fft on samples of an audio file in matlab

Question

I'm trying to extract information from a sound file in order to use it in a video classification algorithm I'm working on.

My problem is that I don't know how to work exactly with audio files in Matlab.

Below is what I need to accomplish:

• open the audio file and get the sampling rate/frequency
• I need to work on a window of 2 seconds so I have to loop over the file and get each 2 seconds as a window and then do the ftt (Fast-Fourier-Transform) on each window.

After that it is my turn to use these values to do what I want

any help would be appreciated

Thanks.

Answer 1

Following code may only give you some idea. You may need to determine another fft size, a windowing function like hamming etc.

To read a wav file:

[data, Fs] = wavread('path.wav');

Splitting to 2 sec windows and getting fft:

frameFFT = [];
timeStep = Fs*2;
for i=1:timeStep:length(data)-timeStep
   frameFFT = [frameFFT; fft(data(i:i+timeStep-1),1024)];
end