Bluetooth audio controls in Android

Question

My app streams music and I want to be able to pause/play/skip from any Bluetooth device that might support these buttons (car, headset, etc). When connected through a car's bluetooth the audio comes through automatically, but the control buttons do not affect my app's audio stream. It instead opens the default media player. How do I route these buttons to affect my app?

Answer 1

Have you registered a BroadcastReceiver in your app to listen to MEDIA_BUTTON events using AudioManager.registerMediaButtonEventReceiver()?

After registering, the button events can be handled by processing the KeyEvent object attached in the extras as EXTRA_KEY_EVENT. For example:

@Override
public void onReceive(Context context, Intent intent) {
    final KeyEvent event = (KeyEvent) intent.getParcelableExtra(Intent.EXTRA_KEY_EVENT);
    if (event.getAction() != KeyEvent.ACTION_DOWN) return;

    switch (event.getKeyCode()) {
        case KeyEvent.KEYCODE_MEDIA_STOP:
            // stop music
            break;
        case KeyEvent.KEYCODE_HEADSETHOOK:
        case KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE:
            // pause music
            break;
        case KeyEvent.KEYCODE_MEDIA_NEXT:
            // next track
            break;
        case KeyEvent.KEYCODE_MEDIA_PREVIOUS:
            // previous track
            break;
    }
}

This Android Developer blog post also have some nice information on the subject.

Answer 2

Further to the accepted answer, please be aware that one of the Keycodes has changed in Ice Cream Sandwich:

The keycode that gets passed for play/pause intent has changed in ICS. See this http://code.google.com/p/media-button-router/issues/detail?id=10#c5

The keycode that had been sent prior to ICS was KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE. Now there are two separate keycodes for play and pause (126 and 127).

It's sending KEYCODE_MEDIA_PLAY (126) and KEYCODE_MEDIA_PAUSE (127).

https://code.google.com/p/android/issues/detail?id=23172

Answer 3

Please note that this API has changed since the accepted answer was written. Please refer to the MediaSession callbacks documentation.