Compression

[Jez]

Hi
I had a quick look around for the answer i need before i posted this with no luck.
So here goes.

I am going to be starting a website that has an audio upload/ stream playback function.

I was wondering if anyone was aware of how online compression is done for audio.
For example www.soundcloud.com or all pod cast web sites' etc.

Im not interested in bit rates, more of the software.
But if i upload an mp3, how is it automatically compressed?? and the compressed file saved or saved along side the original for streaming?

Is there software on the server eg (flash compressor) that compressors the files whilst you upload them? or is it done with in-house coding?


can anyone help?
Thankyou :)
J