WPF中使用MediaElement显示GIF

<MediaElement x:Name="myGif" MediaEnded="myGif_MediaEnded" UnloadedBehavior="Manual" Source="file://C:\waiting.GIF" LoadedBehavior="Play" Stretch="None"/>

    private void myGif_MediaEnded(object sender, RoutedEventArgs e)
    {
        myGif.Position = new TimeSpan(0, 0, 1);
        myGif.Play();
    }