How to get rid of black borders on all sides on a 21:9 monitor?

So since i got this new monitor i've wanted to rewatch the Harry Potter collection, but there's one thing i noticed: The movie itself(even the original bluray's and streaming services, as seen here https://www.youtube.com/watch?v=-ojN9LOtYF4) contains black borders on the top and bottom of the screen, which the player cannot filter on it's own, the overall size including the borders is 1920*1080, and thus it causes extra borders on the left and right side(2560*1080), creating a letterbox.

Is there a way to use some form of edge detection to get rid of the borders on at least 2 sides? The built-in zoom functions do not work properly as they crop a part of the image. The subtiltes are not hardcoded so that won't be an issue.

The reason i bought a 21:9 screen is that it better fits movies and creates a more immersive experience, yet some movie companies decided adding black borders to the movie stream itself(i'm going to guess because of subtitles). The entire complete collection on bluray has this letterbox issue on 21:9 screens.

This is possible if you use Madvr as the video renderer.

Madvr settings > Processing > Zoom control > Automatically detect hard codec black bars

Thank you, yes i do use MadVR so it was just a press of a button. But sadly, it doesn't work. It doesn't seem to detect the black borders properly.

Edit: Apparently video frame was set to "Normal Size" rather than "Touch Window From Inside". MadVR's setting only seem to work with the "Touch Window From Inside" setting, even if it's set to full-screen. The movie almost fits the whole screen now with only a very tiny upper and lower border. 21:9 is great!

Yes, "Touch Window From Inside" is required, and that is also the default setting in MPC-HC.

"Normal size" is a bad setting. That keeps video at 100% regardless of the size of the player window. So bigger window means black bars, and smaller window means part of video gets cut off. It is only for specific situation where you want to see video without any resizing, even in full screen.

Yeah it must've happened while i was fiddling with the zoom function in the player trying to get the black borders to go, but in the end MadVR always saves the day.