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/*
* maxiMFCC.h
* mfccs
*
* Created by Chris on 08/03/2011.
* Copyright 2011 Goldsmiths Creative Computing. All rights reserved.
*
Based on Matthew Yee-King's MFCCMYK java class
*/
#pragma once
#pragma pack(16)
#include "maxiFFT.h"
#include <math.h>
#include <iostream>
#include <cstdlib>
#ifdef __APPLE_CC__
#include <Accelerate/Accelerate.h>
#endif
using namespace std;
// implements this formula:
// mel = 2595 log10(Hz/700 + 1)
inline double hzToMel(double hz){
return 2595.0 * (log10(hz/700.0 + 1.0));
}
// implements this formula
// Hz = 700 (10^(mel/2595) - 1)
inline double melToHz(double mel){
return 700.0 * (pow(10, mel/2595.0) - 1.0);
}
template <class T>
class maxiMFCCAnalyser {
public:
T *melBands;
maxiMFCCAnalyser():melFilters(NULL),dctMatrix(NULL), melBands(NULL){};
~maxiMFCCAnalyser() {
if (melFilters) {
delete[] melFilters;
delete[] melBands;
delete[] dctMatrix;
#ifdef __APPLE_CC__
delete doubleSpec;
#endif
}
}
void setup(unsigned int numBins, unsigned int numFilters, unsigned int numCoeffs, double minFreq, double maxFreq, unsigned int sampleRate)
{
this->numFilters = numFilters;
this->numCoeffs = numCoeffs;
this->minFreq = minFreq;
this->maxFreq = maxFreq;
this->sampleRate = sampleRate;
this->numBins = numBins;
melFilters = NULL;
melBands = (T*) malloc(sizeof(T) * numFilters);
#ifdef __APPLE_CC__
doubleSpec = (T*)malloc(sizeof(T) * numBins);
#endif
//create new matrix
dctMatrix = (T*)malloc(sizeof(T) * numCoeffs * numFilters);
calcMelFilterBank(sampleRate, numBins);
createDCTCoeffs();
}
void mfcc(float* powerSpectrum, T *mfccs) {
melFilterAndLogSquare(powerSpectrum);
dct(mfccs);
}
private:
unsigned int numFilters, numCoeffs;
double minFreq, maxFreq;
unsigned int sampleRate;
T *melFilters;
unsigned int numBins;
T *dctMatrix;
#ifdef __APPLE_CC__
T *doubleSpec;
#endif
#ifdef __APPLE_CC__
void dct(T *mfccs); //define later
#else
void dct(T *mfccs) {
for(int i=0; i < numCoeffs; i++) {
mfccs[i] = 0.0;
}
for(int i=0; i < numCoeffs; i++ ) {
for(int j=0; j < numFilters; j++) {
int idx = i + (j * numCoeffs);
mfccs[i] += (dctMatrix[idx] * melBands[j]);
}
}
for(int i=0; i < numCoeffs; i++) {
mfccs[i] /= numCoeffs;
}
}
#endif
void melFilterAndLogSquare(float* powerSpectrum);
void melFilterAndLogSq_Part2(float *powerSpectrum);
void calcMelFilterBank(double sampleRate, int numBins) {
double mel, dMel, maxMel, minMel, nyquist, binFreq, start, end, thisF, nextF, prevF;
int numValidBins;
// ignore bins over nyquist
numValidBins = numBins;
nyquist = sampleRate/2;
if (maxFreq > nyquist) {
maxFreq = nyquist;
}
maxMel = hzToMel(maxFreq);
minMel = hzToMel(minFreq);
dMel = (maxMel - minMel) / (numFilters + 2 - 1);
T *filtPos = (T*) malloc(sizeof(double) * (numFilters + 2));
// first generate an array of start and end freqs for each triangle
mel = minMel;
for (int i=0;i<numFilters + 2;i++) {
// start of the triangle
filtPos[i] = melToHz(mel);
// std::cout << "[" << i << "] MFCC: centre is at " <<filtPos[i]<<"hz "<<mel<<" mels" << endl;
mel += dMel;
}
// now generate the coefficients for the mag spectrum
melFilters = (T*) malloc(sizeof(T) * numFilters * numValidBins);
for (int filter = 1; filter < numFilters; filter++) {
for (int bin=0;bin<numValidBins;bin++) {
// frequency this bin represents
binFreq = (T) sampleRate / (T) numValidBins * (T) bin;
thisF = filtPos[filter];
nextF = filtPos[filter+1];
prevF = filtPos[filter-1];
int idx = filter + (bin * numFilters);
if (binFreq > nextF || binFreq < prevF) {
// outside this filter
melFilters[idx] = 0;
//cout << "MFCCMYK: filter at " <<thisF << " bin at " <<binFreq <<" coeff " <<melFilters[filter][bin] << endl;
}
else {
T height = 2.0 / (nextF - prevF);
if (binFreq < thisF) {
// up
start = prevF;
end = thisF;
melFilters[idx] = (binFreq - start) * (height / (thisF - start));
}
else {
// down
start = thisF;
end = nextF;
melFilters[idx] = height + ((binFreq - thisF) * (-height /(nextF - thisF)));
}
// cout << "MFCCMYK: filter at " <<thisF << " bin at " <<binFreq <<" coeff " <<melFilters[filter][bin] << endl;
//cout << "MFCCMYK: filter at " <<thisF << " bin at " <<binFreq <<" coeff " <<melFilters[idx] << endl;
}
}
}
}
void createDCTCoeffs() {
T k = 3.14159265358979323846/numFilters;
T w1 = 1.0/(sqrt(numFilters));
T w2 = sqrt(2.0/numFilters);
//generate dct matrix
for(int i = 0; i < numCoeffs; i++)
{
for(int j = 0; j < numFilters; j++)
{
int idx = i + (j * numCoeffs);
if(i == 0)
dctMatrix[idx]= w1 * cos(k * (i+1) * (j + 0.5));
else
dctMatrix[idx] = w2 * cos(k * (i+1) * (j + 0.5));
}
}
}
};
typedef maxiMFCCAnalyser<double> maxiMFCC;
//typedef maxiMFCCAnalyser<float> maxiFloatMFCC;
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