user@user-K56CM:/tmp$ ./ffmpeg -i output.avi -acodec libvorbis -ac 2 -ab 96k -ar 44100 -b 345k -s 1366x768 -crf 20 -minrate 2000k  output.webm
ffmpeg version N-59480-g8feaa83 Copyright (c) 2000-2014 the FFmpeg developers
  built on Jan  2 2014 05:36:33 with gcc 4.6 (Debian 4.6.3-1)
  configuration: --prefix=/root/ffmpeg-static/64bit --extra-cflags='-I/root/ffmpeg-static/64bit/include -static' --extra-ldflags='-L/root/ffmpeg-static/64bit/lib -static' --extra-libs='-lxml2 -lexpat -lfreetype' --enable-static --disable-shared --disable-ffserver --disable-doc --enable-bzlib --enable-zlib --enable-postproc --enable-runtime-cpudetect --enable-libx264 --enable-gpl --enable-libtheora --enable-libvorbis --enable-libmp3lame --enable-gray --enable-libass --enable-libfreetype --enable-libopenjpeg --enable-libspeex --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-version3 --enable-libvpx
  libavutil      52. 59.100 / 52. 59.100
  libavcodec     55. 47.100 / 55. 47.100
  libavformat    55. 22.102 / 55. 22.102
  libavdevice    55.  5.102 / 55.  5.102
  libavfilter     4.  0.103 /  4.  0.103
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
[avi @ 0x2b2d7a0] non-interleaved AVI
Guessed Channel Layout for  Input Stream #0.1 : stereo
Input #0, avi, from 'output.avi':
  Metadata:
    encoder         : Lavf53.21.1
  Duration: 00:00:05.13, start: 0.000000, bitrate: 6072 kb/s
    Stream #0:0: Video: theora (theo / 0x6F656874), yuv420p, 1366x768 [SAR 1:1 DAR 683:384], 30 tbr, 30 tbn, 30 tbc
    Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
Please use -b:a or -b:v, -b is ambiguous
File 'output.webm' already exists. Overwrite ? [y/N] y
[libvpx @ 0x2b34860] v1.0.0
Output #0, webm, to 'output.webm':
  Metadata:
    encoder         : Lavf55.22.102
    Stream #0:0: Video: vp8 (libvpx), yuv420p, 1366x768 [SAR 1:1 DAR 683:384], q=-1--1, 345 kb/s, 1k tbn, 30 tbc
    Stream #0:1: Audio: vorbis (libvorbis), 44100 Hz, stereo, fltp, 96 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (theora -> libvpx)
  Stream #0:1 -> #0:1 (pcm_s16le -> libvorbis)
Press [q] to stop, [?] for help
frame=   44 fps=2.7 q=0.0 Lsize=    1405kB time=00:00:39.35 bitrate= 292.3kbits/s
video:140kB audio:1258kB subtitle:0 global headers:4kB muxing overhead 0.211189%