Python opencv 多进程之间使用共享内存传递图像数据

import numpy as np
from multiprocessing import Process, Value, sharedctypes
import ctypes
import cv2

class Camera_p(Process):
    def __init__(self, arr, isGrab):
        super(Camera_p, self).__init__()
        self.arr = arr
        self.isGrab = isGrab

    def run(self):
        cap = cv2.VideoCapture(0)
        while self.isGrab.value:
            _, frame = cap.read()
            frame = frame.ravel()
            temp = np.frombuffer(self.arr, dtype=np.uint8)
            temp[:] = frame

class ShowWindow:
    def __init__(self):
        self.camera_arr = sharedctypes.RawArray(ctypes.c_uint8, 640 * 480 * 3)
        self.isGrab = Value('i', True)

    def show_pic(self):
        cam_pro = Camera_p(self.camera_arr, self.isGrab)
        cam_pro.start()

        while True:
            frame_show = np.frombuffer(self.camera_arr, dtype=np.uint8).reshape(480, 640, 3)
            cv2.imshow('Camera Feed', frame_show)

            key = cv2.waitKey(1) & 0xFF
            if key == ord('q'):
                self.isGrab.value = False
                break

        cam_pro.join()

def main():
    show = ShowWindow()
    show.show_pic()

if __name__ == '__main__':
    main()