OK so Silverlight 4 is adding [support for capturing from microphones (and webcams)](http://timheuer.com/blog/archive/2009/11/18/whats-new-in-silverlight-4-complete-guide-new-features.aspx#webcam), however for this facility to be useful (in my case at least) I'd need to upload this captured data to a server to save.

The AudioCaptureDevice will record PCM audio on the client, and as we all know PCM is not the most efficient encoding... the data would be too large to upload uncompressed.

Ideally, I could encode this PCM stream to AAC right on the client, then upload that compressed stream to the server.

Something like [this library](http://www.codeproject.com/KB/audio-video/Aumplib.aspx), may be useful. However it doesn't support AAC.

(I'm choosing AAC because (unlike MP3) it is royalty-free to encode, and is supported by popular PMP devices.)

Any thoughts out there on the best way to accomplish this? All options are on the table: full-trust, Google Gears, etc...

Thanks for any help!