Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height ffmpeg -i test.mp4 -acodec libvorbis -vcodec libvpx out.webm
ffmpeg version N-57647-g1880294 Copyright (c) 2000-2013 the FFmpeg developers
  built on Oct 30 2013 19:25:44 with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-3)
  configuration: --prefix=/usr/local --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvpx --enable-libfaac --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libvo-aacenc --enable-libxvid --disable-ffplay --enable-shared --enable-gpl --enable-postproc --enable-nonfree --enable-avfilter --enable-pthreads --extra-cflags=-fPIC --arch=x86_64
  libavutil      52. 48.100 / 52. 48.100
  libavcodec     55. 39.100 / 55. 39.100
  libavformat    55. 19.104 / 55. 19.104
  libavdevice    55.  5.100 / 55.  5.100
  libavfilter     3. 90.100 /  3. 90.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf55.19.104
  Duration: 00:01:47.16, start: 0.023220, bitrate: 273 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 320x180 [SAR 1:1 DAR 16:9], 192 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 74 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
File 'out.webm' already exists. Overwrite ? [y/N] y
[libvpx @ 0xc4bd00] v0.9.0
[libvpx @ 0xc4bd00] Failed to initialize encoder: ABI version mismatch
Output #0, webm, to 'out.webm':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf55.19.104
    Stream #0:0(und): Video: vp8, yuv420p, 320x180 [SAR 1:1 DAR 16:9], q=-1--1, 200 kb/s, 90k tbn, 25 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: vorbis, 44100 Hz, mono, fltp (default)
    Metadata:
      handler_name    : SoundHandler
Stream mapping:
  Stream #0:0 -&gt; #0:0 (h264 -&gt; libvpx)
  Stream #0:1 -&gt; #0:1 (aac -&gt; libvorbis)
Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height


Is my CLI wrong? Do I need to specify more commands.
This is an issue with your ffmpeg installation.  You have a mismatch between the version numbers of the libraries you are trying to use.  Most likely, your version of the webm libraries is not built on the same version of ffmpeg as you are using.