Opencv识别设备ID 打开指定摄像头

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当使用Opencv打开多个摄像头时，可能需要指定正确的设备ID。通过跟踪源码，可以找到videoInput::listDevices函数来获取设备列表，从而选择合适的index，确保打开的是目标摄像头。参考链接提供了实现这一功能的详细步骤。

Opencv识别设备ID 打开指定摄像头

Opencv中打开摄像头的语句是：
Videocapture cap;
cap.open(index);

Opencv中打开摄像头，当有多个摄像头时，有时候打开的不是想要的那个，因此有必要获得设备列表并选择合适的index。

跟踪源码，到cap_show.cpp中，在1293行发现了 int videoInput::listDevices(bool silent)函数。
把它单独摘出来，修改一下，即可获得设备列表。在此参考了https://blog.youkuaiyun.com/hyqwmxsh/article/details/74479694 这个链接。

int listDevices(vector& list) {

//COM Library Initialization
//comInit();

//if (!silent) DebugPrintOut("\nVIDEOINPUT SPY MODE!\n\n");


ICreateDevEnum *pDevEnum = NULL;
IEnumMoniker *pEnum = NULL;
int deviceCounter = 0;
CoInitialize(NULL);

HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL,
    CLSCTX_INPROC_SERVER, IID_ICreateDevEnum,
    reinterpret_cast<void**>(&pDevEnum));


if (SUCCEEDED(hr))
{
    // Create an enumerator for the video capture category.
    hr = pDevEnum->CreateClassEnumerator(
        CLSID_VideoInputDeviceCategory,
        &pEnum, 0);

    if (hr == S_OK) {

        printf("SETUP: Looking For Capture Devices\n");
        IMoniker *pMoniker = NULL;

        while (pEnum->Next(1, &pMoniker, NULL) == S_OK) {

            IPropertyBag *pPropBag;
            hr = pMoniker->BindToStorage(0, 0, IID_IPropertyBag,
                (void**)(&pPropBag));

            if (FAILED(hr)) {
                pMoniker->Release();
                continue;  // Skip this one, maybe the next one will work.
            }


            // Find the description or friendly name.
            VARIANT varName;
            VariantInit(&varName);
            hr = pPropBag->Read(L"Description", &varName, 0);

            if (FAILED(hr)) hr = pPropBag->Read(L"FriendlyName", &varName, 0);

            if (SUCCEEDED(hr)) 
            {

                hr = pPropBag->Read(L"FriendlyName", &varName, 0);

                int count = 0;
                char tmp[255] = { 0 };
                //int maxLen = sizeof(deviceNames[0]) / sizeof(deviceNames[0][0]) - 2;
                while (varName.bstrVal[count] != 0x00 && count < 255) 
                {
                    tmp[count] = (char)varName.bstrVal[count];
                    count++;
                }
                list.push_back(tmp);
                //deviceNames[deviceCounter][count] = 0;

                //if (!silent) DebugPrintOut("SETUP: %i) %s\n", deviceCounter, deviceNames[deviceCounter]);
            }

            pPropBag->Release();
            pPropBag = NULL;

            pMoniker->Release();
            pMoniker = NULL;

            deviceCounter++;
        }

        pDevEnum->Release();
        pDevEnum = NULL;

        pEnum->Release();
        pEnum = NULL;
    }

    //if (!silent) DebugPrintOut("SETUP: %i Device(s) found\n\n", deviceCounter);
}

//comUnInit();

return deviceCounter;

}

完整测试工程可点此下载