DShow捕捉视频采集卡的问题，急急急

halleyzhang3 2015-01-23 05:44:41

用DShow捕捉视频采集卡的信号实现远程视频，现在遇到的问题是：十次里有差不多有9次正常，但偶尔会有不出视频的情况，所有调用和初始化都成功，但就是Grabber收不到数据。把Graph存起来用GraphEdi打开，成功和失败情况的Graph是一样，在GraphEdit里播放也是正常的。更为奇怪的线索是Debug调试总是不出视频，直接运行（还是Debug版程序）一般都可以，而且在Debug时pGraph->Run()后面加个断点断一下，再继续也正常了。但是用Sleep或者MessageBox模拟断点的效果却不起作用。
请各位老大帮我分析分析，可能是什么原因。
我创建Graph是让系统自动连接的，过程大概是这个样子



    hr = m_pGraph.CoCreateInstance( CLSID_FilterGraph );

    hr = m_pGraph->AddFilter( pCap, L"Cap" );

    hr = m_pGrabber.CoCreateInstance( CLSID_SampleGrabber );

    hr = m_pGrabber->SetMediaType( &VideoType ); // shouldn't fail

    hr = m_pGraph->AddFilter( pGrabBase, L"Grabber" );

    CComPtr<ICaptureGraphBuilder2> pCGB2;

    hr = pCGB2.CoCreateInstance (CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC);

    hr = pCGB2->SetFiltergraph( m_pGraph );

    IAMStreamConfig *pVSC;      // for video cap

    hr = pCGB2->FindInterface(&PIN_CATEGORY_CAPTURE,

                               &MEDIATYPE_Interleaved,

                                pCap, IID_IAMStreamConfig, (void **)&pVSC);

    if(hr != NOERROR)

    {

        hr = pCGB2->FindInterface(&PIN_CATEGORY_CAPTURE,

                                 &MEDIATYPE_Video, pCap,

                                 IID_IAMStreamConfig, (void **)&pVSC);

    }

    AM_MEDIA_TYPE *pmt;

	hr = pVSC->GetFormat(&pmt);

	

	// DV capture does not use a VIDEOINFOHEADER

	if(hr == NOERROR)

	{

		if(pmt->formattype == FORMAT_VideoInfo)

		{

			VIDEOINFOHEADER *pvi = (VIDEOINFOHEADER *)pmt->pbFormat;

			if(m_nVideoQualityMode)

				pvi->AvgTimePerFrame = (LONGLONG)(10000000 / m_nVideFrameRate);

                        ...

			hr = pVSC->SetFormat(pmt);

		}

		DeleteMediaType(pmt);

	}

    hr = pCGB2->RenderStream(

                            &PIN_CATEGORY_PREVIEW,

                            &MEDIATYPE_Interleaved, 

                            pCap, 

                            pGrabBase, 

                            pRenderer);

    if (FAILED (hr))

    {

        // try to render preview pin

        hr = pCGB2->RenderStream( 

                                &PIN_CATEGORY_PREVIEW, 

                                &MEDIATYPE_Video,

                                pCap, 

                                pGrabBase, 

                                pRenderer);



        // try to render capture pin

        if( FAILED( hr ) )

        {

            hr = pCGB2->RenderStream( 

                                    &PIN_CATEGORY_CAPTURE, 

                                    &MEDIATYPE_Video,

                                    pCap, 

                                    pGrabBase, 

                                    pRenderer);

        }

    }

    AM_MEDIA_TYPE mt;

    hr = m_pGrabber->GetConnectedMediaType( &mt );

    

    VIDEOINFOHEADER * vih = (VIDEOINFOHEADER*) mt.pbFormat;



	vih->bmiHeader.biSize=m_BmpU->bmiHeader.biSize;

	vih->bmiHeader.biWidth=m_BmpU->bmiHeader.biWidth;

	vih->bmiHeader.biHeight=m_BmpU->bmiHeader.biHeight;

	vih->bmiHeader.biPlanes=m_BmpU->bmiHeader.biPlanes;

	vih->bmiHeader.biBitCount=m_BmpU->bmiHeader.biBitCount;

	vih->bmiHeader.biSizeImage=m_BmpU->bmiHeader.biSizeImage;



	m_pGrabber->SetMediaType(&mt);



    mCB.pOwner = this;

    mCB.lWidth  = vih->bmiHeader.biWidth;

    mCB.lHeight = vih->bmiHeader.biHeight;

    FreeMediaType( mt );



    hr = m_pGrabber->SetBufferSamples( FALSE );

    hr = m_pGrabber->SetOneShot( FALSE );

    hr = m_pGrabber->SetCallback( &mCB, 1 );



    CComQIPtr< IVideoWindow, &IID_IVideoWindow > pWindow = m_pGraph;

    hr = pWindow->put_Owner( (OAHWND) m_VideoWnd );

   ..



    CComQIPtr< IMediaControl, &IID_IMediaControl > pControl = m_pGraph;

    hr = pControl->Run( );

.