private static void InitSource()
        {
            if (source == null) {
                PlayerEngineCore.StateChanged += OnPlayerEngineStateChanged;

                source = new PodcastSource ();
                SourceManager.AddSource (source);

                source.Load ();
            }
        }
        private static void DestroySource()
        {
            if (source != null) {
                PlayerEngineCore.StateChanged -= OnPlayerEngineStateChanged;

                SourceManager.RemoveSource (source);
                source.Dispose ();

                source = null;
            }
        }