Vertical Rolling on PAL Dreamcast

[Jase]

I'm using a PAL Dreamcast with my main TV - a 2013 Panasonic Viera plasma and the A/V connection is RGB SCART. This setup has been working well for me but I've run into problems with a couple of Homebrew titles: Doom and Wolfenstein 3D. Both games cause the display to roll vertically as can be seen in this short video:

https://youtu.be/tqE0i2MLfP0

What's going on here? Do they require a VGA monitor or is there something about my TV that both games dislike? I've removed and reinserted the RGB SCART cable on the Dreamcast's side in case that might remedy the issue - as this often does the trick when the machine becomes "confused" with displaying the image correctly but it doesn't work here, the game just continues to roll vertically.

Can anyone shed some light on this please? I searched through the forum but couldn't find any similar instances.

[Roel]

It would seem that these games have configured the Dreamcast's video output signal in a way that doesn't sit well with your TV. Perhaps they use a 60Hz PAL signal instead of the standard 50Hz one?

[Jase]

Perhaps they use a 60Hz PAL signal instead of the standard 50Hz one?

Perhaps but it shouldn't be an issue for the Viera because it's a multi-system TV and I've played DC games on it in PAL 60Hz mode without any issues.

It would seem that these games have configured the Dreamcast's video output signal in a way that doesn't sit well with your TV.

I think you're onto something there.

Here's what happened when I tested both games using my LED TV:





Unlike the Viera, the image doesn't vertically roll but it's duplicated instead and the bottom duplicate is corrupted. I then ran another test - this time using a considerably older LCD TV from 2001 that always works with everything and behold:






Perfection!

It's a bit annoying though that I have to resort to a 20 year old TV if I want to play two particular games. I wonder why the newer TVs can't cope with whatever is going on with the configuration of the video output signal?

[Ian Micheal]

If you use my updates for wolf it has a 50/60 selector pal and ntsc

[Jase]

If you use my updates for wolf it has a 50/60 selector pal and ntsc

Is that this release?

[Ian Micheal]

Yes when it boots it will have a 50/60 selector alng with doom update i remember the problems when i use to live in australia.. if you use vga output all these is solved on most things

[Jase]

Yes when it boots it will have a 50/60 selector alng with doom update i remember the problems when i use to live in australia.. if you use vga output all these is solved on most things

Thanks but I've burned both CDI's that are available in that thread and neither of them offer a 50hz/60hz selector when they boot.

[Ian Micheal]

Dang you mean i dis-abled and forgot that's a shame doom does feature it the update in the menu you can select 50/60 that's not disabled see i only use vga now so i dont need it ..

get a vga cable vga to hdmi will solve all problems like this about $25

I use to do all dev on rca back in the day but last 3 years I only do vga to hdmi

Guess if it's really wanted i can put the selector back if you said it's missing you see since i dont use it i prolly disabled it and forgot had a lot health and famly health problems the last months so my memory is not great it was last year no one had a problem

[Ian Micheal]

https://www.dreamcast-talk.com/forum/vi ... it=dc+doom

[Jase]

get a vga cable vga to hdmi will solve all problems like this about $25

I use to do all dev on rca back in the day but last 3 years I only do vga to hdmi

I'm not using composite video though, it's an RGB SCART cable but I'll look into the VGA options.

Guess if it's really wanted i can put the selector back if you said it's missing you see since i dont use it i prolly disabled it and forgot had a lot health and famly health problems the last months so my memory is not great it was last year no one had a problem

Both of your Wolfenstein 3D CDIs work flawlessly on my LED TV using the RGB SCART connection and without any worries regarding 50hz/60hz. On my Panasonic plasma they also display correctly - albeit with the image slightly shifted to the left and no means no re-centre the image.

https://www.dreamcast-talk.com/forum/vi ... it=dc+doom

Thanks so much for this - it's fantastic!

It works great on my LED TV in 50hz and 60hz but on the plasma the image shifts massively to the left regardless of whichever settings are used. This makes me doubt that it's a NTSC/PAL issue (especially seeing as the plasma is definitely multi-system) but rather an incompatibility with newer TVs and whatever video tricks are used by some DC Homebrew titles.

I'll use my older LED or LCD TVs because they respectively play perfectly or better with the DC than my plasma. Thanks for all the help.