graeme@Linux1 ~ $ cd Videos
graeme@Linux1 ~/Videos $ ffmpeg -i Anastasia.mkv
ffmpeg version 0.8.1-4:0.8.1-0ubuntu1, Copyright (c) 2000-2011 the Libav developers
  built on Mar 22 2012 05:29:10 with gcc 4.6.3
This program is not developed anymore and is only provided for compatibility. Use avconv instead (see Changelog for the list of incompatible changes).
[matroska,webm @ 0x9a96260] Estimating duration from bitrate, this may be inaccurate

Seems stream 0 codec frame rate differs from container frame rate: 47.95 (5000000/104271) -> 23.98 (24000/1001)
Input #0, matroska,webm, from 'Anastasia.mkv':
  Duration: 01:34:10.65, start: 0.000000, bitrate: 1536 kb/s
    Stream #0.0(eng): Video: h264 (High), yuv420p, 1280x544, PAR 1:1 DAR 40:17, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc
    Stream #0.1(eng): Audio: dca (DTS), 48000 Hz, 5.1, s16, 1536 kb/s (default)
At least one output file must be specified
graeme@Linux1 ~/Videos $