OpenCV VideoCapture Not Opening

Question

I'm trying to use OpenCV's cv2 python bindings on an Amazon server running Ubuntu 14.04 and I can't seem to get VideoCapture to work properly.

I tried opening the default capture as follows:

import cv2
cap = cv2.VideoCapture(0)
cap.isOpened() #Returns false

I tested this on my local machine and it was true as expected, so there is something wrong with my open CV configuration. I've tried a variety of things:

Using an actual filepath that I confirmed points to an .mp4 file
Using -1 and 1 in place of 0 on the second line
Installing ffmpeg (from a ppa as it isn't available by default on Ubuntu 14.04) and rebuilding OpenCV
Removing my OpenCV directory entirely and rebuilding using the script here
Verifying and reinstalling various other libraries including x264, gstreamer, and gtk

I'm kind of out of ideas at this point. Any ideas of what could be going wrong?

Edit: OpenCV version is 2.4.9.

As I know VideoCapture is for capturing video from camera but Amazon servers have not camera. — furas
VideoCapture is also used to capture video from files, which is what I'm trying to do. — The Bearded Templar
As I see in documentations VideoCapture(0) means use default camera. Probabably need more code to do this. — furas
Yes, after reading your comment I considered that, perhaps it only works locally because I have a camera on my local machine. However, switching VideoCapture(0) with VideoCapture("/path/to/video/video.mp4") returns the same error. — The Bearded Templar
Thanks - it actually just started working. I'm not entirely sure why, but the most recent thing I did was reinstall ffmpeg via instructions here: trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu — The Bearded Templar

Ravish Kumar Sharma Ravish Kumar Sharma · Accepted Answer · 2017-09-04T20:58:34

I also faced a similar problem. Possible solutions:

Check if you have given the correct path.
If you have installed OpenCV using pip, it will not work. You can remove OpenCV and reinstall it looking at the official documentation.
Ways to install via pip,
pip install opencv-python Only installs main module
pip install opencv-contrib-python Install main and contrib module, so use this command.

OpenCV VideoCapture Not Opening

2 Answers