There are good sides and bad sides to YouTube. The good? More video than you could watch in a hundred lifetimes, just waiting to be explored. The bad? The comments that typically live below those videos. And then there’s the nigh-incomprehensible, like the service adding the option to stream 4K video on mobile devices — even if you don’t have a 4K screen.
What the 4K?
Typically if you don’t have a supported device, the Android YouTube app won’t allow you to set video quality to 2160p60, or 4K. That seems to have changed, according to members of the YouTube subreddit (as spotted by the chaps over at XDA).
You might ask yourself, what’s the point of watching video in 4K on a phone when you’ve only got a 720p display? That’s a seriously valid question. It’s possible that what has been spotted out in the wild is just a bug and it’ll soon disappear from the various Android devices it has turned up on.
But it’s also possible that the move is intentional. Offering the option to every version of the app likely means a little less work for the devs, and it can also result in better image quality for users. Another Reddit thread explains how this ‘feature’ could do that. The Next Web explains further, saying “…video compression means that very rarely are you actually getting the claimed resolution in practice.”
In other words, setting video to 4K while using a 720p or 1080p display gives you a greater chance of a video playing at the full resolution your device supports. But… you’ll be consuming data at a 4K rate, whether you can see it or not. Just something to consider, if you’re not on a home WiFi network and really want to watch the Mortal Kombat trailer in true HD.
Source: XDA Developers