Scanlines jitter

[rutra80]

Toni would it be possible to add more multipliers on Filter tab? Most shaders have visible scanlines jitter if I set vert. size to anything else than 1764, even with 4x multiplier. Free textbox would be ideal.

[Toni Wilen]

8x would mean really huge internal D3D texture size, most GPUs probably don't even support it..

But it can be added.

[rutra80]

Thank you.
Is there any other way to avoid scanlines jitter?

[Toni Wilen]

Which kind of scanlines? RGB mask scanlines probably are the only ones that can work with shader scanlines but it better to use shader filters that include scanlines.

(better ask someone who makes shaders, I am not that interested..)

[guest.r]

It's common for such things to happen due the display technology. Changing vertical resolution actually produces a different final image which may or may not trigger the effect.

For example, with my display even the screenshots may jitter.
Usually it doesn't happen when the vertical input resolution is lower, like with most games.

Example of 'jittering screenshot':


Edit: i checked with my other 1080p display and the screenie is without jittering. In my case it's display technology for sure.

[rutra80]

I mean shader scanlines. I gave up the others as they're not satisfactory and I'm able to get almost perfect results with guest'r shaders.
On my FullHD display in Hires/Double mode I don't get jitter with CRT shaders only when Vert. size slider is at ~1764. If I want NTSC with right proportions (scaling set do Default) then jitter makes it almost useless, unless I set multiplier to 4x - then it's still visible but bearable with games that don't scroll vertically.

BTW since both of you guys are at this thread I think there's a bug with screen position in either shaders or WinUAE (I bet the latter) - in Double line mode it's rendered a bit lower than in Single.

Single with WinUAE scanlines:


Double with WinUAE scanlines:


One could say not a big deal, but it borks shaders' scanlines.

CRT-Guest-SM-Hires-SmartRes-Interlace in Double line mode:

Scanlines are correct.

CRT-Guest-SM-Hires-SmartRes-Interlace in Single line mode:

Scanlines are shifted.

Shifted scanlines are most visible in laced modes and there's no way to fix it other than editing the shader:


guest'r: could you please add an offset option to shaders? At least to CRT-Guest-SM-Hires-SmartRes-Interlace and CRT-Pi-SmartRes.

Toni: do you confirm that the shift is problematic, and can it be fixed?

And I'm still open to suggestions how to deal with shaders' scanlines jitter other than using big multipliers/supersampling

PS how do I post thumbnails instead of full images dammit?

[guest.r]

Thanks for explaining a bit and mentioning the exact shader. Helped a lot. I fixed the shader, should be regular now. I will update the shader pack soon.
WinUAE is fine here.

Edit: You can test the shader for convenience. CRT Pi seems to work fine though in it's scope.

[rutra80]

Thanks guest.r it's better but take a look at A500 boot screen - this shader now has some bleeding of darks to adjacent scanlines.

not with stype set to 1 though...

[guest.r]

It should look better now.

[rutra80]

Bleeding is gone but in laced modes scanlines are shifted

[guest.r]

Yeah, that's the tradeoff. With interlaced content and these shaders every other line can be skipped or can be cut by a scanline, some setups use skipping.

As it works now the shader is also usable with other internal resolutions, offsetting it by one input pixel would mean that doubled low res lines would 'get cut'.

In this situation using mild scanlines can mitigate the situation in a visual way.

I can do some more testing, but it's ok to acknowledge that these are more or less 'gaming shaders'.

[rutra80]

So it's not possible to have properly looking universal scanlines shader which supports everything from lores to hires laced?

[guest.r]

It supports. But it's a solution with a compromise for 'laced'.

In a normal, non interlaced situation, you get something like this:

Line1
Line1
Line2
Line2


With 'line skipping' with laced it's like:

Line1
Line1
Line3
Line3


With interlaced screens and 'interlaced' shader it's more like this:

Line1
Line2
Line3
Line4

The benefits of the latter setup is that lines/info isn't discarded. Shifting the scanline presentation one line up or down would not improve the situation but would spoil scanlines with ordinary graphics.

Currently there is no mechanism within shaders to detect 'laced' screens in double line mode. It might be possible, since 'laced' screens in single line mode use a flickering like effect.

Appealing scanlines at 1080p aren't possible even with this info. Maybe a processing without scanlines could take place etc. But it's a heavy niche, since RTG setups AFAIK doesn't support filters and it's the next level for productivity.

[rutra80]

Toni if you're still here: any chances to have selectable separate shader for laced and non-laced modes?