无法使用 python 和 opencv 保存视频

Question

我正在尝试将视频更改为灰度并保存，但视频仅在完成后运行过程中显示运行我点击保存的文件，但我只收到无法呈现文件的消息

import cv2
import numpy as np
import matplotlib.pyplot as plt


import numpy as np
import cv2



    cap = cv2.VideoCapture ('DJI_0055.mov')

    ret, frame = cap.read()
    print('ret =', ret, 'W =', frame.shape[1], 'H =', frame.shape[0], 
    'channel =', frame.shape[2])


     FPS= 60.0
     FrameSize=(frame.shape[1], frame.shape[0])
     fourcc = cv2.VideoWriter_fourcc(*'MJPG')
     out = cv2.VideoWriter('Video_output3.mov', fourcc, FPS, FrameSize, 
      0)

     while(cap.isOpened()):
     ret, frame = cap.read()

     gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
     frame = gray

     # Save the video
     out.write(frame)

     cv2.imshow('frame',frame)
     if cv2.waitKey(1) & 0xFF == ord('q'):
     break

     cap.release()
     out.release()
     cv2.destroyAllWindows()

除了无法呈现文件消息外，我还在视频结束后收到此消息运行在空闲时

     Traceback (most recent call last):
     File "C:\Users\fido\Desktop\Practice\E-1-00pm-12m-1mps- 
     8wp\BlackAndWhite.py", line 25, in <module>
     gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
     cv2.error: OpenCV(4.1.1) C:\projects\opencv- 
     python\opencv\modules\imgproc\src\color.cpp:182: error: 
    (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

Answer 1

在最后一帧之后，ret ---> False and Frame ---> []，这就是你将得到的。这就是 cvtColor 显示此错误的原因。

因此，如果您添加

if not ret:
    break

它将正确退出循环，您的视频将被保存。

像这样编辑您的代码：

while(cap.isOpened()):
     ret, frame = cap.read()

     if not ret:
         break

     gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
     frame = gray

     # Save the video
     out.write(frame)

     cv2.imshow('frame',frame)
     if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()
out.release()
cv2.destroyAllWindows()

无法使用 python 和 opencv 保存视频

Cannot save video using python and opencv

python

opencv

video-capture