view Source/initMFCCVariables.m @ 1:e86e9c111b29

Updates stuff that potentially fixes the memory leak and also makes it work on Windows and Linux (Need to test). Still have to fix fftw include for linux in Jucer.

function [mfccFilterWeights mfccDCTMatrix] = initMFCCVariables(sampleRate, FFTsize)

Fs   = sampleRate;
Nfft = FFTsize;
    
%Filter bank parameters
lowestFrequency = 133.3333;
linearFilters = 13;
linearSpacing = 66.66666666;
logFilters = 27;
logSpacing = 1.0711703;
cepstralCoefficients = 13;

% Keep this around for later....
totalFilters = linearFilters + logFilters;

% Now figure the band edges.  Interesting frequencies are spaced
% by linearSpacing for a while, then go logarithmic.  First figure0
% all the interesting frequencies.  Lower, center, and upper band
% edges are all consecutive interesting frequencies. 
freqs = lowestFrequency + (0:linearFilters-1)*linearSpacing;
freqs(linearFilters+1:totalFilters+2) = freqs(linearFilters) * logSpacing.^(1:logFilters+2);
lower  = freqs(1:totalFilters);
center = freqs(2:totalFilters+1);
upper  = freqs(3:totalFilters+2);

% each filter has unit weight, assuming a triangular weighting function
mfccFilterWeights = zeros(totalFilters,Nfft/2);
triangleHeight = 2./(upper-lower);
fftFreqs = (0:Nfft/2-1)/(Nfft)*Fs;
for chan=1:totalFilters
	mfccFilterWeights(chan,:) = (fftFreqs > lower(chan) & fftFreqs <= center(chan)).* triangleHeight(chan).*(fftFreqs-lower(chan))/(center(chan)-lower(chan)) + ...
                                (fftFreqs > center(chan) & fftFreqs < upper(chan)) .* triangleHeight(chan).*(upper(chan)-fftFreqs)/(upper(chan)-center(chan));
end

% Figure out Discrete Cosine Transform.  We want a matrix
% dct(i,j) which is totalFilters x cepstralCoefficients in size.
% The i,j component is given by cos( i * (j+0.5)/totalFilters pi )
% where we have assumed that i and j start at 0.
mfccDCTMatrix      = 1/sqrt(totalFilters/2)*cos((0:(cepstralCoefficients-1))' * (2*(0:(totalFilters-1))+1) * pi/2/totalFilters);
mfccDCTMatrix(1,:) = mfccDCTMatrix(1,:) * sqrt(2)/2;