Create sound file and download

Hi all,

I am creating a sound mixer in AS3 and I want the user to be able to download the final mix.
The mixer has 7 different sounds that loads from the library and the user changes the 7 volumes with the use of volume bars.

How can I create one sound file (mp3?) out of the final mixed sounds and save it to my server in order to download it?

Thanks
k.//