проблемы с захватом очереди кадров с определенным интервалом

if (fCaptured || (savedArray == null))
            {
                return 1;
            }
            fCaptured = true;
            if ((pBuffer != IntPtr.Zero) && (BufferLen > 1000) && (BufferLen <= savedArray.Length))
            {
                try
                {
                    Marshal.Copy(pBuffer, savedArray, 0, BufferLen);
                }
                catch (Exception exc)
                {
                    throw;
                }
            }
            else
            {
                return 1;
            }
            this.BeginInvoke(new PictureDone(OnCaptureDone));
            return 0;

void OnCaptureDone()
        {
            int hr = 0;
            if (sampGrabber == null) return;
            try
            {
                hr = sampGrabber.SetCallback(null, 0);
                DsError.ThrowExceptionForHR(hr);
                int w = videoInfoHeader.BmiHeader.Width;
                int h = videoInfoHeader.BmiHeader.Height;
                if (((w & 0x03) != 0) || (w < 32) || (w > 4096) || (h < 32) || (h > 4096))
                    return;
                int stride = w * 3;
                try
                {
                    GCHandle handle = GCHandle.Alloc(savedArray, GCHandleType.Pinned);
                    int scan0 = handle.AddrOfPinnedObject().ToInt32();
                    handle.Free();
                    scan0 += (h - 1) * stride;
                    IntPtr scan = (IntPtr)scan0;
                    Bitmap b = new Bitmap(w, h, -stride, PixelFormat.Format24bppRgb, scan);
                    scan = IntPtr.Zero;
                    savedArray = null;
                    picPreview.Image = (Image)b.Clone();
                    if (picBuffer.Count == bufLength)
                        picBuffer.Dequeue();
                    picBuffer.Enqueue((Bitmap)picPreview.Image);
                    WaitForSave.Set();
                    b.Dispose();
                }
                catch (Exception exc)
                {
                    throw;
                }
            }
            catch (Exception ee)
            {
                MessageBox.Show(this, ee.Message, "DirectShow.NET", MessageBoxButtons.OK, MessageBoxIcon.Stop);
            }
        }

private void picWorker_DoWork(object sender, DoWorkEventArgs e)
        {
            Bitmap[] q = (Bitmap[])e.Argument;
            int i = 0;
            lock (q.SyncRoot)
            {
                foreach (Bitmap bmp in q)
                {
                    string picpath = pth + "\\" + String.Format("{0:00}", i) + "_shot.jpg";
                    bmp.Save(picpath, ici, ep);
                    i++;
                }
            }
            q = null;
        }

private void picWorker_DoWork(object sender, DoWorkEventArgs e)
        {
            Bitmap[] q = (Bitmap[])e.Argument;
            int i = 0;
            string picpath = string.Empty;
            foreach (Bitmap bmp in q)
            {
                picpath = pth + "\\" + String.Format("{0:00}", i) + "_shot.jpg";
                Image picObj = (Image)bmp.Clone();
                try
                {
                    picObj.Save(picpath, ici, ep);
                }
                catch (Exception exc)
                {
                    if (exc is AccessViolationException)
                        throw;
                }
                finally
                {
                    picObj.Dispose();
                }
                picpath = string.Empty;
                i++;
            }
            q = null;
        }

void OnCaptureDone()
        {
            int hr = 0;
            if (sampGrabber == null) return;
            try
            {
                hr = sampGrabber.SetCallback(null, 0);
                DsError.ThrowExceptionForHR(hr);
                int w = videoInfoHeader.BmiHeader.Width;
                int h = videoInfoHeader.BmiHeader.Height;
                if (((w & 0x03) != 0) || (w < 32) || (w > 4096) || (h < 32) || (h > 4096))
                    return;
                int stride = w * 3;
                GCHandle handle = GCHandle.Alloc(savedArray, GCHandleType.Pinned);
                int scan0 = handle.AddrOfPinnedObject().ToInt32();
                handle.Free();
                scan0 += (h - 1) * stride;
                IntPtr scan = (IntPtr)scan0;
                Image b = new Bitmap(w, h, -stride, PixelFormat.Format24bppRgb, scan);
                Image oPic = new Bitmap(m_videoWidth, m_videoHeight);
                Graphics g = Graphics.FromImage(oPic);
                g.DrawImage(b, 0, 0);
                string date = DateTime.Now.ToString();
                SizeF d = g.MeasureString(date, transparentFont);
                float sLeft = (m_videoWidth - d.Width) / 2;
                float sTop = m_videoHeight - d.Height - fSize;
                g.DrawString(date, transparentFont, transparentBrush, sLeft, sTop);
                b.Dispose();
                g.Dispose();
                scan = IntPtr.Zero;
                savedArray = null;
                picPreview.Image = oPic;
                if (picBuffer.Count == bufLength)
                    picBuffer.Dequeue();
                picBuffer.Enqueue((Bitmap)oPic);
                WaitForSave.Set();
            }
            catch (Exception ee)
            {
                MessageBox.Show(this, ee.Message, "DirectShow.NET", MessageBoxButtons.OK, MessageBoxIcon.Stop);
            }
        }

private void picWorker_DoWork(object sender, DoWorkEventArgs e)
        {
            Bitmap[] q = (Bitmap[])e.Argument;
            int i = 0;
            string picpath = string.Empty;
            foreach (Bitmap bmp in q)
            {
                picpath = pth + "\\" + String.Format("{0:00}", i) + "_shot.jpg";
                Image picObj = new Bitmap(bmp.Width, bmp.Height);
                Graphics g = Graphics.FromImage(picObj);
                g.DrawImage(bmp, 0, 0);                
                g.Dispose();
                try
                {
                    picObj.Save(picpath, ici, ep);
                }
                catch (Exception exc)
                {
                    if (exc is AccessViolationException)
                        throw;
                }
                finally
                {
                    picObj.Dispose();
                }
                picpath = string.Empty;
                i++;
            }
            q = null;
        }