$dbus = new Dbus(Dbus::BUS_SESSION);

$clementine_player_proxy = $dbus->createProxy('org.mpris.clementine', '/Player', 'org.freedesktop.MediaPlayer');

var_dump($clementine_player_proxy->GetMetaData());

/*
Exception throwns : DbusObject::__call(): org.freedesktop.DBus.Error.UnknownMethod: No such method 'GetMetaData' in interface 'org.freedesktop.MediaPlayer' at object path '/Player' (signature '')
*/