IVMRMixerControl9为什么QueryInterface不成功呢？

[alangsos]

IBaseFilter* pVmr = NULL;

// Create the VMR and add it to the filter graph.
HRESULT hr = CoCreateInstance(CLSID_VideoMixingRenderer, NULL,
CLSCTX_INPROC, IID_IBaseFilter, (void**)&pVmr);




if (SUCCEEDED(hr))
{
hr = m_pGB->AddFilter(pVmr, L"Video Mixing Renderer");
if (SUCCEEDED(hr))
{
// Set the rendering mode and number of streams.
IVMRFilterConfig* pConfig;

hr = pVmr->QueryInterface(IID_IVMRFilterConfig, (void**)&pConfig);
if( SUCCEEDED(hr))
{
pConfig->SetRenderingMode(VMRMode_Windowless);
pConfig->Release();
}

hr = pVmr->QueryInterface(IID_IVMRWindowlessControl, (void**)&m_pWC);
if( SUCCEEDED(hr))
{
m_pWC->SetVideoClippingWindow(hWnd);

}


hr = pVmr->QueryInterface(IID_IVMRMixerControl9, (void**)&m_pMixerC);
if (FAILED(hr))
{
AfxMessageBox("error");//就在错误！总是FAILED
}

================================================
我想用dshow来抓图，并实现图象的色度，亮度调节 ，想用IVMRMixerControl9接口的
SetProcAmpControl 来做！得QueryInterface总是不成功，是什么原因呢？
或者哪位知道可以用VC来做摄像头抓图并可以调节亮度的例子或代码，多谢了～

[alangsos]

没人帮我啊

[rightorwrong]

CoInitialize(NULL)

[alangsos]

和这没关系的吧CoInitialize(NULL)
上面几个QueryInterface 都SUCCEEDED的啊！

[rightorwrong]

[Quote=引用 2 楼 的回复:]
和这没关系的吧CoInitialize(NULL)
上面几个QueryInterface 都SUCCEEDED的啊！
[/Quote]

没关系
看看hr是多少，查一查