https://blog.faceutil.com/2017/03/20/%eb%8f%99%ec%98%81%ec%83%81-%ec%9e%90%eb%a5%b4%ea%b8%b0-free-video-cutter-%ec%84%a4%ec%b9%98-%eb%b0%8f-%ec%82%ac%ec%9a%a9%eb%b2%95-%e2%85%a7/