How to use WebCam in XNA

In our previous sample we have seen how to use Microphone device. Now we will be talking about Webcam.

In our previous sample we have seen how to use Microphone device. Now we will be talking about Webcam.

For Webcam we have several alternatives.Com Registration and DirectShow.

I have chosen the DirectShow way! Let me remind one thing: DirectShowLib says No Warranty what happens to your webcam or computer,so I shall tell you so :)

Its much more easier and no-com register at all.

Ok lets start!

Create a new XNA 4.0 Windows Game Project(i named it WebCamXNA)

1.gif

Add these namespaces and references to your project.

System
System.Drawing
DirectShowLib

using System.Windows.Forms;
using DirectShowLib;
using System.Drawing;

Then add Capture.cs file to your project there are lots of comments so no  need to explain further :) but if you need me to explain,please write a comment under this article so i would be more helpful;

Which has this structure:

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Collections;
using System.Runtime.InteropServices;
using System.Threading;
using System.Diagnostics;
using System.Windows.Forms;
using DirectShowLib;

namespace WebCamXNA
{
    internal class Capture : ISampleGrabberCB, IDisposable
    {
        #region Member variables
        /// <summary> graph builder interface. </summary>
        private IFilterGraph2 m_FilterGraph = null;
        // Used to snap picture on Still pin
        private IAMVideoControl m_VidControl = null;
        private IPin m_pinStill = null;
        /// <summary> so we can wait for the async job to finish </summary>
        private ManualResetEvent m_PictureReady = null;
        private bool m_WantOne = false;
        /// <summary> Dimensions of the image, calculated once in constructor for perf. </summary>
        private int m_videoWidth;
        private int m_videoHeight;
        private int m_stride;
        /// <summary> buffer for bitmap data.  Always release by caller</summary>
        private IntPtr m_ipBuffer = IntPtr.Zero;
#if DEBUG
        // Allow you to "Connect to remote graph" from GraphEdit
        DsROTEntry m_rot = null;
#endif
        #endregion
        #region APIs
        [DllImport("Kernel32.dll", EntryPoint="RtlMoveMemory")]
        private static extern void CopyMemory(IntPtr Destination, IntPtr Source, [MarshalAs(UnmanagedType.U4)] int Length);
        #endregion
        // Zero based device index and device params and output window
        public Capture(int iDeviceNum, int iWidth, int iHeight, short iBPP, Control hControl)
        {
            DsDevice [] capDevices;
            // Get the collection of video devices
            capDevices = DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDevice);
            if (iDeviceNum + 1 > capDevices.Length)
            {
                throw new Exception("No video capture devices found at that index!");
            }
            try
            {
                // Set up the capture graph
                SetupGraph( capDevices[iDeviceNum], iWidth, iHeight, iBPP, hControl);
                // tell the callback to ignore new images
                m_PictureReady = new ManualResetEvent(false);
            }
            catch
            {
                Dispose();
                throw;
            }
        }
        /// <summary> release everything. </summary>
        public void Dispose()
        {
#if DEBUG
            if (m_rot != null)
            {
                m_rot.Dispose();
            }
#endif
            CloseInterfaces();
            if (m_PictureReady != null)
            {
                m_PictureReady.Close();
            }
        }
        // Destructor
        ~Capture()
        {
            Dispose();
        }
        /// <summary>
        /// Get the image from the Still pin.  The returned image can turned into a bitmap with
        /// Bitmap b = new Bitmap(cam.Width, cam.Height, cam.Stride, PixelFormat.Format24bppRgb, m_ip);
        /// If the image is upside down, you can fix it with
        /// b.RotateFlip(RotateFlipType.RotateNoneFlipY);
        /// </summary>
        /// <returns>Returned pointer to be freed by caller with Marshal.FreeCoTaskMem</returns>
        public IntPtr Click()
        {
            int hr;
            // get ready to wait for new image
            m_PictureReady.Reset();
            m_ipBuffer = Marshal.AllocCoTaskMem(Math.Abs(m_stride) * m_videoHeight);
            try
            {
                m_WantOne = true;
                // If we are using a still pin, ask for a picture
                if (m_VidControl != null)
                {
                    // Tell the camera to send an image
                    hr = m_VidControl.SetMode(m_pinStill, VideoControlFlags.Trigger);
                    DsError.ThrowExceptionForHR( hr );
                }
                // Start waiting
                if ( ! m_PictureReady.WaitOne(9000, false) )
                {
                    throw new Exception("Timeout waiting to get picture");
                }
            }
            catch
            {
                Marshal.FreeCoTaskMem(m_ipBuffer);
                m_ipBuffer = IntPtr.Zero;
                throw
           }
            // Got one
            return m_ipBuffer;
        }
        public int Width
        {
            get
            {
                return m_videoWidth;
            }
        }
        public int Height
        {
            get
            {
                return m_videoHeight;
            }
        }
        public int Stride
        {
            get
            {
                return m_stride;
            }
        }
        /// <summary> build the capture graph for grabber. </summary>
        private void SetupGraph(DsDevice dev, int iWidth, int iHeight, short iBPP, Control hControl)
        {
            int hr;
            ISampleGrabber sampGrabber = null;
            IBaseFilter capFilter = null;
            IPin pCaptureOut = null;
            IPin pSampleIn = null;
            IPin pRenderIn = null;
            // Get the graphbuilder object
            m_FilterGraph = new FilterGraph() as IFilterGraph2;
            try
            {
#if DEBUG
                m_rot = new DsROTEntry(m_FilterGraph);
#endif
                // add the video input device
                hr = m_FilterGraph.AddSourceFilterForMoniker(dev.Mon, null, dev.Name, out capFilter);
                DsError.ThrowExceptionForHR( hr );
                // Find the still pin
                m_pinStill = DsFindPin.ByCategory(capFilter, PinCategory.Still, 0);
                // Didn't find one.  Is there a preview pin?
                if (m_pinStill == null)
                {
                    m_pinStill = DsFindPin.ByCategory(capFilter, PinCategory.Preview, 0);
                }
                // Still haven't found one.  Need to put a splitter in so we have
                // one stream to capture the bitmap from, and one to display.  Ok, we
                // don't *have* to do it that way, but we are going to anyway.
                if (m_pinStill == null)
                {
                    IPin pRaw = null;
                    IPin pSmart = null;
                    // There is no still pin
                    m_VidControl = null;
                    // Add a splitter
                    IBaseFilter iSmartTee = (IBaseFilter)new SmartTee();
                    try
                    {
                        hr = m_FilterGraph.AddFilter(iSmartTee, "SmartTee");
                        DsError.ThrowExceptionForHR( hr );
                        // Find the find the capture pin from the video device and the
                        // input pin for the splitter, and connnect them
                        pRaw = DsFindPin.ByCategory(capFilter, PinCategory.Capture, 0);
                        pSmart = DsFindPin.ByDirection(iSmartTee, PinDirection.Input, 0);
                        hr = m_FilterGraph.Connect(pRaw, pSmart);
                        DsError.ThrowExceptionForHR( hr );
                        // Now set the capture and still pins (from the splitter)
                        m_pinStill = DsFindPin.ByName(iSmartTee, "Preview");
                        pCaptureOut = DsFindPin.ByName(iSmartTee, "Capture");
                        // If any of the default config items are set, perform the config
                        // on the actual video device (rather than the splitter)
                        if (iHeight + iWidth + iBPP > 0)
                        {
                            SetConfigParms(pRaw, iWidth, iHeight, iBPP);
                        }
                    }
                    finally
                    {
                        if (pRaw != null)
                        {
                            Marshal.ReleaseComObject(pRaw);
                        }
                        if (pRaw != pSmart)
                        {
                            Marshal.ReleaseComObject(pSmart);
                        }
                        if (pRaw != iSmartTee)
                        {
                            Marshal.ReleaseComObject(iSmartTee);
                        }
                    }
                }
                else
                {
                    // Get a control pointer (used in Click())
                    m_VidControl = capFilter as IAMVideoControl;
                    pCaptureOut = DsFindPin.ByCategory(capFilter, PinCategory.Capture, 0);
                    // If any of the default config items are set
                    if (iHeight + iWidth + iBPP > 0)
                    {
                        SetConfigParms(m_pinStill, iWidth, iHeight, iBPP);
                    }
                }
                // Get the SampleGrabber interface
                sampGrabber = new SampleGrabber() as ISampleGrabber;
                // Configure the sample grabber
                IBaseFilter baseGrabFlt = sampGrabber as IBaseFilter;
                ConfigureSampleGrabber(sampGrabber);
                pSampleIn = DsFindPin.ByDirection(baseGrabFlt, PinDirection.Input, 0);
                // Get the default video renderer
                IBaseFilter pRenderer = new VideoRendererDefault() as IBaseFilter;
                hr = m_FilterGraph.AddFilter(pRenderer, "Renderer");
                DsError.ThrowExceptionForHR( hr );
                pRenderIn = DsFindPin.ByDirection(pRenderer, PinDirection.Input, 0);
                // Add the sample grabber to the graph
                hr = m_FilterGraph.AddFilter( baseGrabFlt, "Ds.NET Grabber" );
                DsError.ThrowExceptionForHR( hr );
                if (m_VidControl == null)
                {
                    // Connect the Still pin to the sample grabber
                    hr = m_FilterGraph.Connect(m_pinStill, pSampleIn);
                    DsError.ThrowExceptionForHR( hr );
                    // Connect the capture pin to the renderer
                    hr = m_FilterGraph.Connect(pCaptureOut, pRenderIn);
                    DsError.ThrowExceptionForHR( hr );
                }
                else
                {
                    // Connect the capture pin to the renderer
                    hr = m_FilterGraph.Connect(pCaptureOut, pRenderIn);
                    DsError.ThrowExceptionForHR( hr );
                    // Connect the Still pin to the sample grabber
                    hr = m_FilterGraph.Connect(m_pinStill, pSampleIn);
                    DsError.ThrowExceptionForHR( hr );
                }
                // Learn the video properties
                SaveSizeInfo(sampGrabber);
                ConfigVideoWindow(hControl);
                // Start the graph
                IMediaControl mediaCtrl = m_FilterGraph as IMediaControl;
                hr = mediaCtrl.Run();
                DsError.ThrowExceptionForHR( hr );
            }
            finally
            {
                if (sampGrabber != null)
                {
                    Marshal.ReleaseComObject(sampGrabber);
                    sampGrabber = null;
                }
                if (pCaptureOut != null)
                {
                    Marshal.ReleaseComObject(pCaptureOut);
                    pCaptureOut = null;
                }
                if (pRenderIn != null)
                {
                    Marshal.ReleaseComObject(pRenderIn);
                    pRenderIn = null;
                }
                if (pSampleIn != null)
                {
                    Marshal.ReleaseComObject(pSampleIn);
                    pSampleIn = null;
                }
            }
        }
        private void SaveSizeInfo(ISampleGrabber sampGrabber)
        {
            int hr;
            // Get the media type from the SampleGrabber
            AMMediaType media = new AMMediaType();
            hr = sampGrabber.GetConnectedMediaType( media );
            DsError.ThrowExceptionForHR( hr );
            if( (media.formatType != FormatType.VideoInfo) || (media.formatPtr == IntPtr.Zero) )
            {
                throw new NotSupportedException( "Unknown Grabber Media Format" );
            }
            // Grab the size info
            VideoInfoHeader videoInfoHeader = (VideoInfoHeader) Marshal.PtrToStructure( media.formatPtr, typeof(VideoInfoHeader) );
            m_videoWidth = videoInfoHeader.BmiHeader.Width;
            m_videoHeight = videoInfoHeader.BmiHeader.Height;
            m_stride = m_videoWidth * (videoInfoHeader.BmiHeader.BitCount / 8);
            DsUtils.FreeAMMediaType(media);
            media = null;
        }
        // Set the video window within the control specified by hControl
        private void ConfigVideoWindow(Control hControl)
        {
            int hr;
            IVideoWindow ivw = m_FilterGraph as IVideoWindow;
            // Set the parent
            hr = ivw.put_Owner(hControl.Handle);
            DsError.ThrowExceptionForHR( hr );
            // Turn off captions, etc
            hr = ivw.put_WindowStyle(WindowStyle.Child | WindowStyle.ClipChildren | WindowStyle.ClipSiblings);
            DsError.ThrowExceptionForHR( hr );
            // Yes, make it visible
            hr = ivw.put_Visible( OABool.True );
            DsError.ThrowExceptionForHR( hr );
            // Move to upper left corner
            Rectangle rc = hControl.ClientRectangle;
            hr = ivw.SetWindowPosition( 0, 0, rc.Right, rc.Bottom );
            DsError.ThrowExceptionForHR( hr );
        }
        private void ConfigureSampleGrabber(ISampleGrabber sampGrabber)
        {
            int hr;
            AMMediaType media = new AMMediaType();
            // Set the media type to Video/RBG24
            media.majorType = MediaType.Video;
            media.subType = MediaSubType.RGB24;
            media.formatType = FormatType.VideoInfo;
            hr = sampGrabber.SetMediaType( media );
            DsError.ThrowExceptionForHR( hr );
            DsUtils.FreeAMMediaType(media);
            media = null;
            // Configure the samplegrabber
            hr = sampGrabber.SetCallback( this, 1 );
            DsError.ThrowExceptionForHR( hr );
        }
        // Set the Framerate, and video size
        private void SetConfigParms(IPin pStill, int iWidth, int iHeight, short iBPP)
        {
            int hr;
            AMMediaType media;
            VideoInfoHeader v;
            IAMStreamConfig videoStreamConfig = pStill as IAMStreamConfig;
            // Get the existing format block
            hr = videoStreamConfig.GetFormat(out media);
            DsError.ThrowExceptionForHR(hr);
            try
            {
                // copy out the videoinfoheader
                v = new VideoInfoHeader();
                Marshal.PtrToStructure( media.formatPtr, v );
                // if overriding the width, set the width
                if (iWidth > 0)
                {
                    v.BmiHeader.Width = iWidth;
                }
                // if overriding the Height, set the Height
                if (iHeight > 0)
                {
                    v.BmiHeader.Height = iHeight;
                }
                // if overriding the bits per pixel
                if (iBPP > 0)
                {
                    v.BmiHeader.BitCount = iBPP;
                }
                // Copy the media structure back
                Marshal.StructureToPtr( v, media.formatPtr, false );
                // Set the new format
                hr = videoStreamConfig.SetFormat( media );
                DsError.ThrowExceptionForHR( hr );
            }
            finally
            {
                DsUtils.FreeAMMediaType(media);
                media = null;
            }
        }
        /// <summary> Shut down capture </summary>
        private void CloseInterfaces()
        {
            int hr;
            try
            {
                if( m_FilterGraph != null )
                {
                    IMediaControl mediaCtrl = m_FilterGraph as IMediaControl;
                    // Stop the graph
                    hr = mediaCtrl.Stop();
                }
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex);
            }
            if (m_FilterGraph != null)
            {
                Marshal.ReleaseComObject(m_FilterGraph);
                m_FilterGraph = null;
            }
            if (m_VidControl != null)
            {
                Marshal.ReleaseComObject(m_VidControl);
                m_VidControl = null;
            }
            if (m_pinStill != null)
            {
                Marshal.ReleaseComObject(m_pinStill);
                m_pinStill = null;
            }
        }
        /// <summary> sample callback, NOT USED. </summary>
        int ISampleGrabberCB.SampleCB( double SampleTime, IMediaSample pSample )
        {
            Marshal.ReleaseComObject(pSample);
            return 0;
        }
        /// <summary> buffer callback, COULD BE FROM FOREIGN THREAD. </summary>
        int ISampleGrabberCB.BufferCB( double SampleTime, IntPtr pBuffer, int BufferLen )
        {
            // Note that we depend on only being called once per call to Click.  Otherwise
            // a second call can overwrite the previous image.
            Debug.Assert(BufferLen == Math.Abs(m_stride) * m_videoHeight, "Incorrect buffer length");
            if (m_WantOne)
            {
                m_WantOne = false;
                Debug.Assert(m_ipBuffer != IntPtr.Zero, "Unitialized buffer");
                // Save the buffer
                CopyMemory(m_ipBuffer, pBuffer, BufferLen);
                // Picture is ready.
                m_PictureReady.Set();
            }
            return 0;
        }
    }
}

This is our class that will capture our WebCam device.

How will we use it?

Open your Game1.cs class and write these code:

Add these namespaces:

using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Imaging;

Add these variables:

private System.Windows.Forms.Button button1;
private System.Windows.Forms.PictureBox pictureBox1;      
private System.ComponentModel.Container components = null;
private System.Windows.Forms.PictureBox pictureBox2;
private Capture cam;
IntPtr m_ip = IntPtr.Zero;

Create a Dispose Function:

protected override void Dispose(bool disposing)
{
   if (disposing)
   {
      if (components != null)
      {
         components.Dispose();
      }
   }
   base.Dispose(disposing);
   if (m_ip != IntPtr.Zero)
   {
      Marshal.FreeCoTaskMem(m_ip);
      m_ip = IntPtr.Zero;
   }
}

Add these codes inside Initialize function which loads 2 picturebox,a button and a camera

this.button1 = new System.Windows.Forms.Button();
this.pictureBox1 = new System.Windows.Forms.PictureBox();
this.pictureBox2 = new System.Windows.Forms.PictureBox();
((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.pictureBox2)).BeginInit();

//
// button1
//
this.button1.Location = new System.Drawing.Point(368, 80);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(75, 40);
this.button1.TabIndex = 0;
this.button1.Text = "Click";
this.button1.Click += new System.EventHandler(this.button1_Click);

//
// pictureBox1
//
this.pictureBox1.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
this.pictureBox1.Location = new System.Drawing.Point(16, 256);
this.pictureBox1.Name = "pictureBox1";
this.pictureBox1.Size = new System.Drawing.Size(320, 240);
this.pictureBox1.TabIndex = 1;
this.pictureBox1.TabStop = false;

//
// pictureBox2
//
this.pictureBox2.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
this.pictureBox2.Location = new System.Drawing.Point(16, 8);
this.pictureBox2.Name = "pictureBox2";
this.pictureBox2.Size = new System.Drawing.Size(320, 240);
this.pictureBox2.TabIndex = 2;
this.pictureBox2.TabStop = false;

Control.FromHandle(Window.Handle).Controls.Add(pictureBox1);
Control.FromHandle(Window.Handle).Controls.Add(pictureBox2);
Control.FromHandle(Window.Handle).Controls.Add(button1);
const int VIDEODEVICE = 0; // zero based index of video capture device to use
const int VIDEOWIDTH = 320; // Depends on video device caps
const int VIDEOHEIGHT = 240; // Depends on video device caps
const int VIDEOBITSPERPIXEL = 24; // BitsPerPixel values determined by device
cam = new Capture(VIDEODEVICE, VIDEOWIDTH, VIDEOHEIGHT, VIDEOBITSPERPIXEL, pictureBox2);

Create a Button Click event

private void button1_Click(object sender, System.EventArgs e)
{
    Cursor.Current = Cursors.WaitCursor;
    // Release any previous buffer
    if (m_ip != IntPtr.Zero)
    {
        Marshal.FreeCoTaskMem(m_ip);
        m_ip = IntPtr.Zero;
    }
    // capture image
    m_ip = cam.Click();
    Bitmap b = new Bitmap(cam.Width, cam.Height, cam.Stride, PixelFormat.Format24bppRgb, m_ip);
    // If the image is upsidedown
    b.RotateFlip(RotateFlipType.RotateNoneFlipY);
    pictureBox1.Image = b;
    Cursor.Current = Cursors.Default;
}

Update your UnloadContent function as shown below:

protected override void UnloadContent()
{
    cam.Dispose();
    if (m_ip != IntPtr.Zero)
    {
        Marshal.FreeCoTaskMem(m_ip);
        m_ip = IntPtr.Zero;
    }
}

And now run the project and see what happens!

Picturebox1 displays webcam output,Picturebox 2 will show your picture when clicked the button.

Here looking at camera :)

2.gif
 
And now I have took a photo of mine and showed it on Picturebox2 :)

3.gif
 
Nice! isnt it? Ok not me perhaps but the project itself :) :)

We have added Webcam functionality to our game but whats the point?

What can you do with Webcam in a game?

You can develop Game-Version of ChatRoulette.in which 2 players view their camera in picturebox1 and picturebox2.And in the right corner they can play nice games such as Chess,Card Games(Hearts,FreeCell) or anything you can imagine ;)

And that would be a great game and even celebs can play with you :)

Allright I showed you today how to use webcam functionality in games with a nice demo.

Hope you like it!

See you in other articles ;)

Cheers