Comparing two audio signals (guitar chords recognizer)

2 visualizzazioni (ultimi 30 giorni)
I want to compare two audio signals and check their similarities however it seems i cannot compare them.. this is supposedly my process.
  • > input audio signal (1 strum on guitar)
  • > read the data and convert to frequency domain
  • > get the raw audio file > read > convert to frequency domain
  • > check their similarities
function guitartrial
recObj = audiorecorder;
disp('Start speaking.')
recordblocking(recObj, 4);
disp('End of Recording.');
myRecording = getaudiodata(recObj);
wavwrite(myRecording,'chordread.wav');
[x, Fs] = wavread('chordread.wav');
[x1, Fs1] = wavread('chordA.wav');
Y = fft(abs(x));
Z = fft(abs(x1));
subplot(3,1,1), plot (Y);
subplot(3,1,2), plot (Z);
[C1, lag1] = xcorr(Y,Z);
subplot(3,1,3), plot(lag1/Fs,C1);
ylabel('Amplitude'); grid on
title('Cross-correlation between Template 1 and Signal')
end
whenever i run the program i get this..
It seems wrong to me.. Im new in matlab programming so If someone can help me I would be very grateful. Is my process wrong? how can I get the percentage of similarity? is there another method that is best suited for my application? thank you very much

Risposte (2)

Suneesh
Suneesh il 4 Mar 2014
If your confusion is regarding the first and second plots then that is because yo uare plotting the complex values returned by FFT. Try:
subplot(3,1,1), plot(abs(Y));
subplot(3,1,2), plot(abs(Z));
Also, in
Y = fft(abs(x));
The abs(x) is not required since audio signals are real signals.
  2 Commenti
Phantom.i7
Phantom.i7 il 5 Mar 2014
[C1, lag1] = xcorr(Y,Z);
is that correct or should i make it
[C1, lag1] = xcorr(abs(Y),abs(Z));
Suneesh
Suneesh il 11 Mar 2014
If you need to look for similarities in the magnitude of the two FFT results then
[C1, lag1] = xcorr(abs(Y),abs(Z));
is correct. This does not consider the phases which is lost by the ABS operation. Also, if the samples are of different lengths then make sure both are normalized.

Accedi per commentare.


KIRAN SL
KIRAN SL il 16 Giu 2017
what is the correlation plot means?

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