How to test for audio tag support in your browser

I am writing a small application at the moment that needs audio tag support for Ogg in Firefox 3.1.

The following is the snippet of code I'm using to test this. (I am using the jQuery library).

audio_elements = $('audio');
if('volume' in audio_elements[0] ) {
// processing here
}

This assumes that there is only one audio element on the page (in my case I dynamically insert one). If the volume property exists, I assume that the element can be used to playback Ogg Vorbis files.

There may also need to be a check that the browser actually has the codec installed. (Add a comment if this is the case, and I'll update this post when I work out how).

Update (19 Nov 2008): A better way is to add a check for the Mozilla browser into the test. At the moment, Safari has the audio tag, but only supports media types that work in Quicktime.

if('volume' in audio_elements[0] && $.browser.mozilla)

A new function has been added to the HTML5 draft spec - canPlayType() - that gets around these problems.