pyqt5和cv调用摄像头

可以使用OpenCV库来调用摄像头，然后将视频流传递到PyQt5中进行显示。以下是一个简单的例子：

import cv2
from PyQt5.QtCore import QThread, Qt, pyqtSignal
from PyQt5.QtGui import QImage, QPixmap
from PyQt5.QtWidgets import QApplication, QLabel, QMainWindow, QWidget, QVBoxLayout

class VideoThread(QThread):
    change_pixmap_signal = pyqtSignal(QImage)

    def __init__(self):
        super().__init__()

    def run(self):
        cap = cv2.VideoCapture(0)
        while True:
            ret, frame = cap.read()
            if ret:
                rgb_image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
                h, w, ch = rgb_image.shape
                bytes_per_line = ch * w
                convert_to_qt_format = QImage(rgb_image.data, w, h, bytes_per_line, QImage.Format_RGB888)
                p = convert_to_qt_format.scaled(640, 480, Qt.KeepAspectRatio)
                self.change_pixmap_signal.emit(p)

class App(QMainWindow):
    def __init__(self):
        super().__init__()
        self.label = QLabel(self)
        self.setCentralWidget(self.label)
        self.video_thread = VideoThread()
        self.video_thread.change_pixmap_signal.connect(self.update_image)
        self.video_thread.start()

    def update_image(self, pixmap):
        self.label.setPixmap(pixmap)

if __name__ == '__main__':
    app = QApplication([])
    window = App()
    window.show()
    app.exec_()

在这个例子中，我们创建了一个VideoThread类来获取视频流并将其转换为QImage格式。然后我们将QImage对象传递给MainWindow中的QLabel来显示视频流。在MainWindow的构造函数中，我们创建了VideoThread对象并启动线程。每当VideoThread对象发出change_pixmap_signal信号时，我们都会调用update_image函数来更新QLabel中的图像。最后，我们启动了PyQt5应用程序。