我想将摄像机输出保存为运动JPEG（MJPG）格式。下面的代码，

import cv2
import numpy as np

cap = cv2.VideoCapture(0)
if (cap.isOpened() == False): 
print("Unable to read camera feed")
frame_width = int(cap.get(3))
frame_height = int(cap.get(4))
frame_per_sec = int('10')

out = cv2.VideoWriter('output.mjpeg',cv2.VideoWriter_fourcc('M','J','P','G'),         (frame_per_sec), (frame_width,frame_height))
while(True):
ret, frame = cap.read()
if ret == True:      
# Write the frame into the file 'output.mjpeg'
out.write(frame) 
# Display the resulting frame    
cv2.imshow('frame',frame)
# Press Q on keyboard to stop recording
if cv2.waitKey(1) & 0xFF == ord('q'):
  break
else:
break 
cap.release()
out.release()
cv2.destroyAllWindows()

运行时，我收到以下错误，

[ WARN:0] OpenCV | GStreamer warning: Cannot query video position: status=0, value=-1, duration=-1
OpenCV: FFMPEG: tag 0x67706a6d/'mjpg' is not supported with codec id 7 and format 'mjpeg / raw MJPEG video'

我能做些什么来解决这些问题呢？我试过改变大小写，（'M'，'J'，'P'，'G'到'm'，'j'，'p'，'g'）没有成功。感谢任何关于解决上述问题的建议，以及GStreamer问题。提前感谢。