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.
alt text

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

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:
alt text

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:
alt text

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:
alt text

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:
alt text

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.