Read after Videocapture on opencv always returns false

Question

I cant figure out what the problem is.

I am using

Ubuntu 17.04
Python 2.7.13
OpenCV Version: 3.3.0

I have gone through all the related problems on internet but have not got the solution for the problem yet. 'v.mp4' file is in the same directory in which my python file is present.

CODE

import cv2 vidcap = cv2.VideoCapture('v.mp4') success,image = vidcap.read() count = 0; print success while success: success,image = vidcap.read() cv2.imwrite("frame%d.jpg" % count, image) # save frame as JPEG file if cv2.waitKey(10) == 27: # exit if Escape is hit break count += 1

can you try to change your file so it is while vidcap.isOpened() ? Can you ensure the file is being read? Also try displaying the frame first using cv2.imshow() before writing it? — Samer Tufail
– Samer Tufail, Commented Oct 4, 2017 at 15:09
@SamerTufail I have already tried while vidcap.isOpened(), but it never enters the while loop. I am not sure that my code is able to read the file on the first place. Since success value always remains false, there is no point of doing cv2.imshow() for now. — arjun gupta
– arjun gupta, Commented Oct 5, 2017 at 8:06
@AlexanderReynolds i have installed opencv using $pip install opencv-python — arjun gupta
– arjun gupta, Commented Oct 5, 2017 at 8:11

alkasm · Accepted Answer · 2017-10-05 08:52:52Z

1

The opencv-python package does not have VideoCapture() support outside of Windows. See my answer here or the PyPI opencv-python documentation, which states:

IMPORTANT NOTE

MacOS and Linux packages do not support video related functionality (not compiled with FFmpeg).

answered Oct 5, 2017 at 8:52

alkasm

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3 Comments

arjun gupta Over a year ago

So, should I compile OpenCV from source if I don't want these type of problems as explained by you in your other answer?

alkasm Over a year ago

@arjungupta yep! If you aren't familiar with compiling stuff from source it can be a bit of a headache, but you'll get comfortable with it after a few tries :). If this answered your question, could you select it as accepted? Thanks!

arjun gupta Over a year ago

Thanks for your advice, that really helped. I found how to compile open cv from source from https://www.pyimagesearch.com/2016/10/24/ubuntu-16-04-how-to-install-opencv/ , but that was tutorial was supported for Ubuntu 16.04, so I downgraded my OS from Ubuntu 17.04 to Ubuntu 16.04 as many of the libraries were not available for Ubuntu 17.04 that were very necessary for my project.

Aleks Vidmantas · Accepted Answer · 2017-12-09 21:51:26Z

For me, I used pycharm as my ide. Every isopened() and read() showed up false. All I had to do to was change the python version that pycharm used to python 2.

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