https://blog.faceutil.com/2017/03/27/5%ec%b4%88%eb%a7%8c%ec%97%90-%eb%8f%99%ec%98%81%ec%83%81-%ed%9a%8c%ec%a0%84-%ed%95%98%ea%b8%b0-video-rotator-%e3%83%af/