//construction
    sink = Gst.ElementFactory.make ("xvimagesink", "sink");
        sink.set("force-aspect-ratio", true);
        visualization = Gst.ElementFactory.make ("goom2k1", "visualization");
        player = Gst.ElementFactory.make ("playbin", "player");
        player.video_sink = sink;
        player.vis_plugin = visualization;
    player.set_state (Gst.State.NULL);

//open
    player.uri = stream;
        player.set_state (Gst.State.READY);

//actually play the stuff
    player.set_state (Gst.State.PLAYING);