Re: Trying to understand pipewire jack emulation better

Hi Chris,

this is some damn valuable information you provided me with, thank you a
lot! There are some follow-up questions below...

* Chris Caudle <[email protected]> [2026-05-27 17:45]:
[...]
> Be sure to read the Debian FAQ on pipewire.  Debian seems to have made the
> decision to not make pipewire-jack the default JACK server, so unless you
> follow the manual steps in the FAQ to link the pipewire provided libjack using
> ld then pipewire-jack will not be loaded by default.
I foung it all on https://wiki.debian.org/PipeWire, great!
 
> If you start jackd then you are using jackd as the JACK server and not
> pipewire-jack.
Can native jackd started as described run at the same time as pipewire
and access the same audio cards?

> Qjackctl is only for starting jackd, it does not have the capability to modify
> pipewire-jack parameters.
Got it.

[...] 
>     How can I tell pipewire to use a different card, eg. an external USB
>     card instead of the built-in one?
> 
> The easiest way is using pavucontrol. There are CLI tools available (e.g.
> pw-cli), but I am not as familiar with those.
Are you sure that pavucontrol is able to change pipewire settings? I am
under the impression that it is a GUI mixer for the PulseAudio server.
 
[...] 
> The CLI tool pw-metadata will change runtime parameters.
> To set buffer size and change sample rate you could run:
> pw-metadata -n settings 0 clock.force-quantum <buffer size>
> pw-metadata -n settings 0 clock.force-rate <sample rate>
> 
> There is also a new-ish Python application named Cable which has a GUI for
> interacting with pipewire server settings.
Thanks! 

Still not sure though if "quantum" is about midi or audio latency...

[...]
> I believe Wireplumber is also used by system services to implement policy
> settings around default devices (for example what to do when a new device is
> added, whether per-user device settings need to be changed).  I'm not positive
> about all the cases where wireplumber is used, but as far as I can tell it is
> not really intended for user interactive use, it is more like system plumbing
> that other tools use.
That was my impression as well.

Thanks again Chris!
best, Peter