yum install -y ffmpeg
使用上面的命令安装却出现以下问题：
Google后发现缺少一些扩展：
wget https://download1.rpmfusion.org/free/el/rpmfusion-free-release-7.noarch.rpm
wget https://download1.rpmfusion.org/nonfree/el/rpmfusion-nonfree-release-7.noarch.rpm
rpm -ivh *.rpm
rpm --import http://li.nux.ro/download/nux/RPM-GPG-KEY-nux.ro 2
rpm -Uvh http://li.nux.ro/download/nux/dextop/el7/x86_64/nux-dextop-release-0-1.el7.nux.noarch.rpm 2
yum -y install ffmpeg ffmpeg-devel
顺序执行以上命令，成功安装。
