Just to clarify, by "on the fly" he means having a program transcode it while streaming it to your PS3, and by "completely" he means having a program create another file that's compatible with your PS3.
Originally posted by will1983: Just use mkv2vob to passtrought everything ! you will not have to re-encode anything !
Not necessarily true.
If the video and/or audio stream within the .mkv is not compliant with the PS3, mkv2vob will automatically re-encode it.
Moreover - though I'm not sure - mkv2vob doesn't support all the subtitle types that .mkvs do. So if, say, you happen to have an episode of some obscure Japanese anime that has .ssa subtitles, mkv2vob won't be able to transfer those subtitles over.