Techniques for WCAG 2.0

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SL24: Using AutoPlay to Keep Silverlight Media from Playing Automatically


This technique relates to:

User Agent and Assistive Technology Support Notes

See User Agents Supported for general information on user agent support.


The objective of this technique is to use the AutoPlay property of MediaElement object, which prevents the MediaElement from playing its media source automatically.

By default the value of AutoPlay is true, which causes any media that is the Source of the MediaElement to play as soon as either the entire source file is loaded (for nonstreaming media) or an initial buffer is loaded (for streaming media). To prevent the possible accessility issues, developers can instead specifically set AutoPlay to false, so that the user always controls whether the media plays. This technique would thus be used in combination with providing user interface controls that go along with the MediaElement, and that enable the user to control the media. In particular, the user interface controls enable the media to play, pause or stop, with event wiring for those controls associated with the Play, Pause or Stop methods of the MediaElement object.


Example 1: Setting AutoPlay to false, and providing the typical MediaElement controls in the UI

This example has a UI definition in XAML and interaction logic in C#.

The following is the basic UI in XAML. Note the AutoPlay="false" setting.

<UserControl x:Class="MediaElementControlsAutoPlay.MainPage"
   <Grid x:Name="LayoutRoot">
           <ColumnDefinition Width="*" />
           <ColumnDefinition Width="*" />
           <ColumnDefinition Width="*"/>
           <RowDefinition Height="*" />
           <RowDefinition Height="Auto" />
       <MediaElement x:Name="media" Source="/xbox.wmv"
          Width="300" Height="300" 
          Grid.Column="0" Grid.Row="0" Grid.ColumnSpan="3"
          AutomationProperties.Name="Video of new Fable game for XBox"           
       <Button Click="StopMedia" 
    Grid.Column="0" Grid.Row="1" Content="Stop" />
       <Button Click="PauseMedia" 
    Grid.Column="1" Grid.Row="1" Content="Pause" />
       <Button Click="PlayMedia" 
    Grid.Column="2" Grid.Row="1" Content="Play" />

The following is the C# logic.

 private void StopMedia(object sender, RoutedEventArgs e)
 private void PauseMedia(object sender, RoutedEventArgs e)
 private void PlayMedia(object sender, RoutedEventArgs e)

This example is shown in operation in the working example of Media Element Controls with AutoPlay False.


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  1. Using a browser that supports Silverlight, open an HTML page that references a Silverlight application through an object tag. The application is expected to use a MediaElement object to play prerecorded media.

  2. Check that the media does not play automatically as soon as the application loads and displays. Rather, the user is presented with a user interface that can start the media per the user's action.

Expected Results

#2 is true.

If this is a sufficient technique for a success criterion, failing this test procedure does not necessarily mean that the success criterion has not been satisfied in some other way, only that this technique has not been successfully implemented and can not be used to claim conformance.

Techniques are Informative

Techniques are informative—that means they are not required. The basis for determining conformance to WCAG 2.0 is the success criteria from the WCAG 2.0 standard—not the techniques. For important information about techniques, please see the Understanding Techniques for WCAG Success Criteria section of Understanding WCAG 2.0.