https://bugs.documentfoundation.org/show_bug.cgi?id=174204
Bug ID: 174204
Summary: Impress on Windows: H.264 video whose width is not a
multiple of 16 plays as diagonal/sheared stripes (row
stride mismatch)
Product: LibreOffice
Version: 26.8.1.1 release
Hardware: All
OS: Windows (All)
Status: UNCONFIRMED
Severity: normal
Priority: medium
Component: Impress
Assignee: [email protected]
Reporter: [email protected]
Description:
In a slide show, an MP4 video plays correctly only if its frame width is a
multiple of 16.
Otherwise every row is offset from the previous one, so the picture turns into
diagonal stripes.
This looks like the row pitch (stride) of the decoded frame being ignored: the
decoder pads each
row to a multiple of 16 pixels, but the frame is read as if rows were exactly
"width" pixels long.
Frame height does not matter: 640x360 (360 is not a multiple of 16) plays
correctly.
Test clips, all made by the same generator, differing only in size
(H.264 High profile, yuv420p, 25 fps, AAC audio):
352x640 OK
360x640 GARBLED
368x640 OK
1000x562 GARBLED
1008x560 OK
640x360 OK
Real-world impact: phone videos recorded in portrait are often 360 or 1080
pixels wide.
Neither is a multiple of 16, so they would all be affected (1080x1920 inferred
from the rule above,
not tested separately).
Steps to Reproduce:
1. File > New > Presentation.
2. Insert > Audio or Video..., choose the attached clip_360x640.mp4.
3. Slide Show > Start from First Slide.
4. Repeat with clip_352x640.mp4 for comparison.
(We started the slide shows with "soffice.exe --show deck.pptx" from a cold
start, so the crash in
bug <BUG1_NUMBER> does not get in the way.)
Actual Results:
clip_360x640.mp4 and clip_1000x562.mp4 show diagonal coloured stripes instead
of vertical colour bars.
Expected Results:
All clips show vertical colour bars, as clip_352x640.mp4 and clip_1008x560.mp4
do.
Reproducible: Always
User Profile Reset: No
Additional Info:
Version: 26.8.1.1 (X86_64)
Build ID: bf6ef2662401c7d6dce671ab4deb26ee0af3a7c1
OS: Windows 11 Pro, build 26200, x64
Locale: en-ZA
CPU: Intel Core i7-6700HQ, 16 GB RAM
GPU: Intel HD Graphics 530, driver 31.0.101.2111 (NVIDIA GTX 960M also present)
The video path uses mfplay.dll (Media Foundation), loaded from
C:\Windows\System32 (10.0.26100.9549).
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