Why an avi file can not be opened in OpenCV-Python

问题

I installed OpenCV vers. 2.4.7.2 on a Windows Vista (32-bit) platform, with no reported errors. Then the following file:

C:\opencv\build\python\2.7\x86\cv2.pyd

was moved to:

C:\python27\Lib\site-packages\

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:

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()

[result returns True for this avi]

However, if I use

import cv2 
path = 'D:/Videos/'
video = 'toy_plane_liftoff.avi' # http://cinelerra.org/footage/
vid = cv2.VideoCapture(path+video)
result = vid.isOpened()

[result returns False for this avi]

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.

来源：https://stackoverflow.com/questions/20703691/why-an-avi-file-can-not-be-opened-in-opencv-python