public void Convert(string fileName, string fileFormat, string targetFormat)
        {
            switch (targetFormat)
            {
            case "Jpg":
                JpgConverter.Convert(fileName, fileFormat);
                break;

            case "Png":
                PngConverter.Convert(fileName, fileFormat);
                break;

            default:
                Console.WriteLine("Target format is not supported.");
                break;
            }
        }
 public VideoConverter()
 {
     JpgConverter = new JpgConverter();
     PngConverter = new PngConverter();
 }