240p CRT look for Naomi games in Retroarch?

[Megahurtz]

I'm really struggling to get my Naomi games looking right in Retroarch.  I'm using the latest Flycast core but can't find any combination of settings and shaders that comes close to matching my HLSL CRT-style setup in MAME.

From what I've researched, Naomi always internally renders in and outputs 640x480.  There is a jumper or dip switch on the motherboard to select between 15khz and 31khz.  Effectively, this toggles between 480p and 480i.

Setting the internal res to 320x240 seems to produce a downscale rather than actually adjusting the internal resolution.  Text looks horrible with this setting.

Right now I have Naomi internal res at 640x480 and integer scaling to a 320x240 window (scaled 4X) on a 1280x1024 monitor with a small black border on the top and bottom of the screen (960 centered on 1024 with a 32 pixel border on each end).  Text and backgrounds look ok, but the sprites in MvC2 look sort of pixelated like some bad scaling has gone on.  I'm not seeing any interlace flickering, much to my surprise though.

I've tried turning on the 480i dip switch, but I don't really notice any difference.  Maybe because of my shaders?

 

I feel like I'm in over my head due to the overwhelming number of video and shader options in play here.  Does anyone have some good settings for a low-ish res 5x4 monitor that will make Naomi (and Dreamcast?) games look like they were on a CRT?

[Megahurtz]

Here are some examples of what I'm working with right now.

 

[filevans]

i use crt geom shader and set height to 224 which looks good on fighting games 

[Ell Aeon]

pretty much the best, that I could set in Retroarch Flycast core (not tried any ArcCabView / Reshade / etc settings yet). Iirc I set internal resolution to 720p, integer scale on and activated the crt-guest-dr-venom-kurozumi shader.

I liked the result for those games. I think Naomi and Dreamcast are a bit tricky, because the sprites come from the 240p era but the games run in 480i/p and the text and 3d backgrounds are not meant for 240p...