如何使用DirectShow捕获RGB中的实时相机帧

#include <dshow.h>

int main()
{
    // 初始化COM库
    CoInitialize(NULL);

    // 创建DirectShow图形
    IGraphBuilder* pGraphBuilder = NULL;
    CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&pGraphBuilder);

    // 枚举视频输入设备
    ICaptureGraphBuilder2* pCaptureGraphBuilder = NULL;
    CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&pCaptureGraphBuilder);
    pCaptureGraphBuilder->SetFiltergraph(pGraphBuilder);
    IBaseFilter* pVideoInputFilter = NULL;
    pCaptureGraphBuilder->RenderStream(&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video, pVideoInputFilter, NULL, NULL);

    // 连接过滤器
    IBaseFilter* pVideoOutputFilter = NULL;
    IEnumPins* pEnumPins = NULL;
    pVideoInputFilter->EnumPins(&pEnumPins);
    IPin* pPin = NULL;
    while (pEnumPins->Next(1, &pPin, NULL) == S_OK)
    {
        IEnumMediaTypes* pEnumMediaTypes = NULL;
        pPin->EnumMediaTypes(&pEnumMediaTypes);
        AM_MEDIA_TYPE* pMediaType = NULL;
        while (pEnumMediaTypes->Next(1, &pMediaType, NULL) == S_OK)
        {
            if (pMediaType->majortype == MEDIATYPE_Video)
            {
                pGraphBuilder->AddFilter(pVideoOutputFilter, L"Video Output Filter");
                pGraphBuilder->Connect(pPin, pVideoOutputFilter->GetPin(0));
            }
            DeleteMediaType(pMediaType);
        }
        pEnumMediaTypes->Release();
        pPin->Release();
    }
    pEnumPins->Release();

    // 开始预览
    IVideoWindow* pVideoWindow = NULL;
    pGraphBuilder->QueryInterface(IID_IVideoWindow, (void**)&pVideoWindow);
    pVideoWindow->put_AutoShow(OATRUE);
    pVideoWindow->put_Caption(L"DirectShow Camera Preview");
    pGraphBuilder->Run();

    // 处理相机帧
    // ...

    // 停止预览
    pGraphBuilder->Stop();

    // 释放资源
    pVideoWindow->Release();
    pVideoOutputFilter->Release();
    pVideoInputFilter->Release();
    pCaptureGraphBuilder->Release();
    pGraphBuilder->Release();
    CoUninitialize();

    return 0;
}