def set_scene_velocity(self, scene_id, velocity):
        """reconfigure a scene by scene ID"""
        if not scene_id in self.state.scenes: # does that scene_id exist?
            err_msg = "Requested to set velocity on scene {sceneNum}, which does not exist".format(sceneNum=scene_id)
            logging.info(err_msg)
            return(False, 0, err_msg)
        self.state.scenes[scene_id] = self.state.scenes[scene_id]._replace(velocity=velocity)
        sequence_number = self.zmq_publisher.publish_scene_velocity(scene_id, velocity)
        logging.debug("set velocity on scene {sceneNum}".format(sceneNum=scene_id))
        if scene_id == self.state.activeSceneId:
            self.state.activeAnimation.set_velocity(velocity)
            self._do_next_frame() # TODO: make it more sensible, e.g. call only if static scene
        return (True, sequence_number, "OK")
reconfigure a scene by scene ID