Bug 164763 - After video is shown, a black box remains (qt6/kf6)
Summary: After video is shown, a black box remains (qt6/kf6)
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Impress (show other bugs)
Version:
(earliest affected)
24.8.4.2 release
Hardware: x86-64 (AMD64) Linux (All)
: low minor
Assignee: Not Assigned
URL:
Whiteboard:
Keywords:
Depends on:
Blocks: KDE, KF5 Media Qt6
  Show dependency treegraph
 
Reported: 2025-01-19 15:51 UTC by Axel Braun
Modified: 2026-01-22 11:46 UTC (History)
3 users (show)

See Also:
Crash report or crash signature:


Attachments
slide with video (48.86 KB, application/vnd.oasis.opendocument.presentation)
2025-02-13 17:37 UTC, Axel Braun
Details
updated slide (6.45 MB, application/vnd.oasis.opendocument.presentation)
2026-01-01 11:38 UTC, Axel Braun
Details

Note You need to log in before you can comment on or make changes to this bug.
Description Axel Braun 2025-01-19 15:51:38 UTC
I have a presentation with a couple of videos inside.
That works well so far, but after a video is shown, a black box remains
Should be: last picture/frame of video is still visible. 
That would help to explain things using the end of the video.
Is there anything I can do on my side, or is it a bug?

Version: 24.8.4.2 (X86_64) / LibreOffice Community
Build ID: 480(Build:2)
CPU threads: 12; OS: Linux 6.12; UI render: default; VCL: kf6 (cairo+xcb)
Locale: de-DE (de_DE.UTF-8); UI: de-DE
Calc: threaded
Comment 1 raal 2025-02-13 17:21:19 UTC
It works for me in Version: 25.8.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: 7da1497aa462e2b719aa9b308a749caf7b9a19b1
CPU threads: 4; OS: Linux 6.8; UI render: default; VCL: gtk3
Locale: cs-CZ (cs_CZ.UTF-8); UI: en-US
Calc: threaded

and mp4 video. Can you share test file?
Comment 2 Axel Braun 2025-02-13 17:37:12 UTC
Created attachment 199190 [details]
slide with video

Find a single slide with video. After display in presentation mode, black box remains
Comment 3 Buovjaga 2025-10-27 19:13:53 UTC
(In reply to Axel Braun from comment #2)
> Created attachment 199190 [details]
> slide with video
> 
> Find a single slide with video. After display in presentation mode, black
> box remains

The file does not contain a video. Verified by unzipping and looking at the files.
Comment 4 Axel Braun 2026-01-01 11:34:28 UTC
(In reply to Buovjaga from comment #3)
> > 
> > Find a single slide with video. After display in presentation mode, black
> > box remains
> 
> The file does not contain a video. Verified by unzipping and looking at the
> files.

Strange. I have added the video again now to the demo-slide, and find it rotated  by 90°. Anyhow, the described effect is still visible

Version: 25.8.3.2 (X86_64) / LibreOffice Community
Build ID: 580(Build:2)
CPU threads: 22; OS: Linux 6.18; UI render: default; VCL: kf6 (cairo+xcb)
Locale: de-DE (de_DE.UTF-8); UI: de-DE
Calc: threaded
Comment 5 Axel Braun 2026-01-01 11:38:28 UTC
Created attachment 204888 [details]
updated slide

had to chose a different video, but the effect remains the same
Comment 6 Buovjaga 2026-01-01 17:34:48 UTC
Repro, only with qt-based UIs.

Arch Linux 64-bit
Version: 25.8.4.2 (X86_64) / LibreOffice Community
Build ID: 580(Build:2)
CPU threads: 8; OS: Linux 6.18; UI render: default; VCL: kf6 (cairo+wayland)
Locale: fi-FI (fi_FI.UTF-8); UI: en-US
25.8.4-1
Calc: CL threaded
Comment 7 Michael Weghorn 2026-01-01 19:25:04 UTC
(In reply to Buovjaga from comment #6)
> Repro, only with qt-based UIs.

I only see this with qt6/kf6, not qt5.
qt6/kf6 use QMediaPlayer for video playback and the behavior is potentially how that one handles the end of the stream (by default).

Version: 26.8.0.0.alpha0+ (X86_64)
Build ID: faf60b6443dab44bd46535f88f76b271b33b4d36
CPU threads: 32; OS: Linux 6.17; UI render: default; VCL: qt5 (cairo+xcb)
Locale: en-GB (en_GB.UTF-8); UI: en-US
Calc: threaded

Version: 26.8.0.0.alpha0+ (X86_64)
Build ID: faf60b6443dab44bd46535f88f76b271b33b4d36
CPU threads: 32; OS: Linux 6.17; UI render: default; VCL: qt6 (cairo+xcb)
Locale: en-GB (en_GB.UTF-8); UI: en-US
Calc: threaded
Comment 8 Michael Weghorn 2026-01-01 20:02:49 UTC
(In reply to Axel Braun from comment #0)
> Should be: last picture/frame of video is still visible. 
> That would help to explain things using the end of the video.
> Is there anything I can do on my side, or is it a bug?

For now: If you start LibreOffice with environment variable SAL_USE_VCLPLUGIN=gtk3 set (e.g. open terminal, run "SAL_USE_VCLPLUGIN=gtk3 libreoffice"), you'll get the so-called gtk3 VCL plugin which behaves the way you want for this use case.
Comment 9 Axel Braun 2026-01-02 11:43:20 UTC
Hello Michael,

(In reply to Michael Weghorn from comment #8)

> For now: If you start LibreOffice with environment variable
> SAL_USE_VCLPLUGIN=gtk3 set (e.g. open terminal, run "SAL_USE_VCLPLUGIN=gtk3
> libreoffice"), you'll get the so-called gtk3 VCL plugin which behaves the
> way you want for this use case.

Does not work for me: 
docb@P1:~> export | grep SAL
declare -x SAL_USE_VCLPLUGIN="gtk3"

LO started -> it still shows
Version: 25.8.3.2 (X86_64) / LibreOffice Community
Build ID: 580(Build:2)
CPU threads: 22; OS: Linux 6.18; UI render: default; VCL: kf6 (cairo+xcb)
Locale: de-DE (de_DE.UTF-8); UI: de-DE
Calc: threaded
Comment 10 Buovjaga 2026-01-02 11:53:41 UTC
(In reply to Axel Braun from comment #9)
> Hello Michael,
> 
> (In reply to Michael Weghorn from comment #8)
> 
> > For now: If you start LibreOffice with environment variable
> > SAL_USE_VCLPLUGIN=gtk3 set (e.g. open terminal, run "SAL_USE_VCLPLUGIN=gtk3
> > libreoffice"), you'll get the so-called gtk3 VCL plugin which behaves the
> > way you want for this use case.
> 
> Does not work for me: 
> docb@P1:~> export | grep SAL
> declare -x SAL_USE_VCLPLUGIN="gtk3"
> 
> LO started -> it still shows
> Version: 25.8.3.2 (X86_64) / LibreOffice Community
> Build ID: 580(Build:2)
> CPU threads: 22; OS: Linux 6.18; UI render: default; VCL: kf6 (cairo+xcb)
> Locale: de-DE (de_DE.UTF-8); UI: de-DE
> Calc: threaded

And what if you just launch from the command line with

SAL_USE_VCLPLUGIN=gtk3 libreoffice

as mentioned without doing your own adaptations?

If it indeed doesn't work, I would say you have a very unusual build. Which Linux distribution is this? I would like to see its packaging definition for LibreOffice.
Comment 11 Axel Braun 2026-01-02 11:56:55 UTC
(In reply to Buovjaga from comment #10)

> And what if you just launch from the command line with
> 
> SAL_USE_VCLPLUGIN=gtk3 libreoffice

Same. No change

> as mentioned without doing your own adaptations?
> 
> If it indeed doesn't work, I would say you have a very unusual build. Which
> Linux distribution is this? I would like to see its packaging definition for
> LibreOffice.

I'm running openSUSE Tumbleweed. Package definition is here:
https://build.opensuse.org/package/show/LibreOffice:Factory/libreoffice
Comment 12 Buovjaga 2026-01-02 12:13:23 UTC
(In reply to Axel Braun from comment #11)
> I'm running openSUSE Tumbleweed. Package definition is here:
> https://build.opensuse.org/package/show/LibreOffice:Factory/libreoffice

Ok, looking at the .spec file I see you need to install this package: https://software.opensuse.org/package/libreoffice-gtk3
Comment 13 Axel Braun 2026-01-03 18:47:06 UTC
(In reply to Buovjaga from comment #12)

> Ok, looking at the .spec file I see you need to install this package:
> https://software.opensuse.org/package/libreoffice-gtk3

That helped, thank you!
Comment 14 Axel Braun 2026-01-05 11:57:03 UTC
(In reply to Michael Weghorn from comment #8)
> (In reply to Axel Braun from comment #0)
> > Should be: last picture/frame of video is still visible. 
> > That would help to explain things using the end of the video.
> > Is there anything I can do on my side, or is it a bug?
> 
> For now: If you start LibreOffice with environment variable
> SAL_USE_VCLPLUGIN=gtk3 set (e.g. open terminal, run "SAL_USE_VCLPLUGIN=gtk3
> libreoffice"), you'll get the so-called gtk3 VCL plugin which behaves the
> way you want for this use case.

Actually, this is not a stable workaround either. I'm currently working on a presentation with some video snippets in it. I added them in the qt6-mode.
When opening the presentation in gtk3 mode, instead of a video a grey rectangle with a music not on is displayed. In presentation mode (Shift-F5) the video is displayed. Afterwards the grey box is back
Comment 15 Michael Weghorn 2026-01-22 11:46:22 UTC
(In reply to Axel Braun from comment #14)
> Actually, this is not a stable workaround either. I'm currently working on a
> presentation with some video snippets in it. I added them in the qt6-mode.
> When opening the presentation in gtk3 mode, instead of a video a grey
> rectangle with a music not on is displayed. In presentation mode (Shift-F5)
> the video is displayed. Afterwards the grey box is back

If videos are not properly displayed when using gtk3, that sounds like a different issue (and I can't reproduce what you describe in a quick test with a "random" video). Can you please create a separate bug report for that and attach a sample video/presentation with which this can be reproduced?

(Please also check whether the same happens when you insert the video in gtk3 right away or whether it's actually related to inserting it in qt6 first. It sounds to me like it should be unrelated, but I might be wrong...)