YouTube has finally brought HDR support to Xbox One X/S as well as Xbox Series X/S. It uses Google's VP9-2 format.
In our extensive review of Xbox Series X, we noted that HDR support for YouTube was still missing despite Microsoft's statement way back in 2017 that YouTube "HDR support (is) coming soon".
YouTube HDR has finally arrived on Xbox. FlatpanelsHD can confirm that it works on both the Xbox One generation (confirmed on Xbox One S) and the new Xbox Series X/S generation (confirmed on Xbox Series X).
YouTube 4K HDR on Xbox Series X (left) and YouTube 1440p HDR on Xbox One S (right)
VP9-2, not AV1
On Xbox Series X we were able to play World in HDR and Costa Rica, both by Jacob and Katie Schwarz, in 4K resolution with HDR and 60fps. Xbox One S gave us up to 1440p with HDR and 60fps.
YouTube HDR on Xbox is using Google's VP9-2 video codec as opposed to the more recent royalty-free AV1 format that Google, Microsoft, Netflix and other major companies have pledged to support. During our tests, Xbox Series X failed to decode AV1 videos, although it may be a software limitation that can be fixed through a future update.
Also read: Review: Xbox Series X
To start enjoying YouTube HDR on your Xbox simply update the app to the latest version.