Subject: Bug#1391: X2Go Flickering on KDE remote desktop with compositor enabled

From: Tom Butler <[email-masked]>
Date: Mon, 10 Jun 2019 19:02:27 +0100

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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From: Stefan Baur <[email-masked]>
Date: Fri, 14 Jun 2019 11:02:02 +0200

Tom,

It would be helpful if you included your session configuration
(preferably the corresponding section from your ~/.x2goclient/sessions
file, rather than screenshots), so we know which settings you were using
to connect.

(Also, I think you are confused regarding how X2Go works, at least in
its normal modes of operation.  But we'll see once you've provided your
config.)

Kind Regards,
Stefan Baur

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From: Ulrich Sibiller <[email-masked]>
Date: Fri, 14 Jun 2019 14:07:32 +0200

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 <[email-masked]> wrote:
> _______________________________________________
> x2go-dev mailing list
> [email-masked]
> https://lists.x2go.org/listinfo/x2go-dev

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From: Stefan Baur <[email-masked]>
Date: Fri, 14 Jun 2019 15:41:12 +0200

Am 14.06.19 um 15:33 schrieb Oleksandr Shneyder:
> X2goKdrive should cover this issue better than NX. And video compression
> will be included later as well. I'm planing to provide some testing
> packages till the end of the month.
Just FYI, Mike#1 is currently working on getting X2GoKDrive packaged.

Kind Regards,
Stefan Baur