[LAD] pipewire

[Lorenzo Sutton]

Hi Wim,

Thanks for the very detailed info!

On 18/01/22 19:24, Wim Taymans wrote:
> On Mon, 17 Jan 2022 at 16:03, Lorenzo Sutton <lorenzofsutton at gmail.com> wrote:
>>
> <snip>
> 
>> My problem with that set-up is that it seemed that something like Ardour
>> would need to be explicitly run via pw-jack so e.g.
>>
>> pw-jack ardour
>>
> 
> You distro probably also has a package that puts the pipewire
> libjack.so in LD_LIBRARY path and then you don't have to type pw-jack
> anymore.
OK, I think it's an AUR package on Arch and derivatives.

I'm wondering if an application is typically able to work with both, 
alsa/pulseaudio and/or jack (Ardour, Pure Data, Yoshimi, MuseScore come 
to mind), how would this work?
Some of these I hardly ever run with alsa/pulseaudio, but for example I 
do sometimes use musescore with pulseaudio, or even Pure Data and 
Yoshimi. With the current set-up if I am running jack, then 
alsa/pulseaudio will just fail, which in this case is good because it is 
'forcing' me to use jack (in the application) in case something 
different was set-up.
In that scenario what would pipewire prioritize? Would there be a way to 
tell piipewiere 'hey now I'd like to be in jack mode as much as 
possible' :-)
SMPlayer has a really simple and neat way of setting this up where in 
the Output driver for audio you can write e.g. 'jack,pulse' (that's the 
setting I have), and it will try to use those in that order, essentially 
failing if jack isn't available and then trying pulseaudio

> 
>> But then setting the samplerate (I have projects at different
>> samplerates), wasn't trivial.
> 
> switch to fixed sample rate (on the fly):
> 
>    pw-metadata -n settings 0 clock.force-rate <samplerate>
> 
> switch back to dynamic control
> 
>    pw-metadata -n settings 0 clock.force-rate 0
> 
> Same for buffersize (quantum) :
> 
>    pw-metadata -n settings 0 clock.force-quantum <quantum>
> 
> and back to dynamic:
> 
>    pw-metadata -n settings 0 clock.force-quantum 0

Cool. Would this be done before running a jack application, e.g. Ardour?

Lorenzo.