mutimedia/build/demo.dist via 🐍 v3.11.10 (mutimedia) 
❯ ./demo
No QtMultimedia backends found. Only QMediaDevices, QAudioDevice, QSoundEffect, QAudioSink, and QAudioSource are available.
Failed to initialize QCamera "Not available"
Failed to create QVideoSink "Not available"
Failed to initialize QMediaCaptureSession "Not available"

import sys

from PySide6.QtMultimedia import QCamera, QMediaCaptureSession, QMediaDevices
from PySide6.QtMultimediaWidgets import QVideoWidget
from PySide6.QtWidgets import QApplication, QVBoxLayout, QWidget


class View(QWidget):
    def __init__(self) -> None:
        super().__init__()
        self.camera = QCamera(QMediaDevices.defaultVideoInput())
        self.camera.start()
        self.viewfinder = QVideoWidget()
        self.captureSession = QMediaCaptureSession()
        self.captureSession.setCamera(self.camera)
        self.captureSession.setVideoOutput(self.viewfinder)
        self.mainLayout = QVBoxLayout(self)
        self.mainLayout.addWidget(self.viewfinder)


def main() -> int:
    app = QApplication()
    view = View()
    view.show()
    return app.exec()


if __name__ == "__main__":
    sys.exit(main())