alsa

audio only records for about a second before going blank (during playback). ffplay and ffmpeg both seems to work with only alsa (no x11grab).

ffmpeg -f x11grab -i :0 -f alsa -i pulse -pix_fmt yuv420p test.mp4
ffmpeg version 2.5.4 Copyright (c) 2000-2015 the FFmpeg developers
  built on Feb 15 2015 21:42:49 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libpulse --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvo-aacenc --enable-libvidstab
  libavutil      54. 15.100 / 54. 15.100
  libavcodec     56. 13.100 / 56. 13.100
  libavformat    56. 15.102 / 56. 15.102
  libavdevice    56.  3.100 / 56.  3.100
  libavfilter     5.  2.103 /  5.  2.103
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, x11grab, from ':0':
  Duration: N/A, start: 1424400527.499640, bitrate: N/A
    Stream #0:0: Video: rawvideo (BGRA / 0x41524742), bgra, 640x480, 29.97 fps, 29.97 tbr, 1000k tbn, 29.97 tbc
Guessed Channel Layout for  Input Stream #1.0 : stereo
Input #1, alsa, from 'pulse':
  Duration: N/A, start: 1424400527.510045, bitrate: 1536 kb/s
    Stream #1:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
File 'test.mp4' already exists. Overwrite ? [y/N] y
[libx264 @ 0x31ceca0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0x31ceca0] profile High, level 3.0
[libx264 @ 0x31ceca0] 264 - core 142 r2491 24e4fed - 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=0x3:0x113 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=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'test.mp4':
  Metadata:
    encoder         : Lavf56.15.102
    Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 640x480, q=-1--1, 29.97 fps, 30k tbn, 29.97 tbc
    Metadata:
      encoder         : Lavc56.13.100 libx264
    Stream #0:1: Audio: aac (libfdk_aac) ([64][0][0][0] / 0x0040), 48000 Hz, stereo, s16, 139 kb/s
    Metadata:
      encoder         : Lavc56.13.100 libfdk_aac
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
frame=   81 fps= 63 q=-1.0 Lsize=     207kB time=00:00:02.63 bitrate= 641.8kbits/s dup=44 drop=42
video:189kB audio:15kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.478986%
[libx264 @ 0x31ceca0] frame I:2     Avg QP:18.73  size: 75274
[libx264 @ 0x31ceca0] frame P:21    Avg QP:23.45  size:  1922
[libx264 @ 0x31ceca0] frame B:58    Avg QP:33.34  size:    30
[libx264 @ 0x31ceca0] consecutive B-frames:  3.7%  0.0%  7.4% 88.9%
[libx264 @ 0x31ceca0] mb I  I16..4: 31.5%  2.5% 66.0%
[libx264 @ 0x31ceca0] mb P  I16..4:  0.3%  0.6%  1.9%  P16..4:  1.3%  0.3%  0.3%  0.0%  0.0%    skip:95.3%
[libx264 @ 0x31ceca0] mb B  I16..4:  0.0%  0.1%  0.0%  B16..8:  0.7%  0.0%  0.0%  direct: 0.0%  skip:99.2%  L0:31.6% L1:68.4% BI: 0.0%
[libx264 @ 0x31ceca0] 8x8 transform intra:8.7% inter:11.0%
[libx264 @ 0x31ceca0] coded y,uvDC,uvAC intra: 49.2% 67.0% 66.0% inter: 0.2% 0.1% 0.1%
[libx264 @ 0x31ceca0] i16 v,h,dc,p: 68% 31%  1%  0%
[libx264 @ 0x31ceca0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 53%  7% 35%  0%  0%  0%  1%  0%  3%
[libx264 @ 0x31ceca0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 42% 24% 10%  2%  4%  5%  4%  4%  5%
[libx264 @ 0x31ceca0] i8c dc,h,v,p: 56% 16% 24%  4%
[libx264 @ 0x31ceca0] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x31ceca0] ref P L0: 61.6%  9.7% 27.6%  1.1%
[libx264 @ 0x31ceca0] ref B L0: 48.8% 46.7%  4.5%
[libx264 @ 0x31ceca0] ref B L1: 91.4%  8.6%
[libx264 @ 0x31ceca0] kb/s:570.32