JACK and PulseAudio multiple sinks

Question

I successfully configured PulseAudio to run ontop of JACK by following this surprisingly easy description.

Now I wonder if there is a way (at first I was certain of it) to have multiple sinks between JACK and PulseAudio, for example to record two PulseAudio applications seperately at once. I tried for example changing load-module module-jackdbus-detect channels=2 in /etc/pulse/default.pa to 4 channels - but then PulseAudio won't even start.

Also, I'd really like to use this feature to reduce the volume of the JACK output before playback because I don't want to blow my ears. I also thought of creating virtual streams in PulseAudio and I may try to figure that out next, though I don't know wether I will find use for it. If I have had an idea, I already forgot. ;-) Tell me if you know already.

[EDIT]

Also think about my related question about JACK Audio muting Speakers but not playing through Headphones, please!

Solution

Multiple pulseaudio sinks/sources are available from pulseaudio v6.0 and later. As Ubuntu uses it's own version numbering, check true version number with:

  pulseaudio --version

Extra sinks/sources can be loaded by terminal command, or using QJackCtl Option 'Execute script after Startup' commands or bash script

pactl load-module module-jack-sink client_name=pulse_sink_2 connect=yes
pactl load-module module-jack-source client_name=pulse_source_2 connect=no

without client_name option additional sinks/sources have number suffix 01, 02 etc

connect option (default is yes) using no stops connection to JACK system capture/playback

There is also a channels option (default 'channels=2')

Comments

[Peter Nerlich]

As my question is not too recent anymore I won't try your suggestion immediately, but even if I forget to, let me say that I really appreciate this! I'll probably run into this problem again in the future anyway.

[Peter Nerlich]

WTF, stumbled over my own question again without realizing it. I'm now on Elementary OS 0.4 Loki, pulse audio version here is pulseaudio 8.0. I tried your two commands and — it works! Thank's for this, even if it's been half a year since then!

[Peter Nerlich]

Ah, yes, this is still here as well. Seems like I am returning to this every year or so from now on. I plan on playing around with Arch in the following month, so I'll need this once more. My annual greetings to you and the future me as well!

[Mark Fisher]

this is awesome. It allowed me to create multiple jack aware sinks/sources so I can route my applications through them and have individual effects in jack applied to each. For cadence users, I was able to incorporate this into /usr/share/cadence/pulse2jack/play+rec.pa and automatically create the pulse-jack sink/sources on startup.

[matanster]

Does this approach allow materializing this scenario just as well?