ref: e1bfde5b4ebe6465f95565b3f3ba978db22bbf30
dir: /src/temporal/filter.c/
/* 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, 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 (aubio_filter_t * f) { return f->a; } lvec_t * aubio_filter_get_feedforward (aubio_filter_t * f) { return f->b; } uint_t aubio_filter_get_order (aubio_filter_t * f) { return f->order; } uint_t aubio_filter_get_samplerate (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); 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[1] = 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; }