[mamachan]

Nvidia Shield 4K video setting recommended are the following:

- 2160p 59,940Hz
- YCbCr 4:2:0 10Bit rec. 2020

For NON 4K videos (on 4K-HDR TV), wich are the best setting?

- 2160p 59,940Hz YCbCr 4:2:0 10Bit rec. 709 are OK?

I think the Shield TV supports resolution switching (but not colour space switching). 

If you have a 4K display I'd run the Shield TV in Rec 709 1080p for non-4K content - as the TV upscaling to 4K will be better than the Shield upscaling to 4K.  For 4K content then if it is UHD I'd run Rec 2020 2160p 10 bit.  If it is some of the rarer Res 709 4K stuff then I'd run Rec 709...  (Media Info will tell you which it is - but any 24fps UHD Blu-ray sourced content is likely to be HDR10 Rec 2020, it's only 50 & 59.904p 4K stuff I'd check the colour gamut of) 

 I do not think the shield supports resolution switching.
And I do not see the big differences between having the upscaling to the shield rather than the TV.
So I prefer to use a fixed resolution 2160p (59,940 o 60Hz) for bot 4K and NO 4K videos.

but I do not know how to set the color space.
for 4K i thinks YCbCr 4:2:0 10Bit rec. 2020 is OK (recommended on nvidia shield stttings tab).
For NON 4K videos? YCbCr 4:2:0 10Bit rec. 709??