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allhavebrainimplantsnmore

Member

Registered: 2020-07-07

Posts: 13

Screen tearing fix - match refresh rates of card and compositor

How would one change compositor's frame rate in Gnome on X Server? Is it possible? This would seem to solve screen tearing at any resolution by matching compositor's frame rate to card's refresh rate.

I tried several solutions to screen tearing without luck.
Screen tearing is due to a mismatch in screen refresh rate and the rate at which compositor processes each frame.
I have fractional refresh rates on most resolutions, but at some I have a whole number 60Hz available.
When switched to lower resolution to get a whole number refresh rate, screen tearing was gone. This suggests that compositor runs at a whole fraction of 60Hz, and that when matched in a whole fraction way to card's frame rate it resolves screen tearing.

d_fajardo

Member

Registered: 2017-07-28

Posts: 1,687

Re: Screen tearing fix - match refresh rates of card and compositor

I tried several solutions to screen tearing without luck.

We won't know those solutions unless you tell us.
What graphics and driver are you using?
You need to provide more info.

allhavebrainimplantsnmore

Member

Registered: 2020-07-07

Posts: 13

Re: Screen tearing fix - match refresh rates of card and compositor

I am running a Gnome on X server on Intel graphics. We just need to figure out how to adjust the compositor's frame rate (or is it also called refresh rate)?

allhavebrainimplantsnmore

Member

Registered: 2020-07-07

Posts: 13

Re: Screen tearing fix - match refresh rates of card and compositor

Sorry, I forgot one thing - I found a fix for screen tearing in Firefox that worked. What had to be done was to force hardware acceleration on. But why turn it on if apparently it's possible without having it on by fixing the rates? Some people might prefer acceleration off by default for security.

seth

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From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 77,762

Re: Screen tearing fix - match refresh rates of card and compositor

The compositor should adhere to the vblank signal - a fixed refresh rate would be just dumb guessing and get you a static tearline for almost sure (the frame time is 16.666ms, a vblank interval maybe ~0.1ms of that…)
The problem you seem to encounter is however that FF renders a torn image into the compositor - altering the compositor (which likely already works) won't fix anything here.

Some people might prefer acceleration off by default for security.

You might want to elaborate on this - but OpenGL is pretty much the only way to get to the vblank signal (X11/xrandr don't know that concept)

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allhavebrainimplantsnmore

Member

Registered: 2020-07-07

Posts: 13

Re: Screen tearing fix - match refresh rates of card and compositor

Thanks a lot!