Left Right Channel separation from mic recording

Question

I am trying to record from mic and send the recorded data to only the left channel separately having zeroes on the right channel but my technique does not seem to work.. I am using audio record and audio track with PCM 16 and mono Mode what do I seem to do wrong ?

package com.example.leftrighttest;

import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioRecord;
import android.media.AudioTrack;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        int freq=44100;
        final int bufferSize = (AudioRecord.getMinBufferSize(freq,AudioFormat.CHANNEL_IN_MONO,
                AudioFormat.ENCODING_PCM_16BIT ));

        AudioRecord audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, freq,AudioFormat.CHANNEL_IN_MONO,
                AudioFormat.ENCODING_PCM_16BIT, bufferSize );


        AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                (int) freq,AudioFormat.CHANNEL_OUT_MONO,
                AudioFormat.ENCODING_PCM_16BIT, bufferSize,
                AudioTrack.MODE_STREAM);

        audioTrack.setPlaybackRate(freq);

        final byte[] buffer = new byte[bufferSize];
       audioRecord.startRecording();




                    byte[] byteBufferFinal = new byte[bufferSize*2]; 

                    //LL RR LL RR LL RR 
                    while(true)
                    {
                    audioRecord.read(buffer, 0, bufferSize);
                   for(int k = 0, index = 0; index < byteBufferFinal.length - 4; k=k+2){
                        byteBufferFinal[index] = buffer[k]; // LEFT {0,1/4,5/8,9/12,13;...}
                        //System.out.println(byteBufferFinal[index]);
                        byteBufferFinal[index+1] = buffer[k+1];
                       // System.out.println(byteBufferFinal[index+1]);
                        index = index + 2;
                        byteBufferFinal[index] =0; //byteBuffer2[k]; // RIGHT {2,3/6,7/10,11;...}
                        //System.out.println(byteBufferFinal[index]);
                        byteBufferFinal[index+1] =0;// byteBuffer2[k+1];
                       // System.out.println(byteBufferFinal[index+1]);
                        index = index + 2;
                    }
                       audioTrack.write( byteBufferFinal, 0, bufferSize*2);
                       audioTrack.play();
                    }

    }



}

Bolten

You're creating a mono AudioTrack, so it will only have one channel. – Spitter

Answer 1

I figured it out so the proper solution was 1)to change the mode from mono to Stereo 2)read the buffer and the format will be as follows (L,L,R,R,L,L,R,R....) so every two bytes are sent to one channel (pcm 16) then I set zeroes to the channel I want to cancel so If I want ONLY the left channel to work my buffer will be (L,L,0,0,L,L,0,0,.....)

Bolten