Routing audio to Bluetooth Headset (non-A2DP) on Android

Posted by Jayesh on Stack Overflow See other posts from Stack Overflow or by Jayesh
Published on 2010-01-27T05:04:53Z Indexed on 2010/04/26 20:33 UTC
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I have a non-A2DP single ear BT headset (Plantronics 510) and would like to use it with my Android HTC Magic to listen to low quality audio like podcasts/audio books.

After much googling I found that only phone call audio can be routed to the non-A2DP BT headsets. (I would like to know if you have found a ready solution to route all kinds of audio to non-A2DP BT headsets)

So I figured, somehow programmatically I can channel the audio to the stream that carries phone call audio. This way I will fool the phone to carry my mp3 audio to my BT headset. I wrote following simple code.

import android.content.*;
import android.app.Activity;
import android.os.Bundle;
import android.media.*;
import java.io.*;
import android.util.Log;

public class BTAudioActivity extends Activity
{
    private static final String TAG = "BTAudioActivity";

    private MediaPlayer mPlayer = null;
    private AudioManager amanager = null;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        amanager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
        amanager.setBluetoothScoOn(true);
        amanager.setMode(AudioManager.MODE_IN_CALL);

        mPlayer = new MediaPlayer();

        try {
            mPlayer.setDataSource(new FileInputStream(
                "/sdcard/sample.mp3").getFD());

            mPlayer.setAudioStreamType(AudioManager.STREAM_VOICE_CALL);

            mPlayer.prepare();

            mPlayer.start();
        } catch(Exception e) {
            Log.e(TAG, e.toString());
        }
    }

    @Override
    public void onDestroy()
    {
        mPlayer.stop();
        amanager.setMode(AudioManager.MODE_NORMAL);
        amanager.setBluetoothScoOn(false);
        super.onDestroy();
    }
}

As you can see I tried combinations of various methods that I thought will fool the phone to believe my audio is a phone call:

  • Using MediaPlayer's setAudioStreamType(STREAM_VOICE_CALL)
  • using AudioManager's setBluetoothScoOn(true)
  • using AudioManager's setMode(MODE_IN_CALL)

But none of the above worked. If I remove the AudioManager calls in the above code, the audio plays from speaker and if I replace them as shown above then the audio stops coming from speakers, but it doesn't come through the BT headset. So this might be a partial success.

I have checked that the BT headset works alright with phone calls.

There must be a reason for Android not supporting this. But I can't let go of the feeling that it is not possible to programmatically reroute the audio. Any ideas?

P.S. above code needs following permission

<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>

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