Dawn@4: function [ymax,inx] = func_pickpeaks(y, winlen)
Dawn@4: % [ymax,inx] = func_pickpeaks(y, winlen)
Dawn@4: % Input:  y - from wavread
Dawn@4: %         winlen - size of window to use
Dawn@4: % Output: ymax - peak values
Dawn@4: %         inx - peak positions
Dawn@4: % Notes:  
Dawn@4: %
Dawn@4: % Author: Yen-Liang Shue and Markus Iseli, Speech Processing and Auditory Perception Laboratory, UCLA
Dawn@4: % Copyright UCLA SPAPL 2009
Dawn@4: 
Dawn@4: % first, get all maxima
Dawn@4: ymin = min(y);
Dawn@4: y = y - ymin;
Dawn@4: dy = [y(1); transpose(diff(y))];   % diff() gives a shift by 1: insert one sample
Dawn@4: inx1 = diff(dy < 0);    % is +1 for maxima, -1 for minima
Dawn@4: inx1(1) = 0; % do not accept maxima at begining
Dawn@4: inx1(end) = 0; % do not accept maxima at end
Dawn@4: inx = inx1 > 0;         % choose maxima only
Dawn@4: ymax= y(inx);
Dawn@4: inx = find(inx);
Dawn@4: %plot(y);
Dawn@4: %hold on;
Dawn@4: %plot(inx,ymax,'or');
Dawn@4: %hold off;
Dawn@4: 
Dawn@4: nofmax = length(ymax);
Dawn@4: if nofmax==1
Dawn@4:    return;
Dawn@4: end
Dawn@4: % now filter maxima with window of length winlen
Dawn@4: for cnt = 1 : nofmax
Dawn@4:    arr = inx(1:cnt);
Dawn@4:    cmp = inx(cnt)-winlen;
Dawn@4:    arr2 = arr>cmp;
Dawn@4:    %ymax(arr2)
Dawn@4:    [m, mi] = max(ymax(arr2));
Dawn@4:    ymax(arr2)=-60000;
Dawn@4:    ymax(mi+length(arr2)-sum(arr2))=m;
Dawn@4:    %ymax(arr2)
Dawn@4: end
Dawn@4: temp = find(ymax>0);
Dawn@4: inx  = inx(temp);
Dawn@4: ymax = ymax(temp);
Dawn@4: %plot(y);
Dawn@4: %hold on;
Dawn@4: %plot(inx,ymax,'or');
Dawn@4: %hold off;
Dawn@4: ymax = ymax + ymin;