Webcam does not stop after closing program

Question

I'm creating wpf application and capturing images with my usb webcam. The library I'm using is Aforge. Everything is fine, I mean I get the live stream from the webcam and I'm able to capture images etc. But the problem is when I close the program camera is still running (Yellow LED is showing) and the program is not ending. How could I get the camera stopped?

protected override void OnClosing(CancelEventArgs e)
{
  base.OnClosing(e);            
  if (WebCam != null)
      if (WebCam.IsRunning)
         {
           WebCam.SignalToStop();
           WebCam.WaitForStop();
           WebCam = null;
          }
}

this is how I'm using NewFreameEventArgs to get stream

 public void Cam_NewFrame(object sender, NewFrameEventArgs eventArgs)
        {            
            try
            {
                System.Drawing.Image img = (Bitmap)eventArgs.Frame.Clone();
                MemoryStream ms = new MemoryStream();
                img.Save(ms, ImageFormat.Jpeg);
                ms.Seek(0, SeekOrigin.Begin);
                BitmapImage bi = new BitmapImage();
                bi.BeginInit();
                bi.StreamSource = ms;
                bi.EndInit();
                bi.Freeze();

                Dispatcher.BeginInvoke(new ThreadStart(delegate
                {
                    previewWindow.Source = bi;

                    mainCameraImageControl.Source = bi;
                }));

            }
            catch (Exception ex)
            {

            }
        }

Amit Joshi · Accepted Answer · 2017-06-20T04:59:16.430

I suggest you should check if you have registered for any event of webcam. If yes, unsubscribe the same.

WebCam.NewFrame -= new NewFrameEventHandler(WebCam_NewFrameReceived);

Edit: Reply to your comments and edited question

WebCam.NewFrame -= new NewFrameEventHandler(WebCam_NewFrameReceived);
Dispatcher.CurrentDispatcher.InvokeShutdown();
WebCam.SignalToStop();
WebCam.WaitForStop();

First, unsubscribe the events. Then call InvokeShutdown(). Following is from Microsoft link:

The Dispatcher does not shut down completely until the event queue unwinds.

This way, events and dispatchers are disconnected from instance. Then you signal the cam to stop and wait for stop.

I've update my question. Sorry for asking stupid question but where and how could I shutdown current dispatcher — TestMan, Jun 16 '17 at 11:40

score 0 · Answer 2 · answered Jun 16 '17 at 08:52

0

You're signaling the webcam to stop, but not actually waiting for it to stop.

Your Webcam object should have a WaitToStop() method, that you should also call after SignalToStop().

Also check this aforge.net thread for more information.

answered Jun 16 '17 at 08:52

Kilazur

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I have tried WaitForStop() method as well, but it helps me partly. I mean some times WebCam stops imediately and some times stop time is hours. – TestMan Jun 16 '17 at 08:58
Definitely check the thread I linked. You may have a multithreading issue, and not using the same Dispatcher to use and stop your webcam. If it helps you, I'll edit the question. – Kilazur Jun 16 '17 at 09:12

Webcam does not stop after closing program

2 Answers2