Dawn@4: function C = SpectralCentroid( signal, windowLength, step, fs)
Dawn@4: 
Dawn@4: % function C = SpectralCentroid(signal,windowLength, step, fs)
Dawn@4: % 
Dawn@4: % This function computes the spectral centroid feature of an audio signal
Dawn@4: % ARGUMENTS:
Dawn@4: %  - signal: the audio samples
Dawn@4: %  - windowLength: the length of the window analysis (in number of samples)
Dawn@4: %  - step: the step of the window analysis (in number of samples)
Dawn@4: %  - fs: the sampling frequency
Dawn@4: % 
Dawn@4: % RETURNS:
Dawn@4: %  - C: the sequence of the spectral centroid feature
Dawn@4: %
Dawn@4: 
Dawn@4: signal = signal / max(abs(signal));
Dawn@4: curPos = 1;
Dawn@4: L = length(signal);
Dawn@4: numOfFrames = floor((L-windowLength)/step) + 1;
Dawn@4: H = hamming(windowLength);
Dawn@4: m = ((fs/(2*windowLength))*[1:windowLength])';
Dawn@4: C = zeros(numOfFrames,1);
Dawn@4: for (i=1:numOfFrames)
Dawn@4:     window = H.*(signal(curPos:curPos+windowLength-1))';    
Dawn@4:     FFT = (abs(fft(window,2*windowLength)));
Dawn@4:     FFT = FFT(1:windowLength);  
Dawn@4:     FFT = FFT / max(FFT);
Dawn@4:     C(i) = sum(m.*FFT)/sum(FFT);
Dawn@4:     if (sum(window.^2)<0.010)
Dawn@4:         C(i) = 0.0;
Dawn@4:     end
Dawn@4:     curPos = curPos + step;
Dawn@4: end
Dawn@4: C = C / (fs/2);