How to diagnose stack trace for AccessViolationException?

I am trying to execute a function that records a portion of a live stream to disk.

This works when the live stream is replaced with a video file that is stored on disk.

After swapping the video file for an IP camera URL I am able to view the live stream, however when I attempt to record the code breaks after writing 79bytes. The error is an AccessViolationException

Here is the full stack trace

System.Exception
  HResult=0x80131500
  Message=Capture error
  Source=Emgu.CV.World
  StackTrace:
   at Emgu.CV.VideoCapture.Run(ExceptionHandler eh)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()

Inner Exception 1:
AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

I have tried to use a command found in this post

netsh winsock reset

but only to achieve the same error.

Can anyone help me?

Here is the methods I am using:

private void ProcessFrame(object sender, EventArgs e)
{
    int fourcc = Convert.ToInt32(_cam1.GetCaptureProperty(CapProp.FourCC));
    string destpath = @"somepath.mp4";
    int Width = Convert.ToInt32(_cam1.GetCaptureProperty(CapProp.FrameWidth));
    int Height = Convert.ToInt32(_cam1.GetCaptureProperty(CapProp.FrameHeight));

    Mat m = new Mat();
    VideoWriter writer = new VideoWriter(destpath, -1, FPS, new Size(Width, Height), true);

    while (FrameNo < 870)
    {
        _cam1.Read(m);
        writer.Write(m);
        cam1Stream.Image = m;
        FrameNo++;

    }
    if (writer.IsOpened)
    {
        writer.Dispose();
        _cam1.Stop();

    }        
}

private void RecordButton_Click(object sender, EventArgs e)
{
    {
        _cam1 = new VideoCapture("udp://someURL", VideoCapture.API.Ffmpeg);
        FPS = _cam1.GetCaptureProperty(CapProp.Fps);
        _cam1.ImageGrabbed += ProcessFrame;
        _cam1.Start();

    }
}

Well looking into your code, I can see two errors.

First, Whenever a image is grabbed from the capture (_cam1) ProcessFrame gets called where it (re-)creates the (Video)writer on every call. Sure you want to do that?

Secondly, have you checked if the FPS property is available on a camera? I assume that it's not.

My advice would be, to see first how it runs a read-only loop on the camera without attempting to write.

Once this part runs smooth, you can take it a step forward and try the writing.