[dspillett]

I've had no trouble with x265 on a Pi4 via LibreELEC, either things I've encoded myself or obtained elsewhere.

The Pi3 could playback 720p x265 fine, and sometimes 1080p OK but far from always (and it would get fairly warm trying, hitting the thermal throttle after a while in summer months).

It comes down to what hardware acceleration is supported and/or how beefy the CPU is otherwise, either your media centre supports 265 in hardware like the Pi4 or it is just has a chunkier set of CPU cores so can cope decoding such content in software (in the latter case, it will be drawing a chunk more power and generating more heat to do so).

I've not tried anything over 1080p on the 4, but IIRC it should be able to do 4K x265. For the size of my TV and how far I usually sit from it, I don't have eyes better than 1080!

[oarsinsync]

The RPi4 can do 4K x265, it’s the reason I have one, and the only thing I use it for (with LibreELEC too, as it happens)

[LilBytes]

Same here. Don't use a client server method for LibreElec or you'll find audio and video stutters a lot, completely unseabke. Instead have the RPI4 running LibreElec access the shares directly instead and you're off to the races. Exclent performance in 4K.