C#

        private CvCapture VideoCapture;
        private IplImage frame;
        private IplImage imgMain;

private void btnVideo_Click(object sender, EventArgs e)
        {
            //double vidWidth, vidHeight;

            if (btnVideo.Text.Equals("Start Video"))
            {
                trainData();

                videoCapture = highgui.CvCreateCameraCapture(0);

                if (videoCapture.ptr == IntPtr.Zero)
                {
                    MessageBox.Show("Failed");
                    return;
                }

                btnVideo.Text = "Stop Video";

                //highgui.CvSetCaptureProperty(ref videoCapture, highgui.CV_CAP_PROP_FRAME_WIDTH, 640);
                //highgui.CvSetCaptureProperty(ref videoCapture, highgui.CV_CAP_PROP_FRAME_HEIGHT, 320);

                highgui.CvQueryFrame(ref videoCapture);

                //vidWidth = highgui.cvGetCaptureProperty(videoCapture, highgui.CV_CAP_PROP_FRAME_WIDTH);
                //vidHeight = highgui.cvGetCaptureProperty(videoCapture, highgui.CV_CAP_PROP_FRAME_HEIGHT);

                //CamImageBox.Width = (int)vidWidth;
                //CamImageBox.Height = (int)vidHeight;

                timerGrab.Interval = 45;
                timerFPS.Interval = 1100;
                timerGrab.Enabled = true;
                timerFPS.Enabled = true;

                hc = new HaarCascade(this);
                abs = new AbsoluteDiff(this);
            }

            else
            {
                btnVideo.Text = "Start Video";
                timerFPS.Enabled = false;
                timerGrab.Enabled = false;

                if (videoCapture.ptr != IntPtr.Zero)
                {
                    highgui.CvReleaseCapture(ref videoCapture);
                    videoCapture.ptr = IntPtr.Zero;
                }
            }
        }

private void timerGrab_Tick(object sender, EventArgs e)
{
    frame = highgui.CvQueryFrame(ref VideoCapture);

    if (frame.ptr == IntPtr.Zero)
    {
        timerGrab.Stop();
        MessageBox.Show("Invalid");
        return;
    }

    imgMain = cxcore.CvCreateImage(cxcore.CvGetSize(ref frame), 8, 3);

    cxcore.CvCopy(ref frame, ref imgMain);
    cxcore.CvFlip(ref imgMain, 0);


    pictureBox1.Image = highgui.ToBitmap(imgMain, false);

    cxcore.CvReleaseImage(ref imgMain);

}