MATLAB: Audio Procesing

audio

Im new to Matlab. I need to split the time dimensions of an audio track into frames of 10mS and for every 10mS frame have to compute the FFT to generate the spectrograph. I need help on this.

Best Answer

Hi Karthik, Why can't you just use spectrogram()? You can specify the window length (the number of samples corresponding to 10 msec) as an input.

If you cannot use spectrogram(), you can use reshape() as one option.

Suppose you have an audio signal sampled at 20 kHz.

Then 200 samples is 10 msec.

x = randn(2e4,1);
x = reshape(x,200,100);

You can then apply the Fourier transform to the columns of x.

Better than the above option is buffer(), which allows you to construct overlapping segments.

x = 1:16;
x = buffer(x,4,2)

Again, spectrogram provides a NOVERLAP input argument that handles this easily.

Related Solutions

MATLAB: How to extract samples from audio and hamming window

x is just a double precision vector that should have 48000 samples. These elements are just indexed from 1 to 48000. So you can just do

y = x(1:160);

20 msec of data with a sampling rate of 16 kHz is 320 samples. So you just have to create a hamming window of length 320 and multiply that element-by-element by a signal segment of the equal length.

y = x(1:320).*hamming(320);

Since both 160 and 320 divide 48000, you can simply reshape your data into matrix with 160 or 320 rows

y = reshape(x,[320 150]);

Then you can multiply each column by a hamming window

y = y.*repmat(hamming(320),1,150);

MATLAB: Plot spectrogram from time by frequency matrix

Try this,

[s, f, t] = spectrogram(x, w ,noverlap, nfft, Fs);
% x is the signal; %w is the window; 
% noverlap is the windowing overlap; nfft is the size of fft;
% and Fs is the samplong rate. 
figure()
surf(t, f, 20*log10(abs(s)));

Best Answer

Related Solutions

MATLAB: How to extract samples from audio and hamming window

MATLAB: Plot spectrogram from time by frequency matrix

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