Weird NES Scrolling Issue on GPi 2 Case

TPR

What is your guys' thoughts on this? Look specifically at the background art and you can notice it more on the windows... Clearly this seems like a refresh rate issue and it is far more pronounced on the GPi 2 than the GPi 1 or even my TV running off the Pi 4.

I have tried three NES cores: Nestopia, QuickNES, and FCEUMM (which is what is playing in the video) and all three of them do this. Any ideas if there is a fix for this or is this just a byproduct of the screen that RetroFlag has used that we have to live it. I'm seeing it happen in a lot of NES games.

Is there any way to fix this?

Video:

Sliver X

@tpr

Try setting Integer Scaling to on in Retroarch. Or enable Bilinear Filtering if you're not using Integer Scaling. Either should make a difference.

barbudreadmon

@tpr What's happening here is that pixels are being zoomed by a non-integer value - let's say 2.5 - but your screen can't display a square of 2.5 x 2.5 pixels, it has to round it to closest borders of its own pixels, which will alternatively switch between 2 and 3 pixels while scrolling.

It might be more visible for you in this specific case but it can happen with any emulator/game on any screen if you don't enable integer scaling. Bilinear filtering might have a placebo effect (does it ?) because the pixels will look less sharp, but it's not gonna fix the root of the issue.

Sliver X

@barbudreadmon

Bilinear filtering basically interpolates the pixels: It blurs everything, but it mostly eliminates the warping effect shown in the video when things move.

I recently set up an image for a device utilizing a 320x240 display: A lot of systems had issues with integer scaling (Particularly low resolution systems like the original Gameboy being tiny) so I was forced to do non-integer scaling. Bilinear flitering had a profound effect on making it work better, at the cost of blur.

The GPi Case 2 has a 640x480 display, however: Integer scaling would work much better for it, and also grants the ability to double pixels for most systems for scanlines/shaders in general to be usable.

TPR

@sliver-x I tried both of those things and there wasn't any noticeable difference.

JayRockets

This isn't a scaling issue, it's something else.

JayRockets

Whats strange is if I play Castlevania on my desktop in Mesen at 1x scale this same phenomena occurs (its not an aspect ratio or integer scaling issue either, those settings dont alter this in anyway) At 2x you can still see it happen but not as apparent. 3x and up it doesnt happen. But if I record gameplay at 4x then open the video in VLC and set zoom to 1/4 bringing the image back down to 1x, there it is again!

What the heck is going on here? Is this some sort of lcd pixel refresh rate thing? It happens in games like Castlevania, 8 Eyes, and Ninja Gaiden, but not Super Mario Brothers. It also happens in other system games like Rastan for Sega Master System. And changing the emulator/core doesnt affect the outcome.

I would love to know exactly what causes this.