PulseAudio loopback module gets unexpected latency upon launching Iriun Webcam or DroidCam


I’m running PulseAudio:

Server Name: pulseaudio
Server Version: 17.0

I redirect my microphone’s audio to the default output:

pactl load-module module-loopback latency_msec=1

Now I hear myself without noticeable latency.

When I launch (even without connecting, which can be done though) either Iriun Webcam (iriunwebcam-bin) or DroidCam (droidcam-obs-plugin) the loopback latency clearly spikes to 200-300 ms and speaking becomes problematic as I start to interrupt myself.

The latency is gone only after a reboot, that is reloading the loopback module or closing a webcam application doesn’t put the latency back to normal.

If I connect a USB webcam and use it in Discord or in OBS via V4L2 video capture I don’t experience any loopback latency ever.

I have all the kernel headers installed.

Would like to receive help. Thanks!


welcome to Manjaro forum @desmitry

The documentation for module-loopback advises for latency_msec option:

The desired latency in milliseconds, from 1 to 2000. Defaults to 200. (Note that this is only a friendly request, the actual latency might be higher or lower than this value)

If the module cannot deliver 1 ms latency for USB webcam it is probably using the default 200 ms instead
I used to use module-loopback with Skype and the best consistent latency I could get for this module was 10-15 ms, with a modified and minimised PulseAudio configuration
For PulseAudio + USB webcam + Discord or OBS, 10-20 ms latency is more likely to achieve consistent results
If latency is below 20 ms there is no audible echo, but there is a phaser effect - sound is ‘hollow’ or ‘metallic’

Upgrading audio hardware to have zero-latency monitoring would be the optimal solution
But if that is not an option (and phaser effect is not annoying)
Use Discord in JACK and add a JACK source in OBS to share audio source with Discord
Or add webcam as an ALSA source for OBS only


I apologize, I thought the hardware is shown in my profile.

CPU: i5-12400
GPU: GTX 1650
Kernel: 6.6.19-1-MANJARO
Desktop: GNOME 45.4

I’ve checked again and the latency in question is actually around 50 ms no matter what I put in latency_msec. I guess that’s the lowest possible latency on an OS level.

Thank you for your answers! I’ll just buy a sound card.

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