https://bugs.kde.org/show_bug.cgi?id=470440
Bug ID: 470440
Summary: ffmpeg screen capture with kmsgrab and vaapi either
fails or gives corrupt video on kwin wayland
Classification: Plasma
Product: kwin
Version: 5.27.5
Platform: Archlinux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: egl
Assignee: kwin-bugs-n...@kde.org
Reporter: vasish...@gmail.com
Target Milestone: ---
SUMMARY
On Intel UHD 620 (8th gen KBL-R), when using KDE with wayland backend, the
default DRM color format is ARGB2101010 (30-bit). When trying to use kmsgrab
with ffmpeg in this mode, it results in the error "drm format not supported by
vaapi" since there is no match in vaapi for this drm format. On specifying
KWIN_DRM_PREFER_COLOR_DEPTH=24 in /etc/environment, the DRM format changes to
ARGB8888 (24-bit), this makes the ffmpeg kmsgrab successful but the output
video is garbled.
This works completely fine on Kwin X11 and GNOME wayland, the only difference I
could find was that in both these cases, the color format was XRGB8888.
Here is the ffmpeg command I am running:
ffmpeg -device /dev/dri/card0 -f kmsgrab -framerate 60 -i - -vf
'hwmap=derive_device=vaapi,scale_vaapi=w=1920:h=1080:format=nv12' -c:v
hevc_vaapi output.mkv
I have tried using h264_vaapi, vp8_vaapi codecs also, the result is same.
STEPS TO REPRODUCE
1. Login to Plasma wayland with KWIN_DRM_PREFER_COLOR_DEPTH=24
2. Record screen with ffmpeg kmsgrab using vaapi.
OBSERVED RESULT
Video output is grabled
EXPECTED RESULT
Normal screen capture
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 6.3.4-zen1-1-zen (64-bit)/5.27.5
(available in About System)
KDE Plasma Version: 5.27.5
KDE Frameworks Version: 5.106.0
Qt Version: 5.15.9
ADDITIONAL INFORMATION
Mesa version: 23.2.0-devel (git-613eb64011)
ffmpeg version: 6.0
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