view src/init.c @ 96:757e6f99dcd7

Dan Stowell: Removed strange "zeroing" part of xtract_mfcc() which was zeroing a load of elements despite the fact that they're ignored by the DCT process called next, and never used for anything. This was writing to an assumed large result array (same size as number of FFT bins) despite the fact that only a small number of MFCCs (typically less than 50) are required, therefore either wasting memory or writing to memory it shouldn't do!

/* 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] = freq_min; // === 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];
        else
            inc = height_norm[n] / (fft_peak[n] - fft_peak[n - 1]);
        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;
}