Matlab error: Index exceeds matrix dimensions

Question

I\'m trying to perform STFT on an audio file. I need to get the fft of each window.

I used the follwing code.

[wave,fs] = wavread(\'40.wav\'); 
w_len         


        

Answer 1

As the error message says, you are trying to access a position in wave tat does not exist.

See this example:

a    = rand(7,1);
step = 4;

1:step:7
ans =
     1     5

when v = 5, you will try to access position v:v+step, i.e. 5 to 9, but a is only defined up to 7 elements.

In your case, wave is defined up to length(wave), but on the last iteration you will go out of bounds.

To avoid it, on approach would be to sample the end sequences and subtract the length of the sequence:

pos = (1+w_length:w_length:length(wave))-w_length
for v = pos
% do stuff
end

However, you will be left with some unprocessed part which you will have to do outside of the loop as last iteration.