comparison toolboxes/MIRtoolbox1.3.2/AuditoryToolbox/CorrelogramFrame.m @ 0:e9a9cd732c1e tip

first hg version after svn

+% pic = CorrelogramFrame(data, picWidth, start, winLen)
+% Compute one frame of a correlogram.  The input data is a
+% two-dimensional array of cochlear data, each row representing
+% firing probabilities from one cochlear channel.  The output
+% picture is a two dimensional array of width "picWidth".
+%
+% The correlogram is computed with autocorrelation using 
+% data from the input array.  For each channel, the data from
+% is extracted starting at column "start" and extending for 
+% "winLength" time steps.  
+
+% (c) 1998 Interval Research Corporation
+
+function pic = CorrelogramFrame(data, picWidth, start, winLen)
+
+if nargin < 2
+	disp('Syntax: pic=CorrelogramFrame(data, picWidth[, start, len])');
+	return
+end
+
+if nargin < 3
+	start = 1;
+end
+
+if nargin < 4
+	[channels, winLen] = size(data);
+end
+	
+[channels, dataLen] = size(data);
+start = max(1, start);
+last = min(dataLen, start+winLen-1);
+
+pic = zeros(channels, picWidth);
+fftSize = 2^(nextpow2(max(picWidth, winLen))+1);
+% disp(['CorrelogramFrame fftSize is ' int2str(fftSize)]);
+
+a = .54;
+b = -.46;
+wr = sqrt(64/256);
+phi = pi/winLen;
+ws = 2*wr/sqrt(4*a*a+2*b*b)*(a + b*cos(2*pi*(0:winLen-1)/winLen + phi));
+
+for i=1:channels
+	f = zeros(1, fftSize);
+%	d = zeros(1, winLen);
+%	d(1:(last-start+1)) = data(i,start:last) .* ws(1:(last-start+1));
+%	f(1:(winLen/2)) = d(winLen/2+1:winLen);
+%	f(fftSize-(winLen/2)+1:fftSize) = d(1:min(length(d),winLen/2));
+	f(1:(last-start+1)) = data(i,start:last) .* ws(1:(last-start+1));
+	f = fft(f);
+	f = ifft(f.*conj(f));
+	pic(i,:) = real(f(1:picWidth));
+	if pic(i,1) > pic(i,2) & pic(i,1) > pic(i,3)
+		pic(i,:) = pic(i,:)/sqrt(pic(i,1));
+	else
+		pic(i,:) = zeros(1,picWidth);
+	end
+end