DesiredFormat in Visual Basic .NET

Drawing Denso QR Bar Code in Visual Basic .NET DesiredFormat

Inherited from the CaptureDevice class, the VideoCaptureDevice class provides further details specifically on the supported format of the captured video device. The key properties of the VideoCaptureDevice class are shown in Table 4-17.

Gets or sets the video format as an AudioFormat object for the captured audio device. Default is null reference. The VideoFormat class provides the specific technical details such as FramesPerSecond, Height, PixelFormat, Stride, and Width of the video format. Returns a generic collection of the VideoFormat objects detailing supported audio formats for the captured audio device.

The CaptureSource class of System.Windows.Media provides a set of APIs to capture and play video and audio from the connected video device, in the online and offline (out of browser) mode, even capturing a video frame to provide a WriteableBitmap image file and convert it to a static image. The key properties, methods, and events of the CaptureSource class are shown in Tables 4-18, 4-19, and 4-20.

Gets or sets the integrated audio capture device. If you want to capture only video then set AudioCaptureDevice value to null. Returns the current capture stated of the associated audio or video devices. The CaptureState contains three members: Stopped when CaptureSource s Stop method is called and the capture is stopped and completed; Started when CaptureSource s Start method is called and capture is still active; and Failed when the requested capture has failed or no operation has started yet. Gets or sets the integrated video capture device. If you want to capture only audio then set VideoCaptureDevice value to null.

CaptureImageAsync Initiates an asynchronous image capture request. You can retrieve the captured image by handling CaptureImageCompleted event and by calling CaptureImageCompletedEventArgs.Result method from the event data. Start Stop Starts the audio and/or video capture devices relevant to CaptureSource. Stops the audio and/or video capture devices relevant to CaptureSource.

Raised when the capture process has failed to capture from the requested audio and/or video devices. Raised when the capture image process has completed and an image is returned. You can retrieve the captured image by calling CaptureImageCompletedEventArgs.Result method from the event data.

As you might have noticed from the previous example, it should not be too difficult to develop a sample example demonstrating connection to the integrated audio and video device, capture and play video, and take a snap shot from the running live video. For that we will enhance our earlier developed Media Integration application. Add a new Silverlight user control and name it WebCameraAndMicrophoneIntegration. Now copy the XAML and code-behind code from WriteableBitmapDemonstrationwithVideoPlayer to replicate the video player functionality with the image capture capabilities. Now we will make a few modifications in the XAML and code-behind code to replace the video player (MediaElement) with the live video from the web camera. We also need only two buttons one to start and play capturing video and another one to stop capturing video. We will continue with the left click event to capture the image. The following is the portion of the modified XAML code of the WriteableBitmapDemonstrationwithVideoPlayer.xaml file. <Rectangle x:Name="sourceVideo" Fill="White" Height="350" Width = "650" Margin="10" MouseLeftButtonDown="sourceVideo_MouseLeftButtonDown"/> <StackPanel Name="VideoControls" Orientation="Horizontal" HorizontalAlignment="Center" Background="DarkBlue" Height="30" Width="700" Margin="5"> <Button Name="CaptureVideo" Background="AntiqueWhite" Content="Capture Web Camera" FontWeight="Bold" Margin="175,5,0,5" Width="150" Click="CaptureVideo_Click"/> <Button Name="VideoStop" Background="AntiqueWhite" Content="Stop" FontWeight="Bold" Margin="50,5,0,5" Width="150" Click="VideoStop_Click"/> </StackPanel> As shown, we have replaced the MediaElement with the Rectangle, which we will fill with the live video captured from the integrated webcam. Also, we removed the not-required check box and pause button and renamed the play button CaptureVideo. To align these two buttons, we changed the Margin property appropriately. The changes in the code-behind WriteableBitmapDemonstrationwithVideoPlayer.cs file are also minimal. First define the CaptureSource class variable at the WebCameraAndMicroPhoneIntegration class level and create the new instance of CaptureSource under the Loaded event, as shown here in the highlighted fonts: CaptureSource CapturedSource; void WebCameraAndMicroPhoneIntegration_Loaded(object sender, RoutedEventArgs e) { DefineImageTransform(); DefineOpacityMask();