The WSE docs for transcoder have several interfaces for listening to frames.
For example, ITranscoderAudioFrameNotify2 can be used to listen to raw decoded audio packets by calling TranscoderSessionAudio.addListener(). Works great. There is an equivalent for video called ITranscoderVideoDecoderNotify.
I can listen to raw encoded video frames using ITranscoderVideoEncoderNotify and calling
TranscoderSessionVideoEncode.addFrameListener.
There is an equivalent documented listener (see WSE Java API reference) for audio called ITranscoderAudioEncoderNotify. However, there seems to be no way to hook it up. (There is no TranscoderSessionAudioEncode.addFrameListener, nor can I find ITranscoderAudioEncoderNotify referenced anywhere else)