sample rate (Fs) in audiowrite

Version: MATLAB R2018

In the document of audiowrite, it is written that the sample rate is any positive scalar between 44100 and 4800 Hz. However, the function accepts sample rates below 44100 Hz, e.g., 39063. More importantly, the document does not mention that the input sample rate must be integer, but the function throws an exception if the sample rate is not an integer.

[Star Strider]

That is not the way I read the documentation for Fs (link).

I would do the ‘Fs’ calculation before the audiowrite call:

Fs = 1E+7/256;

then pass that value of ‘Fs’ to the function.

Also, the limits you cite apply only to .m4a and .mp4 files, and Windows. From the documentation:

‘When writing to .m4a or .mp4 files on Windows platforms, audiowrite supports only samples rates of 44100 and 48000.’

[Amir Tadayon]

Yes, you are right about the doc on Fs. But the provided solution, calculating fs before calling audiowrite, does not solve the problem. Here it is:

Answer 1

[Guillaume]

Yes, the documentation does not match the actual code of audiowrite, at least in R2018b and R2019a. The documentation states that "Values of Fs are truncated to integer boundaries" but audiowrite actually doesn't do any truncating and simply errors if Fs is not integer.

I'll report the bug. Most likely, the problem is with the documentation and you can only pass integer values as Fs (which would make sense since audio formats store it as integer).