My son loaned me an MKV file of a recent episode of Top Gear. It is in high-def, 1280x720 resolution -- or "720p" as it's more popularly known.
It turns out MKV is a "container" format, popular for tv shows, which includes the video and audio tracks in a single file. It is an open source competitor to AVI, also a container file, and one that is more broadly supported.
I did some research: MKV is short for "Matroska Multimedia Container", and the "Matroska" is a loose transliteration of the Russian word for their nesting dolls. But to Russians, "matroska" apparently means "sailor suit!"
I have a $37 media player box -- dunno what else to call it -- from retailPlus. It has a USB and an SD card connectors. It reads media files -- videos, music, photos -- and plays them back through an HDMI connector. I hook it up to the projector in my media room, and watch stuff on the 100" screen. But it does not support MKV.
I found a free MKV to AVI converter (AllToAvi), but progress is slow. It takes about six hours to convert one hour of video! Fortunately, I can watch MKV files on computers without conversion using VLC. (WinAmp and many other software media players also work.)
Dice Player for Android
Samsung supports MKV on the Galaxy S phones, as do some other smartphones. I didn't test my Vibrant yet, but my new Google Nexus S phone plays it back -- but only after I tested 16 media players. Of them all, I found just one -- very nearly at the end of list at the appstore -- that worked correctly with the enormous 1.5GB MKV file. All other players suffered from lagging audio or no audio at all, and most displayed serious artifacts in the video.So, congratulations to Dice Player from innoSoft!
Dice could use improvements to the user interface. Bizzarely, the menu button locks and unlocks the screen. But at least it plays back hi-def MKV files.