RTSS Scanline Sync HOWTO

[Digika]

So I've encountered issue I'm not sure how to solve - framerate/frametime in Serious Sam Syberian Mayhem is too unstable. When using FCAT moving bar in RTSS my tearline ALL over the place, constantly moving up-> down even when FPS seeming stable (you cant get SS:SM stable, its FPS ALWAYS fluctuates wildly for whatever reason)

Normal vsync induces insane penalty on this engine. What would be option getting smoother experience under these conditons? My aim is 80 fps (80.0415 my precise refresh rate) and lowering settings I can get 100-95 FPS in 1% gameplay (excluding loads).

[Reds]

What is causing the scanline to jump back the the center of the screen? Maybe i am not understanding something?

The issue i am seeing is the Sync Line 0 and Sync Line 1 metrics stay the same on the OSD panel but visually the Tearline jumps back to the center of the screen after like 20 seconds of restarting RTSS or also after manually setting the lines using the keyboard arrow keys.

[Reds]

What is causing the scanline to jump back the the center of the screen? Sorry if this has already been covered i tried searching but it get hard to sift through comment when there is more than 10 pages of posts.

The issue i am seeing is the

Sync Line 0

and Sync Line 1 metrics stay the same on the OSD panel but visually the scanline jumps back to the center of the screen after like 20 seconds of restarting RTSS or after manually setting the lines using the keyboard arrow keys.

[RealNC]

The issue i am seeing is the Sync Line 0 and Sync Line 1 metrics stay the same on the OSD panel but visually the scanline jumps back to the center of the screen after like 20 seconds of restarting RTSS or after manually setting the lines using the keyboard arrow keys.

Why are you using two sync lines to begin with? Also note that the time distance between the two lines requires the game to run fast enough to achieve that time. For example if the distance between the lines is 2ms, then that means the game must achieve 500FPS. If the game cannot achieve the required frame time, then obviously the line will jump.

[Chief Blur Buster]

If you do not want center-of-screen scanlines, never, never, never use two scanlines. Use only line 0.

Framerate fluctuations create major problems with the two-scanline approach. You need 500fps at low GPU utilization for it to be very reliable.

Besides, you will have erratic latency variability everytime the tearline moves suddenly -- because latency is lowest right below a tearline, and highest right above a tearline. The most lag-advantageous tearingless VSYNC OFF is for the tearline is moved to right above the top edge of the screen.

[Reds]

My post formatted strange that is not how i formatted lol and yeah for some reason there was two scanline set i worked this out while waiting for the first post to be approved. Its working now.

[Reds]

Ok i worked out what is happening sorry wrapping my head around this I have my monitor at 75hz with the fps cap set to 74.96 i done testing at these settings and set the scanline0 to 1052.

I now want to do x2 my refresh rate so 150fps so i set the Scanline sync to x2 this is giving my the second Scanline so what is right because i have read earlier in the thread about this but know you are saying you need "500 fps" and "you don't want two scanlines"?

[RealNC]

I now want to do x2 my refresh rate so 150fps so i set the Scanline sync to x2 this is giving my the second Scanline so what is right because i have read earlier in the thread about this but know you are saying you need "500 fps" and "you don't want two scanlines"?

x2 mode means you get at least one tearline. What are you trying to achieve? If you want a tear-free image, don't use x2.

Also, you don't need to cap FPS with scanline sync, unless you know what you're doing.

[Chief Blur Buster]

While I prefer x1 Scanline Sync -- for visual quality...

x2 has a lower-latency advantage if you can tolerate 1 tearline just above your crosshairs (keep it above it, because lag is lowest right underneath tearlines). It can be a good compromise to VSYNC OFF, with much less jitter, as long as you can tolerate a mostly stationary tearline. Do try to adjust it somewhat significantly above the crosshairs, so it doesn't splice across any enemies in the middle of the screen, best place for 2nd tearline is roughly 1/3 or 2/5 way down from top edge of screen. It is a pick-poison. You get slightly lower lag (by approximately 0.5/75sec), depending on visible tearline position) of 150fps, with the tradeoff of introducing 1 annoyingly stationary tearline. Pick your poison.

In almost all cases (unless you have intimate experience with rasters, raster interrupts or weird beam racing behaviors) -- never use a framerate cap when you've got RTSS Scanline Sync enabled. Scanline Sync is an automatic cap that synchronizes to Hz or 2xHz.

[MrEWhite]

So, I'm using Scanline Sync with the new DXGI Swapchain option in the Nvidia drivers (I've noticed this lets Scanline Sync work with Vulkan games) with the Quake remaster, which runs on Vulkan, from last year. But, I'm having an odd thing occur with it. If I just setup Scanline Sync like usual (no FPS caps), I get a really jittery frametime, but if I use a 120 FPS FPS cap in Rivatuner, the frametime becomes flat once again. Does anyone know why this is happening? Here's images with and without the FPS cap:



[Edit: Made images zoomable]