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1 function [pitch,salience]=CorrelogramPitch(correlogram, width, sr, low, high);
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2 % pitch=CorrelogramPitch(correlogram, width [, sr, lowPitch, highPitch])
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3 % computes the pitch of a correlogram sequence by finding the time lag
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4 % with the largest correlation energy.
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5 %
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6 % (c) 1998 Interval Research Corporation
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7
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8 if nargin < 3; sr=22254.54; end;
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9 if nargin < 4; low=0; end;
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10 if nargin < 5; high=inf; end;
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11
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12 dropLow = floor(sr/high);
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13 if low > 0
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14 dropHigh = min(width,ceil(sr/low));
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15 else
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16 dropHigh = width;
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17 end
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18
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19 [pixels frames] = size(correlogram);
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20 channels = pixels/width;
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21 if channels < 1 | floor(channels) ~= channels
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22 error('Correlogram Size Error');
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23 end
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24
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25 pitch = zeros(1,frames);
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26 salience = zeros(1,frames);
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27 for j=1:frames
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28 % Get one frame from the correlogram, reshape it, and compute
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29 % the sum (as a function of time lag) across all channels.
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30 if channels == 1
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31 summary=reshape(correlogram(:,j),channels,width);
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32 else
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33 summary=sum(reshape(correlogram(:,j),channels,width));
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34 end
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35 zeroLag = summary(1);
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36 % Now we need to find the first pitch past the peak at zero
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37 % lag. The following lines smooth the summary pitch a bit, then
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38 % look for the first point where the summary goes back up.
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39 % Everything up to this point is zeroed out.
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40 windowLength=16;
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41 sumfilt=filter(ones(1,windowLength),[1],summary);
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42 sumdif=sumfilt(2:width)-sumfilt(1:width-1);
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43 sumdif(1:windowLength) = zeros(1,windowLength);
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44 valleys=find(sumdif>0);
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45 summary(1:valleys(1)) = zeros(1,valleys(1));
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46 summary(1:dropLow) = zeros(1,dropLow);
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47 summary(dropHigh:width) = zeros(1,width-dropHigh+1);
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48 plot(summary);
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49 drawnow;
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50 % Now find the location of the biggest peak and call this the pitch
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51 [m p] = max(summary);
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52 pitch(j) = sr/(p-1);
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53 salience(j) = m/zeroLag;
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54 end
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