在python中opencv读取rtsp视频流延时800毫秒左右，如何控制在300毫秒左右

请问各位大佬，在python中opencv读取rtsp视频流延时800毫秒左右，如何控制在300毫秒左右，下面是我的测试代码，请大佬帮忙看看，怎么可以控制在300毫秒左右。

import multiprocessing
from multiprocessing import Process
import cv2


def run1(que, video):
    cap = cv2.VideoCapture(video)
    cap.set(cv2.CAP_PROP_FOURCC,cv2.VideoWriter_fourcc('M','J','P','G'))
    cap.set(cv2.CAP_PROP_FRAME_WIDTH,1920)
    cap.set(cv2.CAP_PROP_FRAME_HEIGHT,1080)
    while 1:
        ret, img = cap.read()

        lenth = que.qsize()
        print("que lenth: ", lenth)

        if lenth > 2:
            for i in range(lenth - 2):
                frame = que.get()  # 清除缓存
        que.put(img)
        cv2.imshow("read", img)

        cv2.waitKey(1)
    # cv2.destroyAllWindows()
    # cap.release()


def test_2(que):
    while 1:
        img = que.get()
        cv2.imshow("show", img)
        key = cv2.waitKey(1)
        if key == 27:
            break
    # cv2.destroyAllWindows()


if __name__ == "__main__":
    manager = multiprocessing.Manager()
    que = manager.Queue()
    # que = Queue()
    test1_start = 1
    test2_start = 1

    video = "rtsp://192.168.1.152/chn0"


    t1 = Process(target=run1, args=(que, video,))
    t1.start()
    test_2(que)
    t1.terminate()