public sealed class GifCreator : IBackgroundTask
{
    public async void Run(IBackgroundTaskInstance taskInstance)
    {
		var deferral = taskInstance.GetDeferral(); 

		var logoFile = await Package.Current.InstalledLocation.GetFileAsync("Assets\\Logo.png");

		var extension = new Transcoder.Extension
		{
			Price = await Transcoder.Extension.GetPriceAsync(), 
			SourceType = "Video",
			SourceFormats = new string[] { ".mp4", ".mov", ".wmv", ".avi" },
			DestinationFormats = new string[] { ".gif" },
			LogoFile = logoFile,
			TranscodeAsync = this.TranscodeGifAsync
		};

		extension.Run(taskInstance, deferral);
    }

    public IAsyncAction TranscodeGifAsync(StorageFile source, StorageFile destination, ValueSet arguments)
    {
        return AsyncInfo.Run(async delegate (CancellationToken token)
        {
			... todo: write transcoding here
		});
	}
}