Mystery volume/levels issues, maybe due to pipewire/jack?

Help, Support & Bugs
1

I just upgraded to the latest Ubuntu (24.04.1) and did a fresh install, so I also reinstalled all my software, including Renoise. As part of the upgrade, the system now seems to be using pipewire for audio routing. There may be other updates to the Ubuntu Studio packages at issue here too.

My problem is intermittent: I open a song that was working perfectly fine, and it’s a crapshoot whether it will work or not. It seems like a levels issue, because when the song won’t play the meter at the top of the window is all the way at max and Renoise is probably clipping the sound. Adjusting the master volume doesn’t seem to fix it. My instrument 02 seems to be the issue–it’s a bass patch from Surge XT. When I test play a note on the keyboard, the levels for the track shoot up to clipping and stick, and all I hear is a click like unplugging a speaker jack. The levels stay there until I press a note in another track, and then the old track drops and the new track has a sticky, clipping note instead.

The mystery about it is that if I reopen the song, that might fix it, and the song and patch will play perfectly normally. Or it might not, and I might need to reopen it. It seems like there’s some kind of wacky thing going on with levels–previously I was getting very garbled playback, and it turned out the master volume was way up there and clipping constantly. Any ideas what might be going on? Why do these clipping levels keep sneaking back in? (I have saved the song with lower master volume level and auto level. Doesn’t solve it.) This was not an issue before the upgrade to the OS.

I know this might be a question for the Linux audio forum but I thought I’d try here first.

2

This is what my conclusion on pipewire and Linux pro-audio looks like so far.
If I can switch between performance mode with a small buffer and listening mode with a sufficient buffer, that seems to be enough.
Then, depending on how loaded the individual environment is, we can adjust the value of quantum in performance mode to 48, 96, 144, 192, 240, 288, 336, 384, 432, 480, 512, 2048, etc. and we are good to go.

https://wiki.linuxaudio.org/wiki/list_of_jack_frame_period_settings_ideal_for_usb_interface

$ sudo grep cpupower /etc/sudoers.d/wheel
%wheel ALL=(ALL:ALL) NOPASSWD: /usr/bin/cpupower
$
$ cat ~/.local/bin/cpupower-performance-toggle.sh
#!/bin/bash

if $(cpupower frequency-info | grep '"powersave"' > /dev/null) ; then
    sudo cpupower frequency-set -g performance
    pw-metadata -n settings 0 clock.force-quantum 192
else
    sudo cpupower frequency-set -g powersave
    pw-metadata -n settings 0 clock.force-quantum 2048
fi
$
3

So you think the buffer is the source of weird levels behavior? Or the USB io interface being out of sync with Jack?

4

I am using Arch, so the method in Ubuntu may be different again, but I guessed that it may be related to not being in performance mode.
In addition to that, I thought I wrote my own conclusion that solves various problems with pipewire.
Sorry if it was a different cause.

5

No I’m not saying you’re wrong! I’m just trying to understand all the parts with Jack and pipewire, which I’m still new to, and figure out how to check it. But you’re right, I forgot to turn on performance mode. That does help.