Increased audio latency in Reaper

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I noticed recently that the audio latency reported by Reaper ran with PIPEWIRE_LATENCY=256/48000 reaper has increased to 15 ms on a system that was getting 5.3 ms latency just a couple weeks ago. Ardour still reports the latency as 5.3 ms but pw-profiler shows there being a 15ms audio driver delay, which seems to be what’s behind the increased delay.

I haven’t changed any configuration during that time and have just been installing updates normally. I’m using the default config for Pipewire. Any idea what might be behind this? I’ve searched Pipewire issues but nothing similar has come up. I’m using Plasma and there is no difference between X11 and Wayland. I did notice that the name of my audio interface (Focusrite Scarlett 2i2) also changing recently in GUIs, but not sure if that’s related.

Journalctl displays access denied errors for Pipewire/Wireplumber not being able make themselves realtime:

May 21 17:59:37 localhost.localdomain pipewire[3971]: mod.rt: RTKit error: org.freedesktop.DBus.Error.AccessDenied
May 21 17:59:37 localhost.localdomain pipewire[3971]: mod.rt: could not set nice-level to -11: Permission denied
May 21 17:59:37 localhost.localdomain wireplumber[3972]: RTKit error: org.freedesktop.DBus.Error.AccessDenied
May 21 17:59:37 localhost.localdomain wireplumber[3972]: could not set nice-level to -11: Permission denied
May 21 17:59:37 localhost.localdomain pipewire-pulse[3973]: mod.rt: RTKit error: org.freedesktop.DBus.Error.AccessDenied
May 21 17:59:37 localhost.localdomain pipewire-pulse[3973]: mod.rt: could not set nice-level to -11: Permission denied
May 21 17:59:37 localhost.localdomain wireplumber[3972]: RTKit error: org.freedesktop.DBus.Error.AccessDenied
May 21 17:59:37 localhost.localdomain wireplumber[3972]: could not make thread 3986 realtime using RTKit: Permission denied
May 21 17:59:37 localhost.localdomain pipewire-pulse[3973]: mod.rt: RTKit error: org.freedesktop.DBus.Error.AccessDenied
May 21 17:59:37 localhost.localdomain pipewire-pulse[3973]: mod.rt: could not make thread 3989 realtime using RTKit: Permission denied
May 21 17:59:37 localhost.localdomain pipewire[3971]: mod.rt: RTKit error: org.freedesktop.DBus.Error.AccessDenied
May 21 17:59:37 localhost.localdomain pipewire[3971]: mod.rt: could not make thread 3991 realtime using RTKit: Permission denied

PipeWire profiling
PipeWire profiling661×2806 147 KB

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In case someone else runs into this issue, it seems to have been caused by a change in ALSA. This Pipewire issue helped me restore the previous latency by creating a lua script with the contents from the PW issue that configures ALSA periods for Scarlett 2i2 into ~/.config/wireplumber/main.lua.d/ and switching the profile to Pro Audio. Now Reaper reports the latency as 5.3 ms, which is what it was before.

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