Created attachment 140312 [details]
stdout of systemsettings5 while reproducing bug

Reproduced in 5.22.4

>Error: "No URI handler implemented for \"https\" from gstreamer

This is a setup issue.
Please install relevant backends.

Bumped into this on FreeBSD. Fixed it there, for reference for fellow packagers:

The needed plugins are:
- gstreamer-plugins-curl for fetching the video data via HTTPS.
- gstreamer-plugins-openh264 to actually play it.

Wanted to reopen this as an issue on Arch. None of the video demonstrations for the desktop effects seem to load. I believe I have all the necessary dependencies, but so far nothing.

So, from what I understand, this is ultimately a downstream issue: if a package is missing that prevents the video from running, the video just doesn't show up / loads endlessly. Particularly problematic for example if you use only flatpaks for videos and don't actually have codecs installed system wide.

Perhaps we could have a cleaner solution by showing a message after a given timeout?

Like: after 15 seconds, if the video is not loaded, show a Label saying "The preview took too long to run. [ ? ]", with the [ ? ] being a ContextualHelpButton saying something like "Your system might be missing essential packages needed to show this preview. Please check with your distribution."

Then we'd have the necessary software mentioned in https://community.kde.org/Distributions/Packaging_Recommendations, and point distros to that to fix things for their users.

(In reply to Thiago Sueto from comment #6)
> So, from what I understand, this is ultimately a downstream issue: if a
> package is missing that prevents the video from running, the video just
> doesn't show up / loads endlessly. Particularly problematic for example if
> you use only flatpaks for videos and don't actually have codecs installed
> system wide.
> 
> Perhaps we could have a cleaner solution by showing a message after a given
> timeout?
> 
> Like: after 15 seconds, if the video is not loaded, show a Label saying "The
> preview took too long to run. [ ? ]", with the [ ? ] being a
> ContextualHelpButton saying something like "Your system might be missing
> essential packages needed to show this preview. Please check with your
> distribution."
> 
> Then we'd have the necessary software mentioned in
> https://community.kde.org/Distributions/Packaging_Recommendations, and point
> distros to that to fix things for their users.

Makes sense, it would certainly help and prevent this issue from cropping up due to user / distro error.

Same here, although the reasons could be different. None of the effect preview videos play, and I get this output on the command line for the first video I click:

[ogg @ 0x7f2fc4001600] Broken file, keyframe not correctly marked.

System info:
===
Operating System: openSUSE Tumbleweed 20241211
KDE Plasma Version: 6.2.4
KDE Frameworks Version: 6.8.0
Qt Version: 6.8.1
Kernel Version: 6.11.8-1-default (64-bit)
Graphics Platform: Wayland
Graphics Processor: NVIDIA GeForce RTX 4070/PCIe/SSE2

Having this problem in arch as well, but I also briefly tested kde neon because the last time I was not able to reproduce it there. However, now it is also broken in kde neon as well. At least it was in the live environment.

Late 2024 and 2025 comments on this bug may be duplicates of bug 470826. I have this problem too on Fedora 41 KDE spin. I commented on that bug. On my system QtMultimedia defaults to using the ffmpeg backend, not gstreamer, and FWIW both
  % gst-launch-1.0 playbin uri=https://files.kde.org/plasma/kwin/effect-videos/invert.mp4
and
  % ffplay https://files.kde.org/plasma/kwin/effect-videos/fade_desktop.ogv
work fine.

*** Bug 470826 has been marked as a duplicate of this bug. ***

We received another openSUSE report about this yesterday (https://bugzilla.suse.com/show_bug.cgi?id=1239569)

Testing with `QT_FFMPEG_DEBUG=1 kcmshell6 kcm_kwin_effects` shows curious things. All files.kde.org mirrors are tested but the preview never plays.

A similar thing can be observed with the qtmultimedia examples apps (tested with `QT_FFMPEG_DEBUG=1 /usr/lib64/qt6/examples/multimedia/player https://files.kde.org/plasma/kwin/effect-videos/snap_helper.mp4`) but the video is played

Git commit a6f6aa19cd1c817fe678b84d83a54f78375fb940 by Oliver Beard.
Committed on 25/04/2025 at 20:48.
Pushed by olib into branch 'master'.

src/kcms,plugins: Remove effects videos
These generally no longer work, and whilst they could be made to work again, they would still be out of date.

If the videos were updated, they would quickly become outdated again as Plasma is updated via wallpaper, theme and other changes.

Effects are previewed easily enough anyway by enabling them and using them in practice.
Related: bug 462932, bug 475633, bug 421884, bug 440398
FIXED-IN: 6.4.0

M  +0    -1    CMakeLists.txt
M  +0    -6    src/kcms/common/effectsmodel.cpp
M  +0    -5    src/kcms/common/effectsmodel.h
M  +0    -28   src/kcms/effects/ui/Effect.qml
D  +0    -43   src/kcms/effects/ui/Video.qml
M  +1    -4    src/plugins/diminactive/metadata.json
M  +0    -1    src/plugins/dimscreen/package/metadata.json
M  +0    -1    src/plugins/fadedesktop/package/metadata.json
M  +1    -4    src/plugins/invert/metadata.json
M  +1    -2    src/plugins/magiclamp/metadata.json
M  +1    -2    src/plugins/magnifier/metadata.json
M  +0    -1    src/plugins/maximize/package/metadata.json
M  +1    -4    src/plugins/mouseclick/metadata.json
M  +1    -4    src/plugins/overview/metadata.json
M  +1    -2    src/plugins/slide/metadata.json
M  +0    -3    src/plugins/slidingpopups/metadata.json
M  +0    -3    src/plugins/snaphelper/metadata.json
M  +0    -1    src/plugins/squash/package/metadata.json
M  +1    -4    src/plugins/trackmouse/metadata.json
M  +1    -4    src/plugins/wobblywindows/metadata.json
M  +1    -2    src/plugins/zoom/metadata.json

https://invent.kde.org/plasma/kwin/-/commit/a6f6aa19cd1c817fe678b84d83a54f78375fb940