avconv -f x11grab -framerate 30 -s 1920x1080 -r 30 -i :0.0+0,0 -vcodec libx264 -s 1280x720 -crf 16 ./srfun.mp4
avconv version 11-6:11-2, Copyright (c) 2000-2014 the Libav developers
  built on Oct 19 2014 20:25:25 with gcc 4.9.1 (Debian 4.9.1-18)
[x11grab @ 0x873700] device: :0.0+0,0 -> display: :0.0 x: 0 y: 0 width: 1920 height: 1080
[x11grab @ 0x873700] shared memory extension  found
[x11grab @ 0x873700] Estimating duration from bitrate, this may be inaccurate
Input #0, x11grab, from ':0.0+0,0':
  Duration: N/A, start: 1418189621.708548, bitrate: 1990656 kb/s
    Stream #0.0: Video: rawvideo, bgra, 1920x1080, 1990656 kb/s, 1000k tbn, 30 tbc
File './srfun.mp4' already exists. Overwrite ? [y/N] y
[libx264 @ 0x894080] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0x894080] profile High, level 3.1
[libx264 @ 0x894080] 264 - core 142 r2431 a5831aa - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3​
 srfun.mp4
​:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=16.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to './srfun.mp4':
  Metadata:
    encoder         : Lavf56.1.0
    Stream #0.0: Video: libx264, yuv420p, 1280x720, q=-1--1, 30 fps, 30 tbn, 30 tbc
    Metadata:
      encoder         : Lavc56.1.0 libx264
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Press ctrl-c to stop encoding
frame=   26 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbitframe=   41 fps= 40 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbitframe=   57 fps= 37 q=22.0 size=      90kB time=10000000000.00 bitrate=   0.0kbi^C^Ce= 9606 fps= 30 q=22.0 size=  123824kB time=318.23 bitrate=3187.5kbits/s