Ubuntu – JACK and PulseAudio multiple sinks

alsajackpulseaudiosound

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.

The JACK routing has only one stereo source and sink from and to PulseAudio

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!

Best Answer

  • 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')