Silverlight 4: How to Capture Video from Default Webcam?

• Download sample application - Silverlight 4 Webcam Demo 

Silverlight 4 Beta 1 has been released by Microsoft on 18^th November 2009. There are lots of goodies that came up with the release of the new version. Among them, most of all are requested by the developers & users of Silverlight. In this post, I will demonstrate one of the new features “Accessing Default Webcam using Silverlight 4”.

To create a Silverlight 4 application, you need “Visual Studio 2010 Beta 2”. Download it from the Microsoft site. Then install the “Silverlight Tools 4 for Visual Studio 2010 Beta 2”. After successful installation, create a Silverlight 4 Application project.

Once you done with the project creation, Visual Studio will open the MainPage.xaml for you. Add a Rectangle & three Buttons inside the Grid. The Rectangle will be responsible for the Video output from your VideoCaptureDevice & buttons will be responsible for the interaction with the device. After adding the same, your XAML will look like this:

<Grid x:Name="LayoutRoot" Background="White">
     <StackPanel HorizontalAlignment="Center">
         <Rectangle x:Name="rectWebCamView" Width="500" Height="400"/>
         <StackPanel Orientation="Horizontal" HorizontalAlignment="Center">
             <Button x:Name="btnCaptureDevice" Content="Capture Device" Margin="5"/>
             <Button x:Name="btnPlayCapture" Content="Start Capture" Margin="5"/>
             <Button x:Name="btnStopCapture" Content="Stop Capture" Margin="5"/>
         </StackPanel>
     </StackPanel>
 </Grid>

Now, go to the code behind file (MainPage.xaml.cs) & create an instance of CaptureSource. Then call TryCaptureDevice() to initiate the Video Capture. This first gets the default Video Capture device & assigns it to the VideoBrush instance of the rectangle. Remember that this will ask the user to grant permission to the user device & upon success only, it will start the device.

private void TryCaptureDevice()
{
    // Get the default video capture device
    VideoCaptureDevice videoCaptureDevice = 
      CaptureDeviceConfiguration.GetDefaultVideoCaptureDevice();

    if (videoCaptureDevice == null)
    {
        // Default video capture device is not setup
        btnPlayCapture.IsEnabled = false;
        btnStopCapture.IsEnabled = false;
        btnCaptureDevice.IsEnabled = true;

        MessageBox.Show("You don't have any default capture device");
    }
    else
    {
        btnPlayCapture.IsEnabled = false;
        btnStopCapture.IsEnabled = false;

        // Set the Capture Source to the VideoBrush of the rectangle
        VideoBrush videoBrush = new VideoBrush();
        videoBrush.SetSource(captureSource);
        rectWebCamView.Fill = videoBrush;

        // Check if the Silverlight has already access
        // to the device or grant access from the user
        if (CaptureDeviceConfiguration.AllowedDeviceAccess || 
            CaptureDeviceConfiguration.RequestDeviceAccess())
        {
            btnPlayCapture.IsEnabled = true;
            btnStopCapture.IsEnabled = false;
            btnCaptureDevice.IsEnabled = false;
        }
    }
}

Codeproject