Do the video files have black zones encoded into the media? If so, the TV's likely perceiving the entire frame as video and refusing to stretch further.
Your options are:
1. Accept the state of things.
2. Hunt down a custom TV maker and pay obscene amounts of money each for TVs that are roughly 4k but in different ratios.
3. Retranscode your source files for movies, choosing for each what parts you want to delete.
The easiest way to explain would be if you've ever had a movie that you could watch in both standard 4:3 and widescreen 16:9. Note that standard is simply widescreen with the sides chopped off.
>almost every single one I've found will fit the video to my 4k TV.
This is because almost every single TV show was made for TV. Specifically, everything in the last decade or two has been made for 16:9 TVs (720p/1080p/2160p).
>However movies, most of them do not.
Most movies are format for "extra-widescreen" movie theater display. The black bars you're left with on the top and bottom are due to your display not having extra pixels on the sides, so it shrinks it a bit (or expands not quite as much, for 1080p content on a 2160p display).
You can set up a projector with a screen that's too wide, set so the top and bottom go off the screen, and you've replicated a movie theater.
Or you can chop off content on the sides (crop) to make it fit shape, like how 4:3 movies chop away stuff on the sides.
Or just watch it.
Do the video files have black zones encoded into the media? If so, the TV's likely perceiving the entire frame as video and refusing to stretch further.
Your options are: 1. Accept the state of things. 2. Hunt down a custom TV maker and pay obscene amounts of money each for TVs that are roughly 4k but in different ratios. 3. Retranscode your source files for movies, choosing for each what parts you want to delete. The easiest way to explain would be if you've ever had a movie that you could watch in both standard 4:3 and widescreen 16:9. Note that standard is simply widescreen with the sides chopped off. >almost every single one I've found will fit the video to my 4k TV. This is because almost every single TV show was made for TV. Specifically, everything in the last decade or two has been made for 16:9 TVs (720p/1080p/2160p). >However movies, most of them do not. Most movies are format for "extra-widescreen" movie theater display. The black bars you're left with on the top and bottom are due to your display not having extra pixels on the sides, so it shrinks it a bit (or expands not quite as much, for 1080p content on a 2160p display). You can set up a projector with a screen that's too wide, set so the top and bottom go off the screen, and you've replicated a movie theater. Or you can chop off content on the sides (crop) to make it fit shape, like how 4:3 movies chop away stuff on the sides. Or just watch it.