https://blog.faceutil.com/2017/03/27/%ec%9d%b8%ed%84%b0%eb%84%b7-%eb%8f%99%ec%98%81%ec%83%81-%ec%a0%80%ec%9e%a5-%ed%94%84%eb%a1%9c%ea%b7%b8%eb%9e%a8-videocacheview-v1-57-%eb%8b%a4%ec%9a%b4-%d1%8c/