Route voice buffer from mic to speaker in Android

Question

I need to increase voice, recorder from microphone on Android device. I try to read buffer from AudioRecord and then write it to AudioTrack... It works, but with delay, because min buffer size, returned bu method AudioRecord.getMinBufferSize with frequency like 44100 is 4480 bytes.

Any ideas?
Thanks.

Answer 1

I noticed there is no threading code. I would recommend trying to thread the recording and playback aspects and see if that better avoids the latency. Fill the buffer in from the mic one thread, and read it out to the speaker in the other. Avoid buffer overflows and underruns by handling those situations with some action (e.g. clearing the buffer for overflows). In theory, one should keep up with the other.

Answer 2

I have this code

AudioRecord and AudioTrack latency

But it happens to that there is a 20ms delay, and I need to solve it, The code above seems that plays something but there is no mic input, does it work?

Thanks!

Answer 3

package org.example.audio;

import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class AudioDemo extends Activity implements OnClickListener {
    private static final String TAG = "AudioDemo";
    private static final String isPlaying = "Media is Playing"; 
    private static final String notPlaying = "Media has stopped Playing"; 

    MediaPlayer player;
    Button playerButton;

    public void onClick(View v) {
        Log.d(TAG, "onClick: " + v);
        if (v.getId() == R.id.play) {
            playPause();
        }
    }

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        //player = MediaPlayer.create(this, R.raw.robotrock);
        player.setLooping(false); // Set looping

        // Get the button from the view
        playerButton = (Button) this.findViewById(R.id.play);
        playerButton.setText(R.string.stop_label);
        playerButton.setOnClickListener(this);

        // Begin playing selected media
        demoPlay();

        // Release media instance to system
        player.release();
    }

    @Override
    public void onPause() {
        super.onPause();
        player.pause();
    }

    // Initiate media player pause
    private void demoPause(){
        player.pause();
        playerButton.setText(R.string.play_label);
        Toast.makeText(this, notPlaying, Toast.LENGTH_LONG).show();
        Log.d(TAG, notPlaying);
    }

    // Initiate playing the media player
    private void demoPlay(){
        player.start();
        playerButton.setText(R.string.stop_label);
        Toast.makeText(this, isPlaying, Toast.LENGTH_LONG).show();
        Log.d(TAG, isPlaying);
    }

    // Toggle between the play and pause
    private void playPause() {
        if(player.isPlaying()) {
            demoPause();
        } else {
            demoPlay();
        }   
    }
}