参考自：https://linuxize.com/post/how-to-install-ffmpeg-on-centos-7/
首先切换至root用户
yum install epel-release
然后
rpm -v --import http://li.nux.ro/download/nux/RPM-GPG-KEY-nux.ro
rpm -Uvh http://li.nux.ro/download/nux/dextop/el7/x86_64/nux-dextop-release-0-5.el7.nux.noarch.rpm
然后可以安装了，这步骤在国内下载会比较慢
yum install ffmpeg ffmpeg-devel
最后查看安装的版本
ffmpeg -version
