Bug 513865

Summary: KRDC on Plasma6/ wayland: Client does not support H.264 in YUV420 mode!
Product: [Applications] krdc Reporter: darwin te <darwin_te>
Component: RDPAssignee: Urs Wolfer <uwolfer>
Status: RESOLVED INTENTIONAL    
Severity: normal CC: ctrlaltca
Priority: NOR    
Version First Reported In: 25.12.0   
Target Milestone: ---   
Platform: Ubuntu   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description darwin te 2025-12-27 04:25:15 UTC 
SUMMARY

2025-12-26T20:10:27.753432-08:00 PC1 krdpserver[19144]: org.kde.krdp: Session setup completed, start processing...
2025-12-26T20:10:43.940659-08:00 PC1 krdpserver[19144]: org.kde.krdp: New client connected:  Unspecified platform Unspecified version
2025-12-26T20:10:43.940884-08:00 PC1 krdpserver[19144]: org.kde.krdp: Attempting authenticating user with PAM
2025-12-26T20:10:44.001416-08:00 PC1 krdpserver[19144]: org.kde.krdp: PAM authentication succeeded for user "dte"
2025-12-26T20:10:44.005197-08:00 PC1 krdpserver[19144]: org.kde.krdp: Video stream initialized
2025-12-26T20:10:44.005379-08:00 PC1 krdpserver[19144]: org.kde.krdp: Initializing Freedesktop Portal Session
2025-12-26T20:10:44.010299-08:00 PC1 kded6[2755]: Registering ":1.129/StatusNotifierItem" to system tray
2025-12-26T20:10:44.019048-08:00 PC1 krdpserver[19144]: org.kde.krdp: Received caps:
2025-12-26T20:10:44.019074-08:00 PC1 krdpserver[19144]: org.kde.krdp:   RDPGFX_CAPVERSION_8 AVC: false YUV420: false
2025-12-26T20:10:44.019089-08:00 PC1 krdpserver[19144]: org.kde.krdp:   RDPGFX_CAPVERSION_81 AVC: false YUV420: false
2025-12-26T20:10:44.019113-08:00 PC1 krdpserver[19144]: org.kde.krdp:   RDPGFX_CAPVERSION_10 AVC: false YUV420: false
2025-12-26T20:10:44.019128-08:00 PC1 krdpserver[19144]: org.kde.krdp:   RDPGFX_CAPVERSION_101 AVC: true YUV420: false
2025-12-26T20:10:44.019141-08:00 PC1 krdpserver[19144]: org.kde.krdp:   RDPGFX_CAPVERSION_102 AVC: false YUV420: false
2025-12-26T20:10:44.019162-08:00 PC1 krdpserver[19144]: org.kde.krdp:   RDPGFX_CAPVERSION_103 AVC: false YUV420: false
2025-12-26T20:10:44.019175-08:00 PC1 krdpserver[19144]: org.kde.krdp:   RDPGFX_CAPVERSION_104 AVC: false YUV420: true
2025-12-26T20:10:44.019188-08:00 PC1 krdpserver[19144]: org.kde.krdp:   RDPGFX_CAPVERSION_105 AVC: false YUV420: true
2025-12-26T20:10:44.019201-08:00 PC1 krdpserver[19144]: org.kde.krdp:   RDPGFX_CAPVERSION_106 AVC: false YUV420: true
2025-12-26T20:10:44.019214-08:00 PC1 krdpserver[19144]: org.kde.krdp:   UNKNOWN_VERSION AVC: false YUV420: false
2025-12-26T20:10:44.019228-08:00 PC1 krdpserver[19144]: org.kde.krdp:   RDPGFX_CAPVERSION_107 AVC: false YUV420: true
2025-12-26T20:10:44.019241-08:00 PC1 krdpserver[19144]: org.kde.krdp: Client does not support H.264 in YUV420 mode!
2025-12-26T20:10:44.019262-08:00 PC1 krdpserver[19144]: [20:10:44:019] [19144:00004c14] [ERROR][com.freerdp.core.peer] - [rdp_set_error_info]: ERRINFO_GRAPHICS_SUBSYSTEM_FAILED [0x0001112F]

STEPS TO REPRODUCE

OBSERVED RESULT

Latest snap install or remmina works though.

EXPECTED RESULT

SOFTWARE/OS VERSIONS

KRDC 25.12.0

cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=26.04
DISTRIB_CODENAME=resolute
DISTRIB_DESCRIPTION="Ubuntu Resolute Raccoon (development branch)"

Operating System: Kubuntu 26.04
KDE Plasma Version: 6.5.4
KDE Frameworks Version: 6.21.0
Qt Version: 6.9.2
Kernel Version: 6.18.0-8-generic (64-bit)
Graphics Platform: Wayland

ADDITIONAL INFORMATION
Comment 1 Fabio 2025-12-29 09:06:16 UTC 
This is a known problem with Ubuntu. They explicitly disable support for h264 and ffmpeg, so this codec is not available to the rdp library krdc is using (freerdp).

In KDE Neon (a KDE ubuntu-based distro) we provide a package supporting ffmpeg:
https://invent.kde.org/neon/backports-noble/freerdp3-noble/-/commit/72a2135cdb35c5ddb92564a7974583cfe7147f5d

Unfortunately we can't fix Ubuntu.