strange findings....
Here is the ffmpeg -i from version distributed with serviio:
-   Code:
 FFmpeg version UNKNOWN, Copyright (c) 2000-2011 the FFmpeg developers
  built on Sep 17 2011 01:00:29 with gcc 4.4.3
  configuration: --enable-static --disable-shared --bindir=/tmp/ffmpeg --disable-ffplay --disable-ffserver --enable-libmp3lame --enable-pthreads --disable-mmx --extra-ldflags=-L/tmp/static/lib --extra-cflags=-I/tmp/static/include
  libavutil     50.36. 0 / 50.36. 0
  libavcore      0.16. 0 /  0.16. 0
  libavcodec    52.108. 0 / 52.108. 0
  libavformat   52.92. 0 / 52.92. 0
  libavdevice   52. 2. 3 / 52. 2. 3
  libavfilter    1.72. 0 /  1.72. 0
  libswscale     0.12. 0 /  0.12. 0
[matroska,webm @ 0x98f94c0] Estimating duration from bitrate, this may be inaccurate
Seems stream 0 codec frame rate differs from container frame rate: 47.95 (20000000/417083) -> 23.98 (20000000/834166)
Input #0, matroska,webm, from 'Swing.Girls.2004.BluRay.720p.DTS.x264-CHD.mkv':
  Duration: 01:44:47.27, start: 0.000000, bitrate: 1536 kb/s
    Stream #0.0(jpn): Video: h264, yuv420p, 1280x690, PAR 1:1 DAR 128:69, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc
    Metadata:
      title           : Swing.Girls.2004.BluRay.720p.DTS.x264-CHD
    Stream #0.1(jpn): Audio: dca, 48000 Hz, 5.1, s16, 1536 kb/s
    Metadata:
      title           : DTS 5.1ch 1536Kbps
At least one output file must be specified
And here is ffmpeg -i running from latest version of ffmpeg for windows 7 x64.
ffmpeg version N-32611-gd55b06b, Copyright (c) 2000-2011 the FFmpeg developers
  built on Sep 15 2011 00:26:45 with gcc 4.6.1
  configuration: --enable-gpl --enable-version3 --enable-runtime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libopenjpeg --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  libavutil    51. 16. 0 / 51. 16. 0
  libavcodec   53. 14. 0 / 53. 14. 0
  libavformat  53. 12. 0 / 53. 12. 0
  libavdevice  53.  3. 0 / 53.  3. 0
  libavfilter   2. 40. 0 /  2. 40. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0
Seems stream 0 codec frame rate differs from container frame rate: 47.95 (20000000/417083) -> 23.98 (24000/1001)
Input #0, matroska,webm, from 'Swing.Girls.2004.BluRay.720p.DTS.x264-CHD.mkv':
  Duration: 01:44:47.27, start: 0.000000, bitrate: 5966 kb/s
    Stream #0.0(jpn): Video: h264 (High), yuv420p, 1280x690, SAR 1:1 DAR 128:69,
 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
    Metadata:
      title           : Swing.Girls.2004.BluRay.720p.DTS.x264-CHD
    Stream #0.1(jpn): Audio: dts (DTS), 48000 Hz, 5.1(side), s16, 1536 kb/s (def
ault)
    Metadata:
      title           : DTS 5.1ch 1536Kbps
At least one output file must be specified[/code]
Notice how the windows version detect the audio as dts (DTS) whereas the linux version of ffmpeg detected the audio as dca.