OpenCv code throws segmentation error(core dumped) Ubuntu 14.04

Question

I'm beginner learning opencv from the official documentation http://docs.opencv.org/trunk/doc/py_tutorials/py_gui/py_video_display/py_video_display.html#display-video

import numpy as np        
import cv2    

cap = cv2.VideoCapture(0)      
while(True):    
    ret, frame = cap.read()
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    cv2.imshow('frame',gray)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()
cv2.destroyAllWindows()

It's giving me error "Segmentation fault (core dumped)" Can anyone please tell me Why is that happening and how to resolve that issue?
Thanks in advance.

I'm dont know how to find that out. All that i got was "segmentation error(core dumped)" nothing else when i run that code. — Lee
Try removing the cap.release() line from your code. From the docs: "In C API, when you finished working with video, release CvCapture structure with cvReleaseCapture(), or use Ptr<CvCapture> that calls cvReleaseCapture() automatically in the destructor." This makes me think memory is freed automatically and calling cap.release() deletes something prematurely. — Ian Leaman
Add checks to your code: if(!cap.isOpened()) print 'error' immediately after cap.open(). Also add if(ret==False) print 'frame missing'. — a-Jays

Jhossep Augusto Popayán Avila Jhossep Augusto Popayán Avila · Accepted Answer · 2015-07-28T04:22:57

Maybe its a little late but what "user3154952" says is true, when you are working with the C++ api you don't need to use the release method, it is already in the video capture Destructor.

This is the code i tested and worked fine:

import sys
import cv2

cap = cv2.VideoCapture(0)

while(1):
    ret,frame = cap.read()
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    cv2.imshow('frame',gray)
    if cv2.waitKey(1) & 0xFF == 27:
        break

cv2.destroyAllWindows()

Update: i have been messing around with my ps3 eye and i've realized that with that camera you get the segmentation error for using only the destroyAllWindows method, to fix that i replaced the destroyAllWindows method with the release method and worked fine, i don't know exactly why that happened i'm just sharing in case someone get that issue. I hope that was helpful.

OpenCv code throws segmentation error(core dumped) Ubuntu 14.04

1 Answers