I had a bit of a look, before I investigate gstreamer any further, I think I may be able get the audio via MCI, just been looking at win32-api-prototype, Then I guess it's a matter of encoding and dynamically inserting the meta-data ID tag on the fly, one way or another.

Heads back to msdn ... :P

Update: MCI doesn't seem to provide an accessible output buffer of the audio...I think (gah). Lower lower lower ...

Comment on Re^2: Dynamically inserting meta-data to an MP3 output stream