[FFmpeg-user] How to grab x11 screen

[jd1008]

I tried
$ ffmpeg -i :0 -vcodec webm -b:v 5000 -b:r 10 -g 300 -s 1920x1080 
/tmp/x11.webm
ffmpeg version N-51556-ge278500 Copyright (c) 2000-2013 the FFmpeg 
developers
   built on Apr  4 2013 05:11:43 with gcc 4.6 (Debian 4.6.3-1)
   configuration: --prefix=/root/ffmpeg-static/32bit --arch=x86_32 
--extra-cflags='-m32 -I/root/ffmpeg-static/32bit/include -static' 
--extra-ldflags='-m32 -L/root/ffmpeg-static/32bit/lib -static' 
--extra-libs='-lxml2 -lexpat -lfreetype' --enable-static 
--disable-shared --disable-ffserver --disable-doc --enable-bzlib 
--enable-zlib --enable-postproc --enable-runtime-cpudetect 
--enable-libx264 --enable-gpl --enable-libtheora --enable-libvorbis 
--enable-libmp3lame --enable-gray --enable-libass --enable-libfreetype 
--enable-libopenjpeg --enable-libspeex --enable-libvo-aacenc 
--enable-libvo-amrwbenc --enable-version3 --enable-libvpx
   libavutil      52. 24.100 / 52. 24.100
   libavcodec     55.  2.100 / 55.  2.100
   libavformat    55.  1.100 / 55.  1.100
   libavdevice    55.  0.100 / 55.  0.100
   libavfilter     3. 49.100 /  3. 49.100
   libswscale      2.  2.100 /  2.  2.100
   libswresample   0. 17.102 /  0. 17.102
   libpostproc    52.  2.100 / 52.  2.100
:0: Protocol not found

My installed ffmpeg packages are
ffmpeg-devel-2.4.6-1.fc21.x86_64
ffmpeg-compat-0.6.7-8.fc21.x86_64
gstreamer-ffmpeg-0.10.13-14.fc21.x86_64
ffmpeg-compat-devel-0.6.7-8.fc21.x86_64
ffmpeg-libs-2.4.6-1.fc21.x86_64
ffmpeg-2.4.6-1.fc21.x86_64