Encoding Audio (to AAC) in Silverlight 4 (on the client)?

OK so Silverlight 4 is adding support for capturing from microphones (and webcams), 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开发者_如何学C client, then upload that compressed stream to the server.

Something like this library, 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!

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There's an audio codec out there called Speex AND Alden Torres ported the SPEEX algorithm to C#. So you have a full managed audio encoder. Here's the relevant blog post where he shows how to encode the audio from the mic with SPEEX. Read also the comments.

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As the answer mentioned above Speex is a voice codec which is not really appropriate if you want to use it for music. However, if you are still interested in Speex on Silverlight than you should take a look at NSpeex which is a port of an earlier version of Speex to C# and it also offers a Silverlight library.

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I need to record a music in Silverlight (e.g. from the line-in) and save it on the server. It must be in a good quality (not like SPEEX). I will try to use a lame encoder on the client. It needs the lame_enc.dll that can be accessed by p-invoke. I will test if it is possible from the silverlight. Do you know some alternatives? Maybe a good stream server (is it possible with wowza)?

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You should know that AAC encoding is patent restricted as well. Check out the Wikipeadia article on it. If you want a free format, you should look into Vorbis or FLAC (or Speex).

If you're on a Windows 7 or Server 2008 R2 box, you might be able to use the SDK to encode AAC (http://msdn.microsoft.com/en-us/library/dd742785(v=VS.85).aspx).

Also, since you're forcing the client to do a bunch of work anyway, why not just zip it before you upload it -- I'm not a Silverlight person, so maybe that's not possible?