1 function S = sfft(s, window, shift)
   2 % 
   3 % short time FFT, S = sfft(s, window, shift)
   4 % 
   5 
   6 frameSize = length(window);
   7 sLength = length(s);
   8 %nFrame = ceil( (sLength-frameSize)/shift )+1;
   9 nFrame = ceil( (sLength-frameSize)/shift );
  10 
  11 if ( nFrame < 1 ), nFrame = 1; end % for the case sLength < frameSize
  12 % adjusting the length of s, padding zero
  13 adjustLength = shift*(nFrame-1) + frameSize; 
  14 s = [s; zeros(adjustLength-sLength,1)]; % column vector
  15 
  16 S=zeros(frameSize, nFrame); 
  17 
  18 begintime=1;
  19 endtime=frameSize;
  20 
  21 for i=1:nFrame,
  22  windowed_signal = s(begintime:endtime) .* window;
  23  S(:,i) = fft(windowed_signal); % rows = frequency bins, columns = number of frames
  24  begintime = begintime + shift;
  25  endtime = endtime + shift;
  26 end;