Cameras enumeration

Summary of your issue

Environment

Windows 10 1909 NuGet packages: <package id="OpenCvSharp4" version="4.3.0.20200524" targetFramework="net48" /> <package id="OpenCvSharp4.runtime.win" version="4.3.0.20200524" targetFramework="net48" /> <package id="OpenCvSharp4.Windows" version="4.3.0.20200524" targetFramework="net48" />

What did you do when you faced the problem?

Camera enumeration. My concern is to define a valid association between VideoCapture index to open a camera and an enumeration of all the cameras connected to the computer.

To enumerate the cameras I use WMI :

    public static List<CameraDevice> GetAllConnectedCameras()
    {
        var cameras = new List<CameraDevice>();
        using (var searcher = new ManagementObjectSearcher("SELECT * FROM Win32_PnPEntity WHERE (PNPClass = 'Image' OR PNPClass = 'Camera')"))
        {
            int openCvIndex = 0;
            foreach (var device in searcher.Get())
            {
                cameras.Add(new CameraDevice()
                {
                    Name = device["Caption"].ToString(),
                    Status = device["Status"].ToString(),
                    DeviceId = device["DeviceId"].ToString(),
                    OpenCvId = i
                });
                ++i;
            }
        }

        return cameras;
    }

    public class CameraDevice
    {
        public int OpenCvId { get; set;}
        
        public string Name { get; set; }
        public string DeviceId { get; set; }
        public string Status { get; set; }
    }

Which gives me an enumeration that is always in the same order. After a lot of test I understood that OpenCv Open method uses an enumeration based on when the camera get connected.

For example if the camera A is connected before camera B, the association is: camera A index 0, camera B index 1. If the camera A is connected before camera B, the association is: camera A index 1, camera B index 0.

I don’t find a way to have a solid association - that could for example be that open method gets a camera name as input, instead of an index.

Do you have any idea how to solve this?

Below the code of how I connect to the camera.

Example code:

var videoCapture = new VideoCapture();

if (!videoCapture.Open(CameraDeviceId))
{
    throw new ApplicationException("Cannot connect to camera");
}

Output:

[
  {
    "OpenCvId": 0,
    "Name": "HP HD Camera",
    "DeviceId": "USB\\VID_0408&PID_5373&MI_00\\6&48E0E83&0&0000",
    "Status": "OK"
  }
]

What did you intend to be?

I’d like a way to get a solid association between OpenCv camera index and camera name.

[ravazquez]

@FrancescoBonizzi This is how I handled this + getting supported formats using Media Foundation.

https://github.com/vvvv/VL.OpenCV/blob/master/src/VideoInInfo.cs

Hope it helps

[lifuhua123]

        [DllImport(“CameraIndex.dll”)]         public extern static int GetCameraIndex(string cameraName);

The return value is the camera index, if not found, it will return -1

------------------ 原始邮件 ------------------ 发件人: “shimat/opencvsharp” <[e-mail]>; 发送时间: 2020年11月13日(星期五) 下午4:10 收件人: “shimat/opencvsharp”<[e-mail]>; 抄送: “Frank”<[e-mail]>;“Manual”<[e-mail]>; 主题: Re: [shimat/opencvsharp] Cameras enumeration (#969)

Yes, please! fbonizzi.90 at gmail.com

Thanks a lot!

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