ffmpeg \
       -f pulse -i default \
       -f x11grab -s 1280x720 -i :0.0 \
       -r 30 \
       -codec:a pcm_s16le \
       -codec:v libx264 -preset ultrafast -pix_fmt yuv420p \
       -af aresample=async=800 \
       -threads 0 \
       $VIDEO_FILE

start timecodes are way off:
-----------

Input #0, pulse, from 'default':
  Duration: N/A, start: 0.004973, bitrate: 1536 kb/s
    Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
Input #1, x11grab, from ':0.0':
  Duration: N/A, start: 1403535582.786433, bitrate: 883852 kb/s
    Stream #1:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1280x720, 883852 kb/s, 29.97 tbr, 1000k tbn, 29.97 tbc

full log:
-----------

ffmpeg version 2.1.2 Copyright (c) 2000-2013 the FFmpeg developers
  built on Jan 13 2014 21:00:22 with gcc 4.8 (SUSE Linux)
  configuration: --shlibdir=/usr/lib64 --prefix=/usr --mandir=/usr/share/man --libdir=/usr/lib64 --enable-shared --disable-static --enable-debug --disable-stripping --extra-cflags='-fmessage-length=0 -grecord-gcc-switches -fstack-protector -O2 -Wall -D_FORTIFY_SOURCE=2 -funwind-tables -fasynchronous-unwind-tables -g -fPIC -I/usr/include/gsm' --enable-gpl --enable-x11grab --enable-version3 --enable-pthreads --enable-avfilter --enable-libpulse --enable-libvpx --enable-libopus --enable-libass --enable-libmp3lame --enable-libvorbis --enable-libtheora --enable-libspeex --enable-libxvid --enable-libx264 --enable-libschroedinger --enable-libgsm --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-postproc --enable-libdc1394 --enable-librtmp --enable-libfreetype --enable-avresample --enable-libtwolame --enable-libvo-aacenc --enable-gnutls
  libavutil      52. 48.101 / 52. 48.101
  libavcodec     55. 39.101 / 55. 39.101
  libavformat    55. 19.104 / 55. 19.104
  libavdevice    55.  5.100 / 55.  5.100
  libavfilter     3. 90.100 /  3. 90.100
  libavresample   1.  1.  0 /  1.  1.  0
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
Guessed Channel Layout for  Input Stream #0.0 : stereo
Input #0, pulse, from 'default':
  Duration: N/A, start: 0.004973, bitrate: 1536 kb/s
    Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
[x11grab @ 0x23c5620] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 1280 height: 720
[x11grab @ 0x23c5620] shared memory extension found
Input #1, x11grab, from ':0.0':
  Duration: N/A, start: 1403535582.786433, bitrate: 883852 kb/s
    Stream #1:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1280x720, 883852 kb/s, 29.97 tbr, 1000k tbn, 29.97 tbc
[swscaler @ 0x239e180] deprecated pixel format used, make sure you did set range correctly
[libx264 @ 0x23e4160] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x23e4160] profile Constrained Baseline, level 3.1
[libx264 @ 0x23e4160] 264 - core 135 - H.264/MPEG-4 AVC codec - Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
Output #0, matroska, to '2014-06-23_16-59h.mkv':
  Metadata:
    encoder         : Lavf55.19.104
    Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv420p, 1280x720, q=-1--1, 1k tbn, 30 tbc
    Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
Stream mapping:
  Stream #1:0 -> #0:0 (rawvideo -> libx264)
  Stream #0:0 -> #0:1 (pcm_s16le -> pcm_s16le)
Press [q] to stop, [?] for help
frame= 5805 fps= 30 q=-1.0 Lsize=   92597kB time=00:03:14.21 bitrate=3905.7kbits/s
video:55891kB audio:36416kB subtitle:0 global headers:0kB muxing overhead 0.314991%
[libx264 @ 0x23e4160] frame I:24    Avg QP:13.38  size:148749
[libx264 @ 0x23e4160] frame P:5781  Avg QP:16.12  size:  9282
[libx264 @ 0x23e4160] mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 0x23e4160] mb P  I16..4:  1.0%  0.0%  0.0%  P16..4:  8.5%  0.0%  0.0%  0.0%  0.0%    skip:90.4%
[libx264 @ 0x23e4160] coded y,uvDC,uvAC intra: 57.5% 54.1% 38.9% inter: 4.9% 5.2% 2.3%
[libx264 @ 0x23e4160] i16 v,h,dc,p: 47% 25% 20%  7%
[libx264 @ 0x23e4160] i8c dc,h,v,p: 52% 25% 17%  6%
[libx264 @ 0x23e4160] kb/s:2363.71