directshow 采集视频

最新推荐文章于 2022-02-20 15:40:02 发布

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最新推荐文章于 2022-02-20 15:40:02 发布

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分类专栏： directshow学习、应用、开发文章标签： null video server library filter

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本文介绍使用DirectShow进行视频采集的过程，包括初始化COM库、创建过滤器图表、枚举并绑定设备、设置视频流属性、配置视频窗口及预览视频。

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Ps:只列主要的，一些执行错误等处理、内存释放无

步骤一、CoInitialize(NULL); //初始化COM Library

步骤二、创建视频采集过滤器图表

//创建视频采集过滤器图表 CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void **)&m_pGraphBuilder); //ICaptureGraphBuilder2接口 CoCreateInstance (CLSID_CaptureGraphBuilder2 , NULL, CLSCTX_INPROC, IID_ICaptureGraphBuilder2, (void **)&m_pCaptureGraphBulid); //过滤器图表添加到管理器中 m_pCaptureGraphBulid->SetFiltergraph(m_pGraphBuilder); //媒体控制接口 m_pGraphBuilder->QueryInterface(IID_IMediaControl, (void **)&m_pMediaCtl); //视频显示窗口 m_pGraphBuilder->QueryInterface(IID_IMediaEvent, (void **) &m_pMediaEvent);

步骤三、枚举并绑定设备

//设备枚举器Interface CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER, IID_ICreateDevEnum, (void**)&pCreateDevEnum); //名称枚举器 HRESULT hr = pCreateDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory,&pEm, 0); if (hr == NOERROR) { pEm->Reset(); } //--------------------------------------------------------- ULONG cFetched; IMoniker *pM = NULL; int index = 0; while(pEm->Next(1, &pM, &cFetched)==S_OK) { IPropertyBag *pBag; hr = pM->BindToStorage(0, 0, IID_IPropertyBag, (void **)&pBag); if(SUCCEEDED(hr)) { VARIANT var; var.vt = VT_BSTR; //设备友好名称 hr = pBag->Read(L"FriendlyName", &var, NULL); if (hr == NOERROR) { if (index == 1) { //将视频设备绑定到基础过滤器上 pM->BindToObject(0, 0, IID_IBaseFilter, (void**)(&m_pBaseFilter)); } SysFreeString(var.bstrVal); } pBag->Release(); } pM->Release(); index++; }

步骤四、将Filter添加到过滤器图表中
m_pGraphBuilder->AddFilter(m_pBaseFilter, L"Capture");

步骤五、设置视频流属性

IAMStreamConfig *pAMStreamConfig=NULL; m_pCaptureGraphBulid->FindInterface(&PIN_CATEGORY_CAPTURE,&MEDIATYPE_Video, m_pBaseFilter,IID_IAMStreamConfig,(void **)&pAMStreamConfig); //得到视频格式大小 AM_MEDIA_TYPE *pmt; pAMStreamConfig->GetFormat(&pmt); //设置视频格式 pmt->majortype = MEDIATYPE_Video; if(nRGBBytes==24) { pmt->subtype = MEDIASUBTYPE_RGB24; } else if(nRGBBytes==32) { pmt->subtype = MEDIASUBTYPE_RGB32; } else if(nRGBBytes==15) { pmt->subtype = MEDIASUBTYPE_RGB555; } else if(nRGBBytes==16) { pmt->subtype = MEDIASUBTYPE_RGB565; } else { pmt->subtype = MEDIASUBTYPE_RGB32; } VIDEOINFOHEADER *pvih = reinterpret_cast<VIDEOINFOHEADER *>(pmt->pbFormat); //设置回去 int nDefualWidth = pvih->bmiHeader.biWidth; int nDefualHeight = pvih->bmiHeader.biHeight; pvih->bmiHeader.biWidth = iWidth; pvih->bmiHeader.biHeight = iHeight; pvih->bmiHeader.biSizeImage = pmt->lSampleSize = iWidth*iHeight*pvih->bmiHeader.biPlanes*pvih->bmiHeader.biBitCount/8; pvih->AvgTimePerFrame = (LONGLONG)(10000000/nFrameRate); pAMStreamConfig->SetFormat(pmt); m_pCaptureGraphBulid->RenderStream(&PIN_CATEGORY_CAPTURE,&MEDIATYPE_Video,m_pBaseFilter,NULL,NULL); m_pCaptureGraphBulid->FindInterface(&PIN_CATEGORY_CAPTURE,&MEDIATYPE_Video, m_pBaseFilter,IID_IVideoWindow,(void **)&m_pVideoWindow);

步骤六、设置视频窗口

if(m_pVideoWindow) { m_pVideoWindow->put_Owner((OAHWND)m_hWnd); } m_pVideoWindow->put_WindowStyle(WS_CHILD | WS_CLIPCHILDREN); if (m_pVideoWindow) { CRect rc; ::GetClientRect(m_hWnd,&rc); m_pVideoWindow->SetWindowPosition(0, 0, rc.right, rc.bottom); } m_pVideoWindow->put_Visible(OATRUE);

步骤七：预览视频

m_pMediaCtl->Run(); //开始 m_pMediaCtl->Stop(); //停止