https://bugs.documentfoundation.org/show_bug.cgi?id=173048
Bug ID: 173048
Summary: UIqt6/QtMultimedia video backend: video renders
near-native resolution, clipped to top-left corner, in
Impress Slide Show mode (edit view correct;
SAL_USE_VCLPLUGIN=gtk3 works around it)
Product: LibreOffice
Version: 26.2.5.2 release
Hardware: x86 (IA32)
OS: Linux (All)
Status: UNCONFIRMED
Severity: normal
Priority: medium
Component: Impress
Assignee: [email protected]
Reporter: [email protected]
Description:
When presenting a slide containing an embedded high-resolution video, the video
appears correctly sized within its placeholder frame in Normal/edit view, but
during Slide Show mode it renders at or near its native resolution instead of
being scaled to the placeholder. This means only the top-left portion of the
video is visible, with the rest extending off-screen.
This occurs when LibreOffice is using the qt6 VCL plugin with the
QtMultimedia/FFmpeg avmedia backend (confirmed via the qt.multimedia.ffmpeg log
output below). Forcing the older Gtk-based avmedia backend by launching with
SAL_USE_VCLPLUGIN=gtk3 fully resolves the issue — the video displays correctly
in Slide Show mode with no other changes.
This may be related to tdf#145735 (qt6: Support video playback in Impress
presentations on Wayland) and its meta bug tdf#145734, which track general
issues with qt6/QtMultimedia video playback path, though neither describes this
specific sizing/clipping symptom.
Launching with the Gtk VCL plugin instead of the default qt6 one resolves the
issue completely:
SAL_USE_VCLPLUGIN=gtk3 soffice video-bug-example.odp
Relevant console output when reproducing with the default (qt6) plugin:
qt.multimedia.ffmpeg: Using Qt multimedia with FFmpeg version n8.1.2 GPL
version 3 or later
Failed to open VDPAU backend libvdpau_nvidia.so: cannot open shared object
file: No such file or directory
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/jRSudE.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.29.100
Duration: 00:00:28.60, start: 0.000000, bitrate: 13729 kb/s
Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661),
yuv420p(progressive), 4096x2048 [SAR 1:1 DAR 2:1], 13726 kb/s, 30 fps, 30 tbr,
15360 tbn (default)
Metadata:
handler_name : VideoHandler
Steps to Reproduce:
1. Launch Impress normally (default qt6 plugin picked up automatically)
2. Open the attached ODP file, which contains a high-resolution video.
3. Start Slide Show mode (F5)
Actual Results:
The video renders at or near its native resolution and is anchored to the
top-left of its placeholder frame, so only a small corner of the frame is
visible. The rest of the video extends beyond the visible slide area.
Expected Results:
The video should be scaled down to fit its placeholder frame during Slide Show
mode, matching what's shown in edit view (and matching PowerPoint's behavior
with the same file, as well as the behavior achieved when launching with
SAL_USE_VCLPLUGIN=gtk3).
Reproducible: Always
User Profile Reset: Yes
Additional Info:
Complete console output, including likely irrelevant noise (decoding errors can
probably be ignored because the video does play; just at the wrong resolution):
This plugin supports grabbing the mouse only for popup windows
This plugin supports grabbing the mouse only for popup windows
qt.multimedia.ffmpeg: Using Qt multimedia with FFmpeg version n8.1.2 GPL
version 3 or later
Failed to open VDPAU backend libvdpau_nvidia.so: cannot open shared object
file: No such file or directory
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/jRSudE.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.29.100
Duration: 00:00:28.60, start: 0.000000, bitrate: 13729 kb/s
Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661),
yuv420p(progressive), 4096x2048 [SAR 1:1 DAR 2:1], 13726 kb/s, 30 fps, 30 tbr,
15360 tbn (default)
Metadata:
handler_name : VideoHandler
This plugin supports grabbing the mouse only for popup windows
This plugin supports grabbing the mouse only for popup windows
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/jRSudE.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.29.100
Duration: 00:00:28.60, start: 0.000000, bitrate: 13729 kb/s
Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661),
yuv420p(progressive), 4096x2048 [SAR 1:1 DAR 2:1], 13726 kb/s, 30 fps, 30 tbr,
15360 tbn (default)
Metadata:
handler_name : VideoHandler
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/jRSudE.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.29.100
Duration: 00:00:28.60, start: 0.000000, bitrate: 13729 kb/s
Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661),
yuv420p(progressive), 4096x2048 [SAR 1:1 DAR 2:1], 13726 kb/s, 30 fps, 30 tbr,
15360 tbn (default)
Metadata:
handler_name : VideoHandler
[h264 @ 0x557c212a76c0] Device does not support the VK_KHR_video_decode_queue
extension!
[h264 @ 0x557c212a76c0] Failed setup for format vulkan: hwaccel initialisation
returned error.
[h264 @ 0x557c31246940] Device does not support the VK_KHR_video_decode_queue
extension!
[h264 @ 0x557c31246940] Failed setup for format vulkan: hwaccel initialisation
returned error.
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