[wesk05]

There is also another very interesting thread over on the Vero 4K forums regarding dodgy mastering of specific 4K HDR Blurays from film studios where the display luminance is not set correctly, and media player workarounds have to be implemented:
HDR too dark on LG OLED - Vero 4K / Vero 4K + - OSMC Forums (click)
I suspect this is why Apple are doing HDR10 Metadata re-mapping and achieving pretty good results in the real world when using Apps like MrMC and Infuse.

The specific issue being discussed in that thread has nothing to do with dodgy mastering. It is the Vero 4K that is for whatever reason unable to read the HDR metadata in HEVC SEI messages of concatenated m2ts files. Yes, there are some studio titles that do not have complete HDR metadata, but that's a different problem.

I can't quite agree with what Apple TV 4K is doing. Replacing the original source HDR metadata with a generic one might work for titles that were graded similar to those values. Titles that are graded on Dolby Pulsar can have upto 4000 nits code value in the content. Apple TV's HDR InfoFrame is set for 1000 nits. Those titles are definitely going to look different on displays that do great tonemapping like the LG OLEDs and Sony X900F & A1E.