GBS 8200/8220 CFW Project

[AndehX]

I dont appear to have a coil on my adapter

[rama]

AndehX:
That is exactly the adapter I have here. This one uses a plain old 3.3V + 1.8V linear regulator.
Please see the pic on how to mod this. I've just added another ground to the connector shield (black wire), as that was unconnected and I wanted to use it as additional ground.
The red wire is meant to go on a convenient 3.3V point on the GBS.

Spoiler

benryves:
Okay, that's fair enough. Thanks for allowing links

The captures are fine imho, even with the quirks.
Youtube is severely lacking in gbscontrol demo captures :p

Edit: I think the GBI software is really doing something weird there, and it's not the cable. Very interesting!

[AndehX]

excellent, that's all I need, thanks!

I'm just busy 3D printing a mount for it to go inside my GBS enclosure

[Iraito]

Uhm i'm noticing a jailbar effect on my megadrive 1, i tried lifting pin6 but it didn't solve the issue, any suggestion ?

[rama]

It depends. If you mean typical MD jailbars, you need extensive modding to fix them.
https://www.retrorgb.com/genesisrgbbypass.html

[AndehX]

well that was a bust. Wired RGB+HV to the secondary output on the GBS, and wired up 3.3v and ground, and couldn't get any display. No idea why....



Any ideas? I know it's wired to 5v, but it doesn't work when wired to 3.3v either.

[rama]

Probably a mistake on the removed VGA connector with regards to the various signals.

[AndehX]

I dont need to wire any of the grounds up since I already have ground connected to the 3.3v regulator, right?

[NoAffinity]

Benryves:
Around 9:40 of this video you can see the transition of sega saturn daytona usa.

https://youtu.be/pAYj-13mJQg

Thats probably quite a few versions of the cfw in the past and maybe doesnt help with what youre looking for but the gbs with cfw handles the transitions quite well (and smooths them for better handling by capture devices, etc.).

Hey rama - you may recall we were troubleshooting the color balancing that seemed to be off in some of my videos. It was a while back but is definitely present in some of the footage in that video. Well, i found recently my old tried and true gbs board had a 430ohm resistor soldered in parallel with the current control resistor. Apparently i had done that mod at one point for testing and then forgot about it. Now that ive corrected that and have the 430ohm path switchable, i think the color is noticeably better all around at either stock or with auto gain adjust doing its thing. Im gonna put together some new footage this weekend, will let you be the judge.

Sent from my SM-G955U using Tapatalk

[Iraito]

It depends. If you mean typical MD jailbars, you need extensive modding to fix them.
https://www.retrorgb.com/genesisrgbbypass.html

My bars are different, more spaced out and i think there might me a different color variation. Holy crap that is a messy situation, to be honest i would like to try something else before spending all that time on the motherboard (which i can't do now) yesterday when checking online it seems that the bars are visible on OSSC too but not on the Framemeister (https://www.videogameperfection.com/for ... cal-lines/) could be possible to create a solution in-software on the GBS ?

EDIT: It seems people enabling the low pass filter don't see the bars anymore, i still have to lift pin 50.

EDIT N.2: I cut the trace to pin 50 and now the bars are 90% invisible, i can live with that but i noticed that before when i lifted pin 6 on the sony chip the picture got slightly unstable (looks like a classic sync instability) it happens rarely, it lasts for less than half a second and it's a small jump, should i put the pin in place again ? (it's a pretty big pin it shouldn't be too hard to put it back)

EDIT N.3: https://pastebin.com/8rfc0J7M Is this similar to the ps1 problem ?

[NoAffinity]

^specifically with regard to the bars showing up more on ossc, ive found this to be fixed by spending time getting the color balancing dialed in. It wont eliminate completley, but if leaving ossc at stock gain and offset settings, the bars are very noticeable. Spending the time to perfectly dial in the color balancing will give significant improvement in this area. Found this to be true for genesis and pce.

Sent from my SM-G955U using Tapatalk

[Shiver_169]

Someone tried to use the GBS control Passtrought with an OSSC and an SNES or NES? it seems to me that if this were possible it would eliminate the incompatibility of the OSSC and help a lot. I did not want to buy an OSSC because of the compatibility with certain TVs.

[rama]

NoAffinity:
Great, I thought there seemed to be something fundamentally wrong, because even after lots of tweaking, it still didn't seem right.
It'd be bad if there was some hidden detail with regards to capture cards, that I'd also have to deal with.
I'd like it if they just represented what we get on the screen, thanks very much :p

Iraito:
The GBS has programmable bandwith limiting for the ADC down to 30MHz.
To hide Genesis jailbars, the filter would have to go down further, but the hardware simply doesn't have it.
So you're left with fixing it on the console side, or using more devices.
A "software bandaid" actually does exist with the coring feature, but it comes with lots of drawbacks.
I'll make this available some day though, not sure how to present it yet.

Shiver_169:
Pass-through modes pass on the filtered source sync, so a lot of the resilience of normal scaling mode is lost.
It will filter out the SNES / NES short scanline jitter, but not much more (such as 240p / 480i switches).
It might be what you're looking for, but I'm not sure.

[Iraito]

Thank you rama, as of now i mostly solved the bars issue but now i get an unstable sync like problem, i also checked my other scart consoles, only the megadrive is unstable, do you have any fix for this issue ?

[NoAffinity]

Back to my Wii2HDMI expirement...

I grounded the crap out of the Wii2HDMI - I have a ground from Wii2HDMI going to the grounds corresponding to R, G and B at GBS P12; I also have a ground traveling with 5V back to the GBS barrel plug, and a ground travelling with 3.3V to P5. I removed the 662K voltage regulator responsible for 5V->3.3V on the Wii2HDMI. I patched in 3.3V from GBS header P5, to where the 662K was outputting 3.3V. I placed a 10uf cap across 5V->ground and 3.3V->ground at the Wii2HDMI. The result is very good, in terms of clarity and color. I am still getting scrolling noise, however.

Not sure there's much else to be done here. but if anyone has any additional suggestions, I'm open game.

Zip file with a couple video samples: https://drive.google.com/file/d/1t3JeT8 ... sp=sharing

Download them and view locally, to avoid online compression. The download shouldn't take more than about 30 seconds.

[Syntax]

Windows users may need a HVEC extension to view those videos.
Dont pay for it, use the free one here
https://www.microsoft.com/en-au/p/hevc- ... verviewtab

[rama]

Hm, the old wave noise issue once more.
Some presets cause them on my VGA to HDMI as well, so one recommendation is to try a different preset.

This kind of noise pattern could be some beat frequency where the sampling system's clock is too close to another clock / noise generator.
I don't know a sure way to fix this. It probably requires a specialist electronic engineer to even diagnose it correctly.

And uh, the videos still have that wrong look.
I'm not too good explaining this stuff, but it's instantly recognizable as all wrong :p

[NoAffinity]

Hm, the old wave noise issue once more.
Some presets cause them on my VGA to HDMI as well, so one recommendation is to try a different preset.

This kind of noise pattern could be some beat frequency where the sampling system's clock is too close to another clock / noise generator.
I don't know a sure way to fix this. It probably requires a specialist electronic engineer to even diagnose it correctly.

And uh, the videos still have that wrong look.
I'm not too good explaining this stuff, but it's instantly recognizable as all wrong :p

All right, well I tried with this Wii2HDMI. Tapping out on that effort.

What do you mean by wrong? I'm looking at the title screen for instance, comparing video footage to arcade cabe, and yeah it's not perfectly identical, but it looks good imho. Any slight variations, I'm calking up to the Color Format handling. Like you said, full range vs. partial range, and various YUV formats. But hey, maybe you're seeing something I'm not, and in that case, ignorance is bliss as far as I'm concerned.

:edit: okay, now you've got me intrigued again. Please check this video out: https://drive.google.com/file/d/1Q7BWqh ... sp=sharing

It is the new GBS I just got (i.e. hasn't been butchered with a bunch of hackery over time). I disabled all of the color format and quantization settings in the capture card software. So, it is handling the input and output however it feels it should be. Never mind the webcam, it's not useful for comparison or anything...that's just how I have things set up normally in OBS, and didn't think to disable it.

[AndehX]

yeah your colour balance is definitely off. Your whites have a strong blue tint to them. Kinda looks like you have blue turned up higher than red and green.

[rama]

Yeah :p
And there's no red. Red is almost like hard clipped to 35%.

I think there's some combined problems there, and I wouldn't be surprised if my Component Out mixing was off as well.
Once you have an RGB dongle, we can work from there

Spoiler

[NoAffinity]

yeah your colour balance is definitely off. Your whites have a strong blue tint to them. Kinda looks like you have blue turned up higher than red and green.

Okay, thanks. Don't think there's much I can do about that? RGB is coming from the game board via an AV-Driver. I did mult-gang calibration per the instructions here (about half way down the page).

Of course, the color pots on the GBS have been removed. And, there is no individual color adjustment in the capture card software.

Also while troubleshooting things just now, I found that auto gain doesn't seem to be working. I used to notice a small increase in brightness when enabling it, and decrease in brightness when disabling it. I see no change now.

For shirts and goggles, I took a screenshot from video produced by OBS and a screenshot from video produced by Magewell Express Capture:

Spoiler

Any difference? Sorry for asking you guys to be my eyes on this. I'm partially color blind...hues of reds and blues are my weakness.

:edit:

Once you have an RGB dongle, we can work from there

sorry, I don't understand what you mean by this

oh, and I'm outputting GBS VGA to a retrotek VGA-to-YPbPr transcoder to capture card.

[AndehX]

you should try capturing directly from the GBS VGA output, instead of through the VGA->YPbPr converter. See what your colours are like.

[rama]

Ah, you were already using standard RGB on the GBS. That's fine then.

In your 2 screenshots, both show a shift towards blue, but the first shot keeps more contrast than the 2nd.
It would be much easier to diagnose this with a color pattern test screen, such as baked in in many arcade boards

Spoiler

Does the VGA->YPbPr converter provide any controls or special instructions?
Same question for the supergun.

I'll check the auto gain feature later. I've had enough for the day (working on frame time lock) :p

[NoAffinity]

you should try capturing directly from the GBS VGA output, instead of through the VGA->YPbPr converter. See what your colours are like.

Unfortunately, the only capture card I have that does VGA in is an Avermedia C127, and it doesn't like any of the formats that the GBS puts out.

Here's a quick comparison of the YUV input settings on the Magewell software. I also turned up the multi-gang pot a hair. I think it was too low. And I think rama's right, we have possibly a couple issues going on here.

Spoiler

YUV BT.601:




YUV BT.709:




YUV BT.2020, after playing with the magewell picture controls:

Seems no matter what I do, reds are always suffering.

No settings or instructions on the retrotek transcoder.

Oh, and once the multi-gang is dialed up, I can see the slight increase in brightness with auto gain turned on/decrease when turned off. Sorry for the false alarm, rama.

[Iraito]

It seems that i can't get a stable signal out of the megadrive, if anyone knows of a way to eliminate the jitter from the megadrive\genesis model 1 please let me know, as of now it's the only console giving me this issue (Yeah some profiles for the GBI interface too) i solved the bars so this is the only problem i have right now.

[Ryoandr]

It seems that i can't get a stable signal out of the megadrive, if anyone knows of a way to eliminate the jitter from the megadrive\genesis model 1 please let me know, as of now it's the only console giving me this issue (Yeah some profiles for the GBI interface too) i solved the bars so this is the only problem i have right now.

What type of sync and sync cable do you use ?
Also, what MD, euro PAL, euro FR, JP ?

[Iraito]

CSYNC PAL euro

It seems that the MD gives off a peculiar csync and that many people tap the CSYNC from the CXA1145 output directly to get a proper sync

EDIT: I just tried connecting the MD directly into my LCD TV which still has a scart port, it gives me a black screen and audio only.

[Ryoandr]

MD CSync cannot be used directly (unlike neogeo aes for example).
You need a capacitor (10µF mini, 220µF will do fine, +to the console) and a resistor (470R) before the display.

If you lifted pin 6 and/or cut VDP trace, composite out will not have subcarrier frequency, and thus will not produce interference, so you can use it directly to the display as sync.

[Iraito]

MD CSync cannot be used directly (unlike neogeo aes for example).
You need a capacitor (10µF mini, 220µF will do fine) and a resistor (470R) before the display.

If you lifted pin 6 and/or cut VDP trace, composite out will not have subcarrier frequency, and thus will not produce interference, so you can use it directly to the display as sync.

So even though i did PIN6 etc. i still need to do this, right ?
https://www.youtube.com/watch?v=xKZ9-Q8SL8w

[Ryoandr]

Does your cable uses AVout pin 7 for sync, to scart pin 20 ?
If yes, is it a straight wire (check inside scart plug, and with a multimeter)?

if it's a straight wire, you need to add the cap and resistor, normally there enough space in the scart plug if using small enough components.

You don't really need to do all that inside of the console. Rewiring composite AVout to cxa1145 csync is if you want to reuse a scart cable wired for composite without getting subcarrier interference.