Android : How to get info of currently playing music using broadcastreceiver while the app isn't running?

I would like to receive broadcasts from music players while the app is in the background.

I found the following code here:

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

    IntentFilter iF = new IntentFilter();
    iF.addAction("com.android.music.metachanged");
    iF.addAction("com.android.music.playstatechanged");
    iF.addAction("com.android.music.playbackcomplete");
    iF.addAction("com.android.music.queuechanged");

    registerReceiver(mReceiver, iF);
}

private BroadcastReceiver mReceiver = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        String cmd = intent.getStringExtra("command");
        Log.v("tag ", action + " / " + cmd);
        String artist = intent.getStringExtra("artist");
        String album = intent.getStringExtra("album");
        String track = intent.getStringExtra("track");
        Log.v("tag", artist + ":" + album + ":" + track);
        Toast.makeText(CurrentMusicTrackInfoActivity.this, track, Toast.LENGTH_SHORT).show();
    }
};

And it works, but only while the activity is running. So I tried to make a static broadcastreceiver:

<receiver
    android:name=".receiver.MusicBroadcastReceiver"
    android:exported="false">
    <intent-filter>
        <action android:name="com.android.music.metachanged" />
        <action android:name="com.android.music.playstatechanged" />
        <action android:name="com.android.music.playbackcomplete" />
        <action android:name="com.android.music.queuechanged" />
    </intent-filter>
</receiver>

The class:

public class MusicBroadcastReceiver extends BroadcastReceiver {
    public MusicBroadcastReceiver() {
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        String cmd = intent.getStringExtra("command");
        Log.v("tag ", action + " / " + cmd);
        String artist = intent.getStringExtra("artist");
        String album = intent.getStringExtra("album");
        String track = intent.getStringExtra("track");
        Log.v("tag", artist + ":" + album + ":" + track);
        Toast.makeText(context, track, Toast.LENGTH_SHORT).show();
    }
}

And it doesn't work. I started searching and I found this question, which claims that the code above should work. But it doesn't, onReceive is not called when I start playing music or skip a track. Imust be doing something very wrong, but I can't figure out what.

Any help would be appreciated. Thanks.