解决讲解CentOS系统 yum 安装mplayer
有次在使用CentOS系统的时候，我下了源码编译却加--enable-gui就出错，不加就过了，过了却没界面，只能听到声音，没办法，找几个rpm文件安装，明明已经安装了的文件却说需要它，最后，我终于寻找到了yum安装mplayer的方法。
首先yum install yum-priorities，yum-priorities插件可以为yum的源仓库指定优先级。如果安装包是用高优先级的源仓库安装的，那么这些包就不能用低优先级别的源仓库去更新。同样的，如果一个包可以从多个源仓库中下载安装，但指定了优先级别之后，这个包就会从最高优先级的源仓库安装。假如用户使用一个或者多个第三方源仓库，这些源仓库都会更新系统文件，有些更新甚至会潜在的危害你的的CentOS系统，这个时候，该插件就特别起作用了。
现在开始编辑 /etc/yum/pluginconf.d/priorities.conf文件，必须先确认其中有以下的设置：[main] enabled=1
然后编辑 /etc/yum.repos.d/，
如下：
CentOS-Base.repo This file uses a new mirrorlist system developed by Lance Davis for CentOS. The mirror system uses the connecting IP address of the client and the update status of each mirror to pick mirrors that are updated to and geographically close to the client. You should use this for CentOS updates unless you are manually picking other mirrors. If the mirrorlist= does not work for you, as a fall back you can try the remarked out baseurl= line instead.
[base] name=CentOS-$releasever - Base mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os #baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5 priority=1 #released updates [updates] name=CentOS-$releasever - Updates mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates #baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5 priority=1 #packages used/produced in the build but not released [addons] name=CentOS-$releasever - Addons mirrorlist=http://mirrorlist.centos.org/?release=$releasever&,汽车尾气达标;arch=$basearch&repo=addons #baseurl=http://mirror.centos.org/centos/$releasever/addons/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5 priority=1 #additional packages that may be useful [extras] name=CentOS-$releasever - Extras mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras #baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5 priority=1 #additional packages that extend functionality of existing packages [centosplus] name=CentOS-$releasever - Plus mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus #baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/ gpgcheck=1 enabled=0 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5 priority=2
也就是每个仓库后面添加了个priority=x，通过上面的设定之后，Yum将不会从低优先级的源更新那些来自base和update仓库的的安装包。这里x必须取1到99之间的整数。CentOS系统仓库的默认优先级是99.序号最小的源仓库具有最高的优先级。同常，最好是为CentOS系统 base 和 update仓库选择非常高的优先级（毕竟是官方的嘛！），在上面的CentOS-Base.repo 文件里，CentOS base 和 update仓库都被指定了最高的优先级 （priority=1）。
下面CentOS系统开始安装mplayer：
安装RPMforge：
先下载rpmforge-release包，根据你的系统，从下面的链接中选择一个下载。
i386http://apt.sw.be/redhat/el5/en/i386/RPMS.dag/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
x86_64 http://apt.sw.be/redhat/el5/en/x86_64/RPMS.dag/rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm
安装DAG's GPG key
#rpm --import http://dag.wieers.com/rpm/packages/RPM-GPG-KEY.dag.txt
检查你下载的包
#rpm -K rpmforge-release-0.3.6-1.el5.rf.*.rpm
装rpmforge包
#rpm -i rpmforge-release-0.3.6-1.el5.rf.*.rpm
运行了上述的命令后，将会向CentOS系统yum源仓库里加入一个配置文件，并且会导入合适的 GPG keys。此时，最好也设置RPMForge仓库的优先级。
用下面的命令检查更新
#yum check-update
最后就安装mplayer了
#yum install mplayer*
然后到这里下载两个编码包all-20071007.tar.bz2和windows-all-20071007.zip
http://www1.mplayerhq.hu/MPlayer/releases/codecs/
yum安装mplayer后编码包默认应安装在/usr/lib/codecs/中