ui.py

import sys
from PyQt5.QtWidgets import QApplication, QDialog, QLabel
from PyQt5.QtGui import QImage, QPixmap
from PyQt5.QtCore import QTimer
import cv2

class AppWindow(QDialog):
    def __init__(self):
        super().__init__()
        self.video = cv2.VideoCapture(0)
        self.initUI()

    def initUI(self):
        self.setWindowTitle('miniMOKE')
        self.setGeometry(300, 300, 800, 600)
        self.label = QLabel(self)
        self.label.setGeometry(0, 0, 1920//4, 1080//4)
        self.label.setScaledContents(True)

        self.timer = QTimer(self)
        self.timer.timeout.connect(self.show_frame)
        self.timer.start(20)

    def show_frame(self):
        _, frame = self.video.read()
        frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
        image = QImage(frame, frame.shape[1], frame.shape[0], 
                       frame.strides[0], QImage.Format_RGB888)
        self.label.setPixmap(QPixmap.fromImage(image))

if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = AppWindow()
    window.show()
    sys.exit(app.exec_())