Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS? EDIT: yes it does

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MaxTendency
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Re: Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS?

Post by MaxTendency » 12 Jul 2020, 10:29

Dirty Scrubz wrote:
07 Jul 2020, 17:55
I highly doubt this. There’s no technical reason it would unless you lost significant FPS or piled on every single filter there is.
First of all the filters can have significant impact on fps : https://youtu.be/6z46P0rlR5U?t=148 You can see the fps instantly dip as soon as the filter is applied.

Secondly there is WAY more to input delay than just fps. Just because you have stable 1k fps (warfork) doesn't mean you have 1ms of overall input delay. All that means is that your frametime (assuming the all the frames got rendered at an even pace) is 1ms. You can have 1k fps and still have massive input delay or have 60 fps and yet have low input delay. Once again, fps is only ONE OF THE FACTORS that contribute to overall input delay.

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Re: Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS?

Post by Dirty Scrubz » 12 Jul 2020, 12:22

MaxTendency wrote:
12 Jul 2020, 10:29
Dirty Scrubz wrote:
07 Jul 2020, 17:55
I highly doubt this. There’s no technical reason it would unless you lost significant FPS or piled on every single filter there is.
First of all the filters can have significant impact on fps : https://youtu.be/6z46P0rlR5U?t=148 You can see the fps instantly dip as soon as the filter is applied.

Secondly there is WAY more to input delay than just fps. Just because you have stable 1k fps (warfork) doesn't mean you have 1ms of overall input delay. All that means is that your frametime (assuming the all the frames got rendered at an even pace) is 1ms. You can have 1k fps and still have massive input delay or have 60 fps and yet have low input delay. Once again, fps is only ONE OF THE FACTORS that contribute to overall input delay.
Post processing is done via the gpu after a frame is rendered and it wouldn’t cause any noticeable input lag increase unless the code was complete garbage. Show me proof that this isn’t the case. All I see here is just empty conjecture and the guy said he tested it never disclosed his methodology so I’ll assume it was a case of “well it felt like it was that way” which unfortunately is just a placebos opinion.

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MaxTendency
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Re: Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS?

Post by MaxTendency » 13 Jul 2020, 02:06

Dirty Scrubz wrote:
12 Jul 2020, 12:22
Post processing is done via the gpu after a frame is rendered
That's already adding 1 frame worth of delay best case scenario. At 240 fps that's a delay of roughly 4ms. And this delay is being added ON TOP of your current system latency that you already have. For reference last I measured my overall input delay with a 240 fps cam it was 4 frames on avg, that's roughly 16ms. So adding a 4ms delay on top of that increases would increase the overall latency by a whopping 25%.

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Re: Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS?

Post by nexina7350 » 13 Jul 2020, 10:43

MaxTendency, you're right that post-processing does add to the input lag. However, it isn't true that it will always cause 1 frame worth of lag. If you think about it, before applying post-processing the frame is ready to be sent to the monitor BUT you hold it back just a little bit more to do some more computation / processing on it. Nothing forces the GPU to wait 1 full frame time before doing that; as soon as it finishes applying post-processing effects, it will send the image to the monitor.

As for you Dirty Scrubz, you wrote yourself that the post-processing effects are applied once the frame is ready. Think about that a little bit more, and realize that you just claimed that it has no choice but to add input lag. In an ideal world it could be as little as a single clock cycle, but it's still 1 clock cycle of additional lag VS no post-processing.

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Re: Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS?

Post by Chief Blur Buster » 13 Jul 2020, 12:55

MaxTendency wrote:
13 Jul 2020, 02:06
That's already adding 1 frame worth of delay best case scenario.
Good News: Incorrect.

Processing is sub-refresh on NVIDIA cards.

The way the framebuffer workflows is that a framebuffer can be immediately/instantly processed by a GPU shader right at the frame presentation time. For example, some operations via a GPU shader (like digitally change saturation / contrast / brightness / GPU scaling / etc), take less than ~0.05ms on some of the faster NVIDIA GPUs.

The latency chain is a highly complex one but this ain't a weak link. The processing workflow at the GPU level on modern GPUs is really amazingly fast, given the humongous bandwidth of graphics memory, so global frame processing is done quite promptly, on a whole frame, darn nearly instantly.

GPU scaling is also another thing that is done practically instantly. 10 years ago it was faster via monitor, but now it's equally as fast (or even faster) via GPU, since it's done in drivers right at frame presentation stage.

Now, if you HAD to do lookahead processing (e.g. interpolate between previous and next frame), there is a frame lag. But FreeStyle doesn't need lookahead processing.

As I have worked with monitor manufacturers, and understand the Present()-to-Photons pipeline well enough to create software that raster-interrupt beam-race those VSYNC OFF tearlines (microsecond-exact placement of VSYNC OFF tearlines!!!), I can definitively tell you that you DO NOT need a full frame latency for FreeStyle-style processing type stuff...

TL;DR: There is probably lag, but it's probably frametime-only lag, rather than a full frame lag.

How To Calculate Lag Differences From Frametime-Differentials
Frametime-based latency is easy to calculate. The latency difference between two framerates, is the time-differential between two frame rates. For example, if a framerate dips from 200fps to 190fps, then the time difference between (1/190sec) - (1/200sec) = 0.26 milliseconds = 260 microsecond input latency difference between 190fps versus 200fps.

Also, some processing takes more time than others, some may only take 50 microseconds (an approximate ~2fps drop at 200fps), while others may take 1 millisecond (an approximate ~35fps drop at 200fps). So to measure the input lag of FreeStyle-style processing:
1. Measure framerate of one location in game
2. Turn on filters
3. Measure new framerate
4. For most existing games, the input lag difference is the frametime difference between two frame rates.

This is how postprocessing lag works nowadays on NVIDIA cards. More complex filters = bigger framerate drop = bigger frametime differences. Whether it's a 2D framebuffer process (e.g. color filters) or a 3D framebuffer process (e.g. adding more textures/detail), it can be done on a sub-frame / sub-refresh latency basis.

See....Not a full frame lag. It's tinier than that.

Is the Benefits Worth it for competitive?
Depends on if human reaction time improves more than the lag added. If you're trying to boost shadows or make picture more colorful, it may make enemies easier to identify quicker. Improve your human reaction time by a slightly bigger degree than the processing time difference. Be warned, many esports games may not allow advanced-processing filters due to cheating rules, although simpler filters are allowed such as those filters built into monitors (shadow boost, gamma, saturation, etc)

Can a full frame lag still happen sometimes?
An absolute fixed-lag of a full framebuffer (or two or an integer count) mainly occurs only if the specific filter chosen, requires lookahead capability. But this will be a tape-delay-style lag (buffer-behind lag) instead of a frame holdup lag (processing lag). Filters that process a current frame using data of both the NEXT frame and PREVIOUS frame, is commonly used by interpolation, which is why lag exists for interpolation.

Yes, it is possible for both latencies to exist simultaneously though (e.g. buffering lag + processing lag).
Yes, it is possible for reprocessing to take so much time, more than the original frametime, but the processing lag is not linked to absolute frametimes like framebuffer lag.
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Dirty Scrubz
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Re: Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS? EDIT: yes it does

Post by Dirty Scrubz » 13 Jul 2020, 16:50

Thanks for that Chief BB, so as I said, you're not going to see any discernible input lag increase with the filters mentioned by the OP (e.g. sharpen). He claimed it was there and then when asked what tools/methods he used, he disappeared. Fact is, if it was even 1 frame of extra input lag then you'd hear about it in reviews, technical whitepapers and from AMD themselves (NVIDIAs competitor).

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hleV
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Re: Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS? EDIT: yes it does

Post by hleV » 14 Jul 2020, 01:54

Which GPUs are we talking about here? In CSGO, my GTX 970 instantly increases GPU usage and tanks FPS when I enable any 1 filter. Sure, if you have FPS capped so the increased GPU usage doesn't affect the FPS, are we really so brave to assume the input lag is unaffected / barely affected? I just wouldn't risk it, unless like Chief mentioned, you really benefit from the filter(s).
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Dirty Scrubz
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Re: Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS? EDIT: yes it does

Post by Dirty Scrubz » 14 Jul 2020, 07:01

hleV wrote:
14 Jul 2020, 01:54
Which GPUs are we talking about here? In CSGO, my GTX 970 instantly increases GPU usage and tanks FPS when I enable any 1 filter. Sure, if you have FPS capped so the increased GPU usage doesn't affect the FPS, are we really so brave to assume the input lag is unaffected / barely affected? I just wouldn't risk it, unless like Chief mentioned, you really benefit from the filter(s).
Of course weaker old GPUs will suffer a bigger FPS drops and with it input lag. Nobody said filters were free on any gpu.
Last edited by Dirty Scrubz on 14 Jul 2020, 16:01, edited 1 time in total.

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Re: Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS? EDIT: yes it does

Post by Brainlet » 14 Jul 2020, 08:03

Anything that uses processing power increases input lag. Even if one thing alone doesnt impact input lag noticeably, stacking things will have a significant impact. Hypothetically, if you have 30 settings that each decrease input lag by 200 microseconds, applying one setting wont have a big impact but as soon as you stack all 30 youll already have cut your input lag by 6ms.
Starting point for beginners: PC Optimization Hub

Alpha
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Re: Does Nvidia FREESTYLE add input lag if it doesn't drop my FPS? EDIT: yes it does

Post by Alpha » 14 Jul 2020, 13:12

nVidia has a guide regarding competitive settings for 240fps on their website. https://www.nvidia.com/en-us/geforce/ne ... ing-guide/

One thing mentioned,with some prosettings is "image sharpening in the NVIDIA control panel to be the best combination for competitive play.".

Any thoughts on this or straight a long Chief's post above? I recall seeing somewhere there was in fact a reason you wouldn't use the overlay for the sharpening and it should be done at the control panel.

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