我正在尝试编写一个python3-opencv3代码来读取彩色视频并将其转换为灰度并保存回来 . （尝试练习学习python和opencv）
当我在ubuntu工作时，我发现cv2.VideoCapture isColor标志不起作用（它仅适用于windows）
import numpy as np
import cv2
cap = cv2.VideoCapture('output.avi')
ret, frame = cap.read()
print('ret =', ret, 'W =', frame.shape[1], 'H =', frame.shape[0], 'channel =', frame.shape[2])
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
height, width = gray.shape[:2]
print(height,width)
cv2.imshow('frame',gray)
FPS= 20.0
FrameSize=(frame.shape[1], frame.shape[0])
fourcc = cv2.VideoWriter_fourcc(*'MJPG')
out = cv2.VideoWriter('Video_output.avi', fourcc, FPS, (width,height))
while(ret):
ret, frame = cap.read()
if cv2.waitKey(1) & 0xFF == ord('q') or ret == False:
break
print('ret =', ret, 'W =', frame.shape[1], 'H =', frame.shape[0], 'channel =', frame.shape[2])
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
# Save the video
out.write(gray)
cv2.imshow('frame',gray)
cap.release()
out.release()
cv2.destroyAllWindows()
它给我这个错误：（-215）img.cols == width && img.rows == height * 3 in function write
我猜，问题是帧大小和灰度图像转换，但我无法搞清楚？我尝试了不同的高度和宽度组合，但没有一个能够正确执行程序 .
有人可以帮忙吗？
按照评论的要求：
Traceback (most recent call last):
File "/home/akash/Coded/VideoCode/Test3", line 70, in <module>
out.write(gray)
cv2.error: /home/travis/miniconda/conda-bld/conda_1486587069159/work/opencv-3.1.0/modules/videoio/src/cap_mjpeg_encoder.cpp:834: error: (-215) img.cols == width && img.rows == height*3 in function write
1 回答
OpenCV错误
-215表示"assertion failed" . 断言中列出了断言本身（短语"Assertion failed"本身也可能应该这样;您可以在OpenCV的bug跟踪器中打开关于此的票证） . （更新：my pull request with this change was accepted on 06.03并在opencv3.4.2发布 . ）正如可以从断言中推断出的那样，它期望帧是3色通道的 . 要制作灰度视频，you need to pass isColor=False to VideoWriter constructor：