(...)
  g_signal_connect (G_OBJECT (camerabutton), "clicked",
		    G_CALLBACK (take_photo), pipeline);

  gst_bus_add_watch (gst_pipeline_get_bus (GST_PIPELINE (pipeline)),
		     my_bus_callback, NULL);

  /*Variables globales */
  frames = 0;

  /* Iniciar el ciclo principal */
  g_object_unref (G_OBJECT (xml));
  gst_element_set_state (pipeline, GST_STATE_PLAYING);
  gst_element_set_state (pngenc, GST_STATE_NULL);
  gst_element_set_state (filesink, GST_STATE_NULL);

  gtk_main ();
(...)