https://bugs.kde.org/show_bug.cgi?id=522515
Bug ID: 522515
Summary: Black screen after connecting to krdp server
Classification: Applications
Product: krdc
Version First 26.04.2
Reported In:
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: RDP
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
DESCRIPTION
I've been a user of krdp and krdc for around a year, and it has worked fine for
my use case in the past. Ever since a few months ago (KDE 6.6), I haven't been
able to remote into my other PC, which is running the same version of
everything as my primary PC. After some digging, I believe that it is because
the krdp server is sending frames with a pixel format that is unsupported by my
GPU (AMD Radeon RX 6600)'s hardware H.264 decoder, and with a recent update,
krdc has forced VAAPI decoding on, which leads to it being unable to decode the
frames and ultimately crashing. I think that this could be fixed by either
making hardware decoding optional in krdc, or by making krdp encode in a pixel
format that is more widely supported by hardware decoders.
I found https://bugs.kde.org/show_bug.cgi?id=502333 which might be related, but
I decided to open this bug report to give more details from my perspective. If
it's a duplicate, I'm fine with this getting closed and I'll instead just go
and comment on that one instead.
I also acknowledge that this may be an issue with a dependency
(freerdp/libavcodec) rather than krdc itself, but I wanted to bring this to the
attention of the KDE team since I rely on KDE's remote desktop implementation
as it's very convenient, and there aren't any good alternatives since wayvnc
doesn't work on KWin. I also don't want new users with a similar GPU as mine to
try to use KDE's remote desktop implementation and have it fail on them, then
end up blaming KDE when it's not a krdp or krdc issue, so that's also why I
included this section in my bug report.
DETAILS
Relevant terminal output when starting krdc:
KRDC: Starting RDP session
[15:35:13:063] [82464:00014229] [INFO][com.freerdp.codec] - [libavcodec_init]:
Using VAAPI for accelerated H264 decoding
[15:35:13:075] [82464:00014229] [INFO][com.freerdp.codec] - [libavcodec_init]:
Using VAAPI for accelerated H264 decoding
[15:35:13:077] [82464:00014229] [WARN][com.freerdp.core.rdp] -
[log_build_warn][0x5565376a9b80]:
*************************************************
[15:35:13:077] [82464:00014229] [WARN][com.freerdp.core.rdp] -
[log_build_warn][0x5565376a9b80]: This build is using [experimental] build
options:
[15:35:13:077] [82464:00014229] [WARN][com.freerdp.core.rdp] -
[log_build_warn][0x5565376a9b80]: * 'WITH_VAAPI=ON'
[15:35:13:077] [82464:00014229] [WARN][com.freerdp.core.rdp] -
[log_build_warn][0x5565376a9b80]: * 'WITH_VAAPI_H264_ENCODING=ON'
[15:35:13:077] [82464:00014229] [WARN][com.freerdp.core.rdp] -
[log_build_warn][0x5565376a9b80]: *
[15:35:13:077] [82464:00014229] [WARN][com.freerdp.core.rdp] -
[log_build_warn][0x5565376a9b80]: [experimental] build options might crash the
application
[15:35:13:077] [82464:00014229] [WARN][com.freerdp.core.rdp] -
[log_build_warn][0x5565376a9b80]:
*************************************************
FreeRDP version: 2:3.27.1
To expand on the pixel format, my GPU only supports H.264 decoding for YUV420,
while I suspect that krdp is encoding frames in YUV444. I also found this line
in krdc's output when trying to connect:
[15:35:51:601] [82464:00014248] [INFO][com.freerdp.gdi] - [gdi_init_ex]: Remote
framebuffer format PIXEL_FORMAT_BGRA32
which states that the format might be BGRA, which is also not supported by my
GPU.
STEPS TO REPRODUCE
1. Connect to a PC running krdp server version 6.7.2
2. Enter username and password
3. Press OK
OBSERVED RESULT
A black screen is shown for a few seconds and then disappears
EXPECTED RESULT
The remote PC's screen should be shown after a few seconds
SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 6.7.2
KDE Frameworks Version: 6.27.0
Qt Version: 6.11.1
ADDITIONAL INFORMATION
Graphics Platform: Wayland
Graphics Processor: AMD Radeon RX 6600
Thank you for reviewing my bug report! Let me know if you need more
information. I believe that this can be reproduced on most GPUs, as they don't
usually support hardware decoding for formats other than YUV420.
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