Per the release notes, rolling scanline simulation was added in v18.
SHADER: Added rolling scan line simulation based on the shader subframe feature.
Anyone know how to access this feature? Or does it need to be built into shaders from the ground up?
It’s kinda hard to find. It depends on having the ‘shader sub-frames’ option enabled, and then it will appear in the same settings > video > synchronization submenu, but the menu needs to refresh before it will appear, so back out of that menu and then go right back in and it should show up below the sub-frames option as ‘Rolling scanline simulation’
Awesome! Unfortunately, I guess it is time for a new monitor!
What’s the benefit from rolling scanline simulation?
it has the potential to be more CRT-like alternative to whole-screen black-frame-insertion, but there are some complications that make it less than perfect.
As it is, this rolling scan simulation should work pretty well on CRT shaders that have very dark scanline gaps, as long as the seams land on those gaps, but on a full, bright screen, you’re going to see obvious seams. We could blend those in a subframe-aware shader, but then you’ll negate the motion-reduction benefits in those transition areas while still losing brightness.
I tried it on a different machine with a 120hz 4K monitor. I didn’t see much, the effect seem to be causing a horizontal tear about halfway down the screen for all the shaders I tried. (I tried Metal Slug 2 with Maximus Royale, Matthias and Dr Guest Venom.)
Is there a specific shader you’d recommend to better demonstrate this? Or do we need a shader designed from the ground up to leverage this?
Still, RA is amazing. The idea of shaders operating at a higher framerate than the underlying game kind of blew me away.
Try a 60fps game.
Metal Slug 1-5 all run at 30fps so you just get double image effect in motion. It’s the same thing on CRTs.
yeah, it does a tearline sort of thing right in the middle. crt-royale-kurozumi or megatron (or plain ol’ 100% dark scanlines) would be good options to try.
The guest advanced shader has this and it works great for me
Rolling? I was just thinking about this, although I can’t test it, my monitor is old, I noticed something that may be related, the checkerboard type shadows vibrate as if it were 480i, although they are 240p games.
hmm, i don’t know about that. could be related to voltage accumulation in general 
Forgotten. I was testing NBA Jam, the shadows were lonely.
Bumping this thread
We got news from Chief Blur Buster
Doesn’t look great on my 240hz monitor, not sure what i’m doing wrong. I’m getting dark colors and obvious horizontal darken stripes that move slowly upwards. And the occasional flicker.
I am going to guess that your monitor is not running at a perfect 240hz but maybe 239.98hz or 240.01hz etc.
Try making a custom 180hz mode see if that fixes it. Alternatively contact blurbusters on twitter or comment on the github thread below.
also, with the dark colors, make sure you adjust the gamma parameter. You should be able to make it neutral there.
I tried this but the colors are still dark.
I can also reduce the banding stripes by lowering my monitor’s RGB gains from 100 to 50. But that makes it even darker.
I don’t have the darkness issue anymore but the horizontal stripes are still there:
I have run it at 120 and ot looks a bit darker (which is to be expected) but no flickering. And the motion clarity really is a lot better.
I do have the darker band which travels up the screen though, does this disappear at higher refresh rates? Or is it something with the ramp of the scan effect?
Maybe @BlurBusters knows something about this…