DirectShow .Net 实现视频预览

1、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()
     { returnGetDeviceCollection(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(stringVideoInputDeviceName)
     {   //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, stringfriendlyname)
     {
         object source = null;
         Guid iid = typeof(IBaseFilter).GUID;
         foreach (DsDevice device inDsDevice.GetDevicesOfCat(category))
         {
             if (device.Name.CompareTo(friendlyname) == 0)
             {
                 device.Mon.BindToObject(null, null, ref iid, out source);
                 break;
             }
         }

         return (IBaseFilter)source;
     }

2、初始化基本的接口对象 

private void InitInterfaces()
     {
         int hr = 0;

         // 获取IGraphBuilder接口对象
         this.m_graphBuilder = (IGraphBuilder)new FilterGraph();
         //获取ICaptureGraphBuilder2接口对象
         this.m_captureGraphBuilder = (ICaptureGraphBuilder2)newCaptureGraphBuilder2();
         //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);
     }

 

 

 

3、开始视频预览
public void VideoPreview()
      try
     {

         int hr =0;                  
         hr = this.m_graphBuilder.AddFilter(theVideoDevice, "VideoCapture");
         DsError.ThrowExceptionForHR(hr);

         // 通过theVideoDevice（IBaseFilter）视频接口对象的PreviewPin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, 0);

          if(m_pinStill == null)
             {
                 m_pinStill = DsFindPin.ByCategory(theVideoDevice,PinCategory.Capture, 0);
             }

             // 获取theVideoDevice的IAMVideoControl对象，对于具有StillPin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> 0)
             {
                 SetConfigParms(m_pinStill, this.videoWidth, this.videoHeight,24);
             }

             //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(0, 0, 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！");
        
     }
     }