ref: 3f99693b6933fb8f098746c48f97ed993ca7fa8c
dir: /src/temporal/biquad.h/
/*
Copyright (C) 2003 Paul Brossier
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef BIQUAD_H
#define BIQUAD_H
/** \file
Second order Infinite Impulse Response filter
This file implements a normalised biquad filter (second order IIR):
\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$
The filtfilt version runs the filter twice, forward and backward, to
compensate the phase shifting of the forward operation.
See also <a href="http://en.wikipedia.org/wiki/Digital_biquad_filter">Digital
biquad filter</a> on wikipedia.
*/
#ifdef __cplusplus
extern "C" {
#endif
/** set coefficients of a biquad filter
\param b0 forward filter coefficient
\param b1 forward filter coefficient
\param b2 forward filter coefficient
\param a1 feedback filter coefficient
\param a2 feedback filter coefficient
*/
uint_t
aubio_filter_set_biquad (aubio_filter_t * f, lsmp_t b0, lsmp_t b1, lsmp_t b2,
lsmp_t a1, lsmp_t a2);
/** create new biquad filter
\param b0 forward filter coefficient
\param b1 forward filter coefficient
\param b2 forward filter coefficient
\param a1 feedback filter coefficient
\param a2 feedback filter coefficient
*/
aubio_filter_t *
new_aubio_filter_biquad (lsmp_t b0, lsmp_t b1, lsmp_t b2, lsmp_t a1, lsmp_t a2,
uint_t channels);
#ifdef __cplusplus
}
#endif
#endif /*BIQUAD_H*/