Originally Posted by CappyJ
I went pretty far down the rabbit hole on this issue. It has to do with blu-ray requirements when it comes to TrueHD.
For TrueHD, blu-Ray players require the ac3 “core” be combined with the THD track. Core in quotes because unlike DTS/DTS HD-MA (where the lossless track is just a “top up” from the lossy core), with THD/AC3, they really are full tracks.
I can’t remember if it’s a limitation of MKVs entirely, or just common practice, but all I’ve seen have the AC3 track separate from the THD. Hence why this (and all BD players?) can’t play the file. They should be able to though, which is frustrating. M2TS should work though as long as it has the THD combined with the AC3.
What I’m confused about though is what device people are using to play MKVs with THD separate from the ac3. I see so many of those files yet have no way without the complicated conversion you referenced (which is time consuming and always results in a stuttering file for me).
More info on THD vs DTS “cores” copied from another forum:
7th July 2010, 10:04
There are 2 different TrueHD streams:
(1) TrueHD+AC3. This is a mixed format. There are both (alternating) TrueHD and AC3 frames in the stream.
(2) TrueHD. This stream only contains TrueHD frames and no AC3 frames.
All Blu-Ray TrueHD streams are (1). All HD DVD TrueHD streams are (2). eac3to can convert between both stream types. Converting from (1) to (2) is very easy: The AC3 frames are simply removed. Converting from (2) to (1) is more difficult: The TrueHD stream must be decoded and reencoded to AC3 and then the AC3 frames must be injected into the TrueHD stream in a specific way.”
Thanks for the interesting background! Like you said about TrueHD it seems like the MKV files generally follow (2) as well, so they require the (2) to (1) conversion operation.
Well, I was able to try my converted M2TS files on the UBK90 yesterday. They all played without a hitch, no issues really. This was the UBK90 feeding a Denon 4400H, it recognized them all as Dolby Atmos.
Two places talk about how to convert:
From here on AVS Forums
The messages around them can help give context and experiences.
I find it pretty amazing how convoluted the whole scene is with regard to audio and video. 4K, HDR, Atmos, DTS:X, varying containers and codecs, streaming box limitations, etc. etc. It gets super confusing! I'm wondering if one day this will all sort itself out, or of these shenanigans will continue forever.
It's all so complicated I feel like I really have to just solve problems I run into in my video and audio explorations on a case by case basis, there will never be a good universal solution.
Overall, getting back to the UBK90 though, I find it to be a very capable player, I like its speed and simplicity - it seems to be able to play most anything the other brands can play as far as file formats I've tried (the MKV files failed in my Sony X700 too). For my dad's setup it is perfect as he also has a Roku Ultra. For streaming he goes to that, for discs he goes to the UBK90.