解决OpenCV读取视频结束后报错的问题

比眉伴天荒 2022-09-11 08:23 160阅读 0赞

最近由于项目的需要，经常需要使用opencv读视频操作，会经常遇到一个问题，就是视频读完之后会出现报错的情况，虽然不影响代码结果，但是对于吹毛求疵的我实在忍受不了。

会报错的程序：

# -*-coding:utf-8-*-
    """
    File Name: read_video.py
    Program IDE: PyCharm
    Create File By Author: Hong
    """
    import cv2
    
    
    def read_video(video_path: str):
        """
        OpenCV读视频小工具，解决视频读完报错的问题
        :param video_path: 输入需要读取的视频文件路径
        :return: 没有返回值
        """
        print('视频路径：', video_path)
        cap = cv2.VideoCapture(video_path)
        while cap.isOpened():
            # get a frame
            ret, frame = cap.read()
    
            cv2.imshow("capture", frame)
    
            if cv2.waitKey(1) & 0xFF == ord('q'):
                break
        print('视频读完！')
        cap.release()
        cv2.destroyAllWindows()
    
    
    if __name__ == '__main__':
        path = r'D:\multi_insect_videos\multi_object00.mp4'
        read_video(path)

可以把视频正常读完，但是结果会输出错误

Traceback (most recent call last):
      File "E:/PyCharmDocument/create_ST_image/multi_insect_processing/crop_video_to_images.py", line 76, in <module>
        read_video(path)
      File "E:/PyCharmDocument/create_ST_image/multi_insect_processing/crop_video_to_images.py", line 65, in read_video
        cv2.imshow("capture", frame)
    cv2.error: OpenCV(4.5.3) C:\Users\runneradmin\AppData\Local\Temp\pip-req-build-uzca7qz1\opencv\modules\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

原因是视频结束后，opencv的imshow()函数读不了帧就出错了。解决方法：在imshow()之前加入判断，只有当有帧时才读，没有帧时直接退出循环。

不会报错的代码：

# -*-coding:utf-8-*-
    """
    File Name: read_video.py
    Program IDE: PyCharm
    Create File By Author: Hong
    """
    import cv2
    
    
    def read_video(video_path: str):
        """
        OpenCV读视频小工具，解决视频读完报错的问题
        :param video_path: 输入需要读取的视频文件路径
        :return: 没有返回值
        """
        print('视频路径：', video_path)
        cap = cv2.VideoCapture(video_path)
        while cap.isOpened():
            # get a frame
            ret, frame = cap.read()
            if not ret:
                break
            cv2.imshow("capture", frame)
    
            if cv2.waitKey(1) & 0xFF == ord('q'):
                break
        print('视频读完！')
        cap.release()
        cv2.destroyAllWindows()
    
    
    if __name__ == '__main__':
        path = r'D:\multi_insect_videos\multi_object00.mp4'
        read_video(path)

程序输出结果：

视频路径： D:\multi_insect_videos\multi_object00.mp4
    视频读完！
    
    Process finished with exit code 0

更多Python小工具请参考GitHub仓库：[python-script-tools/read\_video.py at master · YouthJourney/python-script-tools · GitHub][python-script-tools_read_video.py at master _ YouthJourney_python-script-tools _ GitHub]

[python-script-tools_read_video.py at master _ YouthJourney_python-script-tools _ GitHub]: https://github.com/YouthJourney/python-script-tools/blob/master/read_video.py