final final

chanvocoder.m

@@ -0,0 +1,57 @@
+function y = chanvocoder(carrier, modul, chan, numband, overlap)
+% y = chanvocoder(carrier, modul, chan, numband, overlap)
+% The Channel Vocoder modulates the carrier signal with the modulation signal
+% chan = number of channels         (e.g., 512)
+% numband = number of bands (<chan) (e.g., 32)
+% overlap = window overlap          (e.g., 1/4)
+
+if numband>chan
+	error('# bands must be < # channels')
+end
+
+[rc, cc]   = size(carrier);
+if cc>rc
+	carrier = carrier';
+end
+
+[rm, cm]   = size(modul);
+if cm>rm
+	modul = modul';
+end
+
+st         = min(rc,cc);                         % stereo or mono?
+if st~= min(rm,cm)
+	error('carrier and modulator must have same number of tracks');
+end
+
+len        = min(length(carrier),length(modul)); % find shortest length
+carrier    = carrier(1:len,1:st);                % shorten carrier if needed
+modul      = modul(1:len,1:st);                  % shorten modulator if needed
+L          = 2*chan;                             % window length/FFT length
+w          = hanning(L); 
+if st==2
+	w=[w w];
+end  % window/ stereo window
+
+bands      = 1:round(chan/numband):chan;         % indices for frequency bands     
+bands(end) = chan;
+y          = zeros(len,st);                      % output vector
+
+ii         = 0;
+while ii*L*overlap+L <= len
+    ind    = round([1+ii*L*overlap:ii*L*overlap+L]);
+    FFTmod = fft( modul(ind,:) .* w );    % window & take FFT of modulator
+    FFTcar = fft( carrier(ind,:) .* w );  % window & take FFT of carrier  
+    syn    = zeros(chan,st);              % place for synthesized output
+    for jj = 1:numband-1                  % for each frequency band
+        b        = [bands(jj):bands(jj+1)-1]; % current band
+        syn(b,:) = FFTcar(b,:)*diag(mean(abs(FFTmod(b,:))));
+    end                                   % take product of spectra
+    midval   = FFTmod(1+L/2,:).*FFTcar(1+L/2,:); % midpoint is special
+    synfull  = [syn; midval; flipud( conj( syn(2:end,:) ) );]; % + and - frequencies
+    timsig   = real( ifft(synfull) );     % invert back to time
+    y(ind,:) = y(ind,:) + timsig;         % add back into time waveform   
+    ii       = ii+1;
+end
+y = 0.8*y/max(max(abs(y)));               % normalize output
+

speech_processing.m

@@ -0,0 +1,28 @@
+%Speech Processing
+pkg load signal
+
+modfile = "modulator22.wav";
+carfile = "carrier22.wav";
+white = "white.wav";
+white_p = "white_periodic.wav";
+outfile = "vocodedsound.wav";
+[modul, sr1] = audioread(modfile);
+[carrier, sr2] = audioread(carfile);
+[carrier_w, sr2_w] = audioread(carfile);
+[carrier_wp, sr2_wp] = audioread(carfile);
+
+if sr1 ~= sr2
+  disp('Your sampling rates dont match');
+endif
+
+y = chanvocoder(carrier,modul, 512, 32, .2);
+audiowrite("vocodedsound.wav", y, sr1);
+y_w = chanvocoder(carrier_w,modul, 512, 32, .2);
+audiowrite("vocodedsound_w.wav", y, sr1);
+y_wp = chanvocoder(carrier_wp,modul, 512, 32, .2);
+audiowrite("vocodedsound_wp.wav", y, sr1);
+
+%spectogram
+frequencySpectrum(modul,sr1,1);
+frequencySpectrum(carrier,sr2,1);
+frequencySpectrum(y,sr1,1);