Could upload a very short clip or provide a link to a video that fails for you? Also it would be worth checking with VLC (good heuristic to see if the video itself is fine) as well as Dragon Player (should use the same player component as Gwenview, i.e. "Phonon") whether those show the same problem.

(In reply to Henrik Fehlauer from comment #1)
> Could upload a very short clip or provide a link to a video that fails for
> you?
Yes here: https://c.gmx.net/@327708989611578698/NOTYkUlSRNyc7V-fqGWKSg

> Also it would be worth checking with VLC (good heuristic to see if the
> video itself is fine) as well as Dragon Player (should use the same player
> component as Gwenview, i.e. "Phonon") whether those show the same problem.
In VLC and also in GMX-Mediacenter the orientation of the video ist correct in portrait mode.

Thanks for the quick update. This is interesting. It works for me on openSUSE Tumbleweed with the VLC Phonon backend (VLC 2.2.6), i.e. VLC, Dragon Player and Gwenview all are playing the video just fine in portrait mode. (I could not get Phonon GStreamer to work…)

As Manjaro is a rolling release distro too, there should not be that much difference in terms of package versions. Not sure what we can do for you from Gwenview's side, but you could try checking two more things:
- What Phonon backend is configured in systemsettings? (Start "kcmshell kcm_phonon" or just use the search.)
- Which version of VLC are you using? (Check with "vlc -version".)

And just to confirm: With "displayed in landscape modus" you mean the video is shown rotated, i.e. you do not see any distortion of the image?

(In reply to Henrik Fehlauer from comment #3)

> Not sure what we can do for you
> from Gwenview's side, but you could try checking two more things:
> - What Phonon backend is configured in systemsettings? (Start "kcmshell
> kcm_phonon" or just use the search.)
> - Which version of VLC are you using? (Check with "vlc -version".)

Phonon backend: PhonenGStreamer 4.9.0
VLC 2.2.6 (revision 2.2.6-0-g1aae78981c)

> And just to confirm: With "displayed in landscape modus" you mean the video
> is shown rotated, i.e. you do not see any distortion of the image?
Yes it is rotated. No distortions.

I kinda hoped you had VLC 3 and some distortion (I was able to get into such a situation with VLC 3 and a different video output mode). Also tried this on KDE Neon (based on Ubuntu 16.04 LTS) with Phonon VLC, where it works fine too.

I'd be interested to know if someone else with a working GStreamer backend can confirm the bug and tell us if only Gwenview or every GStreamer based player is affected.

You best bet is probably to switch Phonon's backend from GStreamer to VLC in the KCM (move it up / "prefer"). If you see only one backend, you may need to install it's respective package (see https://wiki.archlinux.org/index.php/KDE#Which_backend_should_I_choose.3F).

Looking at bug 361829, digiKam claims to use GStreamer (first via Qt5Multimedia, later via QtAV). And indeed, in digiKam the video is played with an incorrect orientation. Same thing with the "Parole" media player. Also finally got my Phonon GStreamer backend to play the video, I can confirm the problem. This means this is a problem in GStreamer.

There is another issue: The orientation of the thumbnail is wrong, too. According to bug 361829, thumbnail generation for videos is delegated to "KDE5 imageio plugins". This can also be seen in Gwenview and Dolphin, where independent of the selected Phonon backend the video orientation is wrong.

In summary:
- As a workaround, switch to the Phonon VLC backend.
- Gwenview should allow the user to override the video orientation. This is useful even for cases where the orientation is read correctly, and the UI is already there for rotating images. Let's track this here.
- GStreamer should be fixed to show the correct video orientation. Upstream bug: https://bugzilla.gnome.org/show_bug.cgi?id=765309
- KDE's thumbnailing infrastructure should respect the video orientation tag. This is tracked in bug 329854, but in case digiKam decides to not use imageio plugins anymore this would need a separate bug.

*** Bug 342667 has been marked as a duplicate of this bug. ***

digikam does not use KIO thumbnailer. Video previews probably have to be fixed in 'ffmpegthumbs'.

Thank you for the bug report. Unfortunately we were not able to get to it yet. Can we ask you to please check if this is still an issue with Gwenview 25.08.0 (the latest released version)?