a screen should be better:
https://abload.de/img/imageshiftqcs9f.jpg
and yes hard coded bars are not detected.
"cleanup image boarders by..." and "if there are big black bars:" works with DXVA native too. i even forgot they exist.
maybe something like: most black bar detection features doesn't work with DXVA native(DXVA copy back is recommended) in a proper english is a enough or it is getting complicated in the end.