opencv根据摄像头名称获取索引值

OpenCV的VideoCapture是一个视频读取与解码的API接口，支持各种视频格式、网络视频流、摄像头读取。

针对一般摄像头的读取，opencv为了实现跨平台读取摄像头时是使用的摄像头索引，

 VideoCapture capture(int index);

一般而言电脑自带的摄像头id=0，但是也存在一些特殊情况，有些usb的摄像头接入笔记本后，usb摄像头的id会变位0，原有的笔记本id则变为1，所以为了程序的稳定性，最好还是使用图像采集设备的名称获取对应的id最后在使用opencv接口打开对应的设备（摄像头、视频采集卡...）。

 #include<opencv2/objdetect/objdetect.hpp>
 #include<opencv2/highgui/highgui.hpp>
 #include "windows.h"
 #include "dshow.h"
 #include <iostream>

 #pragma comment(lib, "strmiids.lib")
 #pragma comment(lib, "quartz.lib")

 using namespace cv;
 using namespace std;

 int listDevices(vector<string>& list) {

     //COM Library Initialization
     //comInit();

     ICreateDevEnum *pDevEnum = NULL;
     IEnumMoniker *pEnum = NULL;
     int deviceCounter = ;
     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, );

         if (hr == S_OK) {

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

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

                 IPropertyBag *pPropBag;
                 hr = pMoniker->BindToStorage(, , 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, );

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

                 if (SUCCEEDED(hr))
                 {

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

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

 int main()
 {
     vector<string> list;
     listDevices(list);
     int capid0 = , capid1 = ;
     cout << "dev_size =      " << list.size() << endl;
     for (int i = ; i<list.size(); i++)
     {
         if (list[i] == "3D Camera")
             capid1 = i;
         if (list[i] == "USB2.0 HD UVC WebCam")
             capid0 = i;
         cout << "device lists:" << list[i] <<'\t'<<"i="<<i<< endl;

         if (list[i]=="CY3014 USB, Analog 01 Capture")
         {
             cout<<"video..."<<'\n';
         }
     }
     getchar();
     return ;
 }

涉及的配置：

opencv的环境不用说自己配置还有两个系统库，需要额外的添加 #pragma comment(lib, “strmiids.lib”) #pragma comment(lib, “quartz.lib”)

note：库存在64位和32位的区别，使用时需要和自己的项目位数相同（以上两个库一般系统都是自带的，不需要额外指定库路径，可以直接引用）

参考博客：

https://blog.csdn.net/wangxiuwen12/article/details/87371359

http://theoractice.github.io/2015/09/18/[Win]%20OpenCV%20管理多摄像头的最简洁方法/

https://docs.opencv.org/2.4/modules/highgui/doc/reading_and_writing_images_and_video.html?highlight=videocapture#reading-and-writing-images-and-video