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我正在使用 DirectShow 来捕获视频。我将相机连接到样本采集器并保存我得到的图像。

在以下代码中，我将IID_ICaptureGraphBuilder2连接到连接到样本采集器 ( ISampleGrabber )的捕获设备 ( CLSID_VideoCaptureSources )。该图连接到IID_IMediaControl。我使用 IID_IMediaControl 运行和停止。大多数情况下，停止会卡住。有某种僵局。我尝试添加IID_IMediaEvent和 m_pEvent->WaitForCompletion(INFINITE, &evCode); 但它仍然不起作用。暂停工作没有问题，但是在尝试停止软件时卡住了

构建图表 

    ICaptureGraphBuilder2   *pBuilder;
    IBaseFilter             *pCamera;
    IPin                    *pOutPin;
    IPin                    *pInPin;
    IBaseFilter     *pSampleGrabberFilter;
    IBaseFilter     *pNullRendererFilter;
    ISampleGrabber  *pSampleGrabber;

    HRESULT hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void **)&m_pGraph); 
    hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (LPVOID*)&pBuilder);
    CHECK_HR(hr, L"Can't create Capture Graph Builder");

    hr = pBuilder->SetFiltergraph(m_pGraph);
    CHECK_HR(hr, L"Can't SetFiltergraph");

    pCamera = CreateFilterByName(pCaptureDeviceName, CLSID_VideoCaptureSources);

    WCHAR err[256];
    wsprintf(err, L"Can't add Camera '%s' to graph", pCaptureDeviceName);

    hr = m_pGraph->AddFilter(pCamera , pCaptureDeviceName);
    CHECK_HR(hr, err);


    WCHAR filterName[256];

    pOutPin = GetPinCapture(pCamera, L"Capture", i);
    if (!pOutPin)
        continue;
    IAMStreamConfig *pConfig = NULL;
    hr = pOutPin->QueryInterface(IID_IAMStreamConfig, (void**)&pConfig);
    CHECK_HR(hr, L"Can't get configuration");

    AM_MEDIA_TYPE *pmt = NULL;
    pConfig->GetFormat(&pmt);

    VIDEOINFOHEADER *pFrmt = (VIDEOINFOHEADER *)pmt->pbFormat;
    pFrmt->bmiHeader.biWidth = 1920;
    pFrmt->bmiHeader.biHeight = 1080;

    pConfig->SetFormat(pmt);
    SAFE_RELEASE(pConfig);
    SAFE_RELEASE(pOutPin);

   // Create a sample grabber
    wsprintf(filterName, L"Sample Grabber %d", i);

    // Create a sample grabber
    hr = CoCreateInstance(CLSID_SampleGrabber, NULL, CLSCTX_INPROC_SERVER, IID_IBaseFilter, (void **)&pSampleGrabberFilter);
    CHECK_HR(hr, L"Unable to create sample grabber filter");

    // Initialize sample grabber

    hr = pSampleGrabberFilter->QueryInterface(IID_ISampleGrabber, (void **)&pSampleGrabber);
    CHECK_HR(hr, L"Unable to get sample grabber");

    hr = pSampleGrabber->SetMediaType(pmt);
    CHECK_HR(hr, L"Unable to set media type");

    hr = pSampleGrabber->SetBufferSamples(false);
    CHECK_HR(hr, L"Unable to set buffer samples!");

    hr = pSampleGrabber->SetOneShot(false);
    CHECK_HR(hr, L"Unable to set one shot!");

    // Add the sample grabber to the graph
    hr = m_pGraph->AddFilter(pSampleGrabberFilter, filterName);
    CHECK_HR(hr, L"Unable to add sample grabber to graph");

    pOutPin = GetPinCapture(pCamera, L"Capture", i);
    pInPin = GetPin(pSampleGrabberFilter, PINDIR_INPUT);
    hr = m_pGraph->ConnectDirect(pOutPin, pInPin, 0);
    CHECK_HR(hr, L"Unable to connect Camera to pSampleGrabberFilter");
    SAFE_RELEASE(pOutPin);
    SAFE_RELEASE(pInPin);

    wsprintf(filterName, L"Null Renderer %d", i);
    // Create a null renderer
    hr = CoCreateInstance(CLSID_NullRenderer, NULL, CLSCTX_INPROC_SERVER, IID_IBaseFilter,(void **)&pNullRendererFilter);
    CHECK_HR(hr, L"Unable to create null renderer filter");

    hr = m_pGraph->AddFilter(pNullRendererFilter, filterName);
    CHECK_HR(hr, L"Unable to add null renderer to graph");

    pOutPin = GetPin(pSampleGrabberFilter, PINDIR_OUTPUT);
    pInPin = GetPin(pNullRendererFilter, PINDIR_INPUT);

    hr = m_pGraph->ConnectDirect(pOutPin, pInPin, 0);

    SAFE_RELEASE(pOutPin);
    SAFE_RELEASE(pInPin);

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

    // Initialize the capture grabber
    m_pCapGrabber[i] = new CapGrabber(i);
    m_pCapGrabber[i]->SetVideoInfoHeader(pFrmt);
    m_pCapGrabber[i]->SetAttachGrabberCB(m_funcAttachGrabber);
    m_pCapGrabber[i]->SetWidth((int)pFrmt->bmiHeader.biWidth);
    m_pCapGrabber[i]->SetHeight((int)pFrmt->bmiHeader.biHeight);

    // Set the capture callback
    hr = pSampleGrabber->SetCallback(m_pCapGrabber[i], 1);

    SAFE_RELEASE(pSampleGrabberFilter);
    SAFE_RELEASE(pSampleGrabber);
    SAFE_RELEASE(pNullRendererFilter);
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2 回答 2

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这个问题很典型，但它只是一种猜测，没有您需要找出的其他细节。启动多线程操作很容易，但是在停止它时，需要同步线程并且这样做不准确是死锁的典型原因 - 你所看到的。

要解决此问题，您通常会将调试器附加到相关进程并检查其调用堆栈。您将看到一个线程调用 stop 并在调用的深处处于休眠状态，等待其他事情发生。很可能还有另一个线程也在做一些可疑的事情。

它们上的线程、调用堆栈和模块会提示问题所在，并将问题隔离到特定的过滤器或库。更重要的是，您可能希望开始减少图表，暂时删除过滤器，直到您看到冻结已经消失，并且您识别出可疑过滤器。

于 2013-02-25T14:26:18.390 回答
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有时最好在停止图形之前暂停图形并等待状态更改。另请注意，根据 msdn stop 不会将图形位置重置为开头。

http://msdn.microsoft.com/en-us/library/windows/desktop/dd390178(v=vs.85).aspx

所以要确保图表在停止后回到开头。我建议使用 SetPosition 接口。下面是我用来停止图表的一小段代码。我假设你有有效的媒体控制和媒体搜索界面。

    IMediaControl *m_pControl = NULL; 
    IMediaSeeking *m_pMediaSeek = NULL;
    //Assuming that you have valid media control interface and media seeking interface    using QueryInterface

    long long m_pStart = 0;
    m_pControl->Pause();
    m_pControl->GetState(1000, NULL);


    m_pMediaSeek->SetPositions(&m_pStart, AM_SEEKING_AbsolutePositioning, NULL,  AM_SEEKING_NoPositioning);
    m_pControl->Run();
    m_pControl->GetState(1000,NULL);

    m_pControl->Stop();
    m_pControl->GetState(1000,NULL);
于 2013-02-25T16:16:11.663 回答