ref: 5dd22a923ed25c385223231be4bb48d4acce9c2b
dir: /src/filterbank.c/
/*
Copyright (C) 2007 Amaury Hazan <ahazan@iua.upf.edu>
and Paul Brossier <piem@piem.org>
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.
*/
#include "aubio_priv.h"
#include "sample.h"
#include "filterbank.h"
#include "mathutils.h"
#define VERY_SMALL_NUMBER 2e-42
/** \brief A structure to store a set of n_filters filters of lenghts win_s */
struct aubio_filterbank_t_ {
uint_t win_s;
uint_t n_filters;
fvec_t **filters;
};
aubio_filterbank_t * new_aubio_filterbank(uint_t n_filters, uint_t win_s){
/** allocating space for filterbank object */
aubio_filterbank_t * fb = AUBIO_NEW(aubio_filterbank_t);
uint_t filter_cnt;
fb->win_s=win_s;
fb->n_filters=n_filters;
/** allocating filter tables */
fb->filters=AUBIO_ARRAY(fvec_t*,n_filters);
for (filter_cnt=0; filter_cnt<n_filters; filter_cnt++)
/* considering one-channel filters */
fb->filters[filter_cnt]=new_fvec(win_s, 1);
return fb;
}
/*
FB initialization based on Slaney's auditory toolbox
TODO:
*solve memory leak problems while
*solve quantization issues when constructing signal:
*bug for win_s=512
*corrections for win_s=1024 -> why even filters with smaller amplitude
*/
aubio_filterbank_t * new_aubio_filterbank_mfcc(uint_t n_filters, uint_t win_s, uint_t samplerate, smpl_t freq_min, smpl_t freq_max){
aubio_filterbank_t * fb = new_aubio_filterbank(n_filters, win_s);
//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++){
fb->filters[filter_cnt]->data[0][bin_cnt]=0.f;
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++){
fb->filters[filter_cnt]->data[0][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)
fb->filters[filter_cnt]->data[0][bin_cnt]=val;
else fb->filters[filter_cnt]->data[0][bin_cnt]=0.f;
//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++)
fb->filters[filter_cnt]->data[0][bin_cnt]=0.f;
}
del_fvec(freqs);
del_fvec(lower_freqs);
del_fvec(upper_freqs);
del_fvec(center_freqs);
del_fvec(triangle_heights);
del_fvec(fft_freqs);
return fb;
}
void del_aubio_filterbank(aubio_filterbank_t * fb){
uint_t filter_cnt;
/** deleting filter tables first */
for (filter_cnt=0; filter_cnt<fb->n_filters; filter_cnt++)
del_fvec(fb->filters[filter_cnt]);
AUBIO_FREE(fb->filters);
AUBIO_FREE(fb);
}
void aubio_filterbank_do(aubio_filterbank_t * f, cvec_t * in, fvec_t *out) {
uint_t n, filter_cnt;
for(filter_cnt = 0; (filter_cnt < f->n_filters)
&& (filter_cnt < out->length); filter_cnt++){
out->data[0][filter_cnt] = 0.f;
for(n = 0; n < in->length; n++){
out->data[0][filter_cnt] += in->norm[0][n]
* f->filters[filter_cnt]->data[0][n];
}
out->data[0][filter_cnt] =
LOG(out->data[0][filter_cnt] < VERY_SMALL_NUMBER ?
VERY_SMALL_NUMBER : out->data[0][filter_cnt]);
}
return;
}
fvec_t * aubio_filterbank_getchannel(aubio_filterbank_t * f, uint_t channel) {
if ( (channel < f->n_filters) ) { return f->filters[channel]; }
else { return NULL; }
}