title: Why an avi file can not be opened in OpenCV-Python
body: <p>I installed OpenCV vers. 2.4.7.2 on a Windows Vista (32-bit) platform, with no reported errors.
  Then the following file:</p>
  
  <pre><code>C:\opencv\build\python\2.7\x86\cv2.pyd
  </code></pre>
  
  <p>was moved to:</p>
  
  <p><code>C:\python27\Lib\site-packages\</code></p>
  
  <p>I have been testing openCV with both images and video (*.avi) files. I have no problems (yet) when
  working with images. However, I have found a problem when trying to open avieo files. First, an 
  example that works fine:</p>
  
  <pre><code>import cv2
  path = 'D:/Videos/'
  video = 'julius.avi'   # a test avi available from me via email attachment
  vid = cv2.VideoCapture(path+video)
  result = vid.isOpened()
  </code></pre>
  
  <p>[result returns True for this avi]</p>
  
  <p>However, if I use</p>
  
  <pre><code>import cv2 
  path = 'D:/Videos/'
  video = 'toy_plane_liftoff.avi' # http://cinelerra.org/footage/
  vid = cv2.VideoCapture(path+video)
  result = vid.isOpened()
  </code></pre>
  
  <p>[result returns False for this avi]</p>
  
  <p>Note, I have tried several other avi files (test avi's downloaded from the web)
  and most of them will not open. What can be done to open any "good" avi file? By good avi file I mean one that plays with Windows media player and VLC 2.1.2. </p>