Audio input works on Bitwig but not on system (Ubuntu 23.04)

[icaria36]

Hi, I have an Evo 16 audio interface connected to a PC running an updated Ubuntu 23.04 with low-latency kernel (plain install, with Pipewire enabled and no PulseAudio). I have a mic connected to the interface's AUX7 and I have my headphones plugged to the interface's headphone's output 2.

On pavucontrol, the Evo 16 is enabled as Pro Audio both for input and output. I can see all the input & output channels enabled including AUX7. The Sound settings look good. Mic doesn't show as muted, volume shows as 100% 0dB. And yet, the audio signal from the mic isn't coming through (the interface display shows that there is an active input signal, green/yellow/red). Playback i.e. playing music or videos in the browser works just fine.

What is more interesting, if I open Bitwig (v5.0.3 with Pipewire enabled), channels are recognized and playback works fine, and... I also can hear and record the audio from the mic with the expected sound volume and quality.

I don't understand why the audio input works for Bitwig but not for the system. I don't know where else to look and I don't know how to debug this problem, even less how to fix it. I'm asking for help here after a couple of hours searching for information and trying out things like upgrading Ubuntu, restarting, changing pavucontrol's configuration, etc. I welcome any advice!

[Impostor]

What I don't understand is why you run pavucontrol if you've got no pulseaudio. It's a mixer tool for the pulseaudio soundserver...

[icaria36]

Hi @Impostor, I use Pavucontrol because it offers a graphical interface to configure input and output devices for Pipewire. It's officially packaged and maintained by the Ubuntu team, and it works just fine without PulseAudio. In fact, currently it offers more functionality to configure Pipewire than Ubuntu's sound settings.

Do you have a suggestion to debug the problem described above?

[Impostor]

Hi @Impostor, I use Pavucontrol because it offers a graphical interface to configure input and output devices for Pipewire [..] and it works just fine without PulseAudio.

Given your problem, how do you come to the conclusion that it works just fine without pulseaudio?

Since pavucontrol stands for pulseaudio volume control, and you use pipewire instead, for troubleshooting purposes, my suggestion would be to find a different way than pavucontrol to configure your audio hardware for use with pipewire.

[sysrqer]

Have a look in qpwgraph. Perhaps it's not routed to the output by default since you probably wouldn't normally want a mic to be routed to the speakers since it would result in feedback. Bitwig has it's own way managing the inputs and outputs.

[icaria36]

find a different way than pavucontrol to configure your audio hardware for use with pipewire.

Fair point, thank you.

Have a look in qpwgraph

Ok, this was very useful. The problem is that, by default, only capture_AUX0 and capture_AUX1 connect to the browser input (AUX0 to Input_FL and AUX1 to Input_FR) I have nothing connected to AUX0 & 1, and the mic on capture_AUX7 isn't connected to anything.

Connecting AUX 7 (mono) to the browser's FL and FR solves the problem. The mic's audio arrives to the browser inputs.

This was the quick and easy part. Then I spent more time trying to find the way to make the changes in this patchbay permanent, or have this patch be loaded by default. After saving the working patchbay and restarting the PC, Pipewire goes back to its default connections. As soon as I load qpwgraph with the changed patchbay, the AUX7 connection is established and all goes well. I have looked at the Pipewire config files on /usr/share and /etc but I couldn't find any with connections data stored. I don't have any /pipewire files under my user .config folder.

Is there a better solution than loading the .qpwgraph manually?

[sysrqer]

Is there a better solution than loading the .qpwgraph manually?

I'm not sure, everything works as I need it on my system, with or without manually opening qpwgraph. The developer for that posts here so might be useful to ping him. I would but can't remember the username now, rnbc or something I think?

Have you looked into wireplumber? I think it's definitely possible to define connections either with that or pipewire itself. Perhaps have a read here https://wiki.archlinux.org/title/WirePlumber and here https://wiki.archlinux.org/title/PipeWire

[icaria36]

I did contact the qpwgraph developer and, long story short, the options for users like me are either use this tool to create the connections you want on every session, or then create a script for your Pipewire's session manager (Wireplumber for most users). I checked the docs and some Lua script examples and, well, for now I'll stick with qpwgraph. It does the trick nicely.

I believe the right solution would be for Pipewire / Wireplumber to make available all inputs / outputs under the Audio Pro profile (and let us deal with the mixing/muting when we use this profile) instead of connecting AUX 0&1 only and call them FR and FL (something that would be fine and expected in "non-Pro" profiles. I might ask... somewhere where the developers/maintaners are, and see what they think. If there are any news, I'll report them here.

[sysrqer]

Ok, in that case just set qpwgraph as a startup application and you should be good to go.