So I just re-read the FAQ and came across the above. I have been trying to get some form of my 4K rips to play smoothly on my Surface Book (1st Gen) since MakeMKV first supported it. My Gaming Rig/Media Server (the machine I rip the 4K Blu-Rays on, which has a NVidia GTX 1060) plays the files just fine in the Microsoft Movies and TV app, they even have the correct colors, so it is processing the HDR/WCG just fine, despite the display being a cheap non-HDR display. However, the only thing that I can get them to play smoothly with is MPV, which I find rather inellegant for a couple of reasons (UI is only okay, not exactly touch friendly, doesn't get installed on the system so I can't double-click a video file to open it in MPV, have to drag-and-drop to play a file). I have tried to reduce the bitrate with both Handbrake and Staxrip and have reduced them down to a bitrate of 15,000 kbps. It still won't play smoothly in Microsoft's built in app, or anything other than MPV.I stopped using VLC, but my powerful computer still can't play MKV files smoothly?
On Blu-ray, each h.264 frame is encoded as 4 independent slices - this means that it is possible to decode any given frame using 4 parallel tasks. On UHD, each HEVC frame is encoded as 8 independent slices. Hardware decoders take advantage of this, but open-source software decoders don't use such acceleration. That's why a smart TV can easily play a high-bitrate HEVC from UHD, but could fail even on much lower bitrate MKVs from Handbrake. (Thanks to Mike for the info!)
I'm really curious to know why this is. My Surface Book has an i5-6300U, which, as a 6th gen i-Series processor, is supposed to support hardware decoding of HEVC. So by the specs, my device should be able to play this, so why can't it in the native software? Is MPV using hardware or software decoding? If MPV is using software decoding and the native software is using hardware decoding, why is the native software struggling to perform?
I realize that we are kind of on the cutting edge of this technology right now, so there may not be any concrete answers.