from cv2 import cv2

for i in range(len('box.mp4')):
    cam = cv2.VideoCapture('box.mp4')
    currentFrame = 0
    while(True):
        ret, frame = cam.read()
        if ret:
            cv2.imwrite(str(currentFrame) + '.jpg', frame)
            currentFrame += 1
        else:
            break
    cam.release()