I am trying to capture the microphone and send the recording to my server.. I tried this method here but it records only a big WAV and the upload can be slow sometimes.
Hey check out this post where i replied to a guy with a similar question as you.
How do I embed a Flash audio recorder in my site
i dont know about client side compressing (i have looked into it before and couldnt find anything). But i know you can severely reduce the size of the file by limiting the rate of recording via these numbers here, where if i recall correctly 16 is 16khz recording
recorder = new MicRecorder(wavencoder,null,50,16);
also sending to the server is not that hard, just look up how to post data, because the wav file is essentially binary data