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 = 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
");
            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
", 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

", deviceCounter);
    }

    //comUnInit();

    return deviceCounter;
}

int main()
{
    vector<string> list;
    listDevices(list);
    int capid0 = 0, capid1 = 0;
    cout << "dev_size =      " << list.size() << endl;
    for (int i = 0; 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] <<'	'<<"i="<<i<< endl;
    
        if (list[i]=="CY3014 USB, Analog 01 Capture")
        {
            cout<<"video..."<<'
';
        }
    }
    getchar();
    return 0;
}

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