python.exe crash if opencv tries to access busy webcam

[ifelsetrue]

Hello,


I have a while loop taking images every 5 minutes from webcam. Unfortunately, 
if the camera is busy, python.exe crashes and there is no exception to catch. 
Is there a way to check if camera is busy to avoid the crash?


Thanks!

from cv2 import *

while True:
    time.sleep(4)
    cam = VideoCapture(0)
    s, img = cam.read()
    if s:    # frame captured without any errors
        namedWindow("cam-test",CV_WINDOW_AUTOSIZE)
        imshow("cam-test",img)
        waitKey(0)
        destroyWindow("cam-test")
        imwrite("filename.jpg",img) #save image
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