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/* libxtract feature extraction library
*
* Copyright (C) 2006 Jamie Bullock
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*/
/* init.c: defines functions that extract a feature as a single value from an input vector */
#include "xtract/libxtract.h"
#include <math.h>
#include <stdlib.h>
int xtract_init_mfcc(int N, float nyquist, int style, float freq_min, float freq_max, int freq_bands, float **fft_tables){
int n, i, k, *fft_peak, M, next_peak;
float 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) / freq_bands;
mel_peak = (float *)malloc((freq_bands + 2) * sizeof(float));
/* +2 for zeros at start and end */
lin_peak = (float *)malloc((freq_bands + 2) * sizeof(float));
fft_peak = (int *)malloc((freq_bands + 2) * sizeof(int));
height_norm = (float *)malloc(freq_bands * sizeof(float));
if(mel_peak == NULL || height_norm == NULL ||
lin_peak == NULL || fft_peak == NULL)
return XTRACT_MALLOC_FAILED;
M = N >> 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 <= freq_bands; 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 < freq_bands; n++){
/*roll out normalised gain of each peak*/
if (style == XTRACT_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 < freq_bands; 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;
/*fill in the rise */
for(; i <= fft_peak[n]; i++){
fft_tables[n][i] = 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;
val += inc;
}
/*zero the rest of the array*/
for(k = next_peak + 1; k < N; k++)
fft_tables[n][k] = 0.f;
}
free(mel_peak);
free(lin_peak);
free(height_norm);
free(fft_peak);
return XTRACT_SUCCESS;
}
int xtract_init_bark(int N, float sr, int *band_limits){
float edges[] = {0, 100, 200, 300, 400, 510, 630, 770, 920, 1080, 1270, 1480, 1720, 2000, 2320, 2700, 3150, 3700, 4400, 5300, 6400, 7700, 9500, 12000, 15500, 20500, 27000}; /* Takes us up to sr = 54kHz (CCRMA: JOS)*/
int bands = XTRACT_BARK_BANDS;
while(bands--)
band_limits[bands] = edges[bands] / sr * N;
/*FIX shohuld use rounding, but couldn't get it to work */
return XTRACT_SUCCESS;
}
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