MKV is a container that can contain almost ANY kind of video type and almost ANY kind of audio. And it can include multiple streams of each type too, and as a standard feature it supports subtitles. This is why it got so popular with the anime fansub communities on-line. Recall that MS's decoder (which uses hardware) can read MP4 (another container, but this time specifically VC-1 video and AC3 2ch audio). For WMV, it is the same profile. This might be the reason a lot of 1080p porn is in this format. XD
I'm getting so tired of reading the word 'port'. For one thing it isn't that easy! Especially stuff like Mplayer, something totally designed for compiling with GCC, not MSVC (Microsoft's official SDK of course uses `cl`, cross-compiles to PowerPC 64-bit, etc). Microsoft support for C (especially newer standards like C99) has been horribly lacking. And that is what most of the code base of mplayer is in. They have compiled mplayer on Windows. You might wonder how. MinGW of course, the native GCC port to Windows (from a UNIX/UNIX-like environment, such as Linux).
The main stumbling points to porting over Mplayer are just that it has a lot of code that may need to be revised to a) compile 100% successfully and optimised for 360 on MSVC and
![cool.gif](style_emoticons/default/cool.gif)
run 100% correctly on a 360 console. Someone with a development console is better off doing this work because of the amount of time it would take. The good news is that Mplayer's DX9 back-end (which can use hardware shaders, like MS wants) is 100% working. It might just work on the 360.
Once all of Mplayer is ported, there's a whole new GUI to make. Obviously you're not going to be typing `mplayer myvideo.mkv` on the 360 (as much as I would like a console and keyboard support on the 360; but it's not a multitasking system).
Good luck to anyone who makes such an endeavour.
The main thing I'd like to see as a start in terms of homebrew multimedia is a good MP3 streamer (Ogg, WMA, etc support as well). Picks up a Samba/Windows share and reads MP3s (reads ID3v2, APE tags correctly!), and then plays. Jukebox, shuffle, all that, skins, etc. A solid (FOSS, but of course no real sharing till a free SDK is available) library for reading MP3 data and passing it to XAudio2 would be great for all developers.