Multiple cameras QML

[NiLe]

Hello everyone,

I have a problem with setting up 2 camera windows in QML.

The error I get is: [0x800705aa] Failed to start (Insufficient system resources exist to complete the requested service.)
When I start the program only the last camera window is showing the camera capture. If I start 2 instances of the application then each of the application shows one camera but the image on one is frozen and on the other one it is working OK.

If I start the application once with only camera 1 and second time only with camera 2 then both cameras are working simultaneously:

The code for camera:

Item{
        id:cameraWindow1
        anchors.left: parent.left
        anchors.right: swipeView.left
        height: parent.height
        signal closed

        Rectangle{
            anchors.fill: parent
            color: "red"
        }

        Camera{
            id:camera1
        }
    }

    VideoOutput{
        id:vo1
        z:99
        source: camera1
        anchors.fill: cameraWindow1
        //focus: visible
        //orientation: 270
    }

Item{
        id:cameraWindow2
        anchors.left: swipeView.right
        anchors.right: parent.right
        height: parent.height
        signal closed

        Rectangle{
            anchors.fill: parent
            color: "blue"
        }

        Camera{
            id:camera2
        }
    }

    VideoOutput{
        id:vo2
        z:99
        source: camera2
        anchors.fill: cameraWindow2
        //focus: visible
        //orientation: 270
    }

Code to specify the camera source:

Component.onCompleted: {
        var myL = QtMultimedia.availableCameras;
        console.log("Loaded", myL.length);
        camera1.deviceId = myL[0].deviceId;
        camera2.deviceId = myL[1].deviceId;
    }

The console returns "qml: Loaded 2" for myL.length

Does anyone have more experience with creating new instances of the same object in QML? Especially cameras.

[NiLe]

Hello community,

After a few days, I think I solved the problem with the cameras.
I made myself a QML file named "CamCam.qml" with the following code:

import QtQuick 2.14
import QtMultimedia 5.12

Item{
    id:cameraWindow
    anchors.fill: parent
    signal closed
    property alias theID: camera.deviceId
    property alias backgroundColor: background.color
    property alias orientation: vo.orientation

    Rectangle{
        id: background
        anchors.fill: parent
        color: "blue"
    }

    Camera{
        id:camera
    }

    VideoOutput{
        id: vo
        z:99
        source: camera
        anchors.fill: parent
    }

}

And then I use it in the "main.qml":

Item{
        id: cameraLeft
        anchors.left: parent.left
        anchors.top: parent.top
        anchors.right: swipeView.left
        anchors.bottom: parent.bottom
        
        CamCam{
            theID: QtMultimedia.availableCameras[0].deviceId
            backgroundColor: "red"
        }
    }
    
Item{
        id: cameraRight
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.left: swipeView.right
        anchors.bottom: parent.bottom
        
        CamCam{
            theID: QtMultimedia.availableCameras[1].deviceId
            backgroundColor: "blue"
        }
    }

It is important to set the deviceId as soon as possible. As I did here "theID: QtMultimedia.availableCameras[x].deviceId"

Now it works perfectly:

[SGaist]

Hi and welcome to devnet,

Since you have a resource error, please give more details about the machine/device you are using for development.

You should as well add the Qt version you are using as well as platform your are working and targeting.

[NiLe]

Thank you for the warm welcome,

Oh yes, sorry about that.
The computer is this:

Qt:
Qt Creator 4.11.1
Based on Qt 5.14.1 (MSVC 2017, 32 bit)
Built on Feb 5 2020 10:36:21
From revision b2ddeacfb5

My target is windows application:

Thank you!

[SGaist]

What are these two cameras ?

[NiLe]

They are USB cameras, not web cameras.

https://i.imgur.com/x71om5B.jpg

[NiLe]

Hello community,

After a few days, I think I solved the problem with the cameras.
I made myself a QML file named "CamCam.qml" with the following code:

import QtQuick 2.14
import QtMultimedia 5.12

Item{
    id:cameraWindow
    anchors.fill: parent
    signal closed
    property alias theID: camera.deviceId
    property alias backgroundColor: background.color
    property alias orientation: vo.orientation

    Rectangle{
        id: background
        anchors.fill: parent
        color: "blue"
    }

    Camera{
        id:camera
    }

    VideoOutput{
        id: vo
        z:99
        source: camera
        anchors.fill: parent
    }

}

And then I use it in the "main.qml":

Item{
        id: cameraLeft
        anchors.left: parent.left
        anchors.top: parent.top
        anchors.right: swipeView.left
        anchors.bottom: parent.bottom
        
        CamCam{
            theID: QtMultimedia.availableCameras[0].deviceId
            backgroundColor: "red"
        }
    }
    
Item{
        id: cameraRight
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.left: swipeView.right
        anchors.bottom: parent.bottom
        
        CamCam{
            theID: QtMultimedia.availableCameras[1].deviceId
            backgroundColor: "blue"
        }
    }

It is important to set the deviceId as soon as possible. As I did here "theID: QtMultimedia.availableCameras[x].deviceId"

Now it works perfectly:

[lxy12345]

Hi NiLe, I am very new to qml ,could you please post your code?

[jsulm]

@lxy12345 Isn't the code just above in the last post from @NiLe ?

[lxy12345]

@jsulm When I tried the code, the error occured.
Here is my code:
main.qml
import QtQuick 2.12
import QtMultimedia 5.12
import QtQuick.Window 2.12

Window {
visible: true
width: 1200
height: 500
title: qsTr("Hello World")
Item{
id: cameraLeft
anchors.left: parent.left
anchors.top: parent.top
anchors.right: swipeView.left
anchors.bottom: parent.bottom

        CamCam{
            theID: QtMultimedia.availableCameras[0].deviceId
            backgroundColor: "red"
        }
    }

Item{
        id: cameraRight
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.left: swipeView.right
        anchors.bottom: parent.bottom

        CamCam{
            theID: QtMultimedia.availableCameras[1].deviceId
            backgroundColor: "blue"
        }
    }

}

CamCam.qml:
import QtQuick 2.12
import QtMultimedia 5.12

Item{
id:cameraWindow
anchors.fill: parent
signal closed
property alias theID: camera.deviceId
property alias backgroundColor: background.color
property alias orientation: vo.orientation

Rectangle{
    id: background
    anchors.fill: parent
    color: "blue"
}

Camera{
    id:camera
}

VideoOutput{
    id: vo
    z:99
    source: camera
    anchors.fill: parent
}

}

The errors:
qrc:/main.qml:15: ReferenceError: swipeView is not defined
qrc:/main.qml:32: TypeError: Cannot read property 'deviceId' of undefined
qrc:/main.qml:28: ReferenceError: swipeView is not defined
libv4l2: error setting pixformat: Device or resource busy
CameraBin error: "Device '/dev/video0' is busy"

The environment is ubuntu16.04(virtual machine), qt5.12.9. The camera is USB camera

[jsulm]

@lxy12345 said in Multiple cameras QML:

anchors.right: swipeView.left

Since you don't have swipeView replace it with parent.