RTSS Scanline Sync HOWTO

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Digika
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Re: RTSS Scanline Sync HOWTO

Post by Digika » 26 Oct 2020, 16:36

Hmm, okay, thanks, the explanation for general recommendation "Pure VSYNC_OFF - offscreen, above the top edge, other pre-defined/aforementioned driver sync methods - just above the bottom edge" now makes a little bit more sense to me. I'm personally still torn about scanlinesync position for the first case, guess I will probably go for "offscreen up" since frame actuality more relevant to me.

Any input if GPU driver setting "MaxRenderFrameQueue" has any relevance to RTSS sync mode?

And sure, this topic is pretty complex (just the existence of my dumb question is proof good enough), which is why we need more normie-friendly tools that can help automate some of the control process. Man, you'd think with all that market share and insane revenue numbers NVIDIA, with all their best in the industry minds, would already came up with some centralized good solution instead of re-inventing some wheels (fast-sync) but ehh, we are still in dark age.

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RealNC
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Re: RTSS Scanline Sync HOWTO

Post by RealNC » 28 Oct 2020, 00:47

terry98 wrote:
26 Oct 2020, 14:32
RealNC wrote:
25 Oct 2020, 22:19
-3FPS cap is for VRR. -0.01FPS cap is for normal vsync without VRR.
I wasn't aware of this.. if I'm using scanline sync then I have to set the screen refresh to 60Hz and set the refresh in the settings to 16.66944ms? (which would be for 59.99fps) or do I have to set it elsewhere?
No. With ssync, RTSS will match your refresh rate, whatever it is. The value in the FPS cap box is ignored.
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Unwinder
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Re: RTSS Scanline Sync HOWTO

Post by Unwinder » 28 Oct 2020, 08:22

RealNC wrote:
28 Oct 2020, 00:47
terry98 wrote:
26 Oct 2020, 14:32
RealNC wrote:
25 Oct 2020, 22:19
-3FPS cap is for VRR. -0.01FPS cap is for normal vsync without VRR.
I wasn't aware of this.. if I'm using scanline sync then I have to set the screen refresh to 60Hz and set the refresh in the settings to 16.66944ms? (which would be for 59.99fps) or do I have to set it elsewhere?
No. With ssync, RTSS will match your refresh rate, whatever it is. The value in the FPS cap box is ignored.
FPS cap box is not ignored in case of using ssync, technically you may still enable framerate cap and apply _both_ waits stages to the same frame: first wait for target scanline position before presenting, then wait for target frametime after presenting. But the second wait will be engaged only when FPS limit is set below refresh rate, and it doesn't make any sense to use such settings combo. That applies to default async framerate limiting mode.
Two new synchronous framerate limiting modes are intended to be used in tandem with ssync by design.

Digika
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Re: RTSS Scanline Sync HOWTO

Post by Digika » 02 Nov 2020, 16:38

Chief Blur Buster wrote:
24 Jan 2019, 02:26
What about SyncScanLine1 for twice framerate versus refresh rate?:
- If unfamiliar with this, keep SyncScanLine1 setting to 0. Worry only about one tearline (SyncScanLine0 or via GUI)
- Even if you do this, please do the easy stuff first before attempting this

If your game is ultra-low GPU (e.g. Quake Live or CS:GO) combined with motion blur reduction, this can reduce strobe lag a further (e.g. 240fps at 120Hz, or 200fps at 100Hz). First, calibrate using VSYNC OFF. You may use two tearlines with Enhanced Sync or Fast Sync -- but not with VSYNC ON (that will frame-throttle you badly). Calibrate the middle tearline to middle of screen (slightly above middle is ideal, to keep it equidistant with the bottommost tearline, but position of middle tearline matters less than the bottommost tearline) but focus on carefully calibrating the bottommost tearline to stay permanently above bottom edge of screen. Ideally, they should be signal-equidistant from each other (half Vertical Total apart, taking into account of VBI versus visible vertical resolution). But this is less critical than keeping the bottommost tearline permanently above bottom edge of screen, in order to avoid those lag spikes during Fast Sync and Enhanced Sync.
Chief Blur Buster
I want to try this with L4D2. My VT is 1092 as per download/file.php?id=987
So, to recap, my VBI space is 12, that means I can get the said equilibrium by positioning middle one at 540+24 and lowest one 1080-12?

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Re: RTSS Scanline Sync HOWTO

Post by Chief Blur Buster » 02 Nov 2020, 17:30

Digika wrote:
02 Nov 2020, 16:38
I want to try this with L4D2. My VT is 1092 as per download/file.php?id=987
So, to recap, my VBI space is 12, that means I can get the said equilibrium by positioning middle one at 540+24 and lowest one 1080-12?
Give the tight VBI a try first, and see if you can get by.

VBI space is extremely tight for hiding a VSYNC OFF tearline unless you're doing force flushing.

The jitter amplitude of the VSYNC OFF tearline during RTSS Scanline Sync is usually more than 12 pixels, which means it's impossible to hide such a jittery tearline in the VBI. I'd lower the refresh rate to 72Hz to enlarge the VBI (keep reduced HT) to allow easier hiding of the VSYNC OFF tearline between refresh cycles. You might find it is a pro/con, 72Hz without tearing or 80Hz with tearing.

However, at only 87.36KHz horizontal scanrate, the tearline jitter may be fairly low, especially in games that use less than 50% GPU. Tearline will jitter more at higher scanrates (pixel rows per second), which mainly happens at higher refresh rates and/or higher resolutions.
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Digika
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Re: RTSS Scanline Sync HOWTO

Post by Digika » 02 Nov 2020, 19:54

I wonder if it just simpler to use FastSync since I have no issues with keeping up frame pace steady and FPS high.
Chief Blur Buster wrote:
02 Nov 2020, 17:30
However, at only 87.36KHz horizontal scanrate, the tearline jitter may be fairly low, especially in games that use less than 50% GPU.
I cant have any leeway with refresh rate since this is already overclocked P2414H that is specced to 60Hz. However, since I have GTX1070, L4D2 runs at about 400fps so there is no GPU demand.

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Re: RTSS Scanline Sync HOWTO

Post by Chief Blur Buster » 02 Nov 2020, 20:24

Digika wrote:
02 Nov 2020, 19:54
I cant have any leeway with refresh rate since this is already overclocked P2414H that is specced to 60Hz. However, since I have GTX1070, L4D2 runs at about 400fps so there is no GPU demand.
Distinction between horizontal refresh rate and vertical refresh rate: I am not talking about vertical refresh rate; I'm talking about horizontal refresh rate. Your screenshot shows an 87360Hz horizontal refresh rate (87360 pixel rows per second transmitted over the video cable, top-to-bottom scanout serialization sequence).

Mathematically, overclocking is just bandwidth bitbucket mathematics, assuming the firmware is VBI-size-insensitve. So, VT1092 80Hz (1092x80 = 87360, the scanrate) means at 72Hz, you can do 87360/72 = VT1213 at 72Hz. Or 87360/78 = VT1120 at 78Hz. As long as you don't increase Pixel Clock, you can sacrifice a smidge of vertical refresh rate into a larger VBI in this manner, keeping your overclocking within margins.

In other words, reducing by 2Hz makes a huge difference in hiding tearlines better (VBI of 40 lines versus VBI of 12 lines), a 3x bigger tearline-hiding window.

However, try calibrating 80 Hz first and see if you can hide tearlines fully in L4D2 without needing to increase VBI. Use the new RTSS moving-bar feature to help you calibrate.

To highlight your screenshot, about the horizontal refresh rate (known as scan rate, in terms of number of pixel rows per second; your mode transmits one pixel row from GPU to monitor in 1/87360sec).
horizontal-refresh.png
horizontal-refresh.png (237.59 KiB) Viewed 912 times
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Digika
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Re: RTSS Scanline Sync HOWTO

Post by Digika » 02 Nov 2020, 23:09

Chief Blur Buster wrote:
02 Nov 2020, 20:24
I am not talking about vertical refresh rate; I'm talking about horizontal refresh rate.
Oh, my bad, read it wrong.
Mathematically, overclocking is just bandwidth bitbucket mathematics, assuming the firmware is VBI-size-insensitve. So, VT1092 80Hz (1092x80 = 87360, the scanrate) means at 72Hz, you can do 87360/72 = VT1213 at 72Hz. Or 87360/78 = VT1120 at 78Hz. As long as you don't increase Pixel Clock, you can sacrifice a smidge of vertical refresh rate into a larger VBI in this manner, keeping your overclocking within margins.
Yeah, that makes sense. Problem is I dont know which front porch and sync width specify for that. I believe this current custom 80HZ setup for my Dell came from this forum a few years back, but I'm not particularly deeply familiar with aspects of overclocking RR.
In other words, reducing by 2Hz makes a huge difference in hiding tearlines better (VBI of 40 lines versus VBI of 12 lines), a 3x bigger tearline-hiding window.
Yep, fair point.

GReeeeN
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Re: RTSS Scanline Sync HOWTO

Post by GReeeeN » 03 Nov 2020, 06:47

I was wondering if I could get some help/ advice

I’ve been using SSync ony tv for about a year and have loved it, most games run flawlessly smooth with a frame time of 16.6 locked.

Out of no where, I’ve noticed every single game I play now has micro spikes in the frame time, I cannot get any game to run at a locked 16.6 anymore for some bizarre reason. Looking at the frame time graph it’s flat for a maybe 1/3 of a second then a very slight spike.

This has always been the case, even in the titles which I got a locked 16.6 a few months ago like Doom Eternal etc.

Has there been any known issues with the most recent nVidia drivers?. I thought it may be driver related and tried everything so did a full pc format and those spikes are still there. Could it be hardware related?, I did add additional ram a few months ago, but I’m sure even after installing it, all my titles were very smooth.

Now I’m trying to play Ori and RE3, while RE3 is playable and somewhat smooth, Ori is just too jittery with the spikes.

My setting are as follows:

[Framerate]
Limit=0
LimitDenominator=1
LimitTime=0
SyncScanline0=-230
SyncScanline1=0
SyncPeriods=0
SyncHotkeys=1
SyncFlush=1
SyncTimeout=1

Any help on how to smooth out my frame time back to what it was would be greatly appreciated.

terry98
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Re: RTSS Scanline Sync HOWTO

Post by terry98 » 03 Nov 2020, 18:11

Umm... is the application detection level set to none?? maybe you have it off...

BTW, maybe you can help me chief with something else.. I just tried a 1080p resolution with 3000 total vertical (1920 VBI) and 2200 total horizontal, the think is most of the VBI is in the back porch, so I tried setting ssync to 960, half VBI so it could move freely "above" the active screen, but the tearline appears onthe top of the screen even at ssync "1", would you happen to know why is this?? which is better more front porch or back porch or same size for both?

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