Bug 513057

Summary: Sound from remote no longer plays on local computer
Product: [Applications] krdc Reporter: ben <benlucky>
Component: RDPAssignee: Urs Wolfer <uwolfer>
Status: REPORTED ---    
Severity: normal CC: benlucky, ctrlaltca, stevenmcfeely42
Priority: NOR    
Version First Reported In: 25.08.3   
Target Milestone: ---   
Platform: Fedora RPMs   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: file output of requested command

Description ben 2025-12-07 20:15:06 UTC
SUMMARY

STEPS TO REPRODUCE
1. Open RDP session to Windows 11 box. On the Host Configuration screen, General Tab, select Sound: On This Computer. Instantiate the connection and get a window of the desktop of the remote Windows 11 box.
2. Run any app that produces sound on remote Windows 11 box. (Same result with firefox, music player, or chrome on Windows 11 box.)

OBSERVED RESULT
No sound plays on host Fedora machine.
On the remote Windows Settings: Sound page, it shows the Windows box is sending sound to Remote Audio.

EXPECTED RESULT
Sound to play on host Fedora machine.

SOFTWARE/OS VERSIONS
OS: Fedora Linux 43 (KDE Plasma Desktop Edition) x86_64
Host: 21HM002EUS (ThinkPad X1 Carbon Gen 11)
Kernel: Linux 6.17.8-300.fc43.x86_64
DE: KDE Plasma 6.5.3
WM: KWin (Wayland)
plasmashell 6.5.3
Qt: 5.15.18
KDE Frameworks: 5.116.0
kf5-config: 1.0

ADDITIONAL INFORMATION
This is new with recent update to Fedora 43, Plasma 6.5.3, and/or KRDC 25.08.3. Before update from Fedora 42, and older Plasma version, sound played locally as expected.

Note: I can still play sound from remote Windows 11 machine on host fedora machine when I connect using Thincast 1.1.658 stable, so feel that the Windows 11
Comment 1 Fabio 2025-12-08 20:55:15 UTC
Sound seems to work for me, so further investigation may bee needed.
Can I ask you to run "WLOG_LEVEL=DEBUG krdc" from a terminal, connect to your RDP host and try to play an audio file?
You should get a quite exhaustive log about what's going on. Lines containing the "rdpsnd" and "audio" keywords should be the more interesting ones.
Comment 2 ben 2025-12-09 05:03:10 UTC
Created attachment 187452 [details]
file output of requested command

I played about 2 seconds of a music file. The remote Windows 11 player showed audio output levels, but alsa on host fedora did not pick up the audio.
Comment 3 Fabio 2025-12-09 09:02:07 UTC
Well I think we have some hints on your log file:

[rdpsnd_load_device_plugin]: [dynamic] Loaded fake backend for rdpsnd

The fake backend is not going go emit any sound.
The available backends from freerdp are listed here: https://github.com/FreeRDP/FreeRDP/blob/44ab77c0354c141468166e71d37be2ebd7962e3b/channels/rdpsnd/client/rdpsnd_main.c#L1023
Its should probably use the "pulse" backend instead for pulseaudio.
Looks like the Fedora 43 freerdp package is supposed to include support for pulse: https://kojipkgs.fedoraproject.org//packages/freerdp/3.18.0/1.fc43/data/logs/x86_64/build.log , so I' not sure why it's not being used here.

Do you mind trying to run "WLOG_LEVEL=DEBUG xfreerdp" from the commandline and see if it works from there?
I'm afraid this is going to be something really specific to Fedora to find out..
Comment 4 ben 2025-12-09 23:13:36 UTC
Thanks Fabio for your help. When I run "WLOG_LEVEL=DEBUG xfreerdp" it doesn't load a connected desktop session. I am not going to debug that (now anyway) to leave my Fedora 43 config near stock so I can better troubleshoot with the Fedora people on the problem you indicated about  fake backend for rdpsnd.
Comment 5 Steve 2025-12-17 06:12:08 UTC
This issue does not seem to be distro specific as I am also experiencing it on two separate Arch Linux machines with KRDC version 25.12.0  ("[rdpsnd_load_device_plugin]: [dynamic] Loaded fake backend for rdpsnd" also appears in journalctl's output). I have not had a chance to try "WLOG_LEVEL=DEBUG xfreerdp", but will do so tomorrow. I can also try to roll back to either 25.08.3 or 25.08.2 to see if that fixes the issue.
Comment 6 Fabio 2025-12-17 07:44:59 UTC
I saw an interesting commit in FreeRDP's repository:
https://github.com/FreeRDP/FreeRDP/pull/12074
It fixes the rdpsnd sound channel loading.

It seems to be broken because of https://github.com/FreeRDP/FreeRDP/commit/1a33e4dea33ce92aaab31a65b83c5cdcefeea69d
Affected freerdp versions are from 3.18.0 to 3.19.1.