Silverlight 4: List Audio and Video Devices

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In this post, we will see how to use Silverlight to list the available audio and video devices on your system. We will list this information into separate ComboBoxes.

The CaptureDeviceConfiguration Class is a helper class for obtaining information about available capture devices (audio or video) and requesting client user permission to access the captures from available devices. We will be using the following 3 important methods of this class

RequestDeviceAccess – This method requests access for all audio or video devices available on the system.

GetAvailableAudioCaptureDevices - Returns a collection of AudioCaptureDevice objects

GetAvailableVideoCaptureDevices - Returns a collection of VideoCaptureDevice objects

Let’s see some code. First design a layout with two TextBlock, two ListBox and a Button control, as shown below:

In the btnFetch_Click event, add the following code:

private void btnFetch_Click(object sender, RoutedEventArgs e)
{
    // First request access
    if (CaptureDeviceConfiguration.RequestDeviceAccess()
            CaptureDeviceConfiguration.AllowedDeviceAccess)
    {
        // Bind the
        lbAudio.ItemsSource =
            CaptureDeviceConfiguration.GetAvailableAudioCaptureDevices();
        lbVideo.ItemsSource =
            CaptureDeviceConfiguration.GetAvailableVideoCaptureDevices();
    }
}

Run the application and click the button. You should see a dialog similar to the one shown below:

The CaptureDeviceConfiguration.AllowedDeviceAccess property checks whether the Silverlight application has permission to access the video and audio devices. If this property returns false, the RequestDeviceAccess() is called and you see this dialog. You can save the permission by checking the box ‘Remember my answer’ and click Yes.

You will see the following output:

As you can see, the device names do not show up. In order to display the name of the device, you’ll need to add an item template to the ListBox which displays the FriendlyName property of each audio and video device. Go back to your XAML code and make the following changes:

1. Add a DataTemplate to the UserControl.Resources as shown below:

<UserControl.Resources>
    <DataTemplate x:Key="MediaTemplate">
        <TextBlock Text="{Binding FriendlyName}" />
    </DataTemplate>
</UserControl.Resources>

2. Now use this Template in both the ListBox as shown below:

<ListBox x:Name="lbAudio" Grid.Column="0" Grid.Row="1"
    ItemTemplate="{StaticResource MediaTemplate}">
</ListBox>

Once the changes have been made, the entire XAML will look similar to one shown below:

Now run the application and click the button and you should be able to see the Audio and Video devices on your machine

In a forthcoming article, we will see how to extend this example and capture video and audio using Silverlight

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About The Author

Suprotim Agarwal, Developer Technologies MVP (Microsoft Most Valuable Professional) is the founder and contributor for DevCurry, DotNetCurry and SQLServerCurry. He is the Chief Editor of a Developer Magazine called DNC Magazine. He has also authored two Books - 51 Recipes using jQuery with ASP.NET Controls. and The Absolutely Awesome jQuery CookBook.

Follow him on twitter @suprotimagarwal.