psolaf.m

matlab code for discrete time signal processing overlay and a

function out=psolaF(in,m,alpha,beta,gamma)
%     . . .
%     gamma newFormantFreq/oldFormantFreq
%     . . .
%     the internal loop as
P = diff(m);   %compute pitch periods
if m(1)<=P(1), %remove first pitch mark
   m=m(2:length(m)); 
   P=P(2:length(P)); 
end

if m(length(m))+P(length(P))>length(in) %remove last pitch mark
    m=m(1:length(m)-1);
    else
    P=[P P(length(P))]; 
end


Lout=ceil(length(in)*alpha);   
out=zeros(1,Lout); %output signal

tk = P(1)+1;                  %output pitch mark
while round(tk)<Lout
 [minimum i]=min(abs(alpha*m-tk) );    % find analysis segment
 pit=P(i);
 pitStr=floor(pit/gamma);	
 gr=in(m(i)-pit:m(i)+pit).*hanning(2*pit+1);
 gr=interp1(-pit:1:pit,gr,-pitStr*gamma:gamma:pit);% stretch segm.
 iniGr=round(tk)-pitStr;endGr=round(tk)+pitStr;
 if endGr>Lout, break; end
 out(iniGr:endGr)=out(iniGr:endGr)+gr; % overlap new segment
 tk=tk+pit/beta;
end % end of while