cv2.error: OpenCV(4.6.0) :-1: er

我的代码：

cap = cv2.VideoCapture("1.mp4") # 获取视频对象
w = cap.get(cv2.CAP_PROP_FRAME_WIDTH) # 注意这里必须是整型
h = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)

out = cv2.VideoWriter('./2.mp4', cv2.VideoWriter_fourcc("M","P","4","V"), 30.0,(w,h),True)
while True:
    ret, img = cap.read()
    if ret:
        out.write(img)
    else:
        break
cap.release()
out.release()
cv2.destroyAllWindows()

报错内容：

cv2.error: OpenCV(4.6.0) :-1: error: (-5:Bad argument) in function 'VideoWriter'
Overload resolution failed:

• Can't parse 'frameSize'. Sequence item with index 0 has a wrong type
• VideoWriter() missing required argument 'frameSize' (pos 5)
• VideoWriter() missing required argument 'params' (pos 5)
• VideoWriter() missing required argument 'frameSize' (pos 5)

或者是：

cv2.error: OpenCV(4.6.0) :-1: error: (-5:Bad argument) in function 'VideoWriter'
Overload resolution failed:

• Can't parse 'frameSize'. Sequence item with index 0 has a wrong type
• Argument 'fourcc' is required to be an integer
• Can't parse 'frameSize'. Sequence item with index 0 has a wrong type
• VideoWriter() missing required argument 'params' (pos 6)

问题：
因为帧的宽度和长度必须是整型的。而我们使用CAP_PROP_FRAME_WIDTH获取的值得类型是float。

解决办法：
将float类型转换为int整型。
例如：

cap = cv2.VideoCapture("1.mp4") # 获取视频对象
w = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)) # 注意这里必须是整型
h = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

out = cv2.VideoWriter('./2.mp4', cv2.VideoWriter_fourcc("M","P","4","V"), 30.0,(w,h),True)
while True:
    ret, img = cap.read()
    if ret:
        out.write(img)
    else:
        break
cap.release()
out.release()
cv2.destroyAllWindows()