On Fri, May 21, 2021 at 3:50 PM Georges Basile Stavracas Neto georges.stavracas@gmail.com wrote:
Greetings ALSA community,
Hey, Georges!
I recently acquired a Motu M4 interface, and seems to be working well so far. Everyday usage is completely functional.
However, I noticed an odd sound artifact that happens from time to time when using DAWs like Ardour and Waveform11. It's a windy, ghostly sound that happens whenever I open any DAWs (the simple act of opening them triggers this). Interestingly, audio apps that use PulseAudio do not suffer from this issue. It's hard to describe it, so I recorded a video reproducing this problem:
A few things I've discovered while trying to understand what's going on:
- It only happens with apps that use JACK or ALSA APIs. Using PulseAudio (through PipeWire) does not trigger it.
I assume you are using PipeWire for JACK support and using "pw-jack ardour" for example to start Ardour.
Could you stop PipeWire with "systemctl --user stop pipewire.service pipewire.socket pipewire-media-session.service pipewire-pulse.service pipewire-pulse.socket" and try to reproduce your issue using the aplay/arecord commands?
Does the dmesg show anything unusual? Perhaps you should enable the kernel boot option "snd_usb_audio.dyndbg=+p"
Seems like this sound is not an artifact of the interface; it appears that this odd sound is sent to the interface through USB. (You can see this in the video.)
It's triggered per track; in the video, for example, the drums and keyboard tracks are affected independetly.
I was oriented in #alsa at Freenode that the output of 'alsa-info' might be helpful, so here it is:
http://alsa-project.org/db/?f=62f686710cc6c9344a8986707bf3d09248c514d1
(I'm running this on top of a 5.12.5 kernel, which should include this fix: https://bugzilla.kernel.org/show_bug.cgi?id=207023)
I'd like to know where should I report this bug (kernel bugzilla?), and if there's any other information I can provide to help fixing it.
Bugzilla definitely is the way to go.
You may need to recompile your kernel with suggested patch changes over and over again.
With respect, Georges