从使用 python 通过 usb 连接的摄像机获取实时 Stream

Question

I want to grab live images from a camera which is connected via USB with my computer.

I am using an Industrial Camera with usb port.

At device manager the camera is shown with its name and id so I think it is connected to PC.

I ran a 'findcam' program but it is not showing any existance of camera

import cv2

cap = cv2.VideoCapture(0)


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

cap.release()
cv2.destroyAllWindows()

The given code which i tried is running for webcam on my laptop but when the same code i run on my PC with an external camera.

it constantly showing an error.

The Error:

Traceback (most recent call last):
  
File "C:/Users/Admin/PycharmProjects/industrialcamera/ICvideocapture.py", line 11, in <module>

cv2.imshow('Live Video', frame)

cv2.error: OpenCV(4.1.0) C:\projects\opencv-python\opencv\modules\highgui\src\window.cpp:352: error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow'

I tried changing Index -1, 0, 1 but the error is constant

please help to find, weather it is my PC problem or camera problem or is their is any other way to stream(in python)

Thank You

Answer 1

I started your code on my PC and it works fine. Try to set the camera resolution manually, if you have an error with size.width and size.height , something like this:

cap = cv2.VideoCapture(0)
cap.set(3,1280)
cap.set(4,920)

Answer 2

You may have installed the wrong version of OpenCV which doesn't support video. Uninstall everything of opencv and then run:

pip install opencv-python

(Source: cv2.VideoCapture.open() always returns FALSE )

Answer 3

尝试通过 pip 安装opencv-contrib-python ： pip install opencv-contrib-python或者尝试升级它的版本： pip install opencv-python --upgrade

Answer 4

you can debugg by checking the ret value:

import cv2
cap = cv2.VideoCapture(0)
counter = 0
while True:.       
    ret, frame = cap.read()
    if ret :
        cv2.imshow('Live Video', frame)
        print(f" frame {counter} : ok ")
    if not ret :
        print(f" frame {counter} : ...")
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
cap.release()
cv2.destroyAllWindows()