Rubberband: How do I know what version I'm using or if it's installed?

I have a program called Mixxx in my NixOS drive, and it can use Soundtouch or Rubberband API.

I’m trying to figure out what version of Rubberband Mixxx uses, but I can’t seem to find it in terminal.
Is there an easy way to find out if I have Rubberband installed, or what version I’m using?

I don’t have it written in my NixOS config file. I could add it to systemPackages, but I’m not sure if Mixxx would be able to use and detect it unless I configure Mixxx in my conf file(?)

Rubberband is a dependency of Mixxx. See here. To check out what version was used, you could, for example, use nix-tree. Just run nix-tree $(which rubberband) and it should appear in the first level of dependencies.

When I input nix-tree $(which rubberband) , this is my output:

which: no rubberband in (/run/wrappers/bin:/home/nprevail/.local/share/flatpak/exports/bin:/var/lib/flatpak/exports/bin:/home/nprevail/.nix-profile/bin:/nix/profile/bin:/home/nprevail/.local/state/nix/profile/bin:/etc/profiles/per-user/nprevail/bin:/nix/var/nix/profiles/default/bin:/run/current-system/sw/bin)
The program 'nix-tree' is not in your PATH. It is provided by several packages.
You can make it available in an ephemeral shell by typing one of the following:
  nix-shell -p haskellPackages.nix-tree
  nix-shell -p nix-tree

My bad, I meant to write nix-tree $(which mixxx). You also seem to be lacking nix-tree in your system, so run nix shell nixpkgs#nix-tree before to temporarily load it in your shell.

You also seem to be lacking nix-tree in your system

Got it! I’ll try to installing it in my config file so all my other desktops can have it installed too.

Edit: It worked. Thank you!