MP4 only supports AAC so I hope they don't. Even if they make a 5.1AAC from a lossless source (not sure if these same devices support 5.1AAC) I would have to use analog to play it (losing all the stuff the receiver does and using my sound cards crappy DACs). Its easy to remux mkv into m2ts for PS3 playback (just no DTS).
Not true about the audio being only AAC in mp4. I take it you meant for AC3/DTS then yes you are limited then to AAC.
- Video: MPEG-4 Part 10 (also known as H.264 and MPEG-4 AVC), MPEG-4 Part 2, MPEG-2, and MPEG-1.
- Audio: AAC (also known as MPEG-2 Part 7), Apple Lossless, MP3 (also known as MPEG-1 Audio Layer 3), MPEG-4 Part 3, MP2 (also known as MPEG-1 Audio Layer 2), MPEG-1 Audio Layer 1, CELP (speech), TwinVQ (very low bitrates), SAOL (MIDI).
- Subtitles: MPEG-4 Timed Text (also known as 3GPP Timed Text).
It all depens on what they put inside the mkv container. I've seen some pretty esoteric mkv in my life...
And also do you still need to buy another piece of hardware just for mkv? I already have 5 "box" able to play divx/xvid, mp4, wmv, avchd etc. etc.
I mostly watch anime in those format (except for the tv that I capture). I find it funny when I see those "upconverted" anime serie available in mkv format when the raw are in 720x480. People end up downloading bigger file containing 1 audio track and subtitles when they could have use a xvid for the same end product but in a smaller file size.