4.1 should not have any issues playing.
In fact, i accidently encoded a file Main@L4.2 (which isnt in the specs, but plays fine)
Like i said, 4.1 on the Old Gen 1 should be fine, it’s the “Reference Frames” you have to watch out for.
The WD-TV only has support upto 4 reframes
http://community.wd.com/t5/WD-TV-Live-Live-Plus/MKV-Pixilation/td-p/151766
I don’t know how many the newer models support … posssibly 12 ? Haven’t had any issues for 3-4 years i’ve been using the newer models.
