Bug 428945

Summary:	Transparency causes flickering in Zoom sessions and screen recording
Product:	[Plasma] kwin	Reporter:	jan.claussen10
Component:	effects-various	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED UNMAINTAINED
Severity:	normal	CC:	nate, nicolamori
Priority:	NOR
Version First Reported In:	5.20.2
Target Milestone:	---
Platform:	Manjaro
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description jan.claussen10 2020-11-10 20:55:11 UTC

SUMMARY
When I have transparency active the parts are flickering when I am using the Zoom application. For me it looks okay, but for the person I present my desktop to, it is very disturbing. 

STEPS TO REPRODUCE
1. Set a translucent theme, e.g. Glassy or Harmony
2. Start a zoom session and share your screen
3. Enter the session with the phone or other client

OBSERVED RESULT
Flickering is visible for Windows that contain transparent elements

EXPECTED RESULT
The other person should see the same I see.

SOFTWARE/OS VERSIONS
Linux: Manjaro
KDE Plasma Version: 5.20.2
KDE Frameworks Version: 5.75.0
Qt Version: 5.15.1

Comment 1 jan.claussen10 2021-01-08 11:17:54 UTC

I just had a screen sharing session via Microsoft Teams and the other participants reported that there was no flickering. In Zoom this happens when compositing is one and probably the transparency effect. Could this be a Zoom issue? Should I file a bug there?

Comment 2 Nicola Mori 2021-04-13 12:41:16 UTC

I have the same issue. In my case I've been able to fix it by switching to XRender for the compositor rendering backend: no flickering event with active transparency. With openGL 3.1 and 2.0 backends I get flickering, so I guess that OpenGL might play a role also for others affected by this issue. All of the above in a X11 session.

My VGA is an Intel UHD Graphics 630 (integrated in a Core i7 8750H mobile CPU), and I'm currently using Mesa 21.0.2 and xf86-video-intel 2.99.917+916+g31486f40.

SOFTWARE/OS VERSIONS
Linux: Archlinux
KDE Plasma Version: 5.21.4
KDE Frameworks Version: 5.81.0
Qt Version: 5.15.2

Comment 3 Nicola Mori 2021-04-13 12:43:29 UTC

I forgot to mention that I have no problem when sharing screen with other applications like Discord.

Comment 4 jan.claussen10 2021-04-13 12:52:36 UTC

This isn’t a Zoom issue per se. The same happens when recording the screen with e.g. Vokoscreen. I am assuming it uses the same video format as Zoom.

Comment 5 David Edmundson 2023-09-06 10:38:53 UTC

This bug was reported against an outdated version of KWin. We have made many changes since the. 
If the issue persists in newer versions can you reopen the bug report updating the version number.