android - How to record sound using bluetooth headset

Question

I am writing an android app for storing and managing voice memos with some basic metadata and tagging. When recording sound I use:

recorder = new MediaRecorder();         
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
recorder.setOutputFile(currentRecordingFileName);
// and so on

This works well when using the phone in a normal fashion. However, it does not detect the presence of a bluetooth headset and still uses the phone's own microphone even when the headset is plugged in.

I also tried using MediaRecorder.AudioSource.DEFAULT, hoping it would automatically choose the correct source, but then no sound was recorded at all.

How can I a) detect if a bluetooth headset is plugged in and/or b) use a bluetooth headset as audio source for the media recorder?

Answer 1

olivierg is basically right (AudioSource can still be MIC), some basic code would look like this:

    am = (AudioManager) getSystemService(Context.AUDIO_SERVICE);

    registerReceiver(new BroadcastReceiver() {

        @Override
        public void onReceive(Context context, Intent intent) {
            int state = intent.getIntExtra(AudioManager.EXTRA_SCO_AUDIO_STATE, -1);
            Log.d(TAG, "Audio SCO state: " + state);

            if (AudioManager.SCO_AUDIO_STATE_CONNECTED == state) { 
                /* 
                 * Now the connection has been established to the bluetooth device. 
                 * Record audio or whatever (on another thread).With AudioRecord you can record with an object created like this:
                 * new AudioRecord(MediaRecorder.AudioSource.MIC, 8000, AudioFormat.CHANNEL_CONFIGURATION_MONO,
                 * AudioFormat.ENCODING_PCM_16BIT, audioBufferSize);
                 *
                 * After finishing, don't forget to unregister this receiver and
                 * to stop the bluetooth connection with am.stopBluetoothSco();
                 */
                unregisterReceiver(this);
            }

        }
    }, new IntentFilter(AudioManager.ACTION_SCO_AUDIO_STATE_CHANGED));

    Log.d(TAG, "starting bluetooth");
    am.startBluetoothSco();

This I stumbled upon this myself just again, I want to point out the importance of slott's comment to include the right permissions, most importantly to set

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

in your manifest file. Without it you will not get any error message but the state will simply not change to connected.