Arch Linux

nooobeee

Member

Registered: 2021-09-17

Posts: 20

[Resolved] Force stereo output on surround device

I have a motherboard with onboard surround (7.1 channel).  My audio setup is stereo so I only have the front L/R output plugged in.  However it seems like the audio is being split into channels (even when the source/file is stereo only).  For example, when I listen to music, it sounds like a background track with instruments (though not always all instruments, drums/high-hat seem to be the dominant audio) at regular volume but the vocals either really low or non-existent.  Even old video files that only have stereo seem to have the issue with only the occasional word or two coming through at full volume.  This makes me think that the sound card is filtering out vocals and trying to send that to a "center" speaker.

My kernel is Arch 5.17.1-arch1-1, alsa-lib 1.2.6.1-1, pipewire 1:0.3.49-1, pipewire-jack 1:0.3.49-1

Is this a config that should be addressed in alsa or pipewire?  FWIW, I had the same issue with pulseaudio and jack2 so I suspect this is something that can be addressed in alsa. 

Alsamixer shows channels like Center, Surround, and LFE along with Front.  I used hdajackretask to try to override the line out to a headphone but that didn't seem to change anything.  I see from https://wiki.archlinux.org/title/Advanc … leshooting that alsa can be configured to remap outputs.  I'm wondering if maybe all the outputs can be directed to a single physical output.

What's the best approach to disable the surround (I never plan on using surround on this setup) and get the line-out to behave as a more standard stereo output?

[EDIT]
One more thing.  I did see that pulseaudio has a setting for "default-sample-channels". https://wiki.archlinux.org/title/PulseAudio/Examples  I didn't check that before I switched to pipewire because I didn't find it until after I had made the change.  I may try to switch back to pulseaudio to try that but I'm hoping there's a fix with alsa/pipewire that can spare me that reversion

Last edited by nooobeee (2022-04-08 23:32:48)

Maniaxx

Member

Registered: 2014-05-14

Posts: 738

Re: [Resolved] Force stereo output on surround device

Install 'pipewire-pulse' and 'pavucontrol' and look up 'configuration/profile' in pavucontrol. Its probably set to a surround profile. Its also advisable to install 'wireplumber' to replace the now obsolete media session manager that still comes with pipewire.

Last edited by Maniaxx (2022-04-08 19:01:22)

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sys2064

nooobeee

Member

Registered: 2021-09-17

Posts: 20

Re: [Resolved] Force stereo output on surround device

I reverted to pulseaudio.  The default-sample-channels was set to 2.  No change.

I switched back to pipewire including reinstalling pipewire-pulse.  This time I also installed wireplumber (thanks for the suggestion).  Checking out pavucontrol.  Most of the profile options were listed as "unavailable".  Switching the profile did not correct the issue.  I tried several, particularly the "Analog Stereo Output" and the "Analog Surround 2.1 Output".  Does pipewire need to be restarted when switching profiles?

Not sure if I can share audio files but here's a sample recorded from my phone of what I expect (USB soundcard)
https://drive.google.com/file/d/1vtjxKM … sp=sharing

And here's what I get from the onboard soundcard
https://drive.google.com/file/d/1RbAAf1 … sp=sharing

This is the same file, same computer, and same speakers.  Only change was the audio device.  Notice the "hey" dialog at timestamp ~24/25 on the onboard sample.  For some reason, that comes through whereas the rest of the dialog is really low.

Maniaxx

Member

Registered: 2014-05-14

Posts: 738

Re: [Resolved] Force stereo output on surround device

I tried several, particularly the "Analog Stereo Output"

Yes, that's the proper stereo profile.

Does pipewire need to be restarted when switching profiles?

No, should be in effect immediately. To see how all the audio stuff is wired together (literally) you can install 'qpwgraph' to get a graphical representation.

Notice the "hey" dialog at timestamp ~24/25 on the onboard sample.  For some reason, that comes through whereas the rest of the dialog is really low.

Sounds like some kind of 'phase cancellation' due to bad connection (defect cable/connection/jack). Try to wiggle the stuff and hear precisely. Also, try to see if 24/25s effect is reproducible.

Last edited by Maniaxx (2022-04-08 21:56:14)

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sys2064

nooobeee

Member

Registered: 2021-09-17

Posts: 20

Re: [Resolved] Force stereo output on surround device

Good call.  I think you're right about the whole cancellation thing.  The computer (stereo) is going into a mono channel.  That loud part was from left only audio which allowed it to come through unimpeded.  I need to get a stereo 1/8 to 2x mono 1/4 "Y" cable to pipe it into one of the mixer's stereo channels.

Thanks for your help @maniaxx.  It was absolutely not a software thing but I think we got it figured out anyway.