I am looking for an audio for teensy (real time encode as well as decode). I am trying to put together my own HT with the use of a DRA818 module. (http://www.dorji.com/docs/data/DRA818V.pdf) But instead of as is the standard application for this module to directly feed the microphone input to the RF unit, what I am trying to do is to first digitally encode the signal and then feed it to the RF from the teensy. Of course on the other side the opposite will have to happen. Hence the need for realtime.

Does anybody know of a ready compiled or compilable speech codec that allows to compress speech down to about 4kbit/sec for the teensy?