IOBoard VGA to 15khz PAL CRT via RGB Scart

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IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Mouseboy007 » Wed Jan 15, 2020 4:49 pm

NTSC vs PAL.jpg
Hi All,

I've just taken delivery of a "SCART TV TO MINIMIG RGB CABLE WITH AUDIO" from the Amiga Kit store in the UK:
https://amigakit.amiga.store/advanced_s ... WITH+AUDIO

I've got two potrable CRT's - a 15" Panasonic Quintrix and a Sony Trinitron.
Both have RGB Scart

When I go to computer cores like the ZX Spectrum, Amiga, or C64 , all looks fine, but when I go to console cores like the SNES, NES, Master System, Megadrive/Genesis, the 50hz PAL option is really squished on the screen. I've tried playing with the Mister.ini (and Mister_alt.ini) files to no avail.
Effectively I can play something like Sonic the Hedgehog 2 on Master System at the right dimensions if I select NTSC, but it's the wrong speed (for me). If I go to PAL then as mentioned the screen gets really squashed down. I don't have an original Master System to try with the TV's, but if memory serves me correctly, the games would always be full screen back when I played them as a kid in the UK on a PAL CRT.

I've scoured forums and posts and can't find anything that addresses the issues I have.
I just want to run PAL consoles on a PAL TV at full size via the VGA to RGB Scart.

Anyone have any thoughts, pointers, or ideas?

Thanks!
NTSC vs PAL.jpg


EDIT:

1) Just to note that the output is fine in HDMI either as the only source or with VGA as a source too. The issues above occur whether I have anything plugged in to HDMI as well in case anyone thought that might be a factor.

2) I know there's a VGA PWR button on the IO Board but I've not flicked it as I've read bad things can happen! That said, I don't know if it's already in the 'On' position or not. It's toggled in the direction of the HDMI & VGA Ports rather than in the direction of the Ethernet port if that makes sense?
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Last edited by Mouseboy007 on Wed Jan 15, 2020 5:24 pm, edited 1 time in total.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Sorgelig » Wed Jan 15, 2020 5:20 pm

Blame your TV.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Mouseboy007 » Wed Jan 15, 2020 5:29 pm

Sorgelig wrote:Blame your TV.


Hi Sorgelig - thanks for the quick reply :D
Happy to bow to your superior knowledge, but I'm surprised that the issue is present exactly the same on two different models of TV by two different (and renowned) manufacturers. I keep seeing posts where Sony Trinitrons in particular are considered to be among the best TV's for this sort of thing before getting into PVM's and BVM's.

Is it possible that there's an issue with the cable at all? And how would I test (though I'd guess not as several cores are fine).
Also, in regards to 'Blame your TV' - why would some cores behave and others not? Is there a way I can get the console cores to mimic the good behaviour of the computer cores for example?

Sorry to question your authority on the matter, but to me it seems that if some cores work fine, then the device chain is functioning okay.
I guess to rephrase -what is the ZX Spectrum doing in its output frequency that's different to the SMS, Genesis, SNES, or NES core for example?

Thanks for your patience and help!

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Sorgelig » Thu Jan 16, 2020 2:03 am

Nothing wrong with the cable.
CRT TV depends on vertical and horizontal frequencies. It's usual to have different position and different size if video parameters are changed. And of course each core generates its own frequencies according to original system.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby paulbnl » Thu Jan 16, 2020 7:08 am

NES and SNES are definitely not fullscreen on PAL. The megadrive had a big colored border making it look like fullscreen. You can enable the border in the menu.

https://youtu.be/A7xAYcqaTUA

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Mouseboy007 » Thu Jan 16, 2020 10:54 am

Thank you Sorgelig and paulbnl!

This is really helpful.
Through HDMI the display seems to remain constant in size - only the speed changes by selecting PAL/US/JAP.

What the core developers do is nothing short of astounding! I'm absolutely blown away by the MiSTer project and only wish I had the technical competence to be able to contribute a bit more. However, if any core-devs are reading this I wonder if anyone could comment on whether something could be done in the cores to help overcome the 50hz-non-full screen issue. As someone who grew up in the UK in the 80's with the Master System, NES, and Genesis (Megadrive) the consoles would always output full screen to my (hazy) memory. I don't remember any letterboxing like this. Perhaps I'm mistaken, and happy to be told I'm wrong (and will take on board your comments paulbnl regards a border) but as an example, if I run a PAL PS2 (one of the few old consoles I still have) through my CRT's on a game that lets me select 50hz or 60hz, this is what I get:

IMG_20200116_100108.jpg
IMG_20200116_095840.jpg
IMG_20200116_095337.jpg
IMG_20200116_095651.jpg


You can see the difference between the MiSTer Master System pictures posted previously and the PS2 - the Matser System resizing makes it virtually unplayable for me on these cores, whereas on original hardware designed to output 50hz going to a 50hz screen, I get a full image with marginal amounts of border.

I'm guessing that the output of those cores is assuming a 60hz display and therefore when finding a 50hz display it's quite noticably truncated, whereas my PS2 is doing the reverse - it expects a 50hz TV as it's a PAL region console and when outputting to 60hz there's a bit of overscan.

I'm not sure I'm explaining this all that well, but ultimately I don't think the issue I've raised is as simple as blaming the TV. My PAL TV has 576 lines and the MiSter Console cores outputing in PAL seem to be using way fewer lines than that. In fact, reading a Wiki "PAL usually has 576 visible lines compared with 486 lines with NTSC, meaning that PAL has a 20% higher resolution". So if PAL has more lines than NTSC, why is changing region from US to UK causing the image to truncate?

As mentiond, I'm not one of the clever people that can fix this so it's easy for me to 'complain' (I'm not complaining so much as raising an issue to be debated :D ) but if there's some way to adjust the configuration of the MiSTer device for us PAL region 50hz folk that would be wonderful! As mentioned other cores like the ZX Spectrum and C64 work fine. I've found a few great examples of their output on my CRT:

IMG_20200116_103033.jpg
IMG_20200116_103526.jpg
IMG_20200116_103559.jpg
IMG_20200116_103236.jpg


So to summarise, on actual 50hz PAL UK original consoles, 50hz PAL images will fill the screen and NTSC 60hz will overscan, but on the MiSTer, the opposite is true - NTSC 60hz fill the screen, but 50hz PAL images squash down - which looks even more peculiar given that PAL has more lines of output to begin with.

Any thoughts on if this could be addressed? I know I'm asking a lot - and wouldn't expect it to be a priority - and would happily Beta test a feature to correct this for us Brits looking for glorious MiSTer nostalgia :D

Thanks community - you're awesome!
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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby paulbnl » Thu Jan 16, 2020 11:24 am

Mouseboy007 wrote: As someone who grew up in the UK in the 80's with the Master System, NES, and Genesis (Megadrive) the consoles would always output full screen to my (hazy) memory. I don't remember any letterboxing like this. Perhaps I'm mistaken, and happy to be told I'm wrong (and will take on board your comments paulbnl regards a border)


It seems your memory is repressing the trauma that is PAL 50Hz. As I have said NES is definitely not full screen on PAL CRTs. I have a PAL NES with CRT here so if you don't believe me I can post some pictures.

NES always outputs 240 active lines and this is full screen on NTSC. PAL video has 288 lines of video so 48 lines are empty with the NES. Other consoles like Megadrive or computers may fill the empty lines with a colored border which make it seem it is full screen but the actual game is squashed.

From PS2 onwards the consoles were able to scale the output to 288p or 576i so you mostly won't get borders with those.

The HDMI output on MiSTer works differently then a CRT and it will only show the active lines so the empty borders are not shown.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Mouseboy007 » Thu Jan 16, 2020 12:25 pm

paulbnl wrote:It seems your memory is repressing the trauma that is PAL 50Hz


:lol: :lol: :lol: :lol:

Haha, well, it sound like it then! Thanks very much for the detailed explanation.

paulbnl wrote:As I have said NES is definitely not full screen on PAL CRTs. I have a PAL NES with CRT here so if you don't believe me I can post some pictures.


I do believe you, but yes, out of morbid curiosity I'd love to see the pics you mention. And if anyone has a Master System I'd be even more intrigued as that's the console I spotted the most 'squishing'. What I don't understand is why things like the C64 in NTSC/60hz output a far less contracted image.

paulbnl wrote:NES always outputs 240 active lines and this is full screen on NTSC. PAL video has 288 lines of video so 48 lines are empty with the NES. Other consoles like Megadrive or computers may fill the empty lines with a colored border which make it seem it is full screen but the actual game is squashed.


Makes sense! So, I've just Googled the what the C64 outputs and found that "the C64 transmits only even (or odd? Don't remember) frames with a vertical resolution of 262 lines (288 in PAL)". Apparently the Master System has the following:

Screen resolutions: 256x192 and 256x224. PAL/SECAM also supports 256x240.
Overscan resolution: 342x262 (NTSC), 342x313 (PAL)
Scanlines: 262 (NTSC), 313 (PAL)

So presumably the Master System vs the NES output, *should* be less squashed if it can output 262/313 scanlines vs the NES's 240?
However, this is what it looks like on both my Trinitron and Quintrix 4:3 UK PAL CRT's:

IMG_20200116_120825.jpg


I know I'm like a dog with a bone with this, and I've definitely got some really helpful answers - so thank you - but I still can't reconcile in my mind the Master System output on my TV. If you (or anyone else) could also show a side-by-side between their Mister NES & Master System output, I'd be really interested - and also if anyone has an actual master system, a MiSTer and PAL TV, I'd love to see the comparison. I've not discounted Sorgelig's comments :wink:

Sorgelig wrote:Blame your TV.


- I just find it odd and it makes my brain hurt. :lol:
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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby sqwirral » Thu Jan 16, 2020 2:03 pm

MiSTer seems to be incorrect

Image

From what I can see it's not squashed but Mister is displaying the image too high on the SMS core. I only have my Mega Drive to check so it's possible the MD displays it wrong, but I've seen mister on other cores doing a similar thing.

Btw our old pal consoles were all squished with borders compared to ntsc. I went to great lengths as a kid to get import consoles and monitors that could display them to get away from the horrors of PAL.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Mouseboy007 » Thu Jan 16, 2020 2:30 pm

sqwirral wrote:MiSTer seems to be incorrect

Image

From what I can see it's not squashed but Mister is displaying the image too high on the SMS core. I only have my Mega Drive to check so it's possible the MD displays it wrong, but I've seen mister on other cores doing a similar thing.

Btw our old pal consoles were all squished with borders compared to ntsc. I went to great lengths as a kid to get import consoles and monitors that could display them to get away from the horrors of PAL.


FANTASTIC! Thanks sqwirral for going to the trouble of grabbing those screenshots - It's nice to know I'm not going (completely) mad :D

Is it possible the MiSTer device is outputting a PAL signal as a 60hz/NTSC scaled PAL image rather than a native PAL image? And if so, is that something that could be corrected in the ini file or would it need to be per-core? i.e is there a way to tell MiSTer - I have a 50hz PAL TV, rather than I have a 60hz NTSC TV that I want to display a 50hz PAL image on? Does that make sense? And could this be the cause? Apologies for my naivety if that's not it.

Thanks again everyone - every day's a school day here for me for sure! :)

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby sqwirral » Thu Jan 16, 2020 2:40 pm

Similar issue with vertical centering in the C64 core, but this time it displays too low down, leaving a larger border on the top than the bottom.

Image

(Ignore difference with horizontal shifting, that's due to composite vs rgb scart, likely colour difference is due to that also)

Btw I have 2 different c64's here, breadbox and c64c, both look the same.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Mouseboy007 » Thu Jan 16, 2020 2:55 pm

sqwirral wrote:Similar issue with vertical centering in the C64 core, but this time it displays too low down, leaving a larger border on the top than the bottom.

Image

(Ignore difference with horizontal shifting, that's due to composite vs rgb scart, likely colour difference is due to that also)

Btw I have 2 different c64's here, breadbox and c64c, both look the same.


Interesting. So I guess the questions are - 1) why is there a difference, and 2) is it correctable?
To be honest, I'd probably not notice too much with things like the C64 and NES - and in actual fact might play most stuff at 60hz - however there's an element of getting that accurate nostalgic feel with some systems and games at an accurate resolution - for me I have fond memories of Sonic 2 and Alex Kid on the Master System at the godawful 50hz PAL speed, and to a lesser degree Super Mario Bros 2 on the NES.

Yes, PAL 50hz was awful, but it would be great to accurately output to this if possible. :)

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby sqwirral » Thu Jan 16, 2020 2:59 pm

Mouseboy007 wrote:Is it possible the MiSTer device is outputting a PAL signal as a 60hz/NTSC scaled PAL image rather than a native PAL image

No, Mister properly displays 50 in pal and 60 in ntsc, you can see the size (number of lines) change. The aspect ratio and speed is fine as far as I can see, it's just not centered correctly in some cores, which it seems in the SMS's case leaves an ugly black bar at the bottom. (On second look, the coloured border at the bottom on SMS stops earlier too, making the black part even more noticable.)

Also make sure to switch border to Yes in the SMS and MD cores. It defaults to No which is not accurate.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Mouseboy007 » Thu Jan 16, 2020 3:16 pm

sqwirral wrote:Also make sure to switch border to Yes in the SMS and MD cores. It defaults to No which is not accurate.


Thanks for the advice - and will do :)

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby sqwirral » Thu Jan 16, 2020 3:18 pm

I just checked the Genesis core in both 50hz and 60hz, compared to real hardware, and there are no problems. I'll spare you the screenshots but both PAL and NTSC look exactly the same on MiSTer versus real hw. So I think it's just an issue with a few particular cores, maybe they will be improved in future (the c64 one has problems with a lot of scene demos too, so it's not the best example of a super accurate core).

I can't be bothered to test any more systems!

It doesn't look like the SMS issue has been reported yet: https://github.com/MiSTer-devel/SMS_MiSTer/issues but I'd rather check on a real PAL SMS first just to be 100% sure. I might be able to borrow one from a friend.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Sorgelig » Thu Jan 16, 2020 3:39 pm

Shifting on some cores are possible due to lack of precise info when hsync/vsync start on specific system. This is completely different issue not related to squashing shown in the first post.
To make exact vertical/horizontal position as on real HW, need to have real HW and CRT monitor which in most cases it's impossible (i don't have CRT and don't want it. Also i have no original consoles/computers). So unless some dev having all this equipment will correct the position it will remain as it is now.
At the end main video output of MiSTer is HDMI. So for example for me, if HDMI picture is fine then it's done. How it will look on CRT - it's task for those who care of it.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Mouseboy007 » Thu Jan 16, 2020 3:42 pm

sqwirral wrote:I just checked the Genesis core in both 50hz and 60hz, compared to real hardware, and there are no problems. I'll spare you the screenshots but both PAL and NTSC look exactly the same on MiSTer versus real hw.


Haha, yes - no need for more screenshots :)

sqwirral wrote:I can't be bothered to test any more systems!


Thank you for testing what you did!

sqwirral wrote:It doesn't look like the SMS issue has been reported yet: https://github.com/MiSTer-devel/SMS_MiSTer/issues but I'd rather check on a real PAL SMS first just to be 100% sure. I might be able to borrow one from a friend.


Wow, that's great! Thank you - As you say, perhaps with borders enabled in MiSTer and forgiving the off-centering, it's fine - but if you do happen to be able to test one against the output in MiSTer that would be much appreciated. It'll certainly be interesting to see if it transpires that the Master System hardware outputs the same (I'm sure it most likely does!) - in particular because for the amount of screen-estate unused on a PAL Master System you'd think there would be more people on the Internet moaning about PAL Master System's other than me!. :lol: :lol:

All I have is MiSTer, a ZX Spectrum +3 boxed in the loft and PS2 consoles onwards so unable to easily test myself.

Thanks so much for your time in replying and testing - and for not giving me a hard time for my stupid questions :D.

What an awesome community

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Mouseboy007 » Thu Jan 16, 2020 3:45 pm

Sorgelig wrote:Shifting on some cores are possible due to lack of precise info when hsync/vsync start on specific system. This is completely different issue not related to squashing.
To make exact vertical/horizontal position as on real HW, need to have real HW and CRT monitor which in most cases it's impossible (i don't have CRT and don't want it. Also i have no original consoles/computers). So unless some dev having all this equipment will correct the position it will remain as it is now.
At the end main video output of MiSTer is HDMI. So for example for me, if HDMI picture is fine then it's done. How it will look on CRT - it's task for those who care of it.


Thank you Sorgelig - that's completely understandable. You've done an amazing thing with MiSTer! :D

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Chris23235 » Thu Jan 16, 2020 5:42 pm

If you want a 100% working solution for the picture size and position on MiSTer, go for an old CRT RGB Monitor.

These monitors always had controls to stretch, squash and move the picture horizontally and vertically, because the different computers of that time all produced a different sized and positioned image, so that manual correction was necessary.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Mouseboy007 » Thu Jan 16, 2020 6:17 pm

Chris23235 wrote:If you want a 100% working solution for the picture size and position on MiSTer, go for an old CRT RGB Monitor.

These monitors always had controls to stretch, squash and move the picture horizontally and vertically, because the different computers of that time all produced a different sized and positioned image, so that manual correction was necessary.


Thanks for the advice - funnily enough, I was thinking just that. I may sell my Trinitron and get a CRT. I kind of prefer my Panasonic Quintrix of the two.
I don;t think my wife will let me have 3x crt's! :D

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby Chris23235 » Thu Jan 16, 2020 6:36 pm

The Commodore 1081s are cheap on ebay (at least here in europe) and they have the advantage, that they come with a composite and a RGB mode, they even have a green switch, which is nice.

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby sqwirral » Thu Jan 16, 2020 8:50 pm

Chris23235 wrote:The Commodore 1081s are cheap on ebay (at least here in europe)

£195 from UK or £190 from Germany. Ouch

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Re: IOBoard VGA to 15khz PAL CRT via RGB Scart

Postby witchmaster » Thu Jan 16, 2020 9:01 pm

Sorgelig wrote:Shifting on some cores are possible due to lack of precise info when hsync/vsync start on specific system. This is completely different issue not related to squashing shown in the first post.
To make exact vertical/horizontal position as on real HW, need to have real HW and CRT monitor which in most cases it's impossible (i don't have CRT and don't want it. Also i have no original consoles/computers). So unless some dev having all this equipment will correct the position it will remain as it is now.
At the end main video output of MiSTer is HDMI. So for example for me, if HDMI picture is fine then it's done. How it will look on CRT - it's task for those who care of it.

I'm not really an fpga developer but I have the hardware needed to do this for some cores. I could have a look if you can give me a hint where to find the necessary code to edit for the C64 core as an example.


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