[LAU] Connect pipewire to running JACK server

[Lorenzo Sutton]

On 28/01/2022 19:35, Paul Davis wrote:
> 
> 
> On Fri, Jan 28, 2022 at 11:12 AM Len Ovens <len at ovenwerks.net 
> <mailto:len at ovenwerks.net>> wrote:
> 
> 
>     The audio world seems to have given up on latencies with buffer
>     sizes any
>     lower than 256/2. Certainly, most recording can be done at even higher
>     latencies with external monitoring but the use of softsynths or
>     software
>     effects that require low latency monitoring from the computer is
>     difficult
>     at best.
> 
> 
> I can use my MOTU USB device at 64/2.

Interestingly I used to be able to get 64/2 with my USB audio devices 
(both a Scarlet 2i2 and a Behringer UMC202) on my previous laptop which 
was just a 'consumer' Acer I got in 2013, with a realtime kernel, CPU 
set to 'performance' mode and disabling WiFi. I was even able to do 
128/2 with the internal sound-card.

On my current machine which is a Tuxedo laptop (obviously with more 
horse-power in terms of CPU and RAM), I cant seem to go below 128/2 
whatever I do. CPU here is managed by proprietary software (well 
especially the fans, otherwise they are always on), which kinda sucks 
for this kind of machine.

It's really hard to understand if it's the hardware, the (new) kernels, 
some other software or OS thing or a mix of all those.

128 is still tolerable for recording and things like Jamulus (which of 
course introduces a bit more latency), but yes, for software effects and 
processing of live input 64 would be nicer.

In both cases there is one specific USB port which works best with audio 
interfaces.

I passed that Acer laptop to my son after upgrading the hard disk to SSD 
and adding some RAM and he is still happily using it (albeit the 
keyboard and other parts are quite a bit bashed by now and the battery 
is dead), so overall it was pretty good buy (8+ years for a laptop isn't 
bad).

What I really find frustrating is that the whole usb audio interface 
chain is near to impossible to 'debug' as there are so many factors and 
so many set-up specific variables.

What's also frustrating is that, intuitively, there should be the CPU, 
RAM, USB bandwidth to have pretty low latencies at least for a 2x2 
simple set-up.

Lorenzo

> 
> 
>     There is also the problem with usb devices that the latency changes
>     every
>     time the audio device is opened by software.
> 
> 
> Apparently now fixed (or certainly much better) in recent kernels.
> 
> 
>     The computer audio world lost when the audio device manufactures jumped
>     from firewire to usb. Maybe (but don't hold your breath) something will
>     change in the future. Or look for a PCIe based audio device like the
>     audioscience cards.
> 
> 
> thunderbird (aka "PCI.? bus on a cable") is presumably the right answer.
> 
> but that's just a reminder that the proximal issue here is "what 
> connections does my laptop provide?"
> 
> 
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