What audio formats are necessary for cross-browser support?

Alright, I'm using jPlayer in a website, which is a cross-platform/cross-browser jQuery solution for audio and video playback on a website. On my website, I will have users upload files either in MP3 or OGG format. I wonder though... in order to truly stay 100% stable on any browser or platform, wouldn't I need to support a corresponding OGG for every MP3 uploaded (and vice-versa)? I know jPlayer uses HTML5 when it can and will fall back to Flash when necessary, but I didn't know if you need to have that file in both formats to have it play everywhere.

If I need both file formats then I suppose I'd have to conv开发者_开发知识库ert the file to the other format using a server-side conversion. If I need just one format... then wouldn't that be just dandy! So my question is, do I need to convert? Or not?

For xbrowser support, a format must be supplied that works in both HTML5 and Flash. Optional additional formats may be supplied to increase xbrowser HTML5 support.

I would say it is neccesary to provide at least a mp3 and ogg format to ensure that everything runs perfectly on each platform. There are many tools to convert a mp3 file to ogg, e.g. ffmpeg-php