iPhone X users notice HDR video now being streamed on YouTube
On Reddit and forums, including those on MacRumors, users have found when toggling the quality of the video they are watching that new designations have popped up. Simply enough, 1080p60 HDR is the best they’ll be able to get on the Super Retina Display of an iPhone X. The phone is the only one from Apple to output HDR content.
While the iPhone 8 and 8 Plus support DCI-P3 cinematic color gamut, they actually do not support true HDR video and HDR10 streaming.