DirectShow采集到的视频无法播放,该如何处理

 //采集相关的变量    IGraphBuilder *pGraph;        ICaptureGraphBuilder2 *pBuild; //视频采集过滤器图表IMediaControl *m_pMediaControl;    //视频采集设备的源Filter       IBaseFilter* pSrc;//---------------------------------------------------------------------//HRESULT hr;    //创建IGraphBuilder    CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC, IID_IGraphBuilder, (void      **)&pGraph);    //创建ICaptureGraphBuilder2    hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL,         CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&pBuild);     // 过滤器图表添加到管理器中    pBuild->SetFiltergraph(pGraph); //--------------------------------------------------------------------------------////以下代码为查找设备    ICreateDevEnum *pDevEnum=NULL;    IEnumMoniker *pClsEnum=NULL;    //创建设备枚举COM对象    CoCreateInstance(CLSID_SystemDeviceEnum,NULL,CLSCTX_INPROC,IID_ICreateDevEnum,(void **)&pDevEnum);    //创建视频采集设备枚举COM对象    pDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory,&pClsEnum,0);    if(pClsEnum == NULL)    {        MessageBox(_T("Sorry, you have no video capture hardware.\r\n\r\nVideo capture will not function properly."));        //如果没有设备，返回        return ;     }     IMoniker *pMoniker = NULL;    //如果先前的createclassenumerator调用成功了，可以用ienummoniker::next得到设备    if(pClsEnum->Next(1,&pMoniker,NULL)==S_OK)    {        //调用imoniker::bindtoobject建立一个和选择的device联合的filter        pMoniker->BindToObject(0,0,IID_IBaseFilter,(void **)&pSrc);        pMoniker->Release();    }    //将设备添加到管理器graph    hr = pGraph->AddFilter(pSrc, L"Video Capture");//---------------------------------------------------------------------------//视频开始采集----------------------------------------------------------------//IFileSinkFilter* fsFilter=NULL;    IBaseFilter* vedioWriter=NULL;    //设置保存文件并初始化vedioWriter    hr=pBuild->SetOutputFileName(&MEDIASUBTYPE_Avi,L"D:\\A.avi",&vedioWriter,&fsFilter);    //保存文件    hr=pBuild->RenderStream(&PIN_CATEGORY_CAPTURE,&MEDIATYPE_Video,pSrc,NULL,vedioWriter);        IMediaControl *pMC = NULL;    hr=pGraph->QueryInterface(IID_IMediaControl, (void **)&pMC);    hr=pMC->Run();    //运行Filter Graph    if(FAILED(hr))    {        MessageBox(_T("加载运行失败！"));          return ;    }