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/*
Copyright (C) 2003-2009 Paul Brossier <piem@aubio.org>
This file is part of aubio.
aubio 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 3 of the License, or
(at your option) any later version.
aubio 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 aubio. If not, see <http://www.gnu.org/licenses/>.
*/
/* Requires lsmp_t to be long or double. float will NOT give reliable
* results */
#include "aubio_priv.h"
#include "fvec.h"
#include "lvec.h"
#include "mathutils.h"
#include "temporal/filter.h"
struct _aubio_filter_t
{
uint_t order;
uint_t samplerate;
lvec_t *a;
lvec_t *b;
lvec_t *y;
lvec_t *x;
};
void
aubio_filter_do_outplace (aubio_filter_t * f, const fvec_t * in, fvec_t * out)
{
fvec_copy (in, out);
aubio_filter_do (f, out);
}
void
aubio_filter_do (aubio_filter_t * f, fvec_t * in)
{
uint_t j, l, order = f->order;
lsmp_t *x = f->x->data;
lsmp_t *y = f->y->data;
lsmp_t *a = f->a->data;
lsmp_t *b = f->b->data;
for (j = 0; j < in->length; j++) {
/* new input */
x[0] = KILL_DENORMAL (in->data[j]);
y[0] = b[0] * x[0];
for (l = 1; l < order; l++) {
y[0] += b[l] * x[l];
y[0] -= a[l] * y[l];
}
/* new output */
in->data[j] = y[0];
/* store for next sample */
for (l = order - 1; l > 0; l--) {
x[l] = x[l - 1];
y[l] = y[l - 1];
}
}
}
/* The rough way: reset memory of filter between each run to avoid end effects. */
void
aubio_filter_do_filtfilt (aubio_filter_t * f, fvec_t * in, fvec_t * tmp)
{
uint_t j;
uint_t length = in->length;
/* apply filtering */
aubio_filter_do (f, in);
aubio_filter_do_reset (f);
/* mirror */
for (j = 0; j < length; j++)
tmp->data[length - j - 1] = in->data[j];
/* apply filtering on mirrored */
aubio_filter_do (f, tmp);
aubio_filter_do_reset (f);
/* invert back */
for (j = 0; j < length; j++)
in->data[j] = tmp->data[length - j - 1];
}
lvec_t *
aubio_filter_get_feedback (const aubio_filter_t * f)
{
return f->a;
}
lvec_t *
aubio_filter_get_feedforward (const aubio_filter_t * f)
{
return f->b;
}
uint_t
aubio_filter_get_order (const aubio_filter_t * f)
{
return f->order;
}
uint_t
aubio_filter_get_samplerate (const aubio_filter_t * f)
{
return f->samplerate;
}
uint_t
aubio_filter_set_samplerate (aubio_filter_t * f, uint_t samplerate)
{
f->samplerate = samplerate;
return AUBIO_OK;
}
void
aubio_filter_do_reset (aubio_filter_t * f)
{
lvec_zeros (f->x);
lvec_zeros (f->y);
}
aubio_filter_t *
new_aubio_filter (uint_t order)
{
aubio_filter_t *f = AUBIO_NEW (aubio_filter_t);
if ((sint_t)order < 1) {
AUBIO_FREE(f);
return NULL;
}
f->x = new_lvec (order);
f->y = new_lvec (order);
f->a = new_lvec (order);
f->b = new_lvec (order);
/* by default, samplerate is not set */
f->samplerate = 0;
f->order = order;
/* set default to identity */
f->a->data[0] = 1.;
f->b->data[0] = 1.;
return f;
}
void
del_aubio_filter (aubio_filter_t * f)
{
del_lvec (f->a);
del_lvec (f->b);
del_lvec (f->x);
del_lvec (f->y);
AUBIO_FREE (f);
return;
}
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