/// <summary>
        /// Grabs one frame. The caller doesn't have to call Start first,
        /// but it's recommended in order to get maximum frame rate.
        ///
        /// The second parameter is the capture format, i.e. one of
        /// V2U_GRABFRAME_FORMAT_* optionally combined with flags
        ///
        /// The last parameter is a pointer to the requested crop rectangle.
        /// Pass null if you need the whole frame.
        /// </summary>
        public unsafe Frame GrabFrame(uint format, V2URect *crop)
        {
            V2U_GrabFrame2 *frame = FrmGrab_Frame(iGrabber, format, crop);

            if (frame != null)
            {
                try {
                    return(new Frame(this, frame));
                } catch {
                    FrmGrab_Release(iGrabber, frame);
                }
            }
            return(null);
        }
 static extern unsafe V2U_GrabFrame2 *FrmGrab_Frame(IntPtr fg, uint format, V2URect *crop);