DirectShowLib 应用实例

作者：zhangkaiforex

转自：http://blog.csdn.net/zhangkaiforex/article/details/4872129

实例引用DirectShowLib-2005.dll，这个DLL可以到http://directshownet.sourceforge.net/直接下载使用。

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()
      { 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) == 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)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);
      }

 

 

 

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

          int hr = 0;                  
          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, 0);

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

              // 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 > 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！");
        
      }
      }