Python OpenCV 从实时网络摄像头流中获取帧速率和帧时间戳

我试图读取/设置我的网络摄像头的fps，并读取从我的网络摄像头捕获的特定帧的时间戳，这让我有点吃力.特别是当我try 使用vc.get(cv2.CAP_PROP_POS_MSEC)、vc.get(cv2.CAP_PROP_FPS)、vc.get(cv2.CAP_PROP_FRAME_COUNT)时，它们分别返回-1、0、-1.显然，我漏掉了一些东西.有人能帮帮忙吗？代码如下所示:

import os
import time

import cv2
import numpy as np
[...]
# Create a new VideoCapture object
vc = cv2.VideoCapture(0, cv2.CAP_DSHOW)
vc.set(cv2.CAP_PROP_FRAME_WIDTH, 1280)
vc.set(cv2.CAP_PROP_FRAME_HEIGHT, 720)

# Initialise variables to store current time difference as well as previous time call value
previous = time.time()
delta = 0
n = len(os.listdir("directory"))

# Keep looping
while True:
    timem = vc.get(cv2.CAP_PROP_POS_MSEC)
    fps = vc.get(cv2.CAP_PROP_FPS)
    total_frames = vc.get(cv2.CAP_PROP_FRAME_COUNT)

    print(timem, fps, total_frames)
    # Get the current time, increase delta and update the previous variable
    current = time.time()
    delta += current - previous
    previous = current

    # Check if 3 (or some other value) seconds passed
    if delta > 3:
        # Operations on image
        # Reset the time counter
        delta = 0

        _, img = vc.read()
        [...]
        # press esc to exit
    if cv2.waitKey(20) == 27:
        break

edit:如果我go 掉cv2.CAP_DSHOW，它可以工作，但我不能使用CAP_PROP_FRAME_WIDTH