[Interest] QML animation flickering on Ubuntu

[Dmitry Volosnykh]

Well, I've searched for this variable, and for tearing issues on Ubuntu
with NVidia adapters. There are multiple reports and many solutions
provided. At least I know the direction for further investigations. Thank
you, Sean.

On Tue, Jan 13, 2015 at 10:21 PM, Sean Harmer <sean.harmer at kdab.com> wrote:

> On Tuesday 13 January 2015 23:06:40 Dmitry Volosnykh wrote:
> > Sean, thanks for your input.
> >
> > I have NVidia GeForce 9800M GTX, and VSync is enabled. Double-checked
> that.
> > Another enabled options: Allow Flipping and Use Conformant Texture
> > Clamping. Do not know what are they for...
> >
> > Regarding your question about monitor's refresh rate. Here is xrandr's
> > output:
> > $ xrandr
> > Screen 0: minimum 8 x 8, current 1680 x 1050, maximum 8192 x 8192
> > DVI-D-0 disconnected (normal left inverted right x axis y axis)
> > LVDS-0 connected 1680x1050+0+0 (normal left inverted right x axis y axis)
> > 331mm x 207mm
> >    1680x1050      59.9*+
> > DVI-D-1 disconnected (normal left inverted right x axis y axis)
> > HDMI-0 disconnected (normal left inverted right x axis y axis)
> >
> > I guess, it means runs on 60Hz refresh rate.
>
> Hmm OK if that didn't work, can you try this trick. Try setting
>
> export __GL_YIELD="USLEEP"
>
> for your X environment. I have this set in /etc/profile.d/tearing.sh on
> Gentoo.
> Not sure where the correct place is on Ubuntu. If this is set when X starts
> this solves the tearing for me on nVidia when using a compositing window
> manager.
>
> Cheers,
>
> Sean
>
> >
> > On Tue, Jan 13, 2015 at 9:35 PM, Sean Harmer <sean.harmer at kdab.com>
> wrote:
> > > On Tuesday 13 January 2015 17:02:40 Dmitry Volosnykh wrote:
> > > > I've tried to capture the issue: see http://youtu.be/KUNyk2YWBaY
> > > > The flickering is more obvious in this video since capturing software
> > > > affecting performance. When running application with no video
> recording
> > > > there's no visual artifacts for about 15 seconds. Then the top of the
> > >
> > > green
> > >
> > > > bar visually looks like be shifted leftwards by a small offset which
> > >
> > > holds
> > >
> > > > on form the moment of its appearance. The height of this 'cap' may
> > >
> > > slightly
> > >
> > > > increase over time. This issue reproduces constantly.
> > >
> > > Sounds like a lack of v-sync is causing tearing and over time the
> offset
> > > between the swapbuffers and screen refresh is changing. Is your monitor
> > > running
> > > at a standard refresh rate?
> > >
> > > Try forcing vsync in the control panel for your graphics card driver.
> At
> > > least
> > > nVidia provide an option for this. I'm not sure about AMD and Intel.
> > >
> > > Cheers,
> > >
> > > Sean
> > > --
> > > Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
> > > Klarälvdalens Datakonsult AB, a KDAB Group company
> > > Tel. Sweden (HQ) +46-563-540090, USA +1-866-777-KDAB(5322)
> > > KDAB - Qt Experts - Platform-independent software solutions
> > > _______________________________________________
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>
> --
> Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
> Klarälvdalens Datakonsult AB, a KDAB Group company
> Tel. Sweden (HQ) +46-563-540090, USA +1-866-777-KDAB(5322)
> KDAB - Qt Experts - Platform-independent software solutions
>
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