Android - How to add my own Audio codec to AudioRecord?

Question

I currently have a Loop back program for testing Audio on Android devices.

It uses AudioRecord and AudioTrack to record PCM audio from the Mic and play PCM audio out the earpiece.

Here is the code:

public class Record extends Thread
  {

          static final int bufferSize = 200000;
          final short[] buffer = new short[bufferSize];
          short[] readBuffer = new short[bufferSize];

          public void run() {  
            isRecording = true;
            android.os.Process.setThreadPriority
            (android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);

            int buffersize = AudioRecord.getMinBufferSize(11025,
            AudioFormat.CHANNEL_CONFIGURATION_MONO,
            AudioFormat.ENCODING_PCM_16BIT);

                           arec = new AudioRecord(MediaRecorder.AudioSource.MIC,
                                           11025,
                                           AudioFormat.CHANNEL_CONFIGURATION_MONO,
                                           AudioFormat.ENCODING_PCM_16BIT,
                                           buffersize);

                           atrack = new AudioTrack(AudioManager.STREAM_VOICE_CALL,
                                           11025,
                                           AudioFormat.CHANNEL_CONFIGURATION_MONO,
                                           AudioFormat.ENCODING_PCM_16BIT,
                                           buffersize,
                                           AudioTrack.MODE_STREAM);


                           atrack.setPlaybackRate(11025);

                           byte[] buffer = new byte[buffersize];
                           arec.startRecording();
                           atrack.play();

                           while(isRecording) {

                                   arec.read(buffer, 0, buffersize);
                                   atrack.write(buffer, 0, buffer.length);
                           }  
          }
  }

So as you can see in the creation of the AudioTrack and AudioRecord the Encoding is supplied via the AudioFormat but this only allows 16 bit or 8 bit PCM.

I have my own G711 Codec implementation now and I want to be able to encode the audio from the Mic and decode it going into the EarPiece, So I have encode(short lin[], int offset, byte enc[], int frames) and decode(byte enc[], short lin[], int frames) methods but I'm unsure as to how to use them to encode and the decode the audio from the AudioRecord and AudioTrack.

Can anyone help me or point me in the right direction?