PS2 Help with GSM and aspect ratios

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Xethron

Forum Noob
I've got one of the PS2 to HDMI dongles which takes in the YPbPr component signal from the PS2 and outputs it through HDMI, no line doubling or scaling. It seems to be working properly though most of the time what is shown on my monitor is the wrong aspect ratio.

If I leave GSM settings off or set it to the default NTSC / PAL then the image is always stretched to something like 15:9. It's fine with widescreen codes but I'd rather have it in 4:3. My monitor does accept the interlaced signal and has great deinterlacing but I can't change the aspect ratio and I'm only given the option to scale the image horizontally when using VGA input.

If I force 480p / 576p or use the native progressive scan option in games that have it I get a slightly squished image just like in this video:
If you look at the HUD in the lower right, it should be a circle but it's a bit taller than it is wide. For some games if I change my monitor's aspect ratio from "4:3" to "Full Screen" it will now be the proper 4:3 size but for other games it will stretch out to the same pillarboxed 15:9 as 480i. I haven't been able to determine a pattern as to why games go one way or the other.

How much of this is expected? Does this sound normal for PS2 component output? And can GSM help with horizontal or vertical scaling? I tried the old GSM v0.23x but I can't exit it without restarting my console so I haven't really been able to test its effects. If anyone knows about this please let me know, thanks.
 
Ok, I see, so the difference I'm seeing between games is down to render resolution differences.

It sounds like if we change DW we can influence the output width but only by factors of the input width, is that right? Or would it not work for some reason? Like in the example of a 512 input being processed with a DW of 1440; if we pushed DW to 1536, bumping the result up to 3x, does that cause some other problem?

Regardless it sounds like if I want real control over horizontal scaling I need something external. I'll start with an HDMI to VGA adapter and see what the limits of my monitor's built in hardware are.

Is vertical the same too then? Is there anything that can be done internally for letterboxed games like Final Fantasy X or Dark Cloud 2?

jolek said:
Maybe one of these threads might be more helpful:
https://github.com/ps2homebrew/Open-PS2-Loader/issues/1636,
https://www.psx-place.com/threads/graphics-synthesizer-mode-selector-gsm.19028/#post-132240.
Click to expand...

I slapped together a build of OPL that lets you control DW and DH and I got some interesting results. I'll attach it if you want to give it a try, DW and DH are taken from H-POS and V-POS, respectively, in the per-game GSM settings. DW is H-POS * 100 and DH is V-POS * 10. Use the struct in https://github.com/ps2homebrew/Open-PS2-Loader/blob/master/src/gsm.c to find the default DW and DH. Unfortunately this means you lose control of the horizontal and vertical position which pushes the visible area off-screen.

So the second build is more useful, all I did for this one is increase DW by 100 for the HD 576P preset. This restores control of the positioning so I recommend setting H-POS to -50 and V-POS to 0 for God of War to center the image. This now takes up the whole 16:9 width with slight letterboxing; though since it's overscaled there's a bit of cropping on the sides and the aspect ratio is wrong so you want a widescreen code that's wider than 16:9.

I also made another build increasing DH by 200 but it's not helpful, the default DH is already the best you're gonna get.

Messing with DW is slightly better for the interlaced presets and can give a closer output to 4:3. It's not quite granular enough to match what I want but overscaling has its uses so I'll keep playing with it.
 

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Xethron said:
Messing with DW is slightly better for the interlaced presets and can give a closer output to 4:3. It's not quite granular enough to match what I want but overscaling has its uses so I'll keep playing with it.
Click to expand...

It looks promising (especially `OPL - DW+100 for 480P and 576P.ELF`).

I needed to use -60 for H-POS for God of War (PAL) with 576p:
4tGPMEk.png

6jPZnl5.png

The image takes almost full screen, however it is a bit to wide (a lil' bit too much cropped) as you mentioned.

On the other hand the FMVs play with a quite good aspect ratio and they are not too much over-scan:
hrytkSV.png


Without GSM (Proper ratio)

fnTsaWi.png

Ci1qBAo.png
 
jolek said:
The image takes almost full screen, however it is a bit to wide (a lil' bit too much cropped) as you mentioned.
Click to expand...
Ya it seems like this is the limit of what we can get out of the PS2 itself. You can see from looking at the default DWs for the interlaced modes that there's more wiggle room so you can always get a pretty close 16:9 image out of it. But for progressive you end up with only a couple levels of scaling being viable which means that certain games that use certain internal resolutions will always end up way underscaled or overscaled with no sweet spot in the middle.

I've been looking around and there are reasonable priced external scalers so I'm going to end up getting one of those.
 
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