Receive callback on all Android media button events all the time (even when another app is playing audio)

Question

Background Info: I need to detect whenever a user presses the play/pause button found on most headsets (KEYCODE_MEDIA_PLAY_PAUSE).

I have it all mostly working using MediaSessions, but when another app starts playing audio, I stop getting callbacks.

It seems like this is because the app that's playing audio created its own MediaSession and Android sends KeyEvents only to the newest MediaSession. To prevent this I create an OnActiveSessionsChangedListener and create a new MediaSession every time it fires.

This does work, but every time I create a new MediaSession, the listener fires again, so I find myself stuck in an inf loop.

My Question: does anyone know how I can do any of the following??:

• Prevent other apps from stealing my media button focus
• Detect when I've lost media button focus to another app, so I can create a new MediaSession only then, rather then whenever the active sessions change
• Check if I currently already have media button focus so I needlessly create a new MediaSession

What didn't work:

• BroadcastReceiver on AudioEffect.ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION didn't work because apps have to manually trigger that Broadcast, and many apps, like NPR One do not
• AudioManager.OnAudioFocusChangeListener didn't work because it requires I have audio focus
• BroadcastReceiver with max priority on android.intent.action.MEDIA_BUTTON & calling abortBroadcast(), but when other apps were playing audio, my receiver wasn't triggered. Also, other apps can set max priority as well.

My Code:

mMediaSessionManager.addOnActiveSessionsChangedListener(controllers -> {
    boolean updateButtonReceiver = false;

    // recreate MediaSession if another app handles media buttons
    for (MediaController mediaController : controllers) {
        if (!TextUtils.equals(getPackageName(), mediaController.getPackageName())) {
            if ((mediaController.getFlags() & (MediaSessionCompat.FLAG_HANDLES_MEDIA_BUTTONS | MediaSessionCompat.FLAG_HANDLES_TRANSPORT_CONTROLS)) != 0L) {
                updateButtonReceiver = true;
            }
        }

    }

    if (updateButtonReceiver) {
        // using a handler with a delay of about 2 seconds because this listener fires very often.
        mAudioFocusHandler.removeCallbacksAndMessages(null);
        mAudioFocusHandler.sendEmptyMessageDelayed(0, AUDIO_FOCUS_DELAY_MS);
    }
}, ClickAppNotificationListener.getComponentName(this));

Here is the handler that gets triggered:

private final Handler mAudioFocusHandler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        if (mShouldBeEnabled) {
            updateButtonReceiverEnabled(true);
        }
    }
};

And finally here is the method that the Handler triggers:

private void updateButtonReceiverEnabled(boolean shouldBeEnabled) {
    // clear old session (not sure if this is necessary)
    if (mMediaSession != null) {
        mMediaSession.setActive(false);
        mMediaSession.setFlags(0);
        mMediaSession.setCallback(null);
        mMediaSession.release();
        mMediaSession = null;
    }

    mMediaSession = new MediaSessionCompat(this, MEDIA_SESSION_TAG);
    mMediaSession.setCallback(mMediaButtonCallback);
    mMediaSession.setFlags(MediaSessionCompat.FLAG_HANDLES_MEDIA_BUTTONS | MediaSessionCompat.FLAG_HANDLES_TRANSPORT_CONTROLS);
    mMediaSession.setPlaybackToLocal(AudioManager.STREAM_MUSIC);
    mMediaSession.setActive(true);
    mMediaSession.setPlaybackState(new PlaybackStateCompat.Builder()
            .setActions(PlaybackStateCompat.ACTION_PLAY_PAUSE)
            .setState(PlaybackStateCompat.STATE_CONNECTING, 0, 0f)
            .build());

    if (shouldBeEnabled != mShouldBeEnabled) {            
        getPackageManager().setComponentEnabledSetting(mMediaButtonComponent,
                shouldBeEnabled
                        ? PackageManager.COMPONENT_ENABLED_STATE_ENABLED
                        : PackageManager.COMPONENT_ENABLED_STATE_DISABLED,
                PackageManager.DONT_KILL_APP);
    }

    mShouldBeEnabled = shouldBeEnabled;
}

Thanks!

Answer 1

if you just want to capture MediaButton you can register a BroadcastReceiver to get Media Button action all the time .

MediaButtonIntentReceiver class :

public class MediaButtonIntentReceiver extends BroadcastReceiver {

  public MediaButtonIntentReceiver() {
    super();
    }

 @Override
 public void onReceive(Context context, Intent intent) {
     String intentAction = intent.getAction();
     if (!Intent.ACTION_MEDIA_BUTTON.equals(intentAction)) {
        return;
       }
     KeyEvent event =   (KeyEvent)intent.getParcelableExtra(Intent.EXTRA_KEY_EVENT);
     if (event == null) {
        return;
       }
     int action = event.getAction();
     if (action == KeyEvent.ACTION_DOWN) {
          // do something
       Toast.makeText(context, "BUTTON PRESSED!", Toast.LENGTH_SHORT).show(); 
        }
    abortBroadcast();
  }
}

add this to manifest.xml:

<receiver android:name=".MediaButtonIntentReceiver">
    <intent-filter>
        <action android:name="android.intent.action.MEDIA_BUTTON" />
    </intent-filter>
</receiver>

and register your BroadcastReceiver like this ( in main activity)

IntentFilter filter = new IntentFilter(Intent.ACTION_MEDIA_BUTTON);
MediaButtonIntentReceiver r = new MediaButtonIntentReceiver();
filter.setPriority(1000); 
registerReceiver(r, filter); 

also look at :

How to capture key events from bluetooth headset with android

How do I intercept button presses on the headset in Android?