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Freesync broken 2019 megathread

Talk about AMD's FreeSync and VESA AdaptiveSync, which are variable refresh rate technologies. They also eliminate stutters, and eliminate tearing. List of FreeSync Monitors.

Freesync broken 2019 megathread

Postby Synoxia » 28 Jun 2019, 10:31

Freesync is broken for me with current drivers, seeking for users with same problem.
Correct Freesync behaviour:
https://www.youtube.com/watch?v=FAFgxt2nAU4

What happens:
Anything that isn't AMD FRTC will break freesync, producing this behaviour:

https://www.youtube.com/watch?v=4vNbAACtlcw RTSS cap to 43 fps
https://www.youtube.com/watch?v=6ret-aP-OU0 in-game engine framelimiter 30 fps


using Chill minimum will break freesync, in-game framelimiter will break freesync, rtss will break freesync, probably fraps and anything else will break freesync.

Now something interesting.

If you use RTSS cap first, alt tab into the game and then use the overlay to FRTC to -1 fps of your target framerate and then put the slider to the exact RTSS cap (example RTSS 50fps > 49fps FRTC then 50fps)

This happens:
https://www.youtube.com/watch?v=ttIRfzQwTXE


Perfect framepacing, perfect refresh rate at the expense of severe input lag (FRTC).


Does now FRTC do a good job of framepacing when paired with freesync regardless of what MSI AB OSD shows? .
Is basically the advice of using freesync on + vsync on + RTSS 142fps now obsolete? How to achieve perfect image and frametimes with least input lag now?
How many users experience this behaviour?

AMD support seems to have recognized the issue and reported to their engineers.


Hardware info:
Monitor xg2401, tried 2 different displayport cable
Vega 64 strix, tried various bioses and drivers, now 19.6.3
CPU Ryzen 2700x
Motherboard Asus CH7 WIFI x470
Windows 10 1903 x64, 1803/1809 show the same behaviour
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Re: Freesync broken 2019 megathread

Postby Kamil950 » 01 Jul 2019, 19:30

Did you try Radeon Chill with MinFPS == MaxFPS (maybe for example at least 2, 3 or 4 FPS less than Hz of monitor)??

Chill is recommended to use with FreeSync by creator of Chill maybe.

Chill can sometimes reduce input lag maybe. It works different than FRTC.

https://www.reddit.com/r/Amd/comments/a ... e/eeqphae/

I found it here - https://www.reddit.com/r/Amd/comments/a ... e/eerb61q/

Link to original comment on YouTube can be find here and link to other video about Chill and lower input lag - https://www.reddit.com/r/Amd/comments/a ... e/eereok4/

Sorry for my English etc. You can just read not my comments from these links above if you want understand Chill better.
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Re: Freesync broken 2019 megathread

Postby Chief Blur Buster » 05 Jul 2019, 10:56

Time to open one of the famous Blur Busters Pandora Boxes.

<Pandora Box>

One Of The Many VRR-Broken Explanations

Blame is hugely varied (game fault, driver fault, display fault, operating system), but I want to help explain better:
Here's a simplified example of imperfect VRR:

Even though VRR eliminates so much microstutter:

VSYNC ON: 16ms....16ms....16ms....16ms....33ms(missed VSYNC)....16ms....16ms....16ms

The wonders of variable refresh rate means there's no such thing as a missed refresh cycle:

FreeSync/GSYNC: 16ms....16ms....16ms....16ms....17ms(delayed refresh)....16ms....16ms....16ms

That's only a +1ms stutter instead of a +16ms stutter! Look at this animation demo of FreeSync/GSYNC.
But in the real world it's often more "jittery", like:

Realistic Situations: 15ms....18ms....17ms....19ms....24ms(delayed refresh)....13ms....16ms....19ms

But wait! It gets more complicated!

<simultaneously>
Game Time: 15ms....18ms....17ms....19ms....24ms(delayed refresh)....13ms....16ms....19ms
Photon Time: 16ms....17ms....19ms....16ms....22ms(delayed refresh)....14ms....16ms....17ms
</simultaneously>

Yessiere, I've seen gametime diverge away from photontime (pixel light hitting human eyes). It's still better than non-VRR, but it's poorly optimized VRR.
- Poorly optimized drivers.
- Poorly optimized operating system.
- Poorly optimized games.
- Fluctuations in rendertimes.
- Power management interference (amplifies the fluctuations in rendertimes)
- All the above happening simultaneously.
- Etc.
All those inaccuracies build up. So button-to-gametime diverges away from button-to-photons, creating an additional microstutter error margin in the VRR framepacing chain.

Multiply the numbers by 10x even, if you want -- for lower frame rate situations. And when divergences get big enough, VRR is sometimes erasing only like 50%-90% of human-visible stutters instead of erasing 98-99% of stutters.

Unfortunately, that's what is happening sometimes.

There you go! The complexities of imperfect VRR.

</Pandora Box>
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Re: Freesync broken 2019 megathread

Postby Synoxia » 12 Jul 2019, 16:09

Hey you seem very knowledgeable, i am not technically advanced as you butwhile agree that broken drivers/erratic game behaviour such as latest assassin creeds (i am not going into this, you know better than me how poorly optimized those are) can mess up VRR, i still don't understand why this user https://www.youtube.com/watch?v=FAFgxt2nAU4 has a better freesync behaviour than me. I want to know if i have to change monitor or gpu...

EDIT: https://community.amd.com/thread/239945 here you can see another user with the same erratic behaviour... at 20fps in 18.6.1 his LFC behaviour is correct or atleast better than mine. I might test this driver and report back
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Re: Freesync broken 2019 megathread

Postby fenderjaguar » 13 Jul 2019, 20:17

Chief Blur Buster wrote:- Poorly optimized drivers.
- Poorly optimized operating system.
- Poorly optimized games.
- Fluctuations in rendertimes.
- Power management interference (amplifies the fluctuations in rendertimes)
- All the above happening simultaneously.
- Etc.
All those inaccuracies build up. So button-to-gametime diverges away from button-to-photons, creating an additional microstutter error margin in the VRR framepacing chain.

Multiply the numbers by 10x even, if you want -- for lower frame rate situations. And when divergences get big enough, VRR is sometimes erasing only like 50%-90% of human-visible stutters instead of erasing 98-99% of stutters.

Unfortunately, that's what is happening sometimes.

There you go! The complexities of imperfect VRR.


Best argument for highest refresh possible with nosync, and ditch VRR (it's too overly complex to implement, and the issues it seeks to solve are naturally ironed out by higher refresh with nosync anyway).

VRR can in some cases amplify the perception of engine related stuttering, where it occuurs. I have been saying this since I got the prototype g-sync monitor.
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Re: Freesync broken 2019 megathread

Postby Kamil950 » 16 Jul 2019, 06:00

Synoxia wrote:(...)

EDIT: https://community.amd.com/thread/239945 here you can see another user with the same erratic behaviour... at 20fps in 18.6.1 his LFC behaviour is correct or atleast better than mine. I might test this driver and report back


That user wrote new message that new drivers (19.6.3) fixed his problem if I understand it correctly.

https://community.amd.com/thread/239945#comment-2919453

Today I tried "19.6.3" driver and "48-144 hertz" (actual range of my monitor) FreeSync range and "AMD Enhanced Sync" feature. In the past, when I did driver update with 48-144 hertz FreeSync range, there was excessive tearing and stuttering in 40-50 FPS range. Now these problems seem to have gone away with driver update.
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