System.AccessViolationException : .NET Runtime Error c# worker thread

Question

I have a picturebox in my windows form that renders a stream from my camera it uses a worker thread as you can see :

 VideoFileReader reader = new VideoFileReader();
        Thread Proceso1;
        Proceso1 = new Thread(new ThreadStart(updateui));

        public void updateui()
        {
            try
            {
                reader.Open(RTSPAddress);
                while (true)
                {

                    var previousFrame = pictureRTSP.BackgroundImage;

                    Bitmap currentFrame = reader.ReadVideoFrame();

                        pictureRTSP.BackgroundImage = currentFrame; 
                    if (previousFrame != null)
                        this.Invoke(new MethodInvoker(delegate () {
                            previousFrame.Dispose();
                        }));
                }
                reader.Close();

            }
            catch(ArgumentException ee)
            {
                //Text = ee.ToString();
            }
        }

I dispose the previous frame because of memory usage .In my form i have a button that use pictureRTSP.BackgroundImage to detect the plate in the video.But when i clicked on button for several time i get this error :

Application: nMCR.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.AccessViolationException
   at <Module>.av_read_frame(libffmpeg.AVFormatContext*, libffmpeg.AVPacket*)
   at Accord.Video.FFMPEG.VideoFileReader.readVideoFrame(Int32, System.Drawing.Imaging.BitmapData)
   at Accord.Video.FFMPEG.VideoFileReader.ReadVideoFrame()
   at nMCR.form.MainForm.updateui()
   at System.Threading.ThreadHelper.ThreadStart_Context(System.Object)
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
   at System.Threading.ThreadHelper.ThreadStart()

My button code:

BitmapImage bmImage = null;

        if (IsRTSP)
        {
            //FinalImage = new Bitmap(_snapshotHandler.TakeSnapshot().ToImage());

                FinalImage = new Bitmap(pictureRTSP.BackgroundImage);



            //Bitmap img = (Bitmap)Image.FromStream(FinalImage);
            bmImage = new BitmapImage();

            using (MemoryStream memStream2 = new MemoryStream())
            {
                FinalImage.Save(memStream2, System.Drawing.Imaging.ImageFormat.Png);
                memStream2.Position = 0;

                bmImage.BeginInit();
                bmImage.CacheOption = BitmapCacheOption.OnLoad;
                bmImage.UriSource = null;
                bmImage.StreamSource = memStream2;
                bmImage.EndInit();
            }

Answer 1

First you have a problem in opening the video reader, I think there is a problem in the Platform target of your solution, try making it 32 bit, some libraries that are using C++ native dlls inside may be 32 bit, and doesn't work with AnyCPU.

Secondly You are changing the background image of the picturebox from a thread other than the main thread :

try calling Invoke when changing picturebox image :

this.Invoke(new Action(()=>  pictureRTSP.BackgroundImage = currentFrame ));