Possible to process a user submitted mp3 upon upload?(make file size smaller?)

[Webjedikungfu]

Hello all,

I have a site where users can upload mp3s. I'd like to process them upon upload to make their file sizes smaller, to house more mp3s.

Is there anything I can look into that will help me? (PHP solution Prefered).

Or is my only solution regulating bitrate and such upon upload?

Thanks