1、安装所需软件
yum install -y automake autoconf libtool gcc gcc-c++
2、安装第三方更新源
rpm -ivh http://apt.sw.be/redhat/el6/en/i386/rpmforge/RPMS/rpmforge-release-0.5.3-1.el6.rf.i686.rpm
3、安装ffmpeg
yum install ffmpeg ffmpeg-devel
会自动安装众多解码器，ffmpeg版本为0.6.5-1.el6.rf。看了下yum安装的解码器版本还不是很旧，但是ffmpeg版本较老。
4、测试一下
将一个.avi视屏转为.flv格式
ffmpeg -i Destination.avi -y -ab 56 -ar 22050 -r 15 -sameq test2.flv
转换前后两个文件的格式比较：
转换前
Destination.avi
General
Complete name : E:PVDestination.avi
Format : AVI
Format/Info : Audio Video Interleave
Format/Family : RIFF
File size : 79.5 MiB
PlayTime : 4mn 1s
Bit rate : 2754 Kbps
StreamSize : 469 KiB
Subject : doobie (2007)
Writing application : VirtualDubMod 1.5.10.2 (build 2540/release)
Writing library : VirtualDubMod build 2540/release
Video #0
Codec : XviD
Codec/Family : MPEG-4
Codec/Info : XviD project
Codec profile : Streaming Video Profile/Level 1
Codec settings/PacketBitStream : Yes
Codec settings/BVOP : Yes
Codec settings/QPel : No
Codec settings/GMC : 0
Codec settings/Matrix : Default
PlayTime : 4mn 1s
Bit rate : 2556 Kbps
Width : 640 pixels
Height : 480 pixels
Display Aspect ratio : 4/3
Frame rate : 29.976 fps
Resolution : 8 bits
Chroma : 4:2:0
Interlacement : Progressive
Bits/(Pixel*Frame) : 0.277
StreamSize : 73.5 MiB
Audio #1
Codec : MPEG-1 Audio layer 3
Codec profile : Joint stereo
PlayTime : 4mn 1s
Bit rate : 190 Kbps
Bit rate mode : CBR
Channel(s) : 2 channels
Sampling rate : 48 KHz
Resolution : 16 bits
StreamSize : 5.47 MiB
Writing library : Gogo (after 3.0)
转换后
test2.flv
General
Complete name : E:PVtest2.flv
Format : Flash Video
File size : 45.0 MiB
PlayTime : 4mn 1s
Bit rate : 1564 Kbps
Video
Codec : Sorenson H263
PlayTime : 4mn 1s
Bit rate : 195 Kbps
Width : 640 pixels
Height : 480 pixels
Display Aspect ratio : 4/3
Frame rate : 15.000 fps
Bits/(Pixel*Frame) : 0.042
Audio
Codec : MPEG-1 Audio Layer 3
Bit rate : 55 bps
Channel(s) : 2 channels
Sampling rate : 22 KHz
Resolution : 16 bits