ffmpeg version N-34616-g8892d04, Copyright (c) 2000-2011 the FFmpeg developers
  built on Nov  9 2011 19:23:36 with gcc 4.4.3
  configuration: --enable-gpl --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --enable-nonfree --enable-postproc --enable-version3 --enable-x11grab
  libavutil    51. 24. 0 / 51. 24. 0
  libavcodec   53. 29. 0 / 53. 29. 0
  libavformat  53. 20. 0 / 53. 20. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 47. 0 /  2. 47. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[alsa @ 0x2f31860] Estimating duration from bitrate, this may be inaccurate
Input #0, alsa, from 'hw:0,0':
  Duration: N/A, start: 1321032532.523250, bitrate: N/A
    Stream #0:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
Output #0, matroska, to 'wtf.mkv':
  Metadata:
    encoder         : Lavf53.20.0
    Stream #0:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le -> pcm_s16le)
Press [q] to stop, [?] for help
[matroska @ 0x2f2c040] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 35 >= 35
av_interleaved_write_frame(): Invalid argument