Qt Multimedia QAbstractVideoFilter Missing in Qt 6.9

track

Hi everyone,

I’m working on a Qt Multimedia-based barcode scanning project using SCodes ZXing Barcode Wrapper with Qt 6.9 (MinGW). The project relied on QAbstractVideoFilter for video frame processing, but with Qt 6.9 I encountered this error: fatal error: QAbstractVideoFilter: No such file or directory

Project Details:
Qt Version: Qt 6.9

Compiler: MinGW 64-bit

Build System: CMake

Modules Used: Qt Multimedia, Qt Quick, SCodes, ZXing
Troubleshooting So Far:

Verified Qt Multimedia is installed via Qt Maintenance Tool.
2 Explicitly linked Qt Multimedia in CMake: "
find_package(Qt6 REQUIRED COMPONENTS Multimedia)
target_link_libraries(my_project PRIVATE Qt6::Multimedia)
"
Any recommended fixes for barcode scanning with Qt Multimedia in Qt 6.9?

If anyone has solved this, your insights would be incredibly helpful!

Thanks in advance!

SGaist

Hi,

You have to port your application. The Qt Multimedia module has seen a massive rewrite for Qt 6 and that class was removed.

See here for more details about what has changed.

track

I ported the application, but the barcode can't be scanned using SCodes ZXing Barcode Wrapper to Qt 6, but I am encountering difficulties when trying to decode the barcode after processing video frames.

The project originally used QAbstractVideoFilter (which was removed in Qt 6) to process video frames. I successfully ported the code by replacing QAbstractVideoFilter with other video frame processing mechanisms, but I am now unable to read the barcode from the frames.

" Problem:

After porting the code, the barcode isn’t detected even though the video frame is processed correctly.

The SBarcodeDecoder works in the sense that it doesn't throw exceptions anymore, but it also doesn't detect any barcodes.

jsulm

@track said in Qt Multimedia QAbstractVideoFilter Missing in Qt 6.9:

The SBarcodeDecoder works in the sense that it doesn't throw exceptions anymore, but it also doesn't detect any barcodes.

Did you check the content of the frames you're passing to SBarcodeDecoder? Store them as images and see what's inside.

track

I checked the images(attached) but they are not detected as barcaodes .Here is the qml file "import QtQuick 2.15
import QtQuick.Controls 2.15
import QtQuick.Layouts 1.15
import QtMultimedia 6
import CustomFilters 1.0

ApplicationWindow {
visible: true
width: 640
height: 480
title: "SCodess QR Scanner"

Camera {
    id: camera
    active: true
    focusMode: Camera.FocusModeAutoNear
    customFocusPoint: Qt.point(0.5, 0.5)  // Focus center
}

CaptureSession {
    id: session
    camera: camera
    videoOutput: videoOutput
}

VideoOutput {
    id: videoOutput
    anchors.fill: parent
    fillMode: VideoOutput.PreserveAspectCrop
}

SBarcodeFilter {
    id: barcodeFilter
    videoSink: videoOutput.videoSink
    captureRect: Qt.rect(0.25, 0.25, 0.5, 0.5)  // Middle 50% of the frame

    onBarcodeDetected: console.log("Detected:", barcodeValue)
}

Rectangle {
    id: scanOverlay
    anchors.centerIn: parent
    width: parent.width * 0.5
    height: parent.height * 0.5
    color: "transparent"
    border.color: "lime"
    border.width: 2
    radius: 4
    z: 10

    Rectangle {
        id: scanLine
        width: parent.width
        height: 2
        color: "lime"
        radius: 1
        y: 0
        anchors.horizontalCenter: parent.horizontalCenter

        SequentialAnimation on y {
            loops: Animation.Infinite
            running: true
            NumberAnimation {
                from: 0
                to: scanOverlay.height - scanLine.height
                duration: 1500
                easing.type: Easing.InOutQuad
            }
            PauseAnimation { duration: 300 }
            NumberAnimation {
                from: scanOverlay.height - scanLine.height
                to: 0
                duration: 1500
                easing.type: Easing.InOutQuad
            }
            PauseAnimation { duration: 300 }
        }
    }
}

Component.onCompleted: {
    console.log("[Debug] VideoSink assigned?", videoOutput.videoSink !== null)
}

}
"

SGaist

Did you try the example that comes with that library ?

track

The example from zxing works

SGaist

Then you should compare your code to it and adjust it.