C# Windows Phone 8.1修剪MP3

我试图修剪一个mp3文件，除了每次它返回错误的坏配置文件，我已经在这2天了，尝试我能找到的每一点信息

这就是我目前所拥有的。我知道这有点乱，我对C还是个新手，我现在只想让它工作起来

    async void TrimFile()
    {

        StorageFolder OutFolder = KnownFolders.MusicLibrary;
        StorageFile OutFile = await OutFolder.GetFileAsync("test.mp3");
        var destFile = OutFile;

        StorageFolder Infolder = Windows.Storage.ApplicationData.Current.LocalFolder;
        StorageFile InFile = await Infolder.GetFileAsync("test.mp3");
        var srcFile = InFile;

        MediaEncodingProfile profile = MediaEncodingProfile.CreateMp3(AudioEncodingQuality.Low);

        MediaTranscoder transcoder = new MediaTranscoder();

        transcoder.TrimStartTime = new TimeSpan(0, 0, 2);

        transcoder.TrimStopTime = new TimeSpan(0, 0, 5);

        PrepareTranscodeResult prepareOp = await transcoder.PrepareFileTranscodeAsync(srcFile, destFile, profile);

        if (prepareOp.CanTranscode)
        {
            var transcodeOp = prepareOp.TranscodeAsync();
            transcodeOp.Progress += new AsyncActionProgressHandler<double>(TranscodeProgress);
            transcodeOp.Completed += new AsyncActionWithProgressCompletedHandler<double>(TranscodeComplete);
        }
        else
        {
            switch (prepareOp.FailureReason)
            {
                case TranscodeFailureReason.CodecNotFound:
                    TextBlock1.Text = "No Codec";
                    break;
                case TranscodeFailureReason.InvalidProfile:
                    TextBlock1.Text = "Invalid Profile";
                    break;
                default:

                    break;
            }
        }
    }

如果有人能帮我指出正确的方向，谢谢