USB摄像头无法重复启动，点开第一次，没问题，但是如果再点第二次就会报错

Question

其中这个代码是报错的部分，我在第一次打开视频的时候，一点问题没有，但是当把窗体的子窗口关闭，再次打开的时候就会报出错误，hr就会变为负值，希望大家可以给出解决的办法吧，谢谢了
这代码主要是实现显示摄像头的图像显示，自己琢磨了好久了也解决不了，希望大家帮忙吧
                Guid cat = PinCategory.Preview;
                //设置媒体类型为视频帧
                Guid med = MediaType.Video;
                //输出视频流
                hr = capGraph.RenderStream(ref cat, ref med, capFilter, null, null);
完整的程序代码如下：
        ///   
        /// 构建Capture Graph 
        ///
        bool SetupGraph()
        {
            int hr;
            try
            {
                //创建Capture Graph Builder组件graphBuilder,并初始化
                hr = capGraph.SetFiltergraph(graphBuilder);
                if (hr < 0)
                    Marshal.ThrowExceptionForHR(hr);
                //通过AddFilter将graphBuilder组件添加到视频捕获设备capFilter中
                hr = graphBuilder.AddFilter(capFilter, "视频驱动");
                if (hr < 0)
                    Marshal.ThrowExceptionForHR(hr);                //DsUtils.ShowCapPinDialog( capGraph, capFilter, this.Handle );
                //设置媒体类型
                AMMediaType media = new AMMediaType();
                media.majorType = MediaType.Video;
                media.subType = MediaSubType.RGB24;
                media.formatType = FormatType.VideoInfo;
                hr = sampGrabber.SetMediaType(media);
                if (hr < 0)
                    Marshal.ThrowExceptionForHR(hr);
                //将graphBuilder添加到baseGrabFlt中
                hr = graphBuilder.AddFilter(baseGrabFlt, "Ds.NET Grabber");
                if (hr < 0)
                    Marshal.ThrowExceptionForHR(hr);
                //选择Preview 输出Pin
                Guid cat = PinCategory.Preview;
                //设置媒体类型为视频帧
                Guid med = MediaType.Video;
                //输出视频流
                hr = capGraph.RenderStream(ref cat, ref med, capFilter, null, null);
                if (hr < 0)
                    Marshal.ThrowExceptionForHR(hr);
                //选择Capture输出Pin
                cat = PinCategory.Capture;
                //选择Capture输出Pin
                med = MediaType.Video;
                //输出视频流
                hr = capGraph.RenderStream(ref cat, ref med, capFilter, null, baseGrabFlt);
                if (hr < 0)
                    Marshal.ThrowExceptionForHR(hr);
                //以下代码实现视频帧捕捉功能
                media = new AMMediaType();
                hr = sampGrabber.GetConnectedMediaType(media);
                if (hr < 0)
                    Marshal.ThrowExceptionForHR(hr);
                if ((media.formatType != FormatType.VideoInfo) || (media.formatPtr == IntPtr.Zero))
                    throw new NotSupportedException("Unknown Grabber Media Format");                videoInfoHeader = (VideoInfoHeader)Marshal.PtrToStructure(media.formatPtr, typeof(VideoInfoHeader));
                Marshal.FreeCoTaskMem(media.formatPtr); media.formatPtr = IntPtr.Zero;                hr = sampGrabber.SetBufferSamples(false);
                if (hr == 0)
                    hr = sampGrabber.SetOneShot(false);
                if (hr == 0)
                    hr = sampGrabber.SetCallback(null, 0);
                if (hr < 0)
                    Marshal.ThrowExceptionForHR(hr);                return true;
            }
            catch (Exception ee)
            {
                LOG.Error(ee.ToString());
                MessageBox.Show(this, "不能启动视频\r\n" + ee.Message, "系统提示：", MessageBoxButtons.OK, MessageBoxIcon.Stop);
                CloseInterfaces();
                return false;
            }
        }

Answer 1

我的问题跟http://topic.csdn.net/t/20060824/15/4972908.html完全一样，但是也没有解决方法，它提到的本身com提供了什么方法没有，例如close或者dispose之类，有没有什么人给点提示啊，不太明白这是什么意思？

Answer 2

释放资源是以下代码，可能还是释放的时候某些资源没有释放掉，所以才会出现问题，望各位大哥给提出宝贵意见！
        /// <summary>
        /// 清理并释放DirectShow. 
        /// </summary>        
        void CloseInterfaces()
        {
            int hr = 0;
            try
            {
                lock (this)
                {
                    if (mediaEvt != null)
                    {
                        hr = this.mediaEvt.SetNotifyWindow(IntPtr.Zero, 0, IntPtr.Zero);
                        //DsError.ThrowExceptionForHR(hr);
                    }
                    // Release and zero DirectShow interfaces
                    if (rotCookie != 0)
                    {
                        DsROT.RemoveGraphFromRot(ref rotCookie);                        
                    }
                    if (mediaCtrl != null)
                    {
                        hr = mediaCtrl.Stop();
                        mediaCtrl = null;
                    }
                    if (mediaEvt != null)
                    {
                        hr = mediaEvt.SetNotifyWindow(IntPtr.Zero, WM_GRAPHNOTIFY, IntPtr.Zero);
                        mediaEvt = null;
                    }                    if (videoWin != null)
                    {
                        hr = videoWin.put_Visible(DsHlp.OAFALSE);
                        hr = videoWin.put_Owner(IntPtr.Zero);
                        videoWin = null;
                    }                    baseGrabFlt = null;
                    if (sampGrabber != null)
                        Marshal.ReleaseComObject(sampGrabber); sampGrabber = null;
                    
                    if (capGraph != null)
                        Marshal.ReleaseComObject(capGraph); capGraph = null;
                    
                    if (graphBuilder != null)
                        Marshal.ReleaseComObject(graphBuilder); graphBuilder = null;
                    
                    if (capFilter != null)
                        Marshal.ReleaseComObject(capFilter); capFilter = null;
                    
                    if (capDevices != null)
                    {
                        foreach (DsDevice d in capDevices)
                            d.Dispose();
                        capDevices = null;
                    }
                    GC.Collect();
                }
            }
            catch (Exception)
            { }
        }