From my experience over the past few weeks and with a ton of help from other forum members, I have discovered that the following works very well for blu ray and UHD 4k mkv playback on my jz2000. It should work on other jz models also. My situation means that I do not have the space for a full AV sound system so I rely on the inbuilt speakers which, I must add, are superb in conjunction with my Cambridge Audio Minx sub.
I ripped all of my bluray and uhd blurays using make mkv. All of them are large files which I wanted to playback directly on the TV via usb as I have no interest in plex etc.
My first attempt was connecting the hdd to the USB port of the TV. No joy at all as my hdd is not formatted to Fat32. No picture, no sound.
My second attempt was using the USB port on my son's xbox on. The drive was recognised and through the built in media player, the files appeared. However, my findings were not ideal. The picture played for every file but only sound played for files using an AC3 or EAC3 codec. Atmos, True HD and DTS codecs failed to work, these files only offered video with no audio.
I persevered. I then downloaded Kodi on the xbox. Again, all files were made available but this was even worse. Video displayed incorrectly and colours were off, washed out. Hdr was not triggered so image was terrible. I then tried VLC and worse again, the app just crashed upon playback. Hopeless.
Not one to give up easily, I continued my research and stumbled on a post from another AV forum in the states. Someone mentioned another xbox app called Movies and TV player. What the hell, let's try it. So I downloaded it.
The drive was recognised, the files were made available and as soon as I pressed play, Hdr triggered on the TV. Both video and audio played perfectly. However, the app then crashed after 3 minutes. Jesus!
I thought I would try one last thing. Something I noticed from using a pc is that single folders populated with huge individual files are difficult for Microsoft to handle. I then attached my hdd to my pc and placed each movie file into its own individual folder rather than having them all in one master folder. It worked a treat!!
HDR is triggered every single time and audio played brilliantly. The only thing it can't handle is DTS True HD, but I expected that to be honest. I got around this by running the DTS only files through Xmedia Recode which is a piece of freeware I picked up. I simply converted the DTS to Dolby 5.1 E-AC3, leaving the video untouched and creating a new mkv file. Each file took about 7 minutes and 5.1 is perfectly acceptable for my tvs speaker system. Now, through this setup everything plays at fantastic quality, both video and audio.
In summary, full UHD mkv rips will play perfectly in HDR on an xbox one through the Movies and TV player app via USB. All audio formats accept DTS will play perfectly. You need to place each individual mkv file into it's own individual folder. No glitches, no stutter, no crashing, no buffering, no drop out. It just works.
I hope my journey goes someway to helping.