A way to mute sound card output in JACK?

[ThatJackElliott]

Hi, I am running Ubuntu Studio 22.04. Pulseaudio is disabled, my input and output device is a USB audio interface, a Presonus Studio 24c.

I need a way to briefly mute the playback card, from within Jack or something, and on a set schedule. Alsamixer shows that this card has no controls so I can't do something simple like have cron issue an ALSA command to mute/unmute the card.

Maybe there is something clever that could be done from within Jack, but I don't see it offhand. Does anyone know of a way to do this? Thank you!

[Impostor]

Hi, I am running Ubuntu Studio 22.04. Pulseaudio is disabled, my input and output device is a USB audio interface, a Presonus Studio 24c.

I need a way to briefly mute the playback card, from within Jack or something, and on a set schedule. Alsamixer shows that this card has no controls so I can't do something simple like have cron issue an ALSA command to mute/unmute the card.

Maybe there is something clever that could be done from within Jack, but I don't see it offhand. Does anyone know of a way to do this? Thank you!

Maybe create two different qjackctl patchbays, one with severed connections to the soundcard, and write a script for on the fly switching between them?

qjackctl --active-patchbay=/path/to/patchbay-profile.xml

Or use jack-mixer which also seems to have some cli-control for muting channels with jack_mixer_cc.

[ThatJackElliott]

Thanks for the ideas!

I'm not running QjackCtl, but rather jackd right off the command line. Loading jack patchbay snapshots with aj-snapshot. Maybe there is a way I can load a snapshot that doesn't send audio to the output card, then reload the normal snapshot. That could be done by cron, the question is whether jackd would enforce the changes.

I clearly need to set up a development PC for these things, the running machine is now part of our radio station's air chain and I don't need to bork a live show by dinking around with stuff.

The jack-mixer thing, which looks to use jack-mixer-cli which looks to be a way to send mysterious (to me) MIDI Control Change messages looks complicated. Not seeing a whole lot examples on the 'net.

[oddy.o.lynx]

maybe non-mixer or if you have a build environment jack_mixer