[LAU] Connect pipewire to running JACK server

[Len Ovens]

On Fri, 28 Jan 2022, ycollette.nospam at free.fr wrote:

> I now that there is a big problem of JACK playback with RT kernels 5.15 and 5.16 ...

JACK and Pipewire use ALSA to talk to the audio device. JACK is capable of 
stable operation at least to 16/2 _IF_ the hardware (both audio device and 
the computer) are capable of it.

> Maybe this card is not yet supported too by pipewire ...

As above, if the device shows up in ALSA, it is already "supported". 
However, as a USB device it is competing with all other USB devices and 
newer kernels do not show interrupt processes as usb1, 2, 4, etc. In fact, 
they tend to group all usb 1.1 and usb 2.0 to one usb port anyway. As 
such, the only way to have a separate irq or irq process to prioritize, is 
to install a separate PCIe USB card just for that audio device (good luck 
with a laptop). The irq for that usb card can then be prioritized.

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.

There is also the problem with usb devices that the latency changes every 
time the audio device is opened by software.

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.


--
Len Ovens
www.ovenwerks.net