C# emgu cv: Recorded Videos playsback to fast/slow

Question

I am trying to write the captured video to a file using VideoWriter and Capture from emguCV, the problem is: If i playback the video that I have just recorded it plays to fast or to slow. How can i fix this, so the video I record will be playbacked/recorded in realtime, so not to slow or to fast?

this is my code:

---

    Capture capture = new Capture();
    VideoWriter vw;
    Size ms_hd_cam_5000_resolution = new Size(1280, 720);
    Label width_label, height_label, recordingTime;
    Button record;
    Thread isRecording;
    Image<Bgr, byte> imageFrame;

    int seconds;
    int minutes;

    public Form1()
    {
        InitializeComponent();
        InitializeConrols();

        //Cam_Properties
        capture.SetCaptureProperty(Emgu.CV.CvEnum.CAP_PROP.CV_CAP_PROP_FRAME_WIDTH, 1280);
        capture.SetCaptureProperty(Emgu.CV.CvEnum.CAP_PROP.CV_CAP_PROP_FRAME_HEIGHT, 720);
        capture.SetCaptureProperty(Emgu.CV.CvEnum.CAP_PROP.CV_CAP_PROP_FPS, 30);

        //VideoWriting_Properties
        vw = new VideoWriter("test.avi", 30, ms_hd_cam_5000_resolution.Width, ms_hd_cam_5000_resolution.Height, true);


    }

    private void InitializeConrols()
    {
        this.BackColor = Color.Black;
        this.ClientSize = new Size(ms_hd_cam_5000_resolution.Width + 25, ms_hd_cam_5000_resolution.Height + 75);
        this.Picture_box.Size = ms_hd_cam_5000_resolution;

        width_label = new Label();
        width_label.Location = new Point(10, ms_hd_cam_5000_resolution.Height + 15);
        width_label.ForeColor = Color.White;
        width_label.Text = "width: " + capture.Width.ToString();

        height_label = new Label();
        height_label.Location = new Point(10, ms_hd_cam_5000_resolution.Height + 40);
        height_label.ForeColor = Color.White;
        height_label.Text = "height: " + capture.Height.ToString();

        recordingTime = new Label();
        recordingTime.Location = new Point(225, ms_hd_cam_5000_resolution.Height + 40);
        recordingTime.ForeColor = Color.White;
        recordingTime.Text = "time: 0";

        record = new Button();
        record.Location = new Point(225, ms_hd_cam_5000_resolution.Height + 15);
        record.ForeColor = Color.White;
        record.Text = "record";

        Controls.Add(width_label);
        Controls.Add(height_label);
        Controls.Add(record);
        Controls.Add(recordingTime);

        record.Click += Record_Click;
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        captureCamImage(sender, e);
        Application.Idle += captureCamImage;
    }

    private void Record_Click(object sender, EventArgs e)
    {
        if (isRecording == null)
        {
            recordingTime.Text = "Time: 0";
            record.Text = "stop";
            isRecording = new Thread(this.Record);
            isRecording.Start(); 
        }
        else
        {
            record.Text = "record";
            isRecording = null;
        }
    }

    private void captureCamImage(object sender, EventArgs e)
    {
        imageFrame = capture.QueryFrame();
        Picture_box.Image = imageFrame.ToBitmap();
        recordTime();
    }

    private void recordTime()
    {
        recordingTime.Text = "Time: " + minutes.ToString() + " : " + seconds.ToString();
    }

    private void Record()
    {
        Stopwatch stopWatch = new Stopwatch();
        stopWatch.Reset();
        stopWatch.Start();
        while (isRecording != null)
        {
            seconds = stopWatch.Elapsed.Seconds;
            minutes = stopWatch.Elapsed.Minutes;

            vw.WriteFrame(imageFrame);
            Thread.Sleep(1000 / 30);
        }
    }

---

Answer 1

Code makes no sense. Hooking to Application.Idle is not a good idea.

Throw code to garbage, have 1 recording thread that capture.QueryFrame() and saves it immediately.
Hell don't even bother with a thread use a timer, set it according to FPS. It won't be exact but better than what you have now.

Answer 2

Try reducing the FPS value.In

vw = new VideoWriter("test.avi", 30, ms_hd_cam_5000_resolution.Width, ms_hd_cam_5000_resolution.Height, true);

Instead of 30 frames/sec provide a lower value.