ref: ce323e4845b423ddbc4a73229eaa7abcf73e39d6
dir: /src/spectral/filterbank_mel.c/
/*
Copyright (C) 2007-2009 Paul Brossier <piem@aubio.org>
and Amaury Hazan <ahazan@iua.upf.edu>
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/>.
*/
#include "aubio_priv.h"
#include "fmat.h"
#include "fvec.h"
#include "cvec.h"
#include "spectral/filterbank.h"
#include "spectral/filterbank_mel.h"
#include "mathutils.h"
uint_t
aubio_filterbank_set_triangle_bands (aubio_filterbank_t * fb,
const fvec_t * freqs, smpl_t samplerate)
{
fmat_t *filters = aubio_filterbank_get_coeffs (fb);
uint_t n_filters = filters->height, win_s = filters->length;
fvec_t *lower_freqs, *upper_freqs, *center_freqs;
fvec_t *triangle_heights, *fft_freqs;
uint_t fn; /* filter counter */
uint_t bin; /* bin counter */
smpl_t riseInc, downInc;
/* freqs define the bands of triangular overlapping windows.
throw a warning if filterbank object fb is too short. */
if (freqs->length - 2 > n_filters) {
AUBIO_WRN ("not enough filters, %d allocated but %d requested\n",
n_filters, freqs->length - 2);
}
if (freqs->length - 2 < n_filters) {
AUBIO_WRN ("too many filters, %d allocated but %d requested\n",
n_filters, freqs->length - 2);
}
for (fn = 0; fn < freqs->length; fn++) {
if (freqs->data[fn] < 0) {
AUBIO_ERR("filterbank_mel: freqs must contain only positive values.\n");
return AUBIO_FAIL;
} else if (freqs->data[fn] > samplerate / 2) {
AUBIO_WRN("filterbank_mel: freqs should contain only "
"values < samplerate / 2.\n");
} else if (fn > 0 && freqs->data[fn] < freqs->data[fn-1]) {
AUBIO_ERR("filterbank_mel: freqs should be a list of frequencies "
"sorted from low to high, but freq[%d] < freq[%d-1]\n", fn, fn);
return AUBIO_FAIL;
} else if (fn > 0 && freqs->data[fn] == freqs->data[fn-1]) {
AUBIO_WRN("filterbank_mel: set_triangle_bands received a list "
"with twice the frequency %f\n", freqs->data[fn]);
}
}
/* convenience reference to lower/center/upper frequency for each triangle */
lower_freqs = new_fvec (n_filters);
upper_freqs = new_fvec (n_filters);
center_freqs = new_fvec (n_filters);
/* height of each triangle */
triangle_heights = new_fvec (n_filters);
/* lookup table of each bin frequency in hz */
fft_freqs = new_fvec (win_s);
/* fill up the lower/center/upper */
for (fn = 0; fn < n_filters; fn++) {
lower_freqs->data[fn] = freqs->data[fn];
center_freqs->data[fn] = freqs->data[fn + 1];
upper_freqs->data[fn] = freqs->data[fn + 2];
}
/* compute triangle heights so that each triangle has unit area */
if (aubio_filterbank_get_norm(fb)) {
for (fn = 0; fn < n_filters; fn++) {
triangle_heights->data[fn] =
2. / (upper_freqs->data[fn] - lower_freqs->data[fn]);
}
} else {
fvec_ones (triangle_heights);
}
/* fill fft_freqs lookup table, which assigns the frequency in hz to each bin */
for (bin = 0; bin < win_s; bin++) {
fft_freqs->data[bin] =
aubio_bintofreq (bin, samplerate, (win_s - 1) * 2);
}
/* zeroing of all filters */
fmat_zeros (filters);
/* building each filter table */
for (fn = 0; fn < n_filters; fn++) {
/* skip first elements */
for (bin = 0; bin < win_s - 1; bin++) {
if (fft_freqs->data[bin] <= lower_freqs->data[fn] &&
fft_freqs->data[bin + 1] > lower_freqs->data[fn]) {
bin++;
break;
}
}
/* compute positive slope step size */
riseInc = triangle_heights->data[fn]
/ (center_freqs->data[fn] - lower_freqs->data[fn]);
/* compute coefficients in positive slope */
for (; bin < win_s - 1; bin++) {
filters->data[fn][bin] =
(fft_freqs->data[bin] - lower_freqs->data[fn]) * riseInc;
if (fft_freqs->data[bin + 1] >= center_freqs->data[fn]) {
bin++;
break;
}
}
/* compute negative slope step size */
downInc = triangle_heights->data[fn]
/ (upper_freqs->data[fn] - center_freqs->data[fn]);
/* compute coefficents in negative slope */
for (; bin < win_s - 1; bin++) {
filters->data[fn][bin] +=
(upper_freqs->data[fn] - fft_freqs->data[bin]) * downInc;
if (filters->data[fn][bin] < 0.) {
filters->data[fn][bin] = 0.;
}
if (fft_freqs->data[bin + 1] >= upper_freqs->data[fn])
break;
}
/* nothing else to do */
}
/* destroy temporarly allocated vectors */
del_fvec (lower_freqs);
del_fvec (upper_freqs);
del_fvec (center_freqs);
del_fvec (triangle_heights);
del_fvec (fft_freqs);
return AUBIO_OK;
}
uint_t
aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb,
smpl_t samplerate)
{
/* Malcolm Slaney parameters */
const smpl_t lowestFrequency = 133.3333;
const smpl_t linearSpacing = 66.66666666;
const smpl_t logSpacing = 1.0711703;
const uint_t linearFilters = 13;
const uint_t logFilters = 27;
const uint_t n_filters = linearFilters + logFilters;
uint_t fn, retval;
smpl_t lastlinearCF;
/* buffers to compute filter frequencies */
fvec_t *freqs;
if (samplerate <= 0) {
AUBIO_ERR("filterbank: set_mel_coeffs_slaney samplerate should be > 0\n");
return AUBIO_FAIL;
}
freqs = new_fvec (n_filters + 2);
/* first step: fill all the linear filter frequencies */
for (fn = 0; fn < linearFilters; fn++) {
freqs->data[fn] = lowestFrequency + fn * linearSpacing;
}
lastlinearCF = freqs->data[fn - 1];
/* second step: fill all the log filter frequencies */
for (fn = 0; fn < logFilters + 2; fn++) {
freqs->data[fn + linearFilters] =
lastlinearCF * (POW (logSpacing, fn + 1));
}
/* now compute the actual coefficients */
retval = aubio_filterbank_set_triangle_bands (fb, freqs, samplerate);
/* destroy vector used to store frequency limits */
del_fvec (freqs);
return retval;
}
static uint_t aubio_filterbank_check_freqs (aubio_filterbank_t *fb UNUSED,
smpl_t samplerate, smpl_t *freq_min, smpl_t *freq_max)
{
if (samplerate <= 0) {
AUBIO_ERR("filterbank: set_mel_coeffs samplerate should be > 0\n");
return AUBIO_FAIL;
}
if (*freq_max < 0) {
AUBIO_ERR("filterbank: set_mel_coeffs freq_max should be > 0\n");
return AUBIO_FAIL;
} else if (*freq_max == 0) {
*freq_max = samplerate / 2.;
}
if (*freq_min < 0) {
AUBIO_ERR("filterbank: set_mel_coeffs freq_min should be > 0\n");
return AUBIO_FAIL;
}
return AUBIO_OK;
}
uint_t
aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb, smpl_t samplerate,
smpl_t freq_min, smpl_t freq_max)
{
uint_t m, retval;
smpl_t start = freq_min, end = freq_max, step;
fvec_t *freqs;
fmat_t *coeffs = aubio_filterbank_get_coeffs(fb);
uint_t n_bands = coeffs->height;
if (aubio_filterbank_check_freqs(fb, samplerate, &start, &end)) {
return AUBIO_FAIL;
}
start = aubio_hztomel(start);
end = aubio_hztomel(end);
freqs = new_fvec(n_bands + 2);
step = (end - start) / (n_bands + 1);
for (m = 0; m < n_bands + 2; m++)
{
freqs->data[m] = MIN(aubio_meltohz(start + step * m), samplerate/2.);
}
retval = aubio_filterbank_set_triangle_bands (fb, freqs, samplerate);
/* destroy vector used to store frequency limits */
del_fvec (freqs);
return retval;
}
uint_t
aubio_filterbank_set_mel_coeffs_htk (aubio_filterbank_t * fb, smpl_t samplerate,
smpl_t freq_min, smpl_t freq_max)
{
uint_t m, retval;
smpl_t start = freq_min, end = freq_max, step;
fvec_t *freqs;
fmat_t *coeffs = aubio_filterbank_get_coeffs(fb);
uint_t n_bands = coeffs->height;
if (aubio_filterbank_check_freqs(fb, samplerate, &start, &end)) {
return AUBIO_FAIL;
}
start = aubio_hztomel_htk(start);
end = aubio_hztomel_htk(end);
freqs = new_fvec (n_bands + 2);
step = (end - start) / (n_bands + 1);
for (m = 0; m < n_bands + 2; m++)
{
freqs->data[m] = MIN(aubio_meltohz_htk(start + step * m), samplerate/2.);
}
retval = aubio_filterbank_set_triangle_bands (fb, freqs, samplerate);
/* destroy vector used to store frequency limits */
del_fvec (freqs);
return retval;
}