Vsync setting has no effect

Bug #212587 reported by denzilla74 on 2008-04-05
104
This bug affects 21 people
Affects Status Importance Assigned to Milestone
compiz (Ubuntu)
Low
Unassigned
Declined for Karmic by Sebastien Bacher
Declined for Maverick by Sebastien Bacher

Bug Description

Open the CCSM and go to General Options -> Display Settings

Enabling "Sync to VBlank" has absolutely no effect on my desktop and screen tearing still occurs. This is a major issue with PC with built-in Intel gfx or Ati gfx cards that utilize the built-in driver that ubuntu comes with. There is no options to enable vsync in the drivers themselves and the CCSM vblank option doesn't work. Nvidia restricted drivers provide the option inside of nvidia-settings so its not a problem for nvidia users. Having screen tear really detracts from the compiz experience and makes everything look unpolished as a whole.

Travis Watkins (amaranth) wrote :

Did you restart compiz after changing this setting? Just press alt-f2 and run 'compiz' to restart it. If you do that does the setting take effect?

Changed in compiz:
status: New → Incomplete

That had no effect. System has also been rebooted since enabling the vblank settings.

What needs to be done to get this confirmed?

Andrew Aylett (andrew-aylett) wrote :

This option doesn't appear to have any effect on my computer either. I get tearing in GL applications whether it's on or off (off by default).

Tessa (unit3) wrote :

This is confirmed in Intrepid-beta on amd64, even with the nvidia drivers (as the nvidia drivers' vsync options don't always work, as reported around the net).

There's a good writeup on nvnews (http://www.nvnews.net/vbulletin/showthread.php?t=113599) about this issue on NVidia cards, and about how Compiz seems to be using "glXWaitVideoSyncSGI", which can be pre-empted (and thus, miss the proper vblank time) instead of glXSwapBuffers.

The nvnews thread also includes a patch which claims to help this issue a bit. It's a small patch, so it should be easy to test, and possibly may be useful for inclusion in the Debian patches to help resolve this issue.

Tessa (unit3) wrote :

Confirming on Intrepid-final, amd64.

Nicholas Janssen (xnicholas) wrote :

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 8.10
Release: 8.10
Codename: intrepid

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 8.10
Release: 8.10
Codename: intrepid

http://img7.imageshack.us/img7/2005/vsyncbrokenlatesti386.png

Nicholas Janssen (xnicholas) wrote :

I just visited freedesktop.org for vsync. Apparently, they don't even know what it is. Nor do they seem willing to find out what it is or why people want it.

Search:
Full Text Search: "vsync"
Results 1 - 3 of 3 results out of about 4669 pages. (3.24 seconds)

Tessa (unit3) wrote :

That's very disheartening, since vsync is one of the best and easiest things you can do to improve the quality of on-screen motion.

Changed in compiz (Ubuntu):
importance: Undecided → Low
status: Incomplete → Triaged
summary: - Hardy 8.04 - Vsync setting has no effect when enabled in CCSM
+ Vsync setting has no effect
sp8472 (sp8472) wrote :

I know it's not up to me, but I'm not sure if I agree with the "low" priority of this bug. This issue is actually one of those things that affects *every* system that uses compiz, and results in a degraded user experience with regard to this aspect in comparison to *not* using compiz. This issue is not simply one of those hard-to-reproduce bugs that impact only a minority (which every system has): it is actually one of those few things that give compiz this "two steps forward, one step back" kind of feel to it, at least to me. (On a related note, in this way it's quite similar to bug #154734, which even received a "wishlist" priority.)

Lack of Vsync is the #1 reason I use windows. I refuse to tolerate an
OS that flickers like a 20 year old street light.

On Fri, Jun 19, 2009 at 5:08 AM, sp8472<email address hidden> wrote:
> I know it's not up to me, but I'm not sure if I agree with the "low"
> priority of this bug. This issue is actually one of those things that
> affects *every* system that uses compiz, and results in a degraded user
> experience with regard to this aspect in comparison to *not* using
> compiz. This issue is not simply one of those hard-to-reproduce bugs
> that impact only a minority (which every system has): it is actually one
> of those few things that give compiz this "two steps forward, one step
> back" kind of feel to it, at least to me. (On a related note, in this
> way it's quite similar to bug #154734, which even received a "wishlist"
> priority.)
>
> --
> Vsync setting has no effect
> https://bugs.launchpad.net/bugs/212587
> You received this bug notification because you are a direct subscriber
> of the bug.
>
> Status in “compiz” source package in Ubuntu: Triaged
>
> Bug description:
> Open the CCSM and go to General Options -> Display Settings
>
> Enabling "Sync to VBlank" has absolutely no effect on my desktop and screen tearing still occurs. This is a major issue with PC with built-in Intel gfx or Ati gfx cards that utilize the built-in driver that ubuntu comes with. There is no options to enable vsync in the drivers themselves and the CCSM vblank option doesn't work. Nvidia restricted drivers provide the option inside of nvidia-settings so its not a problem for nvidia users. Having screen tear really detracts from the compiz experience and makes everything look unpolished as a whole.
>

Tessa (unit3) wrote :

That's sort of a non sequitur, since Windows doesn't vsync properly on any video card I own (including my 8800GT). Regardless, lack of vsync is really, really annoying, considering it's something we've known how to do since the mid 80s. There's really no excuse for it at this point.

Nicholas Janssen (xnicholas) wrote :

I am running windows xp nvidia 7600gs, with the latest drivers. Forced
Vsync option enabled. I get 100% vsync when I move windows around
rapidly and take screenshot.

I get 0% vsync doing same thing on latest kubuntu, with latest
proprietary nvidia drivers, and open source "nv" driver, with all
vsync options enabled. Strangely, I do have fps cap at 60 fps on glx
gears. Yet applications visibly tears apart if I move them around too
fast, movies also tear apart mid frame, even though my pc is more than
fast enough to handle full hd video playback without tearing on
windows xp.

What really is the issue perhaps might be, there is no concrete way of
testing if vsync is working besides high speed window movement and
printscreen. Most other bugs are easily verified, yet vsync is hard to
confirm on a stationary screen. Anyone care to develop a program that
reads the framebuffer and determines if vsync is working?

Nick

On Fri, Jun 19, 2009 at 2:22 PM, Graeme Humphries<email address hidden> wrote:
> That's sort of a non sequitur, since Windows doesn't vsync properly on
> any video card I own (including my 8800GT). Regardless, lack of vsync is
> really, really annoying, considering it's something we've known how to
> do since the mid 80s. There's really no excuse for it at this point.
>
> --
> Vsync setting has no effect
> https://bugs.launchpad.net/bugs/212587
> You received this bug notification because you are a direct subscriber
> of the bug.
>
> Status in “compiz” source package in Ubuntu: Triaged
>
> Bug description:
> Open the CCSM and go to General Options -> Display Settings
>
> Enabling "Sync to VBlank" has absolutely no effect on my desktop and screen tearing still occurs. This is a major issue with PC with built-in Intel gfx or Ati gfx cards that utilize the built-in driver that ubuntu comes with. There is no options to enable vsync in the drivers themselves and the CCSM vblank option doesn't work. Nvidia restricted drivers provide the option inside of nvidia-settings so its not a problem for nvidia users. Having screen tear really detracts from the compiz experience and makes everything look unpolished as a whole.
>

Mike Pelley (mikepelley) wrote :

This thread might be related: http://ubuntuforums.org/showthread.php?t=646356

Basically, he says that compiz runs before the nvidia-settings are "enabled" or something. It would seem that the correct fix would ensure that the nvidia-settings are "enabled" before compiz runs.

oranges (oranges10e) wrote :

I have the same problem. If i use metacity only, without the advanced compiz effects, and then enable the vsync-options in the Nvidia CP, I get the full vsync in my videos. However, as soon as I enable compiz again, the tearing begins. I have tried enabling vsync in compiz itself, which indeed does help - but only for the windows on the desktop and so on. It doesn't do much for my videos. I must say, at least for me, this IS one of the reasons why I have to keep Windows on dualboot. If I can't watch a movie with decent vsync or play a game on my 26" fullhd, then why am I using it? I have tried to find ANYTHING related to this on Google and the boards - no one seems to have a solution for this and many who have told me not to have it, have it but don't notice it ( I have asked for screenshots ). I agree, on a small LCD it doesn't matter that much, but on bigger screens, my god, it's too much. My school is planning to switch to Ubuntu BUT has a problem with this vsync bug (?). I was the one recommending Ubuntu. Like a bunch of ppl, they want to do more then just write text, they need good, fluid and vsync'd video quality. This should be one of those top-ten bugs, as this affects many areas. What good is all the extra eye candy compiz gives you, if it tears all the time - especially with cube effects. Some told me that is the main reason, which can't be. I have used something like compiz (and the cube) on Windows before - not one bit of tearing. Anyway, realizing there is a vsync-option in compiz, it should be obvious it is meant to have it, but must be broken somehow. So, please fix this. I could get Ubuntu on a bunch of systems around here, if this actually gets attention and fixed.

Thank you.

Oranges

oranges (oranges10e) wrote :

PS: BTW, another vote for vsync ON at default. No configurations should have to be done for this feature. We're closing in on 2010, this is a must-have feature.

Thank you.

Travis Watkins (amaranth) wrote :

Alright, so there are actually a couple issues here. Let me see if I can clear them all up.

1) nVidia's OpenGL Sync to VBlank option only affects glXSwapBuffers but we don't use it. In order to use this option we would have to do a full screen redraw every frame and while AaronP might think this isn't a problem we don't all have nVidia graphics cards. Even if we did use this option it would only help compiz and not any videos or OpenGL applications compiz is managing. There is currently no way to ensure such things are flicker free when using any compositor as you don't want to sync to vblank but to the compositor's redraw rate. As you cannot get this information from the compositor there is no way to even try to do this. See http://dri.freedesktop.org/wiki/CompositeSwap for all the gory details.

That pretty much wraps it all up, actually. Just a couple more little notes.

2) The compiz way of doing sync to vblank doesn't guarantee vsync if your computer is under heavy load. There is no way to fix this with what we have available right now. It also "fights" with the nvidia-settings sync to vblank option.

3) We don't enable sync to vblank in compiz by default because in the past it caused suspend/resume issues with nvidia cards and right now it causes intel users to get about 0.5 frames per second. Even if we did enable it by default it wouldn't help with the issues most of you seem to be having.

oranges (oranges10e) wrote :

Hello, first of all, thank you for posting and giving a good and easy to understand respond.

What would you suggest to do then? Just use Meta (I feel like in Windows98/XP with that)?

The windows tear but the videos seem to be just fine (vsync'd). By the way, just because I'm curious, how does Vista do or handle the 3D stuff on the desktop with vsync? Is there ANY alternativ on Ubuntu? I mean, anything that will give me at least a few effects, like the ones in Vista, AND guarantee smooth video-playback? I think such things like, for example vsync, are much more important, then a few nice effects, but it would be nice to have that modern feel they give. Anyway, I will suggest my school to use the netbook remix instead. It should be a piece of cake, even if it's for netbooks, right?
Since one doesn't really need any special effects there and videos seem to play just fine, it is, up untill now, the only way I see to do this.

Oranges

Travis Watkins (amaranth) wrote :

All compositors will cause this tearing, as I said. There is no way to get effects and flicker free drawing.

Tessa (unit3) wrote :

I'm not sure that's what you meant to say, since other OSes on the same hardware can achieve effects and flicker free drawing. Maybe what you meant to say is that without significant changes to X and to how compositing is done, this is currently very difficult under Linux.

And that's a fair assessment, but it doesn't mean that it shouldn't be worked towards. Because it is sort of ridiculous we can't have this on modern hardware with current Linux distros.

oranges (oranges10e) wrote :

@Graeme: was about to say the same thing. We should start a vote on this or make this more visible to discuss about. Maybe a thread with a voting-poll? Like I said, this is something that really should be in a modern OS. Productivity over eye-candy - just my opinion and from the users I have installed Ubuntu on, including my school.

Oranges

oranges (oranges10e) wrote :

Okay, nevermind the forum suggestion. I just opened a thread - to discuss this and a poll, to see who wants what and why -> http://ubuntuforums.org/showthread.php?t=1305320 Actually this is interesting. Let's see how it goes, shall we?

Oranges

Nicholas Janssen (xnicholas) wrote :

I also was going to say the same thing. If microsoft and apple can
achieve vsync on the same hardware and lower performing hardware then
ubuntu can also. I understand that it will be difficult from a
technical perspective, but vsync is essential for mainstream adoption.

On Thu, Oct 29, 2009 at 6:55 PM, Graeme Humphries <email address hidden> wrote:
> I'm not sure that's what you meant to say, since other OSes on the same
> hardware can achieve effects and flicker free drawing. Maybe what you
> meant to say is that without significant changes to X and to how
> compositing is done, this is currently very difficult under Linux.
>
> And that's a fair assessment, but it doesn't mean that it shouldn't be
> worked towards. Because it is sort of ridiculous we can't have this on
> modern hardware with current Linux distros.
>
> --
> Vsync setting has no effect
> https://bugs.launchpad.net/bugs/212587
> You received this bug notification because you are a direct subscriber
> of the bug.
>
> Status in “compiz” package in Ubuntu: Triaged
>
> Bug description:
> Open the CCSM and go to General Options -> Display Settings
>
> Enabling "Sync to VBlank" has absolutely no effect on my desktop and screen tearing still occurs. This is a major issue with PC with built-in Intel gfx or Ati gfx cards that utilize the built-in driver that ubuntu comes with. There is no options to enable vsync in the drivers themselves and the CCSM vblank option doesn't work. Nvidia restricted drivers provide the option inside of nvidia-settings so its not a problem for nvidia users. Having screen tear really detracts from the compiz experience and makes everything look unpolished as a whole.
>

kopiwe (kopiwe) wrote :

I had the same problem, here is the solution:

http://ubuntuforums.org/showthread.php?t=1390284

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