QVideoWidget stopped working as viewfinder after Qt upgrade 6.2.0->6.2.1 - bug?

StarterKit

Hi all,
I have a code that uses QVideoWidget as a viewfinder for QCamera. Code snipped is below, here are my comments:

I use Linux for my tests;
this code works ok with PySide6 6.2.0 - I see live image in viewfinder;
with PySide6 6.2.1 the viewfinder is black;
there are commented pieces of code - I added this to check 6.2.1 more and image is successfully saved if I press the button (i.e. QImageCapture itself works);
no errors are printed by this code;

Does it mean I missed some change between 6.2.0 and 6.2.1? Or something is broken?

Code:

from PySide6.QtWidgets import QApplication, QMainWindow, QWidget, QVBoxLayout, QPushButton
from PySide6.QtMultimedia import QCamera, QMediaCaptureSession, QImageCapture
from PySide6.QtMultimediaWidgets import QVideoWidget
from PySide6.QtGui import QImage

class CameraWnd(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)
        self.layout = QVBoxLayout()

        self.viewfinder = QVideoWidget(self)
        self.layout.addWidget(self.viewfinder)
        self.viewfinder.setMinimumSize(720, 405)

        self.button = QPushButton(self)
        self.button.setText("Check state")
        self.layout.addWidget(self.button)

        self.wnd = QWidget(self)
        self.wnd.setLayout(self.layout)
        self.setCentralWidget(self.wnd)

        self.camera = QCamera()
        self.captureSession = QMediaCaptureSession()
        self.img_capture = QImageCapture(self.camera)

        self.captureSession.setCamera(self.camera)
        self.captureSession.setVideoOutput(self.viewfinder)
        self.captureSession.setImageCapture(self.img_capture)

        self.button.clicked.connect(self.on_button)
        self.img_capture.errorOccurred.connect(self.on_error)
        self.camera.errorOccurred.connect(self.on_cam_error)
        # self.img_capture.imageCaptured.connect(self.captured)

        self.camera.start()

    def on_button(self):
        if self.img_capture.isReadyForCapture():
            print("READY")
            # self.img_capture.capture()
        else:
            print("NOT READY")

    def on_error(self, _id, _error, error_str):
        print(f"Error: {error_str}")

    def on_cam_error(self, _error, error_str):
        print(f"Error: {error_str}")

    # def captured(self, id: int, img: QImage):
    #     print(id)
    #     img.save('/home/user/test.png')

def main():
    app = QApplication()

    camera = CameraWnd()
    camera.show()

    return app.exec()

if __name__ == '__main__':
    main()

SGaist

Hi,

Since your code is pretty simple and does look correct, It looks like a regression.

StarterKit

@SGaist, thanks. So, I'll go and report a bug

eyllanesc

@StarterKit I have compiled the official example https://doc.qt.io/qt-6/qtmultimedia-multimediawidgets-camera-example.html and I reproduce the error so it is clearly a bug.

eyllanesc

@StarterKit You must report it as a QtMultimedia bug, not PySide6

StarterKit

@eyllanesc have you tried it on Linux also? or another OS?

eyllanesc

@StarterKit On Linux, with Qt 6.2.0 it worked great but no longer on Qt 6.2.1

StarterKit

https://bugreports.qt.io/browse/QTBUG-97911