public void Convert(string fileName, string fileFormat, string targetFormat)
        {
            switch (targetFormat)
            {
            case "Mp3":
                Mp3Converter.Convert(fileName, fileFormat);
                break;

            case "Ogg":
                OggConverter.Convert(fileName, fileFormat);
                break;

            default:
                Console.WriteLine("Target format is not supported.");
                break;
            }
        }
 public AudioConverter()
 {
     Mp3Converter = new Mp3Converter();
     OggConverter = new OggConverter();
 }