Error in accessing webcam with Python's OpenCV module

Question

Python 3.7.6, opencv-python 4.4.0, Windows 10

Code

import cv2
cap = cv2.VideoCapture(1)
while True:
    success, frame = cap.read()
    cv2.imshow("frame", frame)
    if cv2.waitKey(0) & 0xFF == ord('q'):
        break

I want to access my external usb webcam. I am new to opencv and got the following error message.

C:\Users\92311\PycharmProjects\ObjectDetector\venv\Scripts\python.exe C:/Users/92311/PycharmProjects/ObjectDetector/main.py
[ WARN:0] global C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-2b5g8ysb\opencv\modules\videoio\src\cap_msmf.cpp (435) `anonymous-namespace'::SourceReaderCB::~SourceReaderCB terminating async callback
Traceback (most recent call last):
  File "C:/Users/92311/PycharmProjects/ObjectDetector/main.py", line 5, in <module>
    cv2.imshow("frame", frame)
cv2.error: OpenCV(4.4.0) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-2b5g8ysb\opencv\modules\highgui\src\window.cpp:376: error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow'


Process finished with exit code 1

Can any one explain what's the real problem.

Did you look at this [OpenCV Python: cv2.VideoCapture can only find 2 of 3 cameras](https://stackoverflow.com/questions/49663474/opencv-python-cv2-videocapture-can-only-find-2-of-3-cameras-windows-camera-app/49901961)? — Ahmet, Sep 22 '20 at 12:02

score 1 · Answer 1 · edited Feb 16 '22 at 12:41

1

Looks like you don't have a second camera try:

cap = cv2.VideoCapture(0)

edited Feb 16 '22 at 12:41

Jeru Luke

20,118
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answered Sep 27 '20 at 09:56

harveeey

41
7

score 1 · Answer 2 · edited Feb 16 '22 at 12:40

1

cv2.VideoCapture(0,cv2.CAP_DSHOW) if it is windows7 Try this it worked for me

edited Feb 16 '22 at 12:40

Jeru Luke

20,118
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80
87

answered May 08 '21 at 09:33

Vatsal

11
1

score 0 · Answer 3 · edited Jan 29 '22 at 07:07

0

try this one

if cv2.waitkey(1) & 0xFF == ord('q'):
    break

note that its waitkey(1) and not 0 as argument.

edited Jan 29 '22 at 07:07

Flair

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answered Jan 25 '22 at 17:33

Siddharth Suresh

1

score -1 · Answer 4 · edited Dec 04 '20 at 01:27

-1

first try to change cap = cv2.VideoCapture(1) to cap = cv2.VideoCapture(0) id still error issue. then uninstall opencv

pip uninstall opencv-python

reinstall it

pip install opencv-python

it works for me

edited Dec 04 '20 at 01:27

shimo

2,156
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answered Dec 03 '20 at 20:08

azhar

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Error in accessing webcam with Python's OpenCV module

4 Answers4