无法在树莓派上打开相机 - VIDIOC_STREAMON：无效参数和 VIDIOC_DQBUF

Question

我有以下 python 脚本来处理相机输入

if __name__ == '__main__':
def run_vc():
cap = cv2.VideoCapture(0)


if cap is None or not cap.isOpened():
    print("Error opening video")
    cap.release()
    cv2.destroyAllWindows()

signal.signal(signal.SIGTERM, signal_term_handler)

try:
    while True:
        retval, img = cap.read()
        .... # do some stuff
    
    # free camera object and exit
    print("app finish")
    cap.release()
    cv2.destroyAllWindows()

except KeyboardInterrupt: # If CTRL+C is pressed, exit cleanly:
    print("Keyboard interrupt")
    cap.release()
    cv2.destroyAllWindows()

except ValueError:
    print("some error" + str(ValueError))
    cap.release()
    cv2.destroyAllWindows()

def signal_term_handler(sigNum, frame):
    # on receiving a signal initiate a normal exit
    raise SystemExit('terminating')

if __name__ == '__main__':
    run_vc()

如果树莓派意外关闭并且我尝试再次运行代码我会收到以下错误

VIDIOC_STREAMON: Invalid argument

所以可能有一些句柄或资源需要释放。 有人可以帮忙吗？