No, I meant if you want to find out how the files are encoded, you can play one with mplayer on Ubuntu and see what it reports like this:
This one has H.264 video at 720p resolution and AAC audio.
$ mplayer /path/to/somefile.mkv
libavformat version 53.21.0 (external)
libavformat file format detected.
[matroska,webm @ 0xb6bc9d80]max_analyze_duration reached
[matroska,webm @ 0xb6bc9d80]Estimating duration from bitrate, this may be inaccurate
[lavf] stream 0: video (h264), -vid 0
[lavf] stream 1: audio (aac), -aid 0
VIDEO: [H264] 1280x720 0bpp 23.976 fps 0.0 kbps ( 0.0 kbyte/s)