OS an HTML5 application in running in?

[Peter Bogdanoff]

I’m planning an HTML5 application that will use audio files. I will have already prepared for Macs  .mov, for Windows .avi. How would I determine which type to use in any particular browser?

The LCS dictionary says:

The platform returns "HTML5" when running in a web browser.
On HTML5 the systemVersion is empty.

Is there something else that would tell me which file type to use?

I will need to use callbacks, which AVI and MOV can handle.

Peter Bogdanoff
UCLA