Question

所以我从http://archive.msdn.microsoft.com/ManagedMediaHelpers下载了样本。

我的代码使用MP3MediaStreamSource。但是，我并不完全理解代码会有一些解释。

public partial class MainPage : PhoneApplicationPage
{
    private static string mediaFileLocation = "http://file-here.mp3";
    private static HttpWebRequest request = null;
    private static Mp3MediaStreamSource mss = null;

    public MainPage()
    {
        InitializeComponent();
    }

    private void RequestCallback(IAsyncResult asyncResult)
    {
        HttpWebResponse response = request.EndGetResponse(asyncResult) as HttpWebResponse;
        Stream s = response.GetResponseStream();
        mss = new Mp3MediaStreamSource(s, response.ContentLength);
        Deployment.Current.Dispatcher.BeginInvoke(
            () =>
            {
                this.wp7AudioElement.Volume = 100;
                this.wp7AudioElement.SetSource(mss);
            });
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        request = WebRequest.CreateHttp(MainPage.mediaFileLocation);

        // NOTICE 
        // Makes this demo code easier but I wouldn't do this on a live phone as it will cause the whole 
        // file to download into memory at once.
        //
        // Instead, use the asynchronous methods and read the stream in the backgound and dispatch its
        // data as needed to the ReportGetSampleCompleted call on the UIThread.
        request.AllowReadStreamBuffering = true;
        IAsyncResult result = request.BeginGetResponse(new AsyncCallback(this.RequestCallback), null);
    }
}

这真的只是我需要解释的最后一种方法，我不明白为什么这是一个坏主意以及如何以不同的方式做到这一点？

Answer 1

基本上，它试图告诉您在播放之前完全正在下载1个文件。这不是一个好主意，因为如果文件是10 MB，它可能需要一段时间才能完全下载。

更好的想法是使用编码器对文件进行分块，并根据需要进行读取。

WP7音频流帮助

1 个答案: