Bug 501964

Summary: ALC4082 is always displayed as a stereo device, but it can be set to "HiFi 5.1 Channels" or to 7.1
Product: [Applications] systemsettings Reporter: Lupe Christoph <kde-ae55haq14l>
Component: kcm_pulseaudioAssignee: Plasma Bugs List <plasma-bugs-null>
Status: RESOLVED UPSTREAM    
Severity: normal CC: sitter
Priority: NOR    
Version First Reported In: 6.3.1   
Target Milestone: ---   
Platform: unspecified   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Output from "pactl list" when ALC4082 is set to 5.1
screenshot of the stereo channels
screenshot including inactive devices

Description Lupe Christoph 2025-03-25 01:47:16 UTC 
***
The ALC4082 on my new mainboard (ASRock Phantom Gaming X870E Nova) is a USB device. While I was researching this, I read many postings that seem to suggest it is USB-only. It is display by the Sound chapter of System Settings as S/PDIF Output, which is correct, the mainboard has no analog channels. It does have a front stereo output / mic input, but I surmise this is implemented by some other hardware.

When I set the device to "HiFi 5.1 Channels" or "HiFi 7.1 Channels" the gadget always display two stereo channels. Which led me on a hunt for an entire Snark *family* until I found the tip to use the command "speaker-test --channels 6 --test wav --nloops 1". This sent output to all channels, and I finally understood that system settings was leading me astray.

I'm in the process of selecting a gaming linux, and I have four candidates on my PC. This provided the unique opportunity to check three different base distributions, Arch, Debian, and Fedora. All at their newest. And this bug was present on all of them.

I normally run Kubuntu, but I only have Ubuntu Server installed on that PC. I don't think that Kubuntu 24.10 will be any different, so I'm leaving it out.
***

SUMMARY
System Settings Sound should follow the number of channels set for a sound device.

STEPS TO REPRODUCE
1. Obtain a PC with a ALC408x sound chip
2. Start System Settings
3. Open the Sound chapter
4. Set the ALC408x to 5.1 or 7.1.
5. See if you can test more than two channels.

OBSERVED RESULT
It is not possible to reach channels 3 to 5/7 or LFE.

EXPECTED RESULT
Should be.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 6.3.3
KDE Plasma Version: 6.3.3
KDE Frameworks Version: 6.12.0
Qt Version: 6.8.2

ADDITIONAL INFORMATION

Gaming Linuxes tested:
Garuda Dr460nized Gaming (Arch Rolling Release)
Nobara Linux 41 (Fedora)
CachyOS (Debian Rolling Release)
Bazzite 41 (FROM Fedora Kinoite)
Comment 1 Harald Sitter 2025-03-25 02:02:14 UTC 
What's the output of 

pactl list

when you have the device set to 5.1

Also please attach a screenshot of the stereo channels in systemsettings
Comment 2 Lupe Christoph 2025-03-25 02:11:43 UTC 
Created attachment 179710 [details]
Output from "pactl list" when ALC4082 is set to 5.1
Comment 3 Lupe Christoph 2025-03-25 02:15:26 UTC 
Created attachment 179711 [details]
screenshot of the stereo channels
Comment 4 Lupe Christoph 2025-03-25 02:16:22 UTC 
Additional Info as requested.
Comment 5 Harald Sitter 2025-03-25 02:27:31 UTC 
I think you need to report this to pipewire (or wireplumber, not actually sure where this needs fixing). Something is weird about this device. I am guessing it'd be visible if you toggled the 'show inactive devices' in the toolbar.

What appears to happen is that if you enable 5.1 another, separate, software device gets created that correctly has the 6 channels. The problem is that this device has no available "ports" and therefore gets hidden.

> Sink #63
>	Channel Map: front-left,front-right,front-center,lfe,rear-left,rear-right
> 	Ports:
> 		[Out] Speaker: Speakers (type: Speaker, priority: 200, availability group: Speaker - Output, not available)
> 	Active Port: [Out] Speaker

Meanwhile the device you are looking at in your screenshot only has stereo channels and at least has unknown availability, which is why it is being displayed.

> Sink #61
> 	Channel Map: front-left,front-right
> 	Ports:
> 		[Out] SPDIF: S/PDIF Output (type: SPDIF, priority: 100, availability unknown)
> 	Active Port: [Out] SPDIF

The UI technically does present the situation correctly. Your S/PDIF output only reports 2 channels and the actual 5.1 output is marked not available, so it gets hidden by default.
Comment 6 Lupe Christoph 2025-03-25 03:31:43 UTC 
Created attachment 179712 [details]
screenshot including inactive devices
Comment 7 Lupe Christoph 2025-03-25 03:36:08 UTC 
You are right, except that there is another inactive device, namely the front stereo output.

Please advise where I can send the bug, pipewire or wireplumber? And if you could provide a pointer to their bug trackers, that would be useful.

Thanks for your efforts!