Warning: Data clipped during write to file-Guitar tuner code

Trying to create a wave file Matlab returns this error, I normalized the amplitude but the problem remained. Moreover the wavwrite function doesn't manage to create and save the file. For other lower main frequencies such as 110 (guitar A note) the problem doesn't show.

[Image Analyst]

Please attach the m-file so we can try it. I can't copy and paste an image into MATLAB's text editor and run it.

[Star Strider]

With a few changes:

f = 330;
Fc = 44100;
t = 0:(1/Fc):1.5;
o = zeros(10,length(t));
a(1) = 5;
for k1 = 1:10
    a(k1) = a(1)*exp(1-k1);
    o(k1,:) = a(k1) * sin(2*pi*k1*f.*t);
end
figure(1)
plot(t,o)
s = sum(o);
s = s./max(abs(s));
figure(2)
plot(t,s)
figure(3)
plot(1:10,a)
gt = audioplayer(s,Fc);
play(gt)
audiowrite(['C:\Users\ ... \MATLAB\ ... \' 'e440.wav'], s, Fc )

I don’t have wavwrite ( R2014a has audoiread and audiowrite ), but with those functions, I didn’t have any problems with 330 or 440 Hz. That’s why this is a comment and not an answer.

[Star Strider]

We resolved the clipping problem in How come I keep getting "Data Clipped" in my Command Window?

[cace]

Thanks for answers, I attached the m file created with your suggestion about scaling. However the code still can't write wav file, maybe the only solution is using audioplayer fun. Thanks everybody.

[Star Strider]

The audioplayer function seems to be new as of R2014a. The information on the various Recording and Playback functions in R2014a are available in the online documentation. (I no longer have access to the documentation on wavwrite and wavread.)

[cace]

You are right, audioplayer function exists and play too on Matlab 2011 but I actually cannot find audiowrite and audioread fun.

Answer 1

[Walter Roberson]

Your a(1) is 5, so your outputs could be as large as 5. wavwrite() requires that the data be in the range -1 to +1 if you are using floating point numbers.

[Star Strider]

He creates s from o, then scales it, so that max(s) = 1.

[Walter Roberson]

Ah, I missed that. In that case the problem is that the actual permitted range is -1 <= x < 1 so +1 exactly is out of range. Scaling by

( max(abs(s)) * (1+eps) )

will ensure that the range does not exceed -1 < x < 1 but it does exclude -1 exactly. You can get fancier and compare max(-s) to max(s) to determine which side of 0 has the greater range and using the (1+eps) factor only when it is the positive side.

[Star Strider]

I might not have noticed it either, except that I typed the code in so I could run it, and I had to read every line. (I also made some changes, since one of my pet peeves are ‘i’ and ‘j’ as anything other than imaginary operators.) I have audioplayer so I can’t experiment with wavwrite any more, and it’s even gone from the online documentation. The new audiowrite seems to be much more tolerant of bad scaling than its predecessors.

[cace]

Thanks for answers, I attached the m file created with your suggestion about scaling. However the code still can't write wav file, maybe the only solution is using audioplayer fun. Thanks everybody.