1. Problem code

A few months ago, a piece of code could be executed normally. Some of the codes are as follows:

def buildVideoByCV():
    videoMake = cv2.VideoWriter()
    fourcc = cv2.VideoWriter_fourcc(*'MP4V') #https://blog.csdn.net/whudee/article/details/108689420
    fps = 12
    videoMake.open(r"g:\video\lightShowCV.MP4", fourcc, fps, (800,600))

    for t in range(65*fps):
        img = makeframe(t*1.0/fps)
        videoMake.write(img)
        if t%20==0:print(f'\r视频制作进度：{(t*100.0)/(66*fps):4.2f}%',end='')
    videoMake.release()

2. Error message

Error in execution today:

Video production progress: 95.96%OpenCV: FFMPEG: tag 0x5634504d/'MP4V' is not supported with codec id 12 and format 'mp4/MP4 (MPEG-4 Part 14)'
OpenCV: FFMPEG: fallback to use tag 0x7634706d/'mp4v'

3. Solution

Set FourCC = cv2.videowriter_FourCC (*'mp4v') is changed to: FourCC = CV2.Videowriter_FourCC (*'mp4v') , just change the encoded uppercase mp4v to lowercase.

4. Summary

This paper introduces the solution to the error reported by opencv videowriter: ffmpeg: tag ‘mp4v’ is not supported. You only need to replace the code ‘mp4v’ with ‘mp4v’.