DirectShow 音?芬袅吭O置???

samurai_beta

??代?如下：
        IGraphBuilder* pGBuilder;
        IMediaControl* pMControl;
        IMediaPosition* pMPos;
        IMediaEvent *pMEvent;
        IVideoWindow *pMVideoWindow;
        IBasicVideo *pMVideo;
        IBasicAudio *pMAudio;

        CoInitialize(NULL); //初始化COM

        CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC, IID_IGraphBuilder, (void**)&pGBuilder);
        pGBuilder->QueryInterface(IID_IMediaControl, (void**)&pMControl);
        pGBuilder->QueryInterface(IID_IMediaPosition, (void**)&pMPos);
        pGBuilder->QueryInterface(IID_IMediaEvent, (void**)&pMEvent);
        pGBuilder->QueryInterface(IID_IVideoWindow, (void**)pMVideoWindow);
        pGBuilder->QueryInterface(IID_IBasicVideo, (void**)pMVideo);
        pGBuilder->QueryInterface(IID_IBasicAudio, (void**)pMAudio);

不?不管如何pMAudio?pMVideo都?o法成功取得介面，不知道是?槭颤N...
主要是需要 IID_IBasicAudio ?碚{整音量大小...

知道原因的人希望能指?б幌

lstarboy

好像在调用RenderFile后才可以获取pMAudio?pMVideo的接口

samurai_beta

??，不?RenderFile之後仍然?o法取得IBaseAudio介面，????有可能是什?原因呢？