ref: cfe40380adeb78c02d19c2f8f20ec3440b43d442
dir: /src/mfcc.c/
/*
Copyright (C) 2006 Amaury Hazan
Ported to aubio from LibXtract
http://libxtract.sourceforge.net/
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 "fft.h"
#include "filterbank.h"
#include "mfcc.h"
#include "math.h"
#define VERY_SMALL_NUMBER 2e-42
#define USE_EQUAL_GAIN 1
/** Internal structure for mfcc object **/
struct aubio_mfcc_t_{
uint_t win_s; /** grain length */
uint_t samplerate; /** sample rate (needed?) */
uint_t channels; /** number of channels */
uint_t n_coefs; /** number of coefficients (= fb->n_filters/2 +1) */
smpl_t lowfreq; /** lowest frequency for filters */
smpl_t highfreq; /** highest frequency for filters */
aubio_filterbank_t * fb; /** filter bank */
fvec_t * in_dct; /** input buffer for dct * [fb->n_filters] */
aubio_mfft_t * fft_dct; /** fft object for dct */
cvec_t * fftgrain_dct; /** output buffer for dct */
};
/** filterbank initialization for mel filters
\param fb filterbank, as returned by new_aubio_filterbank method
\param nyquist nyquist frequency, i.e. half of the sampling rate
\param style libxtract style
\param freqmin lowest filter frequency
\param freqmax highest filter frequency
*/
void aubio_filterbank_mfcc_init(aubio_filterbank_t * fb, smpl_t nyquist, int style, smpl_t freq_min, smpl_t freq_max);
aubio_mfcc_t * new_aubio_mfcc (uint_t win_s, uint_t samplerate ,uint_t n_coefs, smpl_t lowfreq, smpl_t highfreq, uint_t channels){
/** allocating space for mfcc object */
aubio_mfcc_t * mfcc = AUBIO_NEW(aubio_mfcc_t);
//we need (n_coefs-1)*2 filters to obtain n_coefs coefficients after dct
uint_t n_filters = (n_coefs-1)*2;
mfcc->win_s=win_s;
mfcc->samplerate=samplerate;
mfcc->channels=channels;
mfcc->n_coefs=n_coefs;
mfcc->lowfreq=lowfreq;
mfcc->highfreq=highfreq;
/** filterbank allocation */
mfcc->fb = new_aubio_filterbank(n_filters, mfcc->win_s);
/** allocating space for fft object (used for dct) */
mfcc->fft_dct=new_aubio_mfft(mfcc->win_s, 1);
/** allocating buffers */
mfcc->in_dct=new_fvec(mfcc->win_s, 1);
mfcc->fftgrain_dct=new_cvec(n_filters, 1);
/** populating the filterbank */
aubio_filterbank_mfcc_init(mfcc->fb, (mfcc->samplerate)/2, mfcc->lowfreq, mfcc->highfreq);
return mfcc;
};
void del_aubio_mfcc(aubio_mfcc_t *mf){
/** deleting filterbank */
del_aubio_filterbank(mf->fb);
/** deleting mfft object */
del_aubio_mfft(mf->fft_dct);
/** deleting buffers */
del_fvec(mf->in_dct);
del_cvec(mf->fftgrain_dct);
/** deleting mfcc object */
AUBIO_FREE(mf);
}
void aubio_mfcc_do(aubio_mfcc_t * mf, cvec_t *in, fvec_t *out){
aubio_filterbank_t *f = mf->fb;
uint_t n, filter_cnt;
for(filter_cnt = 0; filter_cnt < f->n_filters; filter_cnt++){
mf->in_dct->data[0][filter_cnt] = 0.f;
for(n = 0; n < mf->win_s; n++){
mf->in_dct->data[0][filter_cnt] += in->norm[0][n] * f->filters[filter_cnt]->data[0][n];
}
mf->in_dct->data[0][filter_cnt] = LOG(mf->in_dct->data[0][filter_cnt] < VERY_SMALL_NUMBER ? VERY_SMALL_NUMBER : mf->in_dct->data[0][filter_cnt]);
}
//TODO: check that zero padding
// the following line seems useless since the in_dct buffer has the correct size
//for(n = filter + 1; n < N; n++) result[n] = 0;
aubio_dct_do(mf, mf->in_dct, out);
return;
}
void aubio_dct_do(aubio_mfcc_t * mf, fvec_t *in, fvec_t *out){
//compute mag spectrum
aubio_mfft_do (mf->fft_dct, in, mf->fftgrain_dct);
int i;
//extract real part of fft grain
for(i=0; i<mf->n_coefs ;i++){
out->data[0][i]= mf->fftgrain_dct->norm[0][i]*COS(mf->fftgrain_dct->phas[0][i]);
}
return;
}
void aubio_filterbank_mfcc_init(aubio_filterbank_t * fb, smpl_t nyquist, int style, smpl_t freq_min, smpl_t freq_max){
int n, i, k, *fft_peak, M, next_peak;
smpl_t norm, mel_freq_max, mel_freq_min, norm_fact, height, inc, val,
freq_bw_mel, *mel_peak, *height_norm, *lin_peak;
mel_peak = height_norm = lin_peak = NULL;
fft_peak = NULL;
norm = 1;
mel_freq_max = 1127 * log(1 + freq_max / 700);
mel_freq_min = 1127 * log(1 + freq_min / 700);
freq_bw_mel = (mel_freq_max - mel_freq_min) / fb->n_filters;
mel_peak = (smpl_t *)malloc((fb->n_filters + 2) * sizeof(smpl_t));
/* +2 for zeros at start and end */
lin_peak = (smpl_t *)malloc((fb->n_filters + 2) * sizeof(smpl_t));
fft_peak = (int *)malloc((fb->n_filters + 2) * sizeof(int));
height_norm = (smpl_t *)malloc(fb->n_filters * sizeof(smpl_t));
if(mel_peak == NULL || height_norm == NULL ||
lin_peak == NULL || fft_peak == NULL)
return NULL;
M = fb->win_s >> 1;
mel_peak[0] = mel_freq_min;
lin_peak[0] = 700 * (exp(mel_peak[0] / 1127) - 1);
fft_peak[0] = lin_peak[0] / nyquist * M;
for (n = 1; n <= fb->n_filters; n++){
/*roll out peak locations - mel, linear and linear on fft window scale */
mel_peak[n] = mel_peak[n - 1] + freq_bw_mel;
lin_peak[n] = 700 * (exp(mel_peak[n] / 1127) -1);
fft_peak[n] = lin_peak[n] / nyquist * M;
}
for (n = 0; n < fb->n_filters; n++){
/*roll out normalised gain of each peak*/
if (style == USE_EQUAL_GAIN){
height = 1;
norm_fact = norm;
}
else{
height = 2 / (lin_peak[n + 2] - lin_peak[n]);
norm_fact = norm / (2 / (lin_peak[2] - lin_peak[0]));
}
height_norm[n] = height * norm_fact;
}
i = 0;
for(n = 0; n < fb->n_filters; n++){
/*calculate the rise increment*/
if(n > 0)
inc = height_norm[n] / (fft_peak[n] - fft_peak[n - 1]);
else
inc = height_norm[n] / fft_peak[n];
val = 0;
/*zero the start of the array*/
for(k = 0; k < i; k++)
//fft_tables[n][k] = 0.f;
fb->filters[n]->data[0][k]=0.f;
/*fill in the rise */
for(; i <= fft_peak[n]; i++){
// fft_tables[n][i] = val;
fb->filters[n]->data[0][k]=val;
val += inc;
}
/*calculate the fall increment */
inc = height_norm[n] / (fft_peak[n + 1] - fft_peak[n]);
val = 0;
next_peak = fft_peak[n + 1];
/*reverse fill the 'fall' */
for(i = next_peak; i > fft_peak[n]; i--){
//fft_tables[n][i] = val;
fb->filters[n]->data[0][k]=val;
val += inc;
}
/*zero the rest of the array*/
for(k = next_peak + 1; k < fb->win_s; k++)
//fft_tables[n][k] = 0.f;
fb->filters[n]->data[0][k]=0.f;
}
free(mel_peak);
free(lin_peak);
free(height_norm);
free(fft_peak);
}