The Matroska Media container is a very popular, open standard Multimedia container which is usually found as .MKV files. It is a very popular format in enthusiast circles and can be played directly in Windows Media Player with suitable codecs installed. We use the Combined Community Codec Pack (CCCP).
We ripped our BluRay disc of The Dark Knight to 1080P MKV and used Windows Media Player to playback the file.
34% CPU usage for 1080P MKV playback isn’t a wonderful result for a home entertainment computer, although it is to be expected with such modest hardware.