diff extractInstrumental.m @ 10:6840f77b83aa

commit

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/extractInstrumental.m	Sun Apr 21 10:55:35 2013 +0200
@@ -0,0 +1,71 @@
+function [y] = extractInstrumental(x,w,N,melodyFile)
+%e.g. y = extractInstrumental(x,hamming(2025),4096,'baby.txt');
+
+
+% Initialize
+M = length(w);   % analysis window size
+Ns = 1024;                               % FFT size for synthesis
+H = 256;                                 % hop size for analysis and synthesis
+soundlength = length(x);                 % length of input sound array
+hNs = Ns/2;                              % half synthesis window size
+hM = (M-1)/2;                            % half analysis window size
+pin = max(hNs+1,1+hM);   % initialize sound pointer to middle of analysis window
+pend = soundlength-max(hM,hNs);          % last sample to start a frame
+fftbuffer = zeros(N,1);                  % initialize buffer for FFT
+y = zeros(soundlength+Ns/2,1);           % output sine component
+w = w/sum(w);                            % normalize analysis window
+sw = zeros(Ns,1);
+ow = triang(2*H-1);                      % overlapping window
+ovidx = Ns/2+1-H+1:Ns/2+H;               % overlap indexes
+sw(ovidx) = ow(1:2*H-1);
+bh = blackmanharris(Ns);                 % synthesis window
+bh = bh ./ sum(bh);                      % normalize synthesis window
+sw(ovidx) = sw(ovidx) ./ bh(ovidx);
+
+
+% Load melody file
+melody = loadMelodyFile(melodyFile);
+melody = [melody zeros(2,1000)];
+i=0;
+
+% For each segment
+while pin<pend
+    
+    i=i+1;
+    
+    % Find predominant pitch for segment
+    melody_seg = melody(:,ceil((pin-hM)/128):round((pin+hM)/128));
+    ind = find(melody_seg(2,:)>150);       % Find pitches larger than 150Hz
+    medpitch = median(melody_seg(2,ind));  % Median pitch in segment
+    
+
+    % Compute FFT for segment
+    xw = x(pin-hM:pin+hM).*w(1:M);         % window the input sound
+    fftbuffer(1:(M+1)/2) = xw((M+1)/2:M);  % zero-phase window in fftbuffer
+    fftbuffer(N-(M-1)/2+1:N) = xw(1:(M-1)/2);
+    X = fft(fftbuffer);                    % compute the FFT
+    
+    
+    % Keep only the melody for each segment
+    if(~isempty(ind)) % if there is melody, remove the melodic bins
+   
+        melodyBinsStart = (medpitch/10.6568) * [1:40];
+        melodyBinsEnd =  N + 2 - ((medpitch/10.6568) * [1:40]);
+        melodyBins = round([melodyBinsStart melodyBinsEnd]);
+        melodyBins = [melodyBins (melodyBins-1) (melodyBins+1) (melodyBins-2) (melodyBins+2) (melodyBins-3) (melodyBins+3) (melodyBins-4) (melodyBins+4) (melodyBins-5) (melodyBins+5) (melodyBins-6) (melodyBins+6)];
+        
+        X(melodyBins) = 0;
+
+    end;
+    
+    
+    ri= pin-hNs;                           % input sound pointer for residual analysis
+    yw = ifft(X);    
+    y(ri:ri+Ns-1) = y(ri:ri+Ns-1)+yw(1:Ns).*sw;
+    pin = pin+H;     
+    
+end
+
+y = (max(x)/max(y))*y; % scale y to original amplitude
+
+%wavwrite(y,44100,'test.wav');
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