Ever since the Fire TV 2 first launched, its 4K capabilities have been limited to video playback. Apps like Netflix display their interface at 1080p to take advantage of the 60fps framerate, which results in a smoother navigation experience, while switching to 4K only when a video is played. This is because 4K output on the Fire TV 2 is limited to 30fps, which could result in a stuttery feeling interface if it were used all the time for an app with many moving elements. It appears that, with the new 18.104.22.168 software update, developers can now choose to display their apps in 4K all the time if they wish. The newly updated YouTube app, which now supports 4K content, is the first Fire TV app to opt for an always-4K approach.
The decision to default to an always-4K interface for the YouTube app makes a lot of sense. Since most YouTube videos are only a few minutes long, having to switch resolutions from 1080p to 2160p and back every time a video plays and ends would be a poor user experience. With an always-4K interface, videos can be played back-to-back with no need to distractingly change output resolutions. The downside to this approach is a slightly less-smooth interface, but it shouldn’t be noticeable in an app like YouTube where you’re just scrolling through thumbnails most of the time. The app does thankfully offer the option to revert to a 1080p interface, like it was before.
Videos played within the YouTube app that are not 4K are upscaled into 4K resolution. This marks the first time a Fire TV app upscales video to 4K. It’s unclear if the interface of the YouTube app is actually being rendered in 4K, or if it’s still being rendered at 1080p and just being upscaled like the non-4K content. Hopefully this new flexibility for apps to always display 4K will result in more apps offering a 4K option.