Python CV2：尝试拍照时“[WARN:0] 终止异步回调”
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CV2: "[ WARN:0] terminating async callback" when attempting to take a picture
提问by Elephant
I am trying to take a picture from the defualt carmera with python, to do this I am using openCV (import cv2from python shell). However, when I attempt to disable the camera it closes but with the error [ WARN:0] terminating async callback.
我正在尝试使用 python 从默认的 carmera 中拍照，为此我使用 openCV（import cv2来自 python shell）。但是，当我尝试禁用相机时，它会关闭但出现错误[ WARN:0] terminating async callback。
This is code I am trying to run:
这是我试图运行的代码：
import cv2
camera_port = 0
camera = cv2.VideoCapture(camera_port)
return_value, image = camera.read()
cv2.imwrite("image.png", image)
camera.release() # Error is here
The code outputs the desired result- it takes a saves an image but I do not understand why the error message occures or how to remove it
代码输出所需的结果 - 它需要保存图像但我不明白为什么会出现错误消息或如何删除它
采纳答案by Aprajita Verma
It's probably showing a warning because you're not releasing the handle to the webcam.
它可能会显示警告，因为您没有松开网络摄像头的手柄。
try adding this to the end of the code
尝试将此添加到代码的末尾
camera.release()
cv2.destroyAllWindows()
I hope this helps!
我希望这有帮助！
回答by Djotchuang Tamo
I had the same warning.
Just modify the line camera = cv2.VideoCapture(camera_port)to camera = cv2.VideoCapture(camera_port, cv2.CAP_DSHOW)and add cv2.destroyAllWindows()as the last line of your code.
我有同样的警告。只需将该行修改camera = cv2.VideoCapture(camera_port)为camera = cv2.VideoCapture(camera_port, cv2.CAP_DSHOW)并添加cv2.destroyAllWindows()为代码的最后一行。
回答by Sumit kumar
camera = cv2.VideoCapture(camera_port,cv2.CAP_DSHOW)
cv2.destroyAllWindows()
回答by robot liu
- first:add
cv2.destroyAllWindows() - second:the camera permission you have banned,and then check it.
- 第一：添加
cv2.destroyAllWindows() - 第二：你已经禁止的相机权限，然后检查它。
回答by Joe Llerena
It works for me as indicated Sumit Kumar
正如Sumit Kumar所示，它对我有用
camera_port = 0
#camera = cv2.VideoCapture(camera_port)
camera = cv2.VideoCapture(camera_port,cv2.CAP_DSHOW)
# Check if the webcam is opened correctly
if not camera.isOpened():
raise IOError("Cannot open webcam")
return_value, image = camera.read()
print("We take a picture of you, check the folder")
cv2.imwrite("image.png", image)
camera.release() # Error is here
cv2.destroyAllWindows()
回答by Brady R
camera = cv2.VideoCapture(camera_port, cv2.CAP_DSHOW) # Added cv2.CAP_DSHOW
return_value, image = camera.read()
cv2.imwrite("image.png", image)
camera.release()
cv2.destroyAllWindows() # Handles the releasing of the camera accordingly
回答by ARUN AK
hey guys found the solution pip install opencv-contrib-python==3.4.7.28 try like this we have to specifically say the version try lesser version mine was 4.x so I did and no error popped up
嘿伙计们找到了解决方案 pip install opencv-contrib-python==3.4.7.28 像这样尝试我们必须特别说明我的版本尝试较小的版本是 4.x 所以我做了并且没有弹出错误
回答by Little_being
I did this & I don't see that warning there after.(only for Windows OS)
我这样做了，之后我没有看到那个警告。（仅适用于 Windows 操作系统）
Open cmd and type:
打开cmd并输入：
setx OPENCV_VIDEOIO_PRIORITY_MSMF 0
