why do i hear echo in my application

[lena1990]

hi all,
i create full duplex application to transmit voice using udp protocol , i use AudioRecord to record voice and AudioTrack to play it but i hear echo

[JamesCherrill]

local app sends sound
remote app plays it
remote microphone hears sound being played
remote app sends what it hears back to you
you hear an echo

[lena1990]

thanks for answering but i hear the echo in the local app first before it is played in the remote app

[JamesCherrill]

In that case it's probably a problem in your code, so without seeing it there's nothing more we can do.

[lena1990]

here is the code :

package com.example.israa.modified_call;

import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioRecord;
import android.media.AudioTrack;
import android.media.MediaRecorder;
import android.os.AsyncTask;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.Log;

import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Arrays;


public class MainActivity extends ActionBarActivity {
    private EditText ip;
    private TextView streamingLabel;
    private Button Call,Answer,End;
    private int sendingport=50005;
    private int recievingport=50006;
    AudioRecord recorder;
    private int sampleRate = 32000 ;    
    private int channelConfig = AudioFormat.CHANNEL_CONFIGURATION_MONO;
    private int audioFormat = AudioFormat.ENCODING_PCM_16BIT;
    AudioTrack speaker;
    private boolean status = true;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ip = (EditText) findViewById (R.id.editText);
        streamingLabel = (TextView) findViewById(R.id.textView);
        Call = (Button) findViewById (R.id.button);
        Answer = (Button) findViewById (R.id.button2);
        End = (Button) findViewById (R.id.button3);
        streamingLabel.setText("Press Start! to begin");
        Call.setOnClickListener (startListener);
        End.setOnClickListener (stopListener);
        Answer.setOnClickListener(receiveListener);
    }

    private final View.OnClickListener stopListener = new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            status = false;
            recorder.release();
            Log.d("VS", "Recorder released");
        }

    };
    private final View.OnClickListener receiveListener = new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            status = true;
           Log.d("Note","RecordAudio");
            startReceiving();
         RecordAudio t=new RecordAudio();
            t.execute();
        }

    };

    private final View.OnClickListener startListener = new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            status = true;
            startStreaming();
            PlayAudio a=new PlayAudio();
            a.execute();

        }

    };

    public void startStreaming() {


        Thread streamThread = new Thread(new Runnable() {

            @Override
            public void run() {
                try {


                    int minBufSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);
                    Log.d("VS", "Socket Created");
                    byte[] buffer = new byte[32000];
                    Log.d("VS","Buffer created of size " + buffer.length);
                    DatagramPacket packet;
                    final InetAddress destination = InetAddress.getByName(ip.getText().toString());
                    Log.d("VS", "Address retrieved");
                    DatagramSocket socket = new DatagramSocket(sendingport);
                    recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,sampleRate,channelConfig,audioFormat,32000);
                    Log.d("VS", "Recorder initialized");
                    recorder.startRecording();
                    while(status == true) {
                        minBufSize = recorder.read(buffer, 0, buffer.length);
                        Log.d("VS", "Reading");

                        packet = new DatagramPacket (buffer,buffer.length,destination,sendingport);
                        Log.d("VS", "creating packet minbuffer="+minBufSize +"         buffer="+buffer.length);
                        socket.send(packet);

                    }



                } catch(UnknownHostException e) {
                    Log.e("VS", "UnknownHostException");
                }
                catch (Throwable t) {
                    Log.e("AudioTrack", "Playback Failed");
                }
           /*    catch (IOException e) {
                Log.e("VS", "IOException");
               }*/


            }

        });
        streamThread.start();
    }
    private class PlayAudio extends AsyncTask<Void, Integer, Void> {
        @Override
        protected Void doInBackground(Void... params) {

                try {

                    DatagramSocket recievingsocket = new DatagramSocket(recievingport);
                    Log.d("VR", "Socket Created");

                    int minBufSize1 = AudioTrack.getMinBufferSize(sampleRate, channelConfig, audioFormat);

                    byte[] buffer1 = new byte[32000];

                    speaker = new AudioTrack(AudioManager.STREAM_VOICE_CALL,sampleRate,channelConfig,audioFormat,32000,AudioTrack.MODE_STREAM);
                DatagramPacket packet1 = new DatagramPacket(buffer1,buffer1.length);
                    speaker.play();
                   while(status == true) {
                        try {
                           recievingsocket.receive(packet1);
                            Log.d("VR", "Packet Received");
                            //reading content from packet
                            buffer1=packet1.getData();
                            Log.d("VR", "Packet data read into buffer    minbuffer="+minBufSize1 +"         buffer="+buffer1.length);

                            speaker.write(buffer1, 0, buffer1.length);
                            Log.d("VR", "Writing buffer content to speaker");

                        } catch(IOException e) {
                            Log.e("VR","IOException");
                        }
                        catch(Throwable t){
                            Log.e("AudioTrack", "Playback Failed");
                        }
                    }


                } catch (SocketException e) {
                    Log.e("VR", "SocketException"+e.getMessage());
                }

                return null;
            }

    }

    public void startReceiving() {

        Thread receiveThread = new Thread (new Runnable() {

            @Override
            public void run() {

                try {

                    DatagramSocket socket = new DatagramSocket(sendingport);
                    Log.d("VR", "Socket Created");

                    int minBufSize = AudioTrack.getMinBufferSize(sampleRate, channelConfig, audioFormat);

                    byte[] buffer = new byte[32000];


                    speaker = new AudioTrack(AudioManager.STREAM_VOICE_CALL,sampleRate,channelConfig,audioFormat,32000,AudioTrack.MODE_STREAM);
                    DatagramPacket packet = new DatagramPacket(buffer,buffer.length);
                   speaker.play();
                    while(status == true) {
                        try {



                            socket.receive(packet);
                            Log.d("VR", "Packet Received");


                            buffer=packet.getData();
                            Log.d("VR", "Packet data read into buffer    minbuffer="+minBufSize +"         buffer="+buffer.length);


                            speaker.write(buffer, 0, buffer.length);
                            Log.d("VR", "Writing buffer content to speaker");

                        } catch(IOException e) {
                            Log.e("VR","IOException");
                        }
                        catch(Throwable t){
                            Log.e("AudioTrack", "Playback Failed");
                        }
                    }


                } catch (SocketException e) {
                    Log.e("VR", "SocketException"+e.getMessage());
                }


            }

        });
        receiveThread.start();
    }
    private class RecordAudio extends AsyncTask<Void, Integer, Void> {
        @Override
        protected Void doInBackground(Void... params) {
            try {


                int minBufSize1 = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);

                Log.d("VS", "Socket Created");
                byte[] buffer1 = new byte[32000];

                Log.d("VS", "Buffer created of size " + minBufSize1);
                DatagramPacket packet1;

                final InetAddress destination = InetAddress.getByName(ip.getText().toString());
                Log.d("VS", "Address retrieved");
                DatagramSocket sendingsocket = new DatagramSocket(recievingport);

                recorder = new AudioRecord(MediaRecorder.AudioSource.MIC, sampleRate, channelConfig, audioFormat,32000);
                Log.d("VS", "Recorder initialized");

                recorder.startRecording();


                while (status == true) {

                    //reading data from MIC into buffer
                    minBufSize1 = recorder.read(buffer1, 0, buffer1.length);
                    Log.d("VS", "Reading");
                    //putting buffer in the packet
                    packet1 = new DatagramPacket(buffer1, buffer1.length,destination,recievingport);
                    Log.d("VS", "creating packet minbuffer= "+minBufSize1 +"         buffer="+buffer1.length);

                    sendingsocket.send(packet1);



                }


            } catch (UnknownHostException e) {
                Log.e("VS", "UnknownHostException");
            } catch (Throwable t) {
                Log.e("AudioTrack", "Playback Failed");
            }
           /*    catch (IOException e) {
                Log.e("VS", "IOException");
               }*/

            return null;
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}