003-2015 Paul Brossier <piem@aubio.org>
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This file is part of aubio.
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aubio is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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aubio 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with aubio. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef AUBIO_FILTER_BIQUAD_H
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#define AUBIO_FILTER_BIQUAD_H
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/** \file
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Second order Infinite Impulse Response filter
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This file implements a normalised biquad filter (second order IIR):
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\f$ y[n] = b_0 x[n] + b_1 x[n-1] + b_2 x[n-2] - a_1 y[n-1] - a_2 y[n-2] \f$
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The filtfilt version runs the filter twice, forward and backward, to
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compensate the phase shifting of the forward operation.
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See also <a href="http://en.wikipedia.org/wiki/Digital_biquad_filter">Digital
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biquad filter</a> on wikipedia.
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\example temporal/test-biquad.c
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** set coefficients of a biquad filter
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\param f filter object as returned by new_aubio_filter()
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\param b0 forward filter coefficient
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\param b1 forward filter coefficient
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\param b2 forward filter coefficient
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\param a1 feedback filter coefficient
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\param a2 feedback filter coefficient
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*/
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uint_t aubio_filter_set_biquad (aubio_filter_t * f, lsmp_t b0, lsmp_t b1,
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lsmp_t b2, lsmp_t a1, lsmp_t a2);
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/** create biquad filter with `b0`, `b1`, `b2`, `a1`, `a2` coeffs
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\param b0 forward filter coefficient
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\param b1 forward filter coefficient
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\param b2 forward filter coefficient
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\param a1 feedback filter coefficient
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\param a2 feedback filter coefficient
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*/
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aubio_filter_t *new_aubio_filter_biquad (lsmp_t b0, lsmp_t b1, lsmp_t b2,
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lsmp_t a1, lsmp_t a2);
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#ifdef __cplusplus
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}
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#endif
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#endif /* AUBIO_FILTER_BIQUAD_H */
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