[FFmpeg-user] The Creating A Screencast command has been modified Ubuntu 10.04 FFmpeg version SVN-r0.5.1-4:0.5.1-1ubuntu1.3(What's the new convention)

[maujhsn]

ubuntu at ubuntu:~$ ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 30 -s 1024x720
-i :0.0 -qscale 1 -acodec pcm_s161e  -vcodec libx264 -vpre
lossless_ultrafast -threads 0 output.mkv

I get this code: Unknown encoder 'libx264'

Can anybody tell me the new convention?