MiSTer FPGA Forum

Hi guys!

The Jotego cores have an option to shift the image in both axes when outputting natively via the IO board. It seems that this is a per core feature. Is it possible to implement this in more cores? Would I have to nag each core developer to implement this? It's such a handy feature and solves the necessity to use RGB shifters.

About the values that core authors allow for vertical and horizontal offsets - can the max values be arbitrarily changed (in the source file) or is there a reason why those max values are set to those values? I notice that these max values are sometimes different between cores. I ask because on a few arcade cores, even when v/h offset is adjusted, ideal game screen position is still not always possible. Example - Rod Land -->

I know someone will suggest "why don't you just adjust your monitor settings", however, for most arcade cores the permitted H/V offset range is sufficient, and adjusting for the few games that don't allow larger offsets breaks the alignment of all the rest.

In this case, the Rodland core, the min/max values can't be changed arbitrarily without making big changes to Jotego's underlying module that handles the video shifting (using Rodland as an example).
In short, the module only accepts (and uses) 4 bits of data, hence the range.

Would that be the jtframe_resync.v module? How difficult is it to change from 4-bit to 8-bit values? Haven't some cores already done this? I'm sure I've seen some that allow for values > 7

That would be the module. I can't speak for difficulty on modifying the module to allow for larger values, because I am no video signal expert. Even worse, I don't have a CRT to conduct tests/research on.
As for other cores that do video shifting and use a different range, they may be doing it a different way and maybe not even using a modified Jotego module.
One thing to note is that a wider option range doesn't necessarily equate to a wider shift in video position...could be just finer control. For example, each value in a -8 to 7 range could be 10 pixels in either direction or in another core's...say -32 to 31 could be 5 pixels.

sorry for necroposting, just wanted to suggest this: https://www.aliexpress.us/item/32568044 ... 4itemAdapt

very cheap (_50€ shipped to italy), i just received it and it works flawlessy with my crt, you can tune both V and H offsets!

v.

Wish it worked with component video. If this exists, then maybe it can be implemented in the main part of the MiSTer in the video chain similar to the scaler. Then in each core save the offsets when saving the core settings.

I would need to see some lag test results before buying a device like that. Even the expensive Extron units introduce lag.

wmd wrote: ↑Wed Mar 27, 2024 1:56 pm

I would need to see some lag test results before buying a device like that. Even the expensive Extron units introduce lag.

i have read this before buying that, it is a review of basically the same device. overall, i can say it works flawlessy: i'm using an old Mivar TV. i haven't done any lag test though, just played a bit with c64 and snes cores.