Non-square pixels, is changing the PAR possible?

[xtcrefugee]

I have an old LCD TV/monitor with a VGA connection that I'm using with my MiSTer at the moment, and after some experimentation I've found out that its native panel resolution is 1280x1024. However it has a 4:3 aspect ratio not 5:4 which seems to make it pretty unusual, an LCD without square pixels!

Ideally I've love to use the panel at its native resolution as the picture is noticeably better, particularly when things are moving vertically. With video_mode=4 in mister.ini the MiSTer menu is displayed perfectly and takes up the whole screen. Unfortunately the other cores seem to assume square pixels and add a border to the top and bottom rather than allowing the image to fill the screen.

Is there anything I can do to change the pixel aspect ratio for these other cores? I've tried a few suggestions from the Discord, integer scaling etc. but it hasn't helped.

[ash2fpga]

To borrow from Nvidia control panel settings, it sounds like you would be looking for "Full-screen" scaling, instead of "Aspect ratio". Or perhaps, the ability to specify what the aspect ratio of the target display is. Not sure if that would actually be different in this case (from a "Full-screen" setting), or if there would be a use case for that level of specificity (of a specific aspect ratio).

If it does not negatively impact the scaling pipeline, I personally think it could be good to add such features. I would also like to see more flexibility around the vscale_border setting. I would like it to be able to go in the "reverse direction" and crop the video output of the core that feeds into the scaler.

(If I can set aside the time for myself to get a dev environment setup, I would like to see if I could figure out how to make some changes.)

[SuperBabyHix]

How well does your monitor handle 4:3 resolutions that only match up on one of the axis (1280x960 or 1366x1024)? I remember I used to have a plasma TV that had non square pixels. It was a 16x9 screen, but the resolution was 1024x768. I remember that feeding it a 1366x768 signal still produced a very good image.

Obviously not the most ideal solution, but might be worth a shot.

[xtcrefugee]

Thanks for the replies.

@SuperBabyHix 1280x960 works reasonably, except Neo Geo which for some reason needs 1280x900 or I'll get a small border. Like you say it's not ideal, but I can live with it.

@ash2fpga Yes, Rysha on the discord also mentioned that "full screen" scaling would be good to add when I brought this up, so hopefully that happens.

[SuperBabyHix]

If the small border are on the left and right sides that is normal. Not all Neo Geo games used the full width of the screen, which is why there is the cropping option of 304px or 320px wide. Setting it to 320px will probably fill the whole screen, but some games may show unwanted garbage on the sides.

Actually you'll probably find various games on all sorts of systems that do not fill the screen entirely, and it is completely normal. Star Fox on SNES has a huge blank border around it. The 16-bit ports of SFII all have borders at the top and bottom. Damn near every PAL game on the various micro computers had a border of some sort.

[xtcrefugee]

Yes that's true, but in this case it was a border at the top and bottom that wasn't present on HDMI.