private int numberWaveletTransforms = 2; // number of wavelet transform iterations, 3?
#endregion Fields
#region Constructors
/// <summary>
/// Create a Mfcc object
/// This method is not optimized in the sense that the Mel Filter Bands
/// and the DCT is created here (and not read in)
/// </summary>
/// <param name="winsize">window size</param>
/// <param name="srate">sample rate</param>
/// <param name="numberFilters">number of filters (MEL COEFFICIENTS). E.g. 36 (SPHINX-III uses 40)</param>
/// <param name="numberCoefficients">number of MFCC COEFFICIENTS. E.g. 20</param>
public MfccMirage(int winsize, int srate, int numberFilters, int numberCoefficients)
{
this.numberCoefficients = numberCoefficients;
double[] mel = new double[srate/2 - 19];
double[] freq = new double[srate/2 - 19];
int startFreq = 20;
// Mel Scale from StartFreq to SamplingRate/2, step every 1Hz
for (int f = startFreq; f <= srate/2; f++) {
mel[f-startFreq] = LinearToMel(f);
freq[f-startFreq] = f;
}
// Prepare filters
double[] freqs = new double[numberFilters + 2];
melScaleFreqsIndex = new int[numberFilters + 2];
for (int f = 0; f < freqs.Length; f++) {
double melIndex = 1.0 + ((mel[mel.Length - 1] - 1.0) /
(freqs.Length - 1.0) * f);
double min = Math.Abs(mel[0] - melIndex);
freqs[f] = freq[0];
for (int j = 1; j < mel.Length; j++) {
double cur = Math.Abs(mel[j] - melIndex);
if (cur < min) {
min = cur;
freqs[f] = freq[j];
}
}
melScaleFreqsIndex[f] = MathUtils.FreqToIndex(freqs[f], srate, winsize);
}
// triangle heights
melScaleTriangleHeights = new double[numberFilters];
for (int j = 0; j < melScaleTriangleHeights.Length; j++) {
melScaleTriangleHeights[j] = 2.0/(freqs[j+2] - freqs[j]);
}
double[] fftFreq = new double[winsize/2 + 1];
for (int j = 0; j < fftFreq.Length; j++) {
fftFreq[j] = ((srate/2)/(fftFreq.Length -1.0)) * j;
}
// Compute the MFCC filter Weights
filterWeights = new Matrix(numberFilters, winsize/2);
for (int j = 0; j < numberFilters; j++) {
for (int k = 0; k < fftFreq.Length; k++) {
if ((fftFreq[k] > freqs[j]) && (fftFreq[k] <= freqs[j+1])) {
filterWeights.MatrixData[j][k] = (float)(melScaleTriangleHeights[j] *
((fftFreq[k]-freqs[j])/(freqs[j+1]-freqs[j])));
}
if ((fftFreq[k] > freqs[j+1]) &&
(fftFreq[k] < freqs[j+2])) {
filterWeights.MatrixData[j][k] += (float)(melScaleTriangleHeights[j] *
((freqs[j+2]-fftFreq[k])/(freqs[j+2]-freqs[j+1])));
}
}
}
#if DEBUG
if (Mirage.Analyzer.DEBUG_INFO_VERBOSE) {
if (Mirage.Analyzer.DEBUG_OUTPUT_TEXT) filterWeights.WriteAscii("melfilters-mirage-orig.ascii");
//filterWeights.DrawMatrixGraph("melfilters-mirage-orig.png");
}
#endif
// Compute the DCT
// This whole section is copied from GetDCTMatrix() from CoMirva package
dct = new DctComirva(numberCoefficients, numberFilters).DCTMatrix;
#if DEBUG
if (Mirage.Analyzer.DEBUG_INFO_VERBOSE) {
if (Mirage.Analyzer.DEBUG_OUTPUT_TEXT) dct.WriteAscii("dct-mirage-orig.ascii");
//dct.DrawMatrixGraph("dct-mirage-orig.png");
}
#endif
}