Left Side of Core Image Gets Cut Off

Hellz
Posts: 9
Joined: Fri Sep 04, 2020 2:35 pm

Left Side of Core Image Gets Cut Off

Unread post by Hellz »

Before describing my issue below, i want to note that i started using a HDMI to VGA converter and a VGA to Scart RGB cable with which the problem occurs. Before this I used a Hdmi to composite converter and connected the MiSTer by Composite where I didn't have any problems.

My setup:

A Mister FPGA -> Hdmi to VGA adapter (AG6200 and ITE6693 chipset both give the same result) -> A VGA to Scart RGB cable -> Beovision MX8000

The problem:

I'm bumping into an issue where the left side of the screen inside several cores (I tested Genesis and Snes) is cut off by a few lines. By using the Overscan test pattern in the 240p test suite for the SNES i found out that on the left side the white line starts to show at 04 pixels (05 pixels for the genesis). While the top, bottom and right side show the line at 01 pixels as it should be.

See the picture below, i moved the picture away from the bezel to show that it is the image that gets cut off and not because of overscan.

Does anyone know how to fix this?
Attachments
cutoff.jpg
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rhester72
Posts: 279
Joined: Thu Jun 11, 2020 2:31 am

Re: Left side of core image get cut off

Unread post by rhester72 »

Why couldn't it be an overscan issue? If the display is 1:1 and the output assumes overscan, that's exactly what it'd look like.
Hellz
Posts: 9
Joined: Fri Sep 04, 2020 2:35 pm

Re: Left side of core image get cut off

Unread post by Hellz »

rhester72 wrote: Wed Sep 30, 2020 5:19 pm Why couldn't it be an overscan issue? If the display is 1:1 and the output assumes overscan, that's exactly what it'd look like.
Im not that familiair with crt's yet, so reading your comment i think it could be overscan related. Is there a way to slide the image horizontally so it doesnt get cut off?
lupin3rd
Posts: 22
Joined: Wed Jun 17, 2020 7:15 pm

Re: Left side of core image get cut off

Unread post by lupin3rd »

Hellz wrote: Wed Sep 30, 2020 5:40 pm ...Is there a way to slide the image horizontally so it doesnt get cut off?
So here's the rub with CRTs. The game developers and console manufacturers actually banked on part of your screen being cut off. If you think about the opposite problem (underscan), then you realize the alternative is battling black bars. So most game developers would intentionally avoid placing critical data right on the very edge. So, if you're on a real CRT, the normal way of dealing with it is to adjust your CRT and not the MiSTer settings. I will say however, that you are battling a horizontal size issue, which is not one of the normal settings you can easily adjust on a standard TV. On an arcade monitor, this is adjusted with the horizontal width coil.

Long story short, it's pretty normal and expected. Chasing down perfection in the CRT realm can drive a person batty.
Hellz
Posts: 9
Joined: Fri Sep 04, 2020 2:35 pm

Re: Left side of core image get cut off

Unread post by Hellz »

lupin3rd wrote: Wed Sep 30, 2020 6:08 pm
Hellz wrote: Wed Sep 30, 2020 5:40 pm ...Is there a way to slide the image horizontally so it doesnt get cut off?
So here's the rub with CRTs. The game developers and console manufacturers actually banked on part of your screen being cut off. If you think about the opposite problem (underscan), then you realize the alternative is battling black bars. So most game developers would intentionally avoid placing critical data right on the very edge. So, if you're on a real CRT, the normal way of dealing with it is to adjust your CRT and not the MiSTer settings. I will say however, that you are battling a horizontal size issue, which is not one of the normal settings you can easily adjust on a standard TV. On an arcade monitor, this is adjusted with the horizontal width coil.

Long story short, it's pretty normal and expected. Chasing down perfection in the CRT realm can drive a person batty.

I Understand it is a battle, however i hope i can get those few lines on the side visible because on a composite cable i do see the full picture. Its only on rgb that this happens.
akeley
Posts: 160
Joined: Mon May 25, 2020 7:54 pm

Re: Left side of core image get cut off

Unread post by akeley »

RGB horizontal shift is a common thing. Newer Sony Trinitrons even have an "RGB centering" option in the user menu to compensate for this.

Try finding service manual / service menu entry codes for that TV. Then try to adjust the horizontal settings. If you're new to this make sure you are careful within this menu (best to take photo of the default settings before tinkering) because it's easy to mess up your image far worse.

Another thing is, don't get too hang up on the 240p suite. It's a good tool, but I prefer to use games to test sometimes, this way you can see if the image is really affected. And also, as mentioned above, chasing perfect CRT image. It does not exist :)
Hellz
Posts: 9
Joined: Fri Sep 04, 2020 2:35 pm

Re: Left side of core image get cut off

Unread post by Hellz »

akeley wrote: Wed Sep 30, 2020 7:28 pm RGB horizontal shift is a common thing. Newer Sony Trinitrons even have an "RGB centering" option in the user menu to compensate for this.

Try finding service manual / service menu entry codes for that TV. Then try to adjust the horizontal settings. If you're new to this make sure you are careful within this menu (best to take photo of the default settings before tinkering) because it's easy to mess up your image far worse.

Another thing is, don't get too hang up on the 240p suite. It's a good tool, but I prefer to use games to test sometimes, this way you can see if the image is really affected. And also, as mentioned above, chasing perfect CRT image. It does not exist :)
I've been tinkering with the Service Menu and there are no options there for horizontal shift, sadly. This is why i was hoping i could do it otherwise :)
akeley
Posts: 160
Joined: Mon May 25, 2020 7:54 pm

Re: Left side of core image get cut off

Unread post by akeley »

It'd be very odd if there was no horizontal shift options in the service menu. I mean, I've never had an B&O but it's common in other sets.

In any case, I just had a go on 240p suite and one of my Trinitrons. Guess what, I had an identical cut off with the circle. The thing is, only in PAL 240p suite ;) In the NTSC version it's pretty much all in. So my advice would be to check which 240p suite you are using and also what kind of systems you want to calibrate for (consoles - mainly NTSC, microcomputers - PAL)

EDIT: I don't think you actually were in the service menu. I found a service manual for this TV and indeed you can adjust centering (Horizontal Phase). But unless you really need to I wouldn't touch that. See about that PAL/NTSC thing first.
Hellz
Posts: 9
Joined: Fri Sep 04, 2020 2:35 pm

Re: Left side of core image get cut off

Unread post by Hellz »

akeley wrote: Wed Sep 30, 2020 8:39 pm It'd be very odd if there was no horizontal shift options in the service menu. I mean, I've never had an B&O but it's common in other sets.

In any case, I just had a go on 240p suite and one of my Trinitrons. Guess what, I had an identical cut off with the circle. The thing is, only in PAL 240p suite ;) In the NTSC version it's pretty much all in. So my advice would be to check which 240p suite you are using and also what kind of systems you want to calibrate for (consoles - mainly NTSC, microcomputers - PAL)

EDIT: I don't think you actually were in the service menu. I found a service manual for this TV and indeed you can adjust centering (Horizontal Phase). But unless you really need to I wouldn't touch that. See about that PAL/NTSC thing first.
Ill try, ive been using the NTSC suite. But it's a PAL tv, so i'm going to try the PAL version!

I've been in the service menu, the horizontal phase just makes the cut part moves along with it.
Thank you!

Update:

I tested the PAL version of the 240p test suite, but it doesn't make a difference.
Hellz
Posts: 9
Joined: Fri Sep 04, 2020 2:35 pm

Re: Left side of core image get cut off

Unread post by Hellz »

I want to give an update:

I received an Extron RGB 192, and with the DDSP setting (So that H-shift works) of i get a rolling image but i can confirm i can shift the image to the right and the missing part becomes visible.

I also found some other people with Beovision MX crt's who reported the same amount missing on the left side.
retrorepair
Posts: 172
Joined: Sun May 24, 2020 9:06 pm

Re: Left side of core image get cut off

Unread post by retrorepair »

I can confirm that at least the genesis, snes, nes and megacd cores are shifted much further to the left than my real hardware cutting off quite a lot and giving a large border on the right.

Output is the same on at least 5 TVs I've tested this on and I'm using the IO board VGA out.
rhester72
Posts: 279
Joined: Thu Jun 11, 2020 2:31 am

Re: Left side of core image get cut off

Unread post by rhester72 »

I think one of the reasons for this is that when border masking is applied, the image is shifted left by the amount of left-side masking done rather than being left in place and just overlaid by the blanked part of the image.
Hellz
Posts: 9
Joined: Fri Sep 04, 2020 2:35 pm

Re: Left side of core image get cut off

Unread post by Hellz »

Sounds like a reason why, yeah. I hope in the future all main mister cores will support a horizontal shift setting.

For now the Extron RGB solved my problem :)
ash2fpga
Posts: 79
Joined: Tue May 26, 2020 6:20 pm

Re: Left side of core image get cut off

Unread post by ash2fpga »

Timings for Genesis and SNES were off for me, too, using analog video on standard IO board, compared to real hardware.

I compared my OSSC settings both of these cores to my consoles (MiSTer hooked up to OSSC compared with consoles hooked up to OSSC). Both cores needed different H. Samplerate compared to the consoles. Sampling Phase seemed "all over the map", too. Genesis core seemed more stable with regards to sampling phase, than SNES core. On SNES core (and NES core*, too), it seemed like I could never get sampling phase in a sweet spot. (*My NES console is not RGB modded, so no direct comparison there.)
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