C# Emgucv turn off webcam

Question

currently my program can open the webcam then dynamic capture the human face, however, I have no idea how to stop the camera because it will keep capturing the face even the windows are closed.

private static VideoCapture _cameraCapture;

public VideoSurveilance()
    {
        InitializeComponent();
        Run();

    }


    void Run()
    {

        try
        {
            _cameraCapture = new VideoCapture();


        }
        catch (Exception e)
        {
            MessageBox.Show(e.Message);
            return;
        }

        _fgDetector = new 
        Emgu.CV.VideoSurveillance.BackgroundSubtractorMOG2();
        _blobDetector = new CvBlobDetector();
        _tracker = new CvTracks();

        Application.Idle += ProcessFrame;
    }

    private void btnStopCamera_Click(object sender, EventArgs e)
    {

        _cameraCapture.Pause();//not working
        _cameraCapture.Stop();//not working
        _cameraCapture.Dispose();//worked but crashed due to memory issue

        this.Close();

        faceManipulate fm = new faceManipulate();
        fm.Show();

Memory issue already solved. However, Dispose will cause the process frame Null Reference Object.

void ProcessFrame(object sender, EventArgs e)
    {
        Mat frame = _cameraCapture.QueryFrame();
        Mat smoothedFrame = new Mat();
        CvInvoke.GaussianBlur(frame, smoothedFrame, new Size(3, 3), 1); 
}

Answer 1

I noticed this code challenge is old and not many solutions have been posted at this time. However, the provided response will not really solve the issue. I encountered the same problem and found a way around it to avoid the memory NullReferenceError. I will use my own code here for convenience, but the challenges are the same, so it applies. Pick the code section that applies to your instance.

MY OBSERVATIONS

1. Any Bitmap object has to be disposed (bitmap.Dispose()) properly to free the memory from overload. The natural garbage collector seems not to pick it up at the end of its function.

2. The Emgu.CV.Capture _capture; object has to be disposed (_capture.Dsipose()) as well but has to be done with boolean control to avoid a NullReference error.

   public partial class Main : Form
   {
       bool isStreaming;
       bool onCamera;
       Capture _capture;
   
       public Main()
       {
           InitializeComponent();
       }
   
       private void btnReset_Click(object sender, EventArgs e)
       {
           onCamera = false;
           isStreaming = false;
           if (_capture != null) _capture.Dispose();
           if (picStream.Image != null) picStream.Image = null;
           if (picCapture.Image != null) picCapture.Image = null;
       }
   
       private void btnStream_Click(object sender, EventArgs e)
       {
           try
           {
               onCamera = true;
               if (_capture != null) _capture.Dispose();
               _capture = new Capture();
               labelStatus.Text = "Streaming...";
               isStreaming = true;
               StreamVideo();
               Application.Idle += Streaming;
           }
           catch {}
       }
   
       private void Streaming(object sender, EventArgs e)
       {
           try
           {
               if(onCamera && isStreaming)
               {
                   if (picStream.Image != null) picStream.Image = null;
   
                   var img = _capture.QueryFrame().ToImage<Bgr, byte>();
                   var bmp = img.Bitmap;
                   picStream.Image = bmp;
               }
           }
           catch {}            
       }
   
       private void btnCapture_Click(object sender, EventArgs e)
       {
           onCamera = true;
           CaptureImage();
           labelStatus.Text = "Captured!";
           if (picCapture.Image != null) picCapture.Image = null;     
           picCapture.Image = picStream.Image;
       }            
   
       private void btnLoadCamera_Click(object sender, EventArgs e)
       {
           try
           {
               if (!isStreaming)
               {
                   _capture = new Capture();
                   StreamVideo();
                   pnlStatus.BackColor = Color.DimGray;
               }
               else
               {
                   _capture.Dispose();
                   Application.Idle -= Streaming;
                   picStream.Visible = true;
                   picStream.Image = null;
                   picCapture.Visible = false;
                   picCapture.Image = null;
                   isStreaming = false;
                   pnlStatus.BackColor = Color.DimGray;
               }
           }
           catch {}            
       }
   }
   

Answer 2

You already solved the issue, you should call the Dispose method.

CameraCapture implements DisposableObject, you should not have it as a static variable, instead you should keep it as a variable and dispose when you are done with it.

I saw that you said that it "worked but crashed due to memory issue", if this is still a problem post a question or comment below describing the memory issue.