Cenos5.5 安装x264-snapshot 疑问：

hjk857

CentOS release 5.7 (Final) 安装x264-snapshot-20100524-2245提示lavf input: no

[root@localhost x264-snapshot-20100524-2245]# uname -a
Linux localhost.localdomain 2.6.18-274.el5PAE #1 SMP Fri Jul 22 05:34:36 EDT 2011 i686 i686 i386 GNU/Linux
[root@localhost x264-snapshot-20100524-2245]# ./configure --enable-shared
./version.sh: line 2: git: command not found
Platform:   X86
System:     LINUX
asm:        yes
avs input:  no
lavf input: no
ffms input: no
mp4 output: no
pthread:    yes
debug:      no
gprof:      no
PIC:        no
shared:     yes
visualize:  no
You can run 'make' or 'make fprofiled' now.

请问如何编译才能lavf input: yes
lavf是什么？