C#中如何通过capGetDriverDescriptionA这个API函数获取视频流

如题，C#中如何通过capGetDriverDescriptionA这个API函数获取视频流。对这个API不是很熟悉，看下面代码如何获取文件流啊，其中picCapture是Image控件！调用这个方法可以在这个控件中生成视频但是不能通过这个控件的Image属性获得！所以想知道如何获取视频流啊  private void OpenPreviewWindow()
        {
            hHwnd = capCreateCaptureWindowA(iDevice.ToString(), (WS_VISIBLE | WS_CHILD), 0, 0, 640, 480, picCapture.Handle.ToInt32(), 0);
            // 
            //  Connect to device
            // 
            if (SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, iDevice, 0) == 1)
            {
                int iHeight = 320;
                int iWidth = 200;
                // 
                // Set the preview scale
                // 
                SendMessage(hHwnd, WM_CAP_SET_SCALE, 1, 0);
                // 
                // Set the preview rate in milliseconds
                // 
                SendMessage(hHwnd, WM_CAP_SET_PREVIEWRATE, 66, 0);
                // 
                // Start previewing the image from the camera
                // 
                SendMessage(hHwnd, WM_CAP_SET_PREVIEW, 1, 0);
                // 
                //  Resize window to fit in picturebox
                // 
                SetWindowPos(hHwnd, HWND_BOTTOM, 0, 0, iWidth, iHeight, (SWP_NOMOVE | SWP_NOZORDER));
            }
            else
            {
                // 
                //  Error connecting to device close window
                //  
                DestroyWindow(hHwnd);
            }
        }