[Question] Splitting headphones and internal speakers on a thinkpad with fedora

edinbruh@feddit.it to Linux@lemmy.ml – 35 points –

When the jack is inserted the internal speakers stop making sound and the only analog out is the jack, as it's common on laptops. But I want to address the two analog output individually so that I can:

  • Still select the speakers when headphones are plugged
  • Have different sounds come from headphones and speaker
  • Mix them with carla or other audio software

My alsa/pipewire settings are all default, I'm on a thinkpad t480s with fedora 38. My sound card is an intel hd audio card, with a realtek ALC257 analog chip.

I tried disabling auto_mute and rising the volume from alsamixer but nothing happens. Then I switching pipewire to "pro audio" but it doesn't separate the analog outputs. I also tried setting the indep_hp hint from hdarackretask but it doesn't change anything.

The hint enables a new "independent hp" option in alsamixer, but it can only be enabled by the cli and it doesn't work either.

I can provide configuration files or other info if needed but since they are all pretty long I didn't include them in the post. Also because I didn't edit them so they are just fedora's default.

Thanks

8

I have good experiences with managing inputs and outputs with pavucontrol, which has a nice GUI. You can choose output per application (I have multiple outputs, headset-microphone on jackplug for meetings, a USB device for HiFi headphones, and a USB device that goes into speakers for when I'm home alone and my noise doesn't bother anyone - pavucontrol covers that).

If you really want to go into the deep end you might try https://jackaudio.org/ but that's a very deep end and I hope you won't need it, but it's very powerful.

From pavucontrol I can't select the interfaces independently (it's what I used to enable pro audio). And Carla uses jack, so no luck with jack either

I could be wrong but I thought that there are only two channels (left, right), and that the output device (speakers, headphones) are a separate concept, meaning you can't have different audio. Similar to most cars --- left right are different, but front and back always mirror each other.

Surround sound/multichannel audio sounds like it might be what you want?

I could be wrong about this of course.

The common audio chips have lots of input/output pins (for complex surround systems), most of the pins are disabled but you can see them on stuff like hdajackretask. I can see that in my case they are on two separate outputs.

On a sidenote, on some systems the manufacturer doesn't enable some unused pins on the OS side, but leaves them enabled on firmware, which can cause problems. So you can use this kind of software to disable them yourself.

I'd try to install qpwgraph and see if anything changes when you plug in/unplug the headphones. If not, that means the switching is done by the firmware or the driver itself and not exposed to the OS, so you won't be able to change it.

If you do see change, it'll help you find a solution.