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General Category => Technical Support => Hardware related => Topic started by: Devlin on 18:52, 27 June 21

Title: certain scrolling effects look weird
Post by: Devlin on 18:52, 27 June 21
I'm trying to get more info on this - in the emulator it looks perfectly smooth, but on my real CPC (464 tallkey, see video) it seems to scroll in 4-pixel(mode0 character?) chunks making it look staggered and scroll weirdly.

Is this my CPC acting up, or is it something to do with the TV not converting the signal right?


Talking in discord, I tried another game that apparently uses a similar trick for scrolling(Skatewars) and it does the same blocky scrolling method while in the emu it's fine

More importantly, is this something I can fix? I only have flat panel TVs/displays available to me, so I can't test on a CRT and see if I get the same result.
https://www.youtube.com/watch?v=LICdPoTaa-c (https://www.youtube.com/watch?v=LICdPoTaa-c)
Title: Re: certain scrolling effects look weird
Post by: roudoudou on 21:38, 27 June 21

the scrolling use a synchronisation trick to be smooth on Amstrad CRT which "cannot" be reproduced on LCD (unless some crazy converter maybe)
Title: Re: certain scrolling effects look weird
Post by: Bryce on 10:33, 28 June 21
The game changes the CRTC setting mid-picture which no LCD can copy because it only displays the picture when the entire screen data has arrived. The game Transmuter is another game that did this too.

Bryce.
 
Title: Re: certain scrolling effects look weird
Post by: Devlin on 23:33, 28 June 21
Well that's good (and also miserable) to know.


If I got a CRT display would the effect work correctly? Or is it a CPC monitor specific thing?
Title: Re: certain scrolling effects look weird
Post by: Bryce on 09:32, 29 June 21
Well that's good (and also miserable) to know.


If I got a CRT display would the effect work correctly? Or is it a CPC monitor specific thing?

The setup needs to have a complete analogue path between the CPC and the CRT. That means, you can use other monitors such as a Commodore 1084 or even an older TV with SCART input. But any setup that converts the signal to a different format, does upscaling or any other signal conditioning will have the same problem.

Bryce.