centos 自带播放器MP4都无法播放，因此安装VCL播放器
安装epel和remi的repository###
sudo yum localinstall --nogpgcheck http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
sudo yum localinstall --nogpgcheck http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
安装noarch的repository###
sudo yum localinstall --nogpgcheck http://download1.rpmfusion.org/free/el/updates/6/i386/rpmfusion-free-release-6-1.noarch.rpm
sudo yum localinstall --nogpgcheck http://download1.rpmfusion.org/nonfree/el/updates/6/i386/rpmfusion-nonfree-release-6-1.noarch.rpm
安装完成后，上述repo会出现在/etc/yum.repos.d文件夹
安装VLC###
sudo yum install vlc
亲测播放视频有声音，不用像网上一些方法说的要调节声卡
参考资料###
Linux社区 fangwei009 CentOS 6.5 下yum安装VLC：http://www.linuxidc.com/Linux/2015-04/116262.htm