diff extra codes/stpt2.m @ 3:1c0f36c348d4

extra code for matlab

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/extra codes/stpt2.m	Sat Apr 20 13:03:01 2013 +0100
@@ -0,0 +1,53 @@
+function y=stpt2(x,w,N,H,t) 
+%Analysis/synthesis of a sound using the peaks 
+%of the short-time Fourier transform 
+%x: input sound, w: analysis window (odd size), N: FFT size, H: hop 
+%size, t: threshold in negative dB, y: output sound 
+  
+%Internal variables 
+M=length(w); 
+N2=N/2+1; 
+soundlength=length(x); 
+hM=(M-1)/2; 
+  
+%Pointers 
+pin=1+hM; 
+pend=soundlength-hM; 
+  
+%Initialize buffers 
+fftbuffer=zeros(N,1); 
+yw=zeros(M,1); 
+y=zeros(soundlength,1); 
+  
+%Analysis/Synthesis windows 
+sw=hanning(M); 
+sw=sw./sum(sw); 
+w=w./sum(w); 
+  
+while pin<pend 
+    %Analysis 
+    xw=x(pin-hM:pin+hM).*w(1:M); %Frame selector 
+    fftbuffer=zeros(N,1);        %Zero-phase windowing 
+    fftbuffer(1:(M+1)/2)=xw((M+1)/2:M); 
+    fftbuffer(N-(M-1)/2+1:N)=xw(1:(M-1)/2); 
+     
+    X=fft(fftbuffer);   %FFT performance 
+    mX=20*log10(abs(X(1:N2))); %Compute the FFT Magnitude (dB) 
+    pX=angle(X(1:N2));  %Compute the FFT phase 
+     
+    ploc=1+find((mX(2:N2-1)>t).*(mX(2:N2-1)>mX(3:N2)).*(mX(2:N2-1)>mX(1:N2-2)));      %Peak finder above threshold (t)    
+    pmag=mX(ploc);     %Peak magnitude recovery 
+    pphase=pX(ploc);   %Peak phase recovery 
+ 
+    %Synthesis 
+    Y=zeros(N,1);    %Memory reserve 
+    Y(ploc)=10.^(pmag/2).*exp(1i.*pphase); %Spectrum reconstruction from peak info 
+    Y(N+2-ploc)=10.^(pmag/20).*exp(-1i.*pphase); %Spectrum reconstruction negative freq. 
+    fftbuffer=real(ifft(Y));     %Compute inverse FFT 
+    yw((M+1)/2:M)=fftbuffer(1:(M+1)/2); %Zero-phase windowing undo 
+    yw(1:(M-1)/2)=fftbuffer(N-(M-1)/2+1:N); 
+    y(pin-hM:pin+hM)=y(pin-hM:pin+hM)+H*N*sw.*yw(1:M); %overlap-add 
+    pin=pin+H;                   %Pointer advance 
+end 
+     
+ 
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