ffmpeg -i recorddesktop20130314-13.08.54.mkv
ffmpeg version 1.1.3 Copyright (c) 2000-2013 the FFmpeg developers
  built on Mar 12 2013 22:28:11 with gcc 4.6.3 (Gentoo 4.6.3 p1.11, pie-0.5.2)
  configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --mandir=/usr/share/man --enable-shared --cc=x86_64-pc-linux-gnu-gcc --cxx=x86_64-pc-linux-gnu-g++ --ar=x86_64-pc-linux-gnu-ar --optflags='-march=athlon64 -O2 -pipe -msse -msse2 -msse3 -mmmx -m3dnow' --extra-cflags='-march=athlon64 -O2 -pipe -msse -msse2 -msse3 -mmmx -m3dnow' --extra-cxxflags='-march=athlon64 -O2 -pipe -msse -msse2 -msse3 -mmmx -m3dnow' --disable-static --enable-gpl --enable-version3 --enable-postproc --enable-avfilter --disable-stripping --disable-debug --disable-doc --disable-network --disable-vaapi --disable-ffplay --disable-runtime-cpudetect --enable-libmp3lame --enable-libvo-amrwbenc --enable-libx264 --disable-indev=oss --disable-indev=jack --enable-x11grab --disable-outdev=oss --disable-outdev=sdl --enable-pthreads --enable-libopencore-amrwb --enable-libopencore-amrnb --disable-altivec --disable-avx --disable-vis --disable-neon --cpu=athlon64 --enable-hardcoded-tables
  libavutil      52. 13.100 / 52. 13.100
  libavcodec     54. 86.100 / 54. 86.100
  libavformat    54. 59.106 / 54. 59.106
  libavdevice    54.  3.102 / 54.  3.102
  libavfilter     3. 32.100 /  3. 32.100
  libswscale      2.  1.103 /  2.  1.103
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Guessed Channel Layout for  Input Stream #0.1 : stereo
Input #0, matroska,webm, from 'recorddesktop20130314-13.08.54.mkv':
  Metadata:
    ENCODER         : Lavf54.59.106
  Duration: 00:15:12.23, start: 0.000000, bitrate: 5851 kb/s
    Stream #0:0: Video: h264 (High 4:4:4 Predictive), yuv444p, 1920x1080, SAR 1:1 DAR 16:9, 10 fps, 10 tbr, 1k tbn, 20 tbc (default)
    Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s (default)
At least one output file must be specified