[ WARN:0] global C:\projects\opencv-python\opencv\modules\videoio\src\cap_msmf.cpp

[rems02]

If you have this error:

[ WARN:0] global C:\projects\opencv-python\opencv\modules\videoio\src\cap_msmf.cpp (674) SourceReaderCB::~SourceReaderCB terminating async callback

You must replace line 3
cam = cv2.VideoCapture(1)
with
cam = cv2.VideoCapture(0, cv2.CAP_DSHOW)

Thanks a lot @rems02
Appreciate it!

[ElectroCoderEC]

Yay!. It works perfectly with opencv 4.5.4

[MustafaLotfi]

Thank you but FPS decreases in this way.

[Shiro951216]

Thank you , i struggle a lot with that error

[bcb2020]

Thanks for the solution

[21dczhang]

如果你有这个错误：

[WARN:0] 全局 C:\projects\opencv-python\opencv\modules\videoio\src\cap_msmf.cpp (674) SourceReaderCB::~SourceReaderCB 终止异步回调

您必须将第 3 行替换 cam = cv2.VideoCapture(1) 为 cam = cv2.VideoCapture(0, cv2.CAP_DSHOW)

thanks，this is very useful

[AtharvaTaras]

You do not need cv2.CAP_DSHOW
OpenCV will give the async callback warning when you pass a camera into VideoCapture that doesn't exist or is not connected to your computer. cv2.VideoCapture(0) will always use the default camera of your system.

[xpshaggy]

pls I do not know anything about python.. how do you go about changing this
cam = cv2.VideoCapture(1)
with
cam = cv2.VideoCapture(0, cv2.CAP_DSHOW)? can comebody pls help me out here?