Opencv根据USB摄像头PID\VID号，获取对应摄像头索引

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#include <iostream>
#include <string>
#include <vector>
#include <DShow.h>
#include <CString>
#include <atlstr.h>
#pragma   comment(lib,"Strmiids.lib")


#define LRDLLTEST_EXPORTS //先定义宏

#ifdef LRDLLTEST_EXPORTS
#define LRDLLTEST_API __declspec(dllexport)
#else
#define LRDLLTEST_API __declspec(dllimport)
#endif

extern "C" LRDLLTEST_API int getCamIDFromPidVid(const char* pidvid);

LRDLLTEST_API int getCamIDFromPidVid(const char* pidvid)
{
	// example std::string pidvid = "0001";
	std::vector<std::string> devList; //设备列表
	int iCameraNum = 0;			//设备个数

	CString str;
	ICreateDevEnum* pDevEnum = NULL;
	IEnumMoniker* pEnum = NULL;
	HRESULT hr = NULL;
	CoInitialize(NULL);
	hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER, IID_ICreateDevEnum, reinterpret_cast<void**>(&pDevEnum));
	if (SUCCEEDED(hr))
	{
		hr = pDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory, &pEnum, 0);
		if (hr == S_OK)
		{
			//枚举捕获设备
			IMoniker* pMoniker = NULL;
			ULONG cFetched;
			while (pEnum->Next(1, &pMoniker, &cFetched) == S_OK)
			{
				IPropertyBag* pPropBag;
				hr = pMoniker->BindToStorage(0, 0, IID_IPropertyBag, reinterpret_cast<void**>(&pPropBag));
				if (SUCCEEDED(hr))
				{
					//获取设备路径,路径里包含pidvid的信息
					VARIANT varName;
					varName.vt = VT_BSTR;
					VariantInit(&varName);
					hr = pPropBag->Read(L"DevicePath", &varName, 0);		//read函数只能够读取CLSID, FriendlyName, DevicePath这三种

					CString sdev(varName);
					
					std::string strStr;
					strStr = sdev.GetBuffer(0);
					//std::cout << "----:n" << strStr<<std::endl;
					devList.push_back(strStr);


					iCameraNum++;
					pPropBag->Release();
				}

				pMoniker->Release();
			}
		}
	}
	//std::cout << devList.size() << std::endl;
	for (int i = 0; i < devList.size(); i++) {
		std::cout << devList[i] << std::endl;
	}
	int iRet = -1;
	//对比,得到id,没有符合的就返回-1
	for (int i = 0; i < devList.size(); i++)
	{
		int index = devList[i].find(pidvid);
		if (index != -1)
		{
			iRet = i;
			break;
		}
	}
	CoUninitialize();
	return iRet;
}

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# -*- coding: utf-8 -*-
from ctypes import *
import cv2
fileName="python_use_cpp.dll"
func=cdll.LoadLibrary(fileName)
string=bytes("vid_0001&pid_0001",encoding="utf-8")
#string="vid_0001&pid_0001".encode()
a=func.getCamIDFromPidVid(string)
print(a)
cap = cv2.VideoCapture(a,cv2.CAP_DSHOW) # 摄像头的ID不同设备上可能不同


while 1:
    ret,img0=cap.read()
    if not ret:
        continue

    cv2.imshow('result', img0)
    key =cv2.waitKey(1)  # 1 millisecond

    if key & 0xFF == ord('q') or key == 27:
        break
cv2.destroyAllWindows()

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#include <iostream>
#include <opencv2/opencv.hpp>
//
//#pragma comment (lib,"python_use_cpp.lib")
extern "C" __declspec(dllexport) int getCamIDFromPidVid(const char* pidvid);
int main(int avgc, char** argv) {

	const char* pidvid = "vid_0001&pid_0001";
	int A = getCamIDFromPidVid(pidvid);
	//int A=getCamIDFromPidVid(argv[1]);
	std::cout << A << std::endl;

	cv::VideoCapture camera0(A, cv::CAP_DSHOW);

	if (!camera0.isOpened()) {
		std::cout << "can not open" << std::endl;
		return 1;
	}
	while (true)
	{
		cv::Mat frame0;
		camera0 >> frame0;
		cv::imshow("frame", frame0);
		char c = cv::waitKey(1);
		if (c == 27)
		{
			break;
			cv::destroyAllWindows();
		}
	}
	return 0;
}