[LAU] A webserver with on-the-fly format conversion?

Hi, I'm trying to make a large collection of audio files available through a HTTP server. The collection consists of mostly Ogg Vorbis and MP3, and a couple of files in other formats. Unfortunately, the client that's supposed to play the files does not support any of these formats except for MP3. Is there any way to set up a webserver that will automatically convert the various audio file formats to MP3? I'm not looking for a web radio, instead each file should be accessible individually and look just like a regular MP3 to the client. Some kind of streaming would be nice though (so the client can start playback before the whole file is converted/transferred). Any suggestions how this could be done? Thanks, Dominic