720p/1080p MKV(+DTS/FLAC/AC3) Player for android
SGS or some devices can play mkv well ( not flac audio ).
but many devices are lack of these features.
rock player / mobo player can play mkv. but only sw decoding.
so 720p/1080p movies are not playable.
diceplayer can do hw decoding. ( not all devices.. )
Nexus-S/Desire HD/Incredible S can play MKV/AVI H.264 720p
DualCore SGS2 / HTC Sensation can play 1080p clips.
no need to convert your HD mkvs to mp4.
go android market and search diceplayer.
(there are 3day trial and commercial version )