wolffd@0: function [pitch,salience]=CorrelogramPitch(correlogram, width, sr, low, high);
wolffd@0: % pitch=CorrelogramPitch(correlogram, width [, sr, lowPitch, highPitch]) 
wolffd@0: % computes the pitch of a correlogram sequence by finding the time lag
wolffd@0: % with the largest correlation energy. 
wolffd@0: %  
wolffd@0: % (c) 1998 Interval Research Corporation
wolffd@0: 
wolffd@0: if nargin < 3; sr=22254.54; end;
wolffd@0: if nargin < 4; low=0; end;
wolffd@0: if nargin < 5; high=inf; end;
wolffd@0: 
wolffd@0: dropLow = floor(sr/high);
wolffd@0: if low > 0
wolffd@0: 	dropHigh = min(width,ceil(sr/low));
wolffd@0: else
wolffd@0: 	dropHigh = width;
wolffd@0: end
wolffd@0: 
wolffd@0: [pixels frames] = size(correlogram);
wolffd@0: channels = pixels/width;
wolffd@0: if channels < 1 | floor(channels) ~= channels
wolffd@0: 	error('Correlogram Size Error');
wolffd@0: end
wolffd@0: 
wolffd@0: pitch = zeros(1,frames);
wolffd@0: salience = zeros(1,frames);
wolffd@0: for j=1:frames
wolffd@0: 	% Get one frame from the correlogram, reshape it, and compute
wolffd@0: 	% the sum (as a function of time lag) across all channels.
wolffd@0: 	if channels == 1
wolffd@0: 		summary=reshape(correlogram(:,j),channels,width);
wolffd@0: 	else
wolffd@0: 		summary=sum(reshape(correlogram(:,j),channels,width));
wolffd@0: 	end
wolffd@0: 	zeroLag = summary(1);
wolffd@0: 	% Now we need to find the first pitch past the peak at zero
wolffd@0: 	% lag.  The following lines smooth the summary pitch a bit, then
wolffd@0: 	% look for the first point where the summary goes back up.  
wolffd@0: 	% Everything up to this point is zeroed out.
wolffd@0: 	windowLength=16;
wolffd@0: 	sumfilt=filter(ones(1,windowLength),[1],summary);
wolffd@0: 	sumdif=sumfilt(2:width)-sumfilt(1:width-1);
wolffd@0: 	sumdif(1:windowLength) = zeros(1,windowLength);
wolffd@0: 	valleys=find(sumdif>0);
wolffd@0: 	summary(1:valleys(1)) = zeros(1,valleys(1));
wolffd@0: 	summary(1:dropLow) = zeros(1,dropLow);
wolffd@0: 	summary(dropHigh:width) = zeros(1,width-dropHigh+1);
wolffd@0: 	plot(summary);
wolffd@0: 	drawnow;
wolffd@0: 	% Now find the location of the biggest peak and call this the pitch
wolffd@0: 	[m p] = max(summary);
wolffd@0: 	pitch(j) = sr/(p-1);
wolffd@0: 	salience(j) = m/zeroLag;
wolffd@0: end