Is this even possible? grab metadata from mp3 from the beginning of an upload!

[Saimon Moore]

My boss has asked me for the following features:

 - Have uploads of mp3 tracks to our service be made asynchronous
 - Immediately allow editing of the track form
 - Grab the tracks metadata (i.e. from the file header) from the
beginning of the upload to prefill the form

My initial reaction was that it wasn't possible but I decided to ask
around to see if other had any other ideas. Would this be possible
perhaps via chunked transfer? Or perhaps some custom flash?

The reason why I'm asking here is that I recognize it could be made
possible with a custom nginx module I guess.

Regards,

Saimon