// called from the main activity
synchronized public void playPause(Context _c, String _s) {
    if (mediaPlayer == null) {
        // show progress dialog
        pd = ProgressDialog.show(_c, "Raw Audio", "connecting to stream...", true, true);

        // not playing -> load stream
        STREAM = _s;
        loadStream();
    }
    else if (mediaPlayer.isPlaying()) {
        // playing -> pause
        mediaPlayer.pause();
    }
    else {
        // paused -> resume
        mediaPlayer.start();
    }
}