WPF: Webcam Control

Prize winner in Competition "Best VB.NET article of November 2011"

WPF_WebcamControl/Screenshot_1.png

Introduction

I have on several occasions scoured the net for a simple to use WPF webcam control and either my search queries were awful or I just wasn't comfortable with whatever I found. This webcam interest was recently increased when I read an article, here on CodeProject, that referred to an application that made use of a webcam. It was a Silverlight article and the ease with which one could utilize a webcam in Silverlight made me envious of WPF's little brother (or is it sister?). The VideoBrush in Silverlight is especially a nice touch.

It is with this pain and envy in mind that I decided to try my hand at creating a WPF control that could;

Display webcam video with little coding effort,
Allow saving of webcam video to harddisk, with little coding effort,
Save the webcam video in a variety of video formats

Background

With the previously mentioned goals in mind, I created a WPF UserControl that has the following features,

Displays webcam video,
Enables saving of webcam videos to harddisk,
Enables saving of webcam videos in either .wmv, .mp4, or .flv format

The UserControl also enables you to take a snapshot of the live webcam video, and save it as a Jpeg, Png, Gif, or any other of the ImageFormat properties.

The Webcam control makes heavy use of the Expression Encoder 4 SDK. You therefore need to have the SDK installed on your machine to make use of the UserControl. You can download the SDK from here.

Requirements

To make use of the Webcam control, you require;

.NET Framework 4.0
Expression Encoder SDK

Using the Webcam Control

To use the Webcam control in your WPF application add a reference to WebcamControl.dll and a using/Imports statement for WebcamControl at the top of your class.

Add a reference to Microsoft.Expression.Encoder.dll . Do this by using the Add Reference dialog box, selecting the .NET tab, and selecting Microsoft.Expression.Encoder from the listbox. The Expression Encoder assemblies should be available if you have installed Expression Encoder 4.

The following example, which is the downloadable sample application, shows the use of the Webcam control. The Webcam control is defined in the Window's XAML markup.

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:cam="clr-namespace:WebcamControl;assembly=WebcamControl"    
    ...
    >
    <Grid>
        <cam:Webcam Name="WebCamCtrl" Margin="12,12,12,204"></cam:Webcam>        
        ...
    </Grid>
</Window>

VB.NET

Imports Microsoft.Expression.Encoder.Devices
Imports WebcamControl
Imports System.IO
Imports Microsoft.Expression.Encoder.Live
Imports Microsoft.Expression.Encoder
Imports System.Drawing
Imports System.Drawing.Imaging

Class MainWindow

    ' Bind Webcam dependency properties to ComboBox property.   
    Private Sub MainWindow_Initialized(ByVal sender As Object, _
                                       ByVal e As System.EventArgs) Handles Me.Initialized
        Dim bndg_1 As New Binding("SelectedValue")
        bndg_1.Source = VidDvcsComboBox
        WebCamCtrl.SetBinding(Webcam.VideoDeviceProperty, bndg_1)

        Dim bndg_2 As New Binding("SelectedValue")
        bndg_2.Source = AudDvcsComboBox
        WebCamCtrl.SetBinding(Webcam.AudioDeviceProperty, bndg_2)
    End Sub

    Private Sub MainWindow_Loaded(ByVal sender As Object, _
                                  ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded
        FindDevices()

        Dim vidPath As String = "C:\VideoClips"
        Dim imgPath As String = "C:\WebcamSnapshots"

        If Directory.Exists(vidPath) = False Then
            Directory.CreateDirectory(vidPath)
        End If

        If Directory.Exists(imgPath) = False Then
            Directory.CreateDirectory(imgPath)
        End If

        ' Set some properties of the Webcam control.
        WebCamCtrl.VideoDirectory = vidPath
        WebCamCtrl.VidFormat = VideoFormat.mp4

        WebCamCtrl.ImageDirectory = imgPath
        WebCamCtrl.PictureFormat = ImageFormat.Jpeg
        
        WebCamCtrl.FrameRate = 30
        WebCamCtrl.FrameSize = New Size(320, 240)

        VidDvcsComboBox.SelectedIndex = 0
        AudDvcsComboBox.SelectedIndex = 0
    End Sub

    ' Find available a/v devices.
    Private Sub FindDevices()
        Dim vidDevices = EncoderDevices.FindDevices(EncoderDeviceType.Video)
        Dim audDevices = EncoderDevices.FindDevices(EncoderDeviceType.Audio)

        For Each dvc In vidDevices
            VidDvcsComboBox.Items.Add(dvc.Name)
        Next

        For Each dvc In audDevices
            AudDvcsComboBox.Items.Add(dvc.Name)
        Next
    End Sub

    Private Sub StartButton_Click(ByVal sender As System.Object, _
                                  ByVal e As System.Windows.RoutedEventArgs) _
                              Handles StartButton.Click
        ' Display webcam images on control.
        Try
            WebCamCtrl.StartCapture()
        Catch ex As Microsoft.Expression.Encoder.SystemErrorException
            MessageBox.Show("Device is in use by another application")
        End Try
    End Sub

    Private Sub EndButton_Click(ByVal sender As Object, _
                                ByVal e As System.Windows.RoutedEventArgs) _
                            Handles EndButton.Click
        ' Stop the display of webcam video.
        WebCamCtrl.StopCapture()
    End Sub

    Private Sub RecordButton_Click(ByVal sender As System.Object, _
                                   ByVal e As System.Windows.RoutedEventArgs) _
                               Handles RecordButton.Click
        ' Start recording of webcam video to harddisk.
        WebCamCtrl.StartRecording()
    End Sub

    Private Sub StopRecordButton_Click(ByVal sender As Object, _
                                       ByVal e As System.Windows.RoutedEventArgs) _
                                   Handles StopRecordButton.Click
        ' Stop recording of webcam video to harddisk.
        WebCamCtrl.StopRecording()
    End Sub

    Private Sub SnapshotButton_Click(ByVal sender As System.Object, _
                                     ByVal e As System.Windows.RoutedEventArgs) _
                                 Handles SnapshotButton.Click
        WebCamCtrl.TakeSnapshot()
    End Sub
End Class

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using Microsoft.Expression.Encoder.Devices;
using WebcamControl;
using System.IO;
using System.Drawing.Imaging;

namespace WPF_Webcam
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        
        public MainWindow()
        {
            InitializeComponent();                    

            // Bind the Video and Audio device properties of the
            // Webcam control to the SelectedValue property of 
            // the necessary ComboBox.
            Binding bndg_1 = new Binding("SelectedValue");
            bndg_1.Source = VidDvcsComboBox;
            WebCamCtrl.SetBinding(Webcam.VideoDeviceProperty, bndg_1);

            Binding bndg_2 = new Binding("SelectedValue");
            bndg_2.Source = AudDvcsComboBox;
            WebCamCtrl.SetBinding(Webcam.AudioDeviceProperty, bndg_2);

            // Create directory for saving video files.
            string vidPath = @"C:\VideoClips";

            if (Directory.Exists(vidPath) == false)
            {
                Directory.CreateDirectory(vidPath);
            }

            // Create directory for saving image files.
            string imgPath = @"C:\WebcamSnapshots";

            if (Directory.Exists(imgPath) == false)
            {
                Directory.CreateDirectory(imgPath);
            }

            // Set some properties of the Webcam control
            WebCamCtrl.VideoDirectory = vidPath;
            WebCamCtrl.VidFormat = VideoFormat.mp4;

            WebCamCtrl.ImageDirectory = imgPath;
            WebCamCtrl.PictureFormat = ImageFormat.Jpeg;
                        
            WebCamCtrl.FrameRate = 30;
            WebCamCtrl.FrameSize = new System.Drawing.Size(320, 240);          

            // Find a/v devices connected to the machine.
            FindDevices();

            VidDvcsComboBox.SelectedIndex = 0;
            AudDvcsComboBox.SelectedIndex = 0;
        }

        private void FindDevices()
        {
            var vidDevices = EncoderDevices.FindDevices(EncoderDeviceType.Video);
            var audDevices = EncoderDevices.FindDevices(EncoderDeviceType.Audio);

            foreach (EncoderDevice dvc in vidDevices)
            {
                VidDvcsComboBox.Items.Add(dvc.Name);
            }

            foreach (EncoderDevice dvc in audDevices)
            {
                AudDvcsComboBox.Items.Add(dvc.Name);
            }

        }

        private void StartButton_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                // Display webcam video on control.
                WebCamCtrl.StartCapture();               
            }
            catch (Microsoft.Expression.Encoder.SystemErrorException ex)
            {
                MessageBox.Show("Device is in use by another application");
            }
        }

        private void EndButton_Click(object sender, RoutedEventArgs e)
        {
            // Stop the display of webcam video.
            WebCamCtrl.StopCapture();
        }

        private void RecordButton_Click(object sender, RoutedEventArgs e)
        {
            // Start recording of webcam video to harddisk.
            WebCamCtrl.StartRecording();
        }

        private void StopRecordButton_Click(object sender, RoutedEventArgs e)
        {
            // Stop recording of webcam video to harddisk.
            WebCamCtrl.StopRecording();
        }

        private void SnapshotButton_Click(object sender, RoutedEventArgs e)
        {
            // Take snapshot of webcam image.
            WebCamCtrl.TakeSnapshot();
        }           
       
    }
}

As you can see from the sample code using the Webcam control is not a hard affair once you have the necessary references and using/Imports statements.

Webcam

The following are the members of interest in class Webcam,

Properties

Name	Description	Type
`VideoDirectory`	Gets or Sets the folder where the recorded webcam video will be saved. This is a dependency property.	`String`
`VidFormat`	Gets or Sets the video format in which the webcam video will be saved. This is a dependency property. (The default format is .wmv)	`VideoFormat`
`VideoDevice`	Gets or Sets the name of the video device to be used. This is a dependency property.	`String`
`AudioDevice`	Gets or Sets the name of the audio device to be used. This is a dependency property.	`String`
`IsRecording`	Gets a value indicating whether video recording is taking place. This is a read-only property.	`Boolean`
`ImageDirectory`	Gets or Sets the folder where a snapshot of the webcam video will be saved. This is a dependency property.	`String`
`PictureFormat`	Gets or Sets the format in which a snapshot of the webcam video will be saved. This is a dependency property. (The default format is Jpeg).	`ImageFormat`
`FrameRate`	Gets or sets the frame rate in frames per second. This is a dependency property. (The default value is 15).	`Integer`
`FrameSize`	Gets or sets the size of the video profile. This is a dependency property. (The default size is 320x240).	`System.Drawing.Size`

Methods

	Name	Description
	`StartCapture`	Displays webcam video on control. (Throws a `Microsoft.Expression.Encoder.SystemErrorException` if a specified device is already in use by another application)
	`StopCapture`	Stops the capturing/display of webcam video. (Stops any current recording of webcam video)
	`StartRecording`	Starts the recording of webcam video to a video file. (Throws a `DirectoryNotFoundException` if the directory specified in the `VideoDirectory` property does not exist)
	`StopRecording`	Stops the recording of webcam video.
	`TakeSnapshot`	Saves a snapshot of the webcam video. (Throws a `DirectoryNotFoundException` if the directory specified in the `ImageDirectory` property does not exist)

The Code

The XAML markup for the UserControl is,

<UserControl x:Class="Webcam" 
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
             Height="Auto" Width="Auto" MinHeight="100" MinWidth="100" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             xmlns:wf="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
             mc:Ignorable="d" d:DesignWidth="320" d:DesignHeight="240" Name="Webcam">
    <Grid>
        <WindowsFormsHost Margin="0,0,0,0" Name="WinFormHost" Background="{x:Null}">
            <wf:Panel x:Name="WebcamPanel" Size="320,240" />
        </WindowsFormsHost>
    </Grid>
</UserControl>

The VideoDevice dependency property is defined as follows,

''' <summary>
''' Gets or Sets the name of the video device to be used.
''' </summary>    
Public Property VideoDevice() As String
    Get
        Return CType(GetValue(VideoDeviceProperty), String)
    End Get
    Set(ByVal value As String)
        SetValue(VideoDeviceProperty, value)
    End Set
End Property

Public Shared VideoDeviceProperty As DependencyProperty = _
    DependencyProperty.Register("VideoDevice", GetType(String), GetType(Webcam), _
                          New FrameworkPropertyMetadata(New PropertyChangedCallback( _
                                                              AddressOf VidDeviceChange)))

Private Shared Sub VidDeviceChange(ByVal source As DependencyObject, _
    ByVal e As DependencyPropertyChangedEventArgs)
    Dim deviceName As String = CType(e.NewValue, String)
    Dim eDev = EncoderDevices.FindDevices(EncoderDeviceType.Video).Where _
               (Function(dv) dv.Name = deviceName)

    If (eDev.Count > 0) Then
        CType(source, Webcam).vidDevice = eDev.First

        Try
            CType(source, Webcam).Display()
        Catch ex As Microsoft.Expression.Encoder.SystemErrorException
            Exit Sub
        End Try
    End If
End Sub

The StartCapture() method displays the webcam video in the WinForm Panel, if the necessary properties are set,

''' <summary>
''' Display webcam video on control.
''' </summary>
Public Sub StartCapture()
    If (canCapture = False) Then
        canCapture = True

        Try
            Display()
        Catch ex As Microsoft.Expression.Encoder.SystemErrorException
            canCapture = False
            Throw New Microsoft.Expression.Encoder.SystemErrorException
        End Try
    Else
        Exit Sub
    End If
End Sub
    
' Display video from webcam.
Private Sub Display()
    If (canCapture = True) Then
        If (vidDevice IsNot Nothing) Then
            StopRecording()
            Dispose()

            job = New LiveJob
            Dim frameDuration As Long = CLng(_frameRate * Math.Pow(10, 7))

            deviceSource = job.AddDeviceSource(vidDevice, audDevice)
            deviceSource.PickBestVideoFormat(_frameSize, frameDuration)
            WebcamPanel.Size = _frameSize
            job.OutputFormat.VideoProfile.Size = _frameSize
            deviceSource.PreviewWindow = New PreviewWindow(New HandleRef(WebcamPanel, WebcamPanel.Handle))

            job.ActivateSource(deviceSource)

            isCapturing = True
        End If
    End If
End Sub

The StartRecording() method records video from the webcam to the harddisk,

''' <summary>
''' Starts the recording of webcam video to a video file.
''' </summary>
Public Sub StartRecording()
    If (vidDirectory <> String.Empty AndAlso job IsNot Nothing) Then
        If (Directory.Exists(vidDirectory) = False) Then
            Throw New DirectoryNotFoundException("The specified directory does not exist")
            Exit Sub
        End If

        ' If isCapturing is true then it means the control is capturing images 
        ' from the webcam.
        If (isCapturing = True) Then
            StopRecording()
            job.PublishFormats.Clear()

            Dim timeStamp As String = DateTime.Now.ToString
            timeStamp = timeStamp.Replace("/", "-")
            timeStamp = timeStamp.Replace(":", ".")
            Dim filePath As String = vidDirectory & "\WebcamVid " & timeStamp & "." & _vidFormat.ToString

            Dim fileArchFormat As New FileArchivePublishFormat(filePath)
            job.PublishFormats.Add(fileArchFormat)
            job.StartEncoding()

            _isRecording = True
        End If
    End If
End Sub

The VideoFormat enumeration contains three members,

Public Enum VideoFormat
    wmv
    mp4
    flv
End Enum

The TakeSnapshot() method saves a snapshot of the webcam video. The image generated is actually a snapshot of the WinForms Panel, WebcamPanel. The size of the image will depend on the size of the Webcam control.

''' <summary>
''' Take snapshot of a webcam image. 
''' </summary>
Public Sub TakeSnapshot()
    If (imgDirectory <> String.Empty AndAlso job IsNot Nothing) Then
        If (Directory.Exists(imgDirectory) = False) Then
            Throw New DirectoryNotFoundException("The specified directory does not exist")
            Exit Sub
        End If

        ' If isCapturing is true then it means the control is capturing video 
        ' from the webcam.
        If (isCapturing = True) Then
            Dim panelWidth As Integer = CInt(Me.ActualWidth)
            Dim panelHeight As Integer = CInt(Me.ActualHeight)

            Dim timeStamp As String = DateTime.Now.ToString
            timeStamp = timeStamp.Replace("/", "-")
            timeStamp = timeStamp.Replace(":", ".")

            Dim filePath As String = imgDirectory & "\Snapshot " & timeStamp & "." & imgFormat.ToString

            Dim pnlPnt As Point = WebcamPanel.PointToScreen(New Point(WebcamPanel.ClientRectangle.X, _
                                                                      WebcamPanel.ClientRectangle.Y))

            Using bmp As New Bitmap(panelWidth, panelHeight)
                Using gcs As Graphics = Graphics.FromImage(bmp)
                    gcs.CopyFromScreen(pnlPnt, Point.Empty, New Size(panelWidth, panelHeight))
                End Using
                bmp.Save(filePath, imgFormat)
            End Using
        End If
    End If
End Sub

You can take a look at the other properties and methods defined in class Webcam by downloading the source files from the download link at the top of this article.

Conclusion

I hope that you picked up something useful from this article. I'm a novice in audio-video-encoding-decoding matters so if you have any questions regarding such technicalities, please try to post them in the associated forums here on CodeProject. Suggestions will be beneficial, as well as answers you receive to any technical queries that may be associated with this article's content. Thanks.