[Interest] QML animation flickering on Ubuntu

Dmitry Volosnykh dmitry.volosnykh at gmail.com
Tue Jan 13 20:06:40 CET 2015


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.


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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