Using Directshow causes the application to crash

Question

Hi，

When I debugged with graphedit, I was able to preview the camera as normal.The graphedit configuration is as follows.

But when I used the code to configure the camera preview, my application crashed. My code configuration is as follows.

hr = CoCreateInstance(CLSID_FilterGraph, nullptr, CLSCTX_INPROC_SERVER, IID_IGraphBuilder,                    (void **) &pGraphBuilder);     
if (FAILED(hr)) {         qDebug() << "create FilterGraph failed";         return false;     } 
hr = CoCreateInstance(CLSID_H264DS, nullptr, CLSCTX_INPROC_SERVER, IID_IBaseFilter,                           (void **) &m_pH264Filter);     
if (FAILED(hr)) {         qDebug() << "create H264 Filter failed: " << hr;         return false;     }
hr = CoCreateInstance(CLSID_EnhancedVideoRenderer, nullptr, CLSCTX_INPROC_SERVER, IID_IBaseFilter,                           (void **) &m_pEvrFilter);     
if (FAILED(hr)) {         qDebug() << "create EVR Filter failed: " << hr;         return false;     }      
hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, nullptr, CLSCTX_INPROC_SERVER,                           IID_ICaptureGraphBuilder2, (void **) &pCaptureGraphBuilder2);     
if (FAILED(hr)) {         qDebug() << "create CaptureGraphBuilder2 failed";         return false;     }      
hr = pCaptureGraphBuilder2->SetFiltergraph(pGraphBuilder);     
if (FAILED(hr)) {         qDebug() << "SetFilterGraph failed: " << hr;         return false;     } 
hr = pGraphBuilder->AddFilter(pVideoCaptureFilter, L"Video Capture");     
if (FAILED(hr)) {         qDebug() << "couldn't add video capture filter to graph hr = " << hr;         return false;     } 
hr = pGraphBuilder->AddFilter(m_pH264Filter, L"H264 DS Filter");     if (FAILED(hr)) {         qDebug() << "couldn't add H264 filter to graph hr = " << hr;         return false;     } 
hr = pGraphBuilder->AddFilter(m_pEvrFilter, L"EVR Filter");     if (FAILED(hr)) {         qDebug() << "couldn't add EVR filter to graph hr = " << hr;         return false;     } 
hr = pCaptureGraphBuilder2->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,                                              pVideoCaptureFilter, nullptr, nullptr);     
if (FAILED(hr)) {         qDebug() << "couldn't render stream hr = " << hr;         return false;     }