Provides necessary information and callbacks to setup a manual controller for a Playback.
This method is called once the renderer of the Playback becomes available. Client should use this callback to setup the manual controller mechanism for the renderer. For example: provide a user interface for controlling the playback.
This method is called once the renderer of the Playback becomes unavailable to it. Client should use this callback to clean up any manual controller mechanism set before. Note that the library also does some cleanup by itself to ensure the sanity of the renderer.