Question

我正在使用DirectShow来捕获视频。我正在将相机连接到样品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 ）。该图表已连接到 IID_IMediaControl 。我使用IID_IMediaControl运行和停止。大多数时候停止卡住了。有某种僵局。我尝试添加 IID_IMediaEvent 和m_pEvent-＆gt; WaitForCompletion（INFINITE，＆amp; evCode）;但它仍然无效。暂停工作没有问题，但是在试图阻止软件时就卡住了

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);

Answer 1

问题很典型，但如果没有您需要了解的其他详细信息，则需要进行猜测。很容易启动多线程操作，但是当它停止它时，需要同步线程并且不准确这样做是造成死锁的典型原因 - 你所看到的。

要解决此问题，通常会将调试程序附加到相关进程并检查其调用堆栈。您将看到一个线程在呼叫中深处呼叫停止和睡眠，等待其他事情发生。可能还有另一个线程正在做一些可疑的事情。

它们上的线程，调用堆栈和模块表明错误并将问题隔离到特定的过滤器或库。更重要的是，您可能希望开始缩小图表，暂时删除过滤器，直到您看到冻结消失为止，并确定可疑过滤器。

Answer 2

有时最好在停止图表之前暂停图表并等待状态更改。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到达开头。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);

停止时IID_IMediaControl卡住了

2 个答案: