Question

我想阅读现有视频，将其转换为灰度并播放灰度视频。代码如下

import cv2
import numpy as np

# read the video
cap = cv2.VideoCapture('input.avi')

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

    # convert it into grayscale
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    cv2.imshow('frame',gray)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
cv2.destroyAllWindows()

灰度视频播放到最后。播放完毕后，会弹出以下错误-

Traceback (most recent call last):
  File "D:\L1.py", line 11, in <module>
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.error: OpenCV(3.4.3) C:\projects\opencv-python\opencv\modules\imgproc\src\color.cpp:181: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

为什么显示此错误？有什么解决办法吗？

我正在使用python 3.6和opencv 3.4

Answer 1

视频播放完后，循环将继续尝试获取帧。您可以检查cap是否返回了图像，或者是否断裂，如下所示。另外，别忘了发布视频。

import cv2
import numpy as np

# read the video
cap = cv2.VideoCapture('input.avi')

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

    if ret:
        # convert it into grayscale
        gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
        cv2.imshow('frame',gray)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
    else:
        break

cap.release()
cv2.destroyAllWindows()

cv2.error：完成播放视频后出现OpenCV（3.4.3）错误

1 个答案: