how to handle accessvoilation exception in c#

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C#

video

for my steganography project i have to paste the embedded frame into the orignal frame ,i am using avifile library but i am facing an exception so i need solution of this exception......
i have to paste a frame but avifile library only deals with the video stream then i made a video stream of 1 frame ...

private void btnPaste_Click(object sender, EventArgs e)
        {
           
            
            OpenFileDialog open = new OpenFileDialog();
           // open.Filter = "Bitmap Image|*.bmp";
            if (open.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    Bitmap bb = new Bitmap(open.FileName);
                    VideoStream CreateVideo = new VideoStream(1111, false, 25, bb);//exception occures here (accessvoilation exception)
                  
                    editableStream.Paste(CreateVideo, 0, 156, 1);
                }
                    catch (System.Exception ex)
            {
                throw new Exception(string.Format("StackTrace = {0}", ex.StackTrace));
            }