Error !_img.empty() in function 'imwrite'

[Oh-JongJin]

[h264 @ 000001d53c84e740] error while decoding MB 4 6, bytestream -9
OpenCV(4.5.5) D:\a\opencv-python\opencv-python\opencv\modules\imgcodecs\src\loadsave.cpp:801: error: (-215:Assertion failed) !_img.empty() in function 'cv::imwrite'

[Oh-JongJin]

The first method is append cap.isOpened()
Check video before read frame,

cap = cv2.VideoCapture(' RTSP ADDRESS ')
if cap.isOpened():
    while True:
        ...