how to read frame width of video in cv2 code example

Example: how to read frame width of video in cv2

import cv2

vcap = cv2.VideoCapture('video.avi') # 0=camera
 
if vcap.isOpened(): 
    # get vcap property 
    width  = vcap.get(cv2.cv.CV_CAP_PROP_FRAME_WIDTH)   # float `width`
    height = vcap.get(cv2.cv.CV_CAP_PROP_FRAME_HEIGHT)  # float `height`
    # or
    width  = vcap.get(3)  # float `width`
    height = vcap.get(4)  # float `height`

    # it gives me 0.0 :/
    fps = vcap.get(cv2.cv.CV_CAP_PROP_FPS)