What's the easiest way to play audio in backgr

问题:

I am working on my Project (a soundcloud client) and the app can play tracks just fine, but not when the app is minimized. I use the MediaElement-Object for playing the mp3 from the url. How can i force the music to continue playing the music, when the app is in the background. Or whats the easiest way/best explained tutorial to implement this. I searched alot for a good answer, but the ones, i found, was too good for me :D What means, that i didn't understand it.

回答1:

To play audio in the background you will have to do a Declaration in Package.appxmanifest for a Background Tasks, enable audio and add an entry point like TestUWP.MainPage page.

Also for the user to easily be able to manage the audio you can use SystemMediaTransportControls

Here is a basic setup with Play and Pause.

xaml

<MediaElement x:Name="mediaElement" Height="100" Width="100" AreTransportControlsEnabled="True"/>

C#

public MainPage()
{
    this.InitializeComponent();

    systemControls = SystemMediaTransportControls.GetForCurrentView();

    // Register to handle the following system transpot control buttons.
    systemControls.ButtonPressed += SystemControls_ButtonPressed;

    mediaElement.CurrentStateChanged += MediaElement_CurrentStateChanged;


    systemControls.IsPlayEnabled = true;
    systemControls.IsPauseEnabled = true;
}

private void MediaElement_CurrentStateChanged(object sender, RoutedEventArgs e)
{
    switch (mediaElement.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;
        case SystemMediaTransportControlsButton.Stop:
            StopMedia();
            break;
        default:
            break;
    }
}

private async void StopMedia()
{
    await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
    {
        mediaElement.Stop();
    });
}

async void PlayMedia()
{
    await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
    {
        if (mediaElement.CurrentState == MediaElementState.Playing)
            mediaElement.Pause();
        else
            mediaElement.Play();
    });
}

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

Output

If you like to enable more controls you can do using the available properties for ex.

systemControls.IsNextEnabled = true;

and you have to add the case in the button switch.

case SystemMediaTransportControlsButton.Next:
                    //handle next song
                    break;

回答2:

You need to use a BackgroundAudio task for this to work on windows mobile. This article will walk you through the github sample provide by Microsoft. https://blogs.windows.com/buildingapps/2016/01/13/the-basics-of-background-audio/