[X2Go-Dev] Bug#1391: Bug#1391: X2Go Flickering on KDE remote desktop with compositor enabled

[Ulrich Sibiller]

Hello Tom

in your video I do not see any flickering. I only see slow graphics
updates. And it is clear, why. X2go uses NX, an NX is optimized for
reducing X traffic. Modern dekstops are not using the X protocol where
NX could optimized but instead send images over the line. While NX
still compresses these it is far less efficient than the X protocol
optimizations. That is what's causing your lags.

You should disable desktop effects altogether in that session. And you
should set the Compositing Type to "Xrender". You can slow try to
disable graphics compression in X2go, see
https://github.com/ArcticaProject/nx-libs/issues/802 for an overview.

We do not offer any video compression/optimization and are not
planning that in the near future (there are more important structural
things to fix first). You can try xpra or Nomachine's commercial NX
product if you need that.

Uli


On Fri, Jun 14, 2019 at 10:53 AM Tom Butler <tom at r.je> wrote:
>
> Package: x2goserver
>
> Version: 4.1.0.3
>
> I am using X2Go to connect to a running KDE desktop over a gigabit LAN
> connection. Both the client machine (running x2goclient) and the server
> are running KDE Plasma 5.15. When the compositor is enabled, it causes
> flickering. It's most visible on windows with transparency effects like
> the taskbar and menu, however the window decorations of any window also
> flickers. I have uploaded a video of the problem here:
> https://www.youtube.com/watch?v=Hg8g1TXLndo  a rather unpleasant
> experience.
>
> The server uses Intel graphics with an i7 8650u if it's a GPU/driver
> issue. The flickering does not happen on the server's display, only when
> viewed using x2go. The same thing happens in VNC, though it is
> significantly less frequent/annoying.
>
> Ideally, x2go would support the compositor. Is it possible to just do
> full-screen polling? I can stream an x264 or vp9 video of the screen
> from the host and view the desktop that way but obviously that lacks
> input, although inefficient, it would solve any display issues if x2go
> could just stream a complete video from ffmpeg and then handle the input.
>
> However, a workaround would be disabling the compositor on a connection.
> Is there currently any method that I can run a script on
> connect/disconnect or even just ask x2goserver how many clients are
> connected so I can stop the compositor when an x2go client connects and
> then re-enable it when there are no clients?
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