Play Back audio from mic in real Time

Question

I have a function , that records audio, and stores it into a file. This is what is looks like:

private void startRecord(){

      File file = new File(Enviro         


        

Answer 1

This works for me:

boolean isRecording = false;
AudioManager am = null;
AudioRecord record = null;
AudioTrack track = null;

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

    initRecordAndTrack();

    am = (AudioManager) this.getSystemService(Context.AUDIO_SERVICE);
    am.setSpeakerphoneOn(true);

    (new Thread()
    {
        @Override
        public void run()
        {
            recordAndPlay();
        }
    }).start();

    Button startButton = (Button) findViewById(R.id.start_button);
    startButton.setOnClickListener(new OnClickListener()
    {
        @Override
        public void onClick(View v)
        {
            if (!isRecording)
            {
                startRecordAndPlay();
            }
        }
    });
    Button stopButton = (Button) findViewById(R.id.stop_button);
    stopButton.setOnClickListener(new OnClickListener()
    {
        @Override
        public void onClick(View v)
        {
            if (isRecording)
            {
                stopRecordAndPlay();
            }
        }
    });
}

private void initRecordAndTrack()
{
    int min = AudioRecord.getMinBufferSize(8000, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
    record = new AudioRecord(MediaRecorder.AudioSource.VOICE_COMMUNICATION, 8000, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT,
                             min);
    if (AcousticEchoCanceler.isAvailable())
    {
        AcousticEchoCanceler echoCancler = AcousticEchoCanceler.create(record.getAudioSessionId());
        echoCancler.setEnabled(true);
    }
    int maxJitter = AudioTrack.getMinBufferSize(8000, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT);
    track = new AudioTrack(AudioManager.MODE_IN_COMMUNICATION, 8000, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT, maxJitter,
                           AudioTrack.MODE_STREAM);
}

private void recordAndPlay()
{
    short[] lin = new short[1024];
    int num = 0;
    am.setMode(AudioManager.MODE_IN_COMMUNICATION);
    while (true)
    {
        if (isRecording)
        {
            num = record.read(lin, 0, 1024);
            track.write(lin, 0, num);
        }
    }
}

private void startRecordAndPlay()
{
    record.startRecording();
    track.play();
    isRecording = true;
}

private void stopRecordAndPlay()
{
    record.stop();
    track.pause();
    isRecording = false;
}

You also need two buttons in your activity_main layout with the id start_button and stop_button.

This sample also contains an EchoCanceler!

Good luck!