Applicability
- Microsoft Silverlight, versions 3 and greater
- Silverlight managed programming model and Silverlight XAML
Microsoft has stopped updating and distributing Silverlight, and authors are encouraged to use HTML for accessible web content.
This technique relates to Success Criterion 1.4.2: Audio Control (Sufficient).
Description
The objective of this technique is to adjust the volume for media
               				that is played in Silverlight applications, as implemented through
               				incorporating the Silverlight MediaElement object.
               				By default, a MediaElement will start playing its
               				media as soon as the UI loads completely AND the media source file
               				is downloaded. For details, see . 
            
At any given time, a Silverlight MediaElement is associated
               				with exactly one media source as specified by the Source property
               				URI value. That source might be audio-only, or audio-video. The Volume property
               				of MediaElement affects the audio playback volume
               				of that particular source when it is playing. The Silverlight plug-in
               				does not have a user option that adjusts the volume of ALL Silverlight
               				applications as run within it, or a standardized user interface that
               				is always present for all uses of MediaElement. Therefore
               				it is the responsibility of Silverlight application authors to provide
               				an adequate set of user interface controls, including volume adjustment,
               				whenever the Silverlight application plays media that has an audio
               				component. 
            
Examples
Example 1: Providing a volume control and a Mute control as part of a set of user interface controls that go with a MediaElement
In addition to the Play Pause Stop controls, application authors can
                  						also provide a dedicated control that changes the Volume property
                  						of the MediaElement. The typical control for setting
                  						a discrete volume is Slider, because Slider is
                  						designed for input of discrete values from a range. Adjusting Volume with
                  						a data bound Slider changes the volume of any actively
                  						playing media, independent of the system volume or of any other audio
                  						source controlled by Silverlight. For Volume as set with the Slider,
                  						the Binding in XAML declares the interaction between
                  						the control and the MediaElement, without requiring
                  						an event handler. However, not all users will be able to interact quickly
                  						with a Slider, particularly if they are not using
                  						a mouse. To help these users, application authors should also include
                  						a "Mute" control. Rather than setting Volume to
                  						0, application authors should instead set IsMuted to
                  						true. Note that Volume and IsMuted values
                  						are not directly related; if IsMuted is set to true,
                  						that does not set Volume to 0, nor does setting Volume to
                  						zero cause IsMuted to be set true. 
               
<UserControl x:Class="MediaElementControls.MainPage"
   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  >
   <Grid x:Name="LayoutRoot">
       <StackPanel>
           <MediaElement x:Name="media" Source="/xbox.wmv"
          Width="300" Height="300" 
          AutomationProperties.Name="Video of new Fable game for XBox"           
       />
           <Grid Name="UIControls">
               <Grid.ColumnDefinitions>
                   <ColumnDefinition Width="*" />
                   <ColumnDefinition Width="*" />
                   <ColumnDefinition Width="*"/>
               </Grid.ColumnDefinitions>
               <Grid.RowDefinitions>
                   <RowDefinition Height="*" />
                   <RowDefinition Height="Auto" />
                   <RowDefinition Height="20" />
               </Grid.RowDefinitions>
               <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" />
               <Button Click="MuteMedia" 
   Grid.Row="2" Grid.Column="0" Content="Mute" />
               <TextBlock Name="VolumeLabel" Grid.Row="2" Grid.Column="1" HorizontalAlignment="Right">Volume</TextBlock>
               <Slider Height="20"
           Value="{Binding Volume, Mode=TwoWay, ElementName=media}"
           Minimum="0" Maximum="1"
           Grid.Row="2" Grid.Column="2" Grid.ColumnSpan="2"
               AutomationProperties.LabeledBy="{Binding ElementName=VolumeLabel}"/>
           </Grid>
       </StackPanel>
   </Grid>
</UserControl>
The following is the C# logic.
 private void StopMedia(object sender, RoutedEventArgs e)
 {
     media.Stop();
 }
 private void PauseMedia(object sender, RoutedEventArgs e)
 {
     media.Pause();
 }
 private void PlayMedia(object sender, RoutedEventArgs e)
 {
     media.Play();
 }
 private void MuteMedia(object sender, RoutedEventArgs e)
 {
    Button target = sender as Button;
    // mute if not muted, unmute if already muted, in either case make sure the button content for text and accessibility info is updated
    if (!media.IsMuted)
    {
       media.IsMuted = true;
       target.Content = "Unmute";
    }
    else
    {
        media.IsMuted = false;
        target.Content = "Mute";
    }
 }
This example is shown in operation in the working example of Media Element Controls.
Resources
Resources are for information purposes only, no endorsement implied.
- Volume
- Audio and Video Overview
- 
                  Silverlight
                     						Media Framework - a framework and a media player control implementation
                  						that incorporates many of the Silverlight techniques related to MediaElement
Tests
Procedure
-  Using a browser that supports Silverlight, open an HTML page that
                     					references a Silverlight application through an object tag. It is
                     					expected that the application incorporates a MediaElement.
- Check that a control is available for controlling volume and that the Volume control controls the volume of the playing media, independently from system volume.
- Check that control is available for muting, and that the Mute control mutes the volume of the playing media, independently from system volume.
Expected Results
#2 OR #3 is true.