Directshow 捕捉视频入门篇

一、关于视频捕捉(About Video Capture in Dshow)

1) 视频捕捉Graph的构建

这里要重点了解捕捉Graph图和一般回放Graph图的定义。

一个能够捕捉音频或者视频的graph图都称之为捕捉graph图。捕捉graph图比一般的文件回放graph图要复杂许多，Directshow提供了一个Capture Graph Builder COM组件使得捕捉graph图的生成更加简单。Capture Graph Builder提供了一个ICaptureGraphBuilder2接口，这个接口提供了一些方法用来构建和控制捕捉graph图。

首先创建一个Capture Graph Builder对象和一个graph manger对象（图对象的管理器)，然后用filter graph manager 作参数，调用ICaptureGraphBuilder2::SetFiltergraph来初始化Capture Graph Builder。看下面的代码吧：

HRESULT InitCaptureGraphBuilder(IGraphBuilder **ppGraph,//Receives the pointerICaptureGraphBuilder2 **ppBuilder)//Receives the pointer{if(!ppGraph || !ppBuilder){return E_POINTER;}IGraphBuilder *pGraph = NULL;ICaptureGraphBuilder2 *pBuild = NULL;//Create the Capture Graph BuilderHRESULT hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&pBuild );if(SECCEEDED(hr)){//Create the Filter Graph Managerhr = CoCreateInstance(CLSID_FilterGraph, 0, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&pGraph);if(SECCEEDED(hr)){//Initialize the Capture Graph BuilderpBuild->SetFiltergraph(pGraph);//Return both interface pointers to the caller*ppBuild = pBuild;*ppGraph = pGraph;//The caller must release both interfacereturn S_OK;}else {pBuild->Release();}}return hr;//Failed}

未完，待续。。。。。哈哈，如有问题可以联系我：QQ:1906733710，我是从事电子签到软件、电子白板、互动投影软件、查询软件开发的，现在要开发视频录制的功能，在对Directshow 研究的过程当中。希望一起研究提高。有需要软件的也可以联系我。