title: Can not Read or Play a Video in OpenCV+Python using VideoCapture
body: <pre><code>import cv2
  import numpy as np
  
  cap = cv2.VideoCapture('traffic.avi')
  
  retval, frame = cap.read()
  
  print retval
  
  ================ RESTART: J:\Python For DIP\traffic_video.py ================
  False
  &gt;&gt;&gt; 
  </code></pre>
  
  <p>The Value of retval is always False, which means the video is not read by the command. It must be True to read frames. I don't know what to do. However when I use my default webcam it turns to be True. I tried many videos and the same problem appears. Note: I have installed the ffmpeg correctly.</p>
  
  <p>Note: This is not the full code, in this step I am only validating cap.read() either True or False</p>