ref: cfd35dbe9ee20e0697abf8b3ffb2b7182b4e2b41
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 "fvec.h"
#include "cvec.h"
#include "spectral/filterbank.h"
#include "mathutils.h"
void
aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb, uint_t samplerate,
smpl_t freq_min, smpl_t freq_max)
{
fvec_t *filters = aubio_filterbank_get_coeffs (fb);
uint_t n_filters = filters->channels, win_s = filters->length;
//slaney params
smpl_t lowestFrequency = 133.3333;
smpl_t linearSpacing = 66.66666666;
smpl_t logSpacing = 1.0711703;
uint_t linearFilters = 13;
uint_t logFilters = 27;
uint_t allFilters = linearFilters + logFilters;
//buffers for computing filter frequencies
fvec_t *freqs = new_fvec (allFilters + 2, 1);
fvec_t *lower_freqs = new_fvec (allFilters, 1);
fvec_t *upper_freqs = new_fvec (allFilters, 1);
fvec_t *center_freqs = new_fvec (allFilters, 1);
fvec_t *triangle_heights = new_fvec (allFilters, 1);
//lookup table of each bin frequency in hz
fvec_t *fft_freqs = new_fvec (win_s, 1);
uint_t filter_cnt, bin_cnt;
//first step: filling all the linear filter frequencies
for (filter_cnt = 0; filter_cnt < linearFilters; filter_cnt++) {
freqs->data[0][filter_cnt] = lowestFrequency + filter_cnt * linearSpacing;
}
smpl_t lastlinearCF = freqs->data[0][filter_cnt - 1];
//second step: filling all the log filter frequencies
for (filter_cnt = 0; filter_cnt < logFilters + 2; filter_cnt++) {
freqs->data[0][filter_cnt + linearFilters] =
lastlinearCF * (pow (logSpacing, filter_cnt + 1));
}
//Option 1. copying interesting values to lower_freqs, center_freqs and upper freqs arrays
//TODO: would be nicer to have a reference to freqs->data, anyway we do not care in this init step
for (filter_cnt = 0; filter_cnt < allFilters; filter_cnt++) {
lower_freqs->data[0][filter_cnt] = freqs->data[0][filter_cnt];
center_freqs->data[0][filter_cnt] = freqs->data[0][filter_cnt + 1];
upper_freqs->data[0][filter_cnt] = freqs->data[0][filter_cnt + 2];
}
//computing triangle heights so that each triangle has unit area
for (filter_cnt = 0; filter_cnt < allFilters; filter_cnt++) {
triangle_heights->data[0][filter_cnt] =
2. / (upper_freqs->data[0][filter_cnt]
- lower_freqs->data[0][filter_cnt]);
}
//AUBIO_DBG("filter tables frequencies\n");
//for(filter_cnt=0; filter_cnt<allFilters; filter_cnt++)
// AUBIO_DBG("filter n. %d %f %f %f %f\n",
// filter_cnt, lower_freqs->data[0][filter_cnt],
// center_freqs->data[0][filter_cnt], upper_freqs->data[0][filter_cnt],
// triangle_heights->data[0][filter_cnt]);
//filling the fft_freqs lookup table, which assigns the frequency in hz to each bin
for (bin_cnt = 0; bin_cnt < win_s; bin_cnt++) {
fft_freqs->data[0][bin_cnt] = aubio_bintofreq (bin_cnt, samplerate, win_s);
}
//building each filter table
for (filter_cnt = 0; filter_cnt < allFilters; filter_cnt++) {
//TODO:check special case : lower freq =0
//calculating rise increment in mag/Hz
smpl_t riseInc =
triangle_heights->data[0][filter_cnt] /
(center_freqs->data[0][filter_cnt] - lower_freqs->data[0][filter_cnt]);
//zeroing begining of filter
for (bin_cnt = 0; bin_cnt < win_s - 1; bin_cnt++) {
filters->data[filter_cnt][bin_cnt] = 0.0;
if (fft_freqs->data[0][bin_cnt] <= lower_freqs->data[0][filter_cnt] &&
fft_freqs->data[0][bin_cnt + 1] > lower_freqs->data[0][filter_cnt]) {
break;
}
}
bin_cnt++;
//positive slope
for (; bin_cnt < win_s - 1; bin_cnt++) {
filters->data[filter_cnt][bin_cnt] =
(fft_freqs->data[0][bin_cnt] -
lower_freqs->data[0][filter_cnt]) * riseInc;
//if(fft_freqs->data[0][bin_cnt]<= center_freqs->data[0][filter_cnt] && fft_freqs->data[0][bin_cnt+1]> center_freqs->data[0][filter_cnt])
if (fft_freqs->data[0][bin_cnt + 1] > center_freqs->data[0][filter_cnt])
break;
}
//bin_cnt++;
//negative slope
for (; bin_cnt < win_s - 1; bin_cnt++) {
//checking whether last value is less than 0...
smpl_t val =
triangle_heights->data[0][filter_cnt] - (fft_freqs->data[0][bin_cnt] -
center_freqs->data[0][filter_cnt]) * riseInc;
if (val >= 0)
filters->data[filter_cnt][bin_cnt] = val;
else
filters->data[filter_cnt][bin_cnt] = 0.0;
//if(fft_freqs->data[0][bin_cnt]<= upper_freqs->data[0][bin_cnt] && fft_freqs->data[0][bin_cnt+1]> upper_freqs->data[0][filter_cnt])
//TODO: CHECK whether bugfix correct
if (fft_freqs->data[0][bin_cnt + 1] > upper_freqs->data[0][filter_cnt])
break;
}
//bin_cnt++;
//zeroing tail
for (; bin_cnt < win_s; bin_cnt++)
filters->data[filter_cnt][bin_cnt] = 0.f;
}
/* destroy temporarly allocated vectors */
del_fvec (freqs);
del_fvec (lower_freqs);
del_fvec (upper_freqs);
del_fvec (center_freqs);
del_fvec (triangle_heights);
del_fvec (fft_freqs);
}