[LAD] pipewire

[Len Ovens]

On Mon, 17 Jan 2022, Fons Adriaensen wrote:

> I'd like to test pipewire as a replacement for Jack (on Arch),

> How do I tell pipewire to use e.g. hw:3,0 and make all of
> its 64 channels appear as capture/playback ports in qjackctl ?
>
> Note: I do not have anything PulseAudio (like pavucontrol)
> installed and don't want to either. If that would be a
> requirement then I'll just forget about using pipewire.

It depends on the reason for not using "anything" pulseaudio. Pipewire is 
a replacement for jack and pulseaudio. So the "JACK" graph will show all 
devices, none of which will be named system:* and some of which will go 
through some sort of SRC. I think it is possible to designate one device 
as master with direct sync and specified latency but the reality is that 
if you wish your one device to be separate from any internal, hdmi, 
webcam, etc. that will not happen. It is possible to select a device 
profile of "Off" for these devices but that would mean any desktop 
application will automatically use you multi channel device "as best it 
can" (ie. connect it's output to all device outs). With PW it is not 
possible to run two audio servers separately, one for desktop and one for 
audio production. (well you can still run JACK separately... and I guess 
for now it is possible to run pulse separately too, but that will go away) 
Pipewire does use all the system bits that puleaudio does, such as dbus 
and of course systemd. I do not think it will run without.

Of course because it is a replacement for pulseaudio, even though it may 
not use any of the pulseaudio code, it's interface to the desktop 
applications uses much the same interface as pulseaudio. Hopefully in a 
better way.

One other thing to be aware of, PW does not load any other backend besides 
ALSA. I think it does have an auto dummy device though.

--
Len Ovens
www.ovenwerks.net