Writing a wav file using Matlab

I have a question: I have created some audio files using Matlab, with a sampling frequency of 10000 Hz, and when I try to use the function wavwrite in order to generate the corresponding wav files, I have this warning:

"Data clipped during write to file..."

I know that this problem is generated by the amplitude of the signals, because it must be normalized to 1, and I have tried to use this line of code:

signal = signal/max(abs(signal));

but the problem isn't solved. Can anyone tell me how can I solve this problem? Thanks a lot.

Answer 1

[Wayne King]

If you are using

 wavwrite(Y,FS,WAVEFILE)

then the acceptable range for the data, Y, is -1.0 <= Y < +1.0

so I'm assuming that you have values in your output equal to 1, which is resulting in the clipping. One thing you can do is to use 32 bits to write the file. That has output format implications -- see the help for wavwrite

wavwrite(Y,FS,32,WAVEFILE)

or you can add a small deltaA to your scaling factor that would avoid you getting a 1.

   deltaA = 0.1;
   signal = signal./(max(abs(signal))+deltaA);

[Micaela]

I have tried both your solutions.

The first has this kind of problem: some files, when I try to reproduce them with a common player, are "empty";

The second doesn't solve my problem and the warning is again:

Warning: Data clipped during write to <file:t> > In wavwrite>PCM_Quantize at 285 In wavwrite>write_wavedat at 301 In wavwrite at 138 In readparameters at 24

[Micaela]

Ok, I have solved the problem with this line of code (supposing that I write the file with 24 bits) :

signal = signal./max(abs(signal(:)))*(1-(2^-(24-1)));

Thank you of all:)

[Shlomit]

This helped a lot, Thank you Micaela!