C# 无法使用windows phone 8中的MediaLibraryExtensions.SaveSong下载音频

我正在尝试下载音频并保存到独立存储，然后保存到emulator

我尝试了以下代码

WebClient m_webClient = new WebClient();
m_webClient.OpenReadAsync(fileUri);
m_webClient.OpenReadCompleted += new OpenReadCompletedEventHandler(webClient_ImageOpenReadCompleted);
m_webClient.AllowReadStreamBuffering = true;  


private static void webClient_ImageOpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
        var isolatedfile = IsolatedStorageFile.GetUserStoreForApplication();
        using (IsolatedStorageFileStream stream = new IsolatedStorageFileStream(_fileName, System.IO.FileMode.Create, isolatedfile))
        {
            byte[] buffer = new byte[e.Result.Length];
            while (e.Result.Read(buffer, 0, buffer.Length) > 0)
            {
                stream.Write(buffer, 0, buffer.Length);
            }
        }
        SaveFileMP3(_fileName);
}

private static void SaveFileMP3(string _fileName)
{
        MediaLibrary lib = new MediaLibrary();
        Uri songUri = new Uri(_fileName, UriKind.RelativeOrAbsolute);
        MediaLibraryExtensions.SaveSong(lib, songUri, null, SaveSongOperation.CopyToLibrary);

}

我面临的问题是，音频被保存到模拟器中，而不是扩展。假设文件名为test.MP3，则将其另存为test，持续时间始终为0:0:00，与原始持续时间无关

我在清单文件中也添加了音频功能

下面是保存歌曲时的屏幕截图，其中有许多例外情况

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如果代码有问题，请更正。提前感谢。

通过添加lib.savesong行，取代了mediaLibraryExtensions，效果非常好

private static void SaveFileMP3(string _fileName)
{
    MediaLibrary lib = new MediaLibrary();
    Uri songUri = new Uri(_fileName, UriKind.RelativeOrAbsolute);
    lib.SaveSong(songUri, null, SaveSongOperation.CopyToLibrary);
    //MediaLibraryExtensions.SaveSong(lib, songUri, null, SaveSongOperation.CopyToLibrary);

}