Question

我正在制作可在后台播放音频流的Windows 8.1应用。但它不会在后台播放音频流，例如，如果应用程序最小化。当应用程序处于焦点时，它可以正常播放音频流。我希望有人能提供帮助。感谢。

MainPage.xaml中：

<Grid Name="mainGrid" Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
    <TextBlock TextWrapping="Wrap" Text="Radio Limfjord" VerticalAlignment="Top" Height="116" FontSize="100" Margin="360,10,360,0"/>
    <MediaElement Visibility="Visible" Name="mediaplayer" AudioCategory="BackgroundCapableMedia" AutoPlay="True" RealTimePlayback="True" AudioDeviceType="Multimedia" HorizontalAlignment="Right" Width="1218" Margin="0,366,63,177" AreTransportControlsEnabled="True" CurrentStateChanged="mediaplayer_CurrentStateChanged" />
    <Button Name="cmdPlay" Content="Afspil" Margin="566,627,0,41" Click="cmdPlay_Click" Width="100" Height="100"/>
    <Button Name="cmdStop" Content="Stop" Margin="714,626,0,41" Click="cmdStop_Click" Width="100" Height="100"/>
</Grid>

MainPage.xaml.cs中：

public sealed partial class MainPage : Page
{
    SystemMediaTransportControls systemControls;
    public MainPage()
    {
        this.InitializeComponent();

    }

    void InitializeTransportControls()
    {
        // Hook up app to system transport controls.
        systemControls = SystemMediaTransportControls.GetForCurrentView();
        systemControls.ButtonPressed += SystemControls_ButtonPressed;

        // Register to handle the following system transpot control buttons.
        systemControls.IsPlayEnabled = true;
        systemControls.IsPauseEnabled = true;
    }

    void MusicPlayer_CurrentStateChanged(object sender, RoutedEventArgs e)
    {
        switch (mediaplayer.CurrentState)
        {
            case MediaElementState.Playing:
                systemControls.PlaybackStatus = MediaPlaybackStatus.Playing;
                break;
            case MediaElementState.Paused:
                systemControls.PlaybackStatus = MediaPlaybackStatus.Paused;
                break;
            case MediaElementState.Stopped:
                systemControls.PlaybackStatus = MediaPlaybackStatus.Stopped;
                break;
            case MediaElementState.Closed:
                systemControls.PlaybackStatus = MediaPlaybackStatus.Closed;
                break;
            default:
                break;
        }
    }

    void SystemControls_ButtonPressed(SystemMediaTransportControls sender,
SystemMediaTransportControlsButtonPressedEventArgs args)
    {
        switch (args.Button)
        {
            case SystemMediaTransportControlsButton.Play:
                PlayMedia();
                break;
            case SystemMediaTransportControlsButton.Pause:
                PauseMedia();
                break;
            default:
                break;
        }
    }

    async void PlayMedia()
    {
        await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
        {
            mediaplayer.Play();
        });
    }

    async void PauseMedia()
    {
        await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
        {
            mediaplayer.Pause();
        });
    }

    private void cmdPlay_Click(object sender, RoutedEventArgs e)
    {
        mediaplayer.Source = new Uri("http://media.wlmm.dk/limfjord", UriKind.Absolute);
        mediaplayer.Play();
    }

    private void cmdStop_Click(object sender, RoutedEventArgs e)
    {
        mediaplayer.Stop();

    }

    private void mediaplayer_CurrentStateChanged(object sender, RoutedEventArgs e)
    {

    }
}

Answer 1

您是否已声明＆＃34;音频 - 后台任务＆＃34;在您的应用清单中？

鲁

更多：http://blogs.msdn.com/b/johnkenn/archive/2013/12/31/supporting-background-audio-in-your-windows-8-1-app.aspx

Answer 2

不确定您是否曾找到并回答此问题，但查看您的代码时，您似乎没有调用InitializeTransportControls（）方法。

Windows 8.1音频流无法在后台播放

2 个答案: