在python中使用OpenCV加载视频

Question

Here is my code which is running...but I didnt understood why we used:

if cv2.waitKey(1000) & 0xFF == ord('q'):
        break

in the code......under display the resulting frame comment:

import numpy as np
import cv2

    cap = cv2.VideoCapture('C:\\Users\\KRK\\Desktop\\Dec17thVideo.mp4')

    while(True):
        # Capture frame-by-frame
        ret, frame = cap.read()

        # Our operations on the frame come here
        gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

        # Display the resulting frame
        cv2.imshow('frame',gray)
        if cv2.waitKey(1000) & 0xFF == ord('q'):
            break

    # When everything done, release the capture
    cap.release()
    cv2.destroyAllWindows()

Answer 1

waitkey displays the image for the specified number of milliseconds. Without it, you actually wouldn't be able to see anything. Then 0xFF == ord('q') detects when the keystroke q is pressed on the keyboard.

Think of waitkey as a pause function. After the code has been executed; at lightning speed :), waitkey says, pause for 1000 milliseconds to display the frame. Within this, detect if the user pressed q. If q is pressed, then get outside of my infinite while loop. When this happens, then the window won't be shown anymore.

Their documentation is a good resource as well.