OK, before I get too far into things, here’s my setup:
4.5TB NAS on Gig Ethernet
Asus O!Play on Gig Ethernet

The NAS is running FreeNAS 0.7 x64 and runs at a balmy 45MB/sec usually. I’d love to upgrade to hardware RAID, but the budget constraints…
The Asus O!Play is model HDP-R1, and it’s been fully updated to the newest firmware (I think 1.22a or something along those lines – if it matters post and I’ll fix it)

I rip all of my DVDs to the NAS for instant retrieval later. I also have a bunch of my music on there also, but that doesn’t matter nearly as much (and the O!Play isn’t very good at music playing anyway). Playing DVD’s as ISOs is a very awesome feature that I use at least once a week at home. But, unfortunately, there isn’t much – if any – upscaling to DVDs on the O!Play. WYSIWYG.

But then I started to rip my Bluray collection. Let me put it this way:
DVD’s ripped: 4GB Average File Size
BD’s ripped: 22GB Average File Size

My 4050GB worth of usable space on the NAS:
DVD’s ripped: 1012.5 total movies
BD’s ripped: 184.1 total movies

You can see my $1200 NAS system will be overrun shortly if I rip too many BDs!

Oh, onto the meat of the problem. I ripped my first two BD’s and attempted to play them on the computer. ISO was not cooperating with WMplayer or VLCplayer. I could, however, select the .m2ts file (DriveLetter:\BDMV\STREAM\sometime.m2ts) and play that using VLC. So I figured I’d try to play it on the O!Play.

Playback of the ISO was simple – just select the movie per usual and it starts playing. But it will not play the true high def audio. 5.1 will play, but not truehd. Unfortunately the first movie only had English in truehd audio format. Booo.

Basically you need to take that fully awesome audio and convert it to 99% fully awesome audio. The way to do this for free:

Download TSMuxer
Unpack TSMuxer
Run tsMuxerGUI.exe
Add the .m2ts file
Under output, click the M2TS muxing radio button
Browse for location and filename to save
Click start muxing

This took roughly 15 minutes on my machine to complete.
I’m going to test either tonight or tomorrow and verify that it works, but the file was slightly smaller so maybe it did.