、获取视频采集设备IBaseFilter接口对象的方法

 //获取所有视频设备名称

 public ArrayList GetVideoInputDevice()

       { return GetDeviceCollection(FilterCategory.VideoInputDevice);}

 private ArrayList GetDeviceCollection(Guid DeviceType)

       {

           ArrayList returnString = new ArrayList();

           foreach (DsDevice ds in DsDevice.GetDevicesOfCat(DeviceType))

           {

               returnString.Add(ds.Name);

           }

           return returnString;

       }

 //通过获取到的视频设备名称设置采集设备的IBaseFilter对象

  public bool SetVideoInputDevice(string VideoInputDeviceName)

       {    //创建视频输入设备接口

           theVideoDevice = CreateFilter(FilterCategory.VideoInputDevice, VideoInputDeviceName);

       }

 //通过过滤器类型和过滤器名称获取IBaseFilter接口

 private IBaseFilter CreateFilter(Guid category, string friendlyname)

       {

           object source = null;

           Guid iid = typeof(IBaseFilter).GUID;

           foreach (DsDevice device in DsDevice.GetDevicesOfCat(category))

           {

               if (device.Name.CompareTo(friendlyname) == )

               {

                   device.Mon.BindToObject(null, null, ref iid, out source);

                   break;

               }

           }

           return (IBaseFilter)source;

       }

 、初始化基本的接口对象 

 private void InitInterfaces()

       {

           int hr = ;

           // 获取IGraphBuilder接口对象

           this.m_graphBuilder = (IGraphBuilder)new FilterGraph();

           //获取ICaptureGraphBuilder2接口对象

           this.m_captureGraphBuilder = (ICaptureGraphBuilder2)new CaptureGraphBuilder2();

           //获取m_graphBuilder 接口对象的IMediaControl对象

           this.m_mediaControl = (IMediaControl)this.m_graphBuilder;

           //获取m_graphBuilder 接口对象的IVideoWindow对象

           this.m_videoWindow = (IVideoWindow)this.m_graphBuilder;

           //获取m_graphBuilder 接口对象的IMediaEventEx对象

           this.m_mediaEventEx = (IMediaEventEx)this.m_graphBuilder;

           //设置ICaptureGraphBuilder2的IGraphBuilder接口对象为当前对象

           hr = this.m_captureGraphBuilder.SetFiltergraph(this.m_graphBuilder);

           DsError.ThrowExceptionForHR(hr);

           //注册事件到应用程序的窗体上

           hr = this.m_mediaEventEx.SetNotifyWindow(this.hwnPropertyPageOwner, WM_GRAPHNOTIFY, IntPtr.Zero);

           DsError.ThrowExceptionForHR(hr);

       }

 、开始视频预览

 public void VideoPreview()

        try

       {

           int hr = ;

           hr = this.m_graphBuilder.AddFilter(theVideoDevice, "Video Capture");

           DsError.ThrowExceptionForHR(hr);

           // 通过theVideoDevice（IBaseFilter）视频接口对象的Preview Pin预览

           hr = this.m_captureGraphBuilder.RenderStream(PinCategory.Preview, MediaType.Video, theVideoDevice, null, null);

           DsError.ThrowExceptionForHR(hr);

            //插入SampleGrabber

           m_pinStill = DsFindPin.ByCategory(theVideoDevice, PinCategory.Still, );

           if (m_pinStill == null)

               {

                   m_pinStill = DsFindPin.ByCategory(theVideoDevice, PinCategory.Capture, );

               }

               // 获取theVideoDevice的IAMVideoControl对象，对于具有Still Pin的对象可以获到，采集设备不具备Still Pin，那么该对象将为Null

               m_VidControl = theVideoDevice as IAMVideoControl;

               // 设置采集视频参数

               if (this.videoHeight + this.videoWidth + this.videoStride > )

               {

                   SetConfigParms(m_pinStill, this.videoWidth, this.videoHeight, );

               }

              //开始拍照功能所需的接口对象

               // 获得SampleGrabber对象接口

               sampGrabber = new SampleGrabber() as ISampleGrabber;

               // 配置sample grabber

               baseGrabFlt = sampGrabber as IBaseFilter;

               ConfigureSampleGrabber(sampGrabber);

               // 将sample grabber添加到图形过滤器中

               hr = m_graphBuilder.AddFilter(baseGrabFlt, "Ds.NET Grabber");

               DsError.ThrowExceptionForHR(hr);

               //通过渲染将采集设备的相关输出Pin与sample grabber对象的输入Pin连接起来

               //如果采集设备提供Still Pin，则通过Still Pin连接，否则直接使用Capture Pin连接

               if (m_VidControl!=null)

               {

                   hr = this.m_captureGraphBuilder.RenderStream(PinCategory.Still, MediaType.Video, theVideoDevice, null, baseGrabFlt);

                   DsError.ThrowExceptionForHR(hr);

               }

               else

               {

                   hr = this.m_captureGraphBuilder.RenderStream(PinCategory.Capture, MediaType.Video, theVideoDevice, null, baseGrabFlt);

                   DsError.ThrowExceptionForHR(hr);

               }

             //设置抓取图片相关参数

               SaveSizeInfo(sampGrabber);

             //拍照功能所需的接口对象添加结束

           // 开始将视频窗口绑定到主窗体上

           hr = this.m_videoWindow.put_Owner(this.hwnVideoWindowOwner);

           DsError.ThrowExceptionForHR(hr);

           hr = this.m_videoWindow.put_WindowStyle(WindowStyle.Child | WindowStyle.ClipChildren);

           DsError.ThrowExceptionForHR(hr);

           if (this.m_videoWindow != null)

           {

               this.m_videoWindow.SetWindowPosition(, , this.videoWidth, this.videoHeight);

           }

           hr = this.m_videoWindow.put_Visible(OABool.True);

           DsError.ThrowExceptionForHR(hr);

           // 开始预览采集设备采集到的视频

           hr = this.m_mediaControl.Run();

           DsError.ThrowExceptionForHR(hr);

           m_IsPreview = true;

       }

       catch

           {

           m_IsPreview = false;

           throw new Exception("VideoPreview函数出现异常，视频预览失败！");

       }

       }