How to center image of retroarch with PI outputing 240p rgb via hat board/gert 666 to pvm?

Molhoy

@rig Hey man, I think I've cracked it...!!

I joined the Facebook group for Arcadeforge, where I bought my pi2scart. There I found a set of timings that solved my vertical position: -

hdmi_timings= 320 1 22 20 42 240 1 6 8 10 0 0 0 60 0 6400000 1

However, these are pushed even more to the left. But... and this is the important bit... I found a post from a great guy on there (Frank Skilton), which specifically explained how to alter the hdmi timings to reposition the picture: -

To shift the image left, increase the horizontal front porch while decreasing the horizontal back porch by an equal amount. Do the opposite to shift right.

To shift the image up, increase the vertical front porch while decreasing the vertical back porch by an equal amount. Do the opposite to shift down.

3rd parameter is horizontal front porch
5th parameter is horizontal back porch
8th parameter is vertical front porch
10th parameter is vertical back porch

So, in the case of the above timings, I was able to reduce the horizontal front porch by 12 and increase the horizontal back porch by 12 to shift the image right and perfectly centre it on my PVM.

See below (changed values highlighted in bold): -

before: hdmi_timings= 320 1 22 20 42 240 1 6 8 10 0 0 0 60 0 6400000 1
after: hdmi_timings= 320 1 10 20 54 240 1 6 8 10 0 0 0 60 0 6400000 1

These now give me a perfectly centred image!

While these may or may not work for you, hopefully the above explanation will allow you to manipulate your timings to achieve the perfect result.

I hope this helps!

rig

Molhoy, awesome! good explanation on the hdmi timings. I'm picking up what your putting down. I will try this out on Monday when I'm off work...

I'm a bit of a crt nutter myself. Thanks for sharing the info on the monitors. A couple of things you mentioned are interesting to me: You mentioned that the 800 line monitor is too sharp. I have been hopeing too pick up a 800 line monitor but maybe this wouldn't be worth it. I have noticed when watching videos of bvms that the scanlines can look too pronounced. I can tell you that pardoxically my 560 line pvm 2030 looks sharper and darker than my 600 line pvm 20m2mdu. and the 2030 has way more miles on it (it's geometry is a bit whack in the corners but It gives it character). The 2030 also has a bit of a sideways caddywompum to it, I adjusted it a little with the pots and I set a piece of wood under one side of it and now the slant is completely gone. Have no idea why the beat up old 560 line 2030 outshines the 20m2mdu...the 2030 was built in 1992 (if I remember correctly) and the 20m2mdu in 2001...Maybe it's cause I rescured the 2030 from the dumpster. 2030 better putout them scanlines or it's going back were I found it mwahahaha

maxriptide

@Molhoy this info about timings is great! Thank you!!!

Molhoy

@rig Yeah, these CRTs are addictive!

Of course, my opinion is very much my own, so don't necessarily let it put you off the idea of an 800 line (or higher) monitor. I've just reached the conclusion that they don't suit my tastes.

I had the opportunity to buy a 2130 (uk version of the 2030) when I bought my 20M2MDE. I must say that I was very impressed with the picture, it looked very bit as sharp - if not sharper - than the 20M2MDE and the colours seemed to pop even more. However, although it was in generally excellent condition, the picture did suffer from some impurity issues (slight yellow tinge in one corner), which is a big no-no for me. Also some geometry issues that would have been hard to correct. Certainly the 2030/2130 have a good reputation and I think date back to a time when Sony were at the very top of their game, which may explain the picture still being so good even today.

Good luck with adjusting your timings. I've been playing with mine some more tonight and I'm really thrilled with it now that my picture is centered.

Let me know how you get on.

Molhoy

@maxriptide You're welcome.

I can't really take credit for it - as I mentioned, I found the solution on Facebook :)

However, I'm glad to share it with you guys and I hope it gives you the desired results!

rig

Molhoy, Problem solved! Picture is dead center. No sharpness lost. Thanks dude. I uncommented all the overscan adjustments and messed with the front porch/ back porch for about half an hour and now it's perfect. Good job persevering on this one Molhoy. You had a hunch that the problem could be solved with the timings and you were right.

Molhoy

@rig You're welcome.

Really pleased to hear that you've got your timings sorted.

It's very satisfying to finally have a perfectly sharp 240p properly centered, isn't it?!

I've been playing lots of Neo Geo stuff, which looks awesome.

Next problem to solve is dynamic resolution switching to overcome the issue of different systems being at different resolutions, but that's a whole different ball game!!

Dochartaigh

@Molhoy said in How to center image of retroarch with PI outputing 240p rgb via hat board/gert 666 to pvm?:

To shift the image left, increase the horizontal front porch while decreasing the horizontal back porch by an equal amount. Do the opposite to shift right.

To shift the image up, increase the vertical front porch while decreasing the vertical back porch by an equal amount. Do the opposite to shift down.

This is great info on how to center the image! Did they shed any light on how to SHRINK the image? (mine is actually OK centered, but definitely WAY too large).

edmaul69

@Dochartaigh overscan settings are what you have to use to fix that. Not sure why it isnt working for you.

Dochartaigh

@edmaul69 said in How to center image of retroarch with PI outputing 240p rgb via hat board/gert 666 to pvm?:

overscan settings are what you have to use to fix that. Not sure why it isnt working for you

Haven't tried overscan quite yet - just trying to get all my ducks in a row for when I have time to mess around with this again (whenever the heck that'll be I do not know lol ;)

I'm planning on balancing the porch settings of HDMI_timings for centering the picture, and will now use overscan alone to scale.

rig

@Molhoy Yeah, the display looks great. I'm glad I made the extra effort to center it. Now I can get back to gaming. I been playing games I always wanted as a kid but couldn't get because they were arcade, or on an obscure system. I'm playing aliens vs predator for arcade right now and shining force for sega cd