Quick workaround for current setups:

  systemd.services.jack.serviceConfig.SupplementaryGroups = [ "users" ];
  systemd.user.services.pulseaudio.environment.JACK_PROMISCUOUS_SERVER = "jackaudio";
  # sample jackd config
  services.jack = {
    jackd = {
      enable = true;
      # to force another sound card
      # extraOptions = [ "-dalsa" "-dhw:Solo" "-r44100" "-p1024" "-n2" ];
    };
  };

Rebuild + re-login and manually issue

pactl load-module module-jack-sink
pactl load-module module-jack-source

I have these errors in systemctl --user status pulseaudio

июл 19 07:27:27 nixos pulseaudio[1179]: E: [pulseaudio] ltdl-bind-now.c: Не удалось открыть модуль module-jack-sink.so: module-jack-sink.so: cannot open shared object file: No such file or directory
июл 19 07:27:27 nixos pulseaudio[1179]: E: [pulseaudio] module.c: Failed to open module "module-jack-sink".
июл 19 07:27:27 nixos pulseaudio[1179]: E: [pulseaudio] ltdl-bind-now.c: Не удалось открыть модуль module-jack-source.so: module-jack-source.so: cannot open shared object file: No such file or directory
июл 19 07:27:27 nixos pulseaudio[1179]: E: [pulseaudio] module.c: Failed to open module "module-jack-source".

@gnidorah do you have pulseaudioFull installed?

@asheshambasta

@gnidorah do you have pulseaudioFull installed?

Like environment.systemPackages = with pkgs; [ pulseaudioFull ];?
It doesn't help

@asheshambasta

@gnidorah do you have pulseaudioFull installed?

Like environment.systemPackages = with pkgs; [ pulseaudioFull ];?
It doesn't help

Good catch! Like this:

  hardware.pulseaudio = {
    package = pkgs.pulseaudioFull;
  };

Now I wonder if the package should default to pulseaudioFull when jack is enabled.

I've managed to get this working with 20.03 VM with user and groups like so

  users.users.jane = {
    isNormalUser = true;
    extraGroups = [ "wheel" "audio" "jackaudio" ];
  };

Most of the VM config:

  environment.systemPackages = with pkgs; [
    wget vim
    jack2Full
    qjackctl
    (mpv.override { jackaudioSupport = true; })
    pavucontrol
  ];

  sound.enable = true;
  hardware.pulseaudio = {
    enable = true;
    package = pkgs.pulseaudioFull;
  };

  services.jack.jackd = {
    enable = true;
    # extraOptions = [ "-dalsa" "-dhw:S3" "-r44100" "-p1024" "-n2" ];
  };

  services.xserver.enable = true;
  services.xserver.displayManager.sddm.enable = true;
  services.xserver.desktopManager.plasma5.enable = true;

  # Define a user account. Don't forget to set a password with ‘passwd’.
  users.users.jane = {
    isNormalUser = true;
    extraGroups = [ "wheel" "audio" "jackaudio" ]; # Enable ‘sudo’ for the user.
  };

Env vars might cause trouble if you don't reboot or log-out and log-in again.

@sorki

This fixes the case when Jack Audio Daemon is running
as a service via services.jack.jackd and Pulseaudio
running as a user service.

Ok, I've added the following configuration rebooted and sound works for me without this PR

  services.jack.jackd.enable = true;
  users.extraUsers.gnidorah.extraGroups = [ "jackaudio" ];
  hardware.pulseaudio.enable = true;
  hardware.pulseaudio.systemWide = false;

Could you please provide a case when this PR is needed? Which programs to use for test etc?

Could you please provide a case when this PR is needed? Which programs to use for test etc?

Use case for this is running pulseaudio as a client for jackd, you can verify that the audio is routed thru pulse -> jack with pavucontrol - check if there's Jack sink in Output devices tab.

Good program for testing both servers is mpv, with this setup you should be able to play audio with both mpv -ao jack and mpv -ao pulse.

Also check that the jackd hooks the correct soundcard via systemctl status jack.

Fixed the issues with default package:

The default pulse package is now set to pulseaudioFull automatically
if services.jack.jackd.enable is set.

@sorki This PR is waiting for a long time. Perhaps we should ask someone to merge it?

@worldofpeace do you think you can take a look? I think this was tested by few people and I'm using it with no issues for months now. The change is quite unobtrusive and only makes setup easier for jackd users.

Yeah, I've thought that it should do this for a while anyways.

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/nixos-and-linux-pro-audio/1788/15