[LAU] Realtime issues with USB-device

[Mitsch]

Am Dienstag, dem 29.03.2022 um 02:02 +0200 schrieb David Kastrup:
> Which sample rate, which period size and count? 

Well, as I'm using pipewire period size is translated with quantum,
right?
pw-top says 2048, which is really big…
And it is something between 3x2⁹ and 3x2¹⁰
Surprisingly, now, that I'm at home, audio sounds okay with realtime
kernel. 🙄️ I bet, I' gonna have problems when I'm at work, again.

>  Personally I have found
> that using a period size of the form 3*2^n rather than 2^n can
> surprisingly improve results at 48kHz or 96kHz of sampling frequency,
> likely due to the timer interval becoming better expressible in terms
> of
> system ticks and/or milliseconds.
> 
> That can lead to a period size of 256 being problematic and a size of
> 48
> samples working fine, depending on the device and drivers in
> question.

I knew that trick when using jackd but I just can't find a
pipewire.conf file to edit on my system (like it is written in
https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/Config-PipeWire#setting-buffer-size
).
Yeah, the buffer setting could probably be a clue…

Greets!
Mitsch