https://gstreamer.freedesktop.org/documentation/additional/splitup.html

gst-plugins-ugly

A set of plug-ins that have good quality and correct functionality, but distributing them might pose problems. The license on either the plug-ins or the supporting libraries might not be how we'd like. The code might be widely known to present patent problems.

Distributors should check if they want/can ship these plug-ins
People writing elements should base their code on these elements

So should there be a condition depending on allowUnfree being true for adding ugly plugins?

I think that if the ugly plugins in nixpkgs are guarded allowUnfree then subtitleeditor should only depend on the ugly plugins if the allowUnfree= true.

That is probably the best we can do.

Right, I forgot to actually check how it is with ugly as nixpkg :) There is no guard currently: https://github.com/NixOS/nixpkgs/blob/nixos-unstable/pkgs/development/libraries/gstreamer/ugly/default.nix

Thanks for checking. I think this is a great addition.

This is my first time reviewing a PR on github.. do I need to do anything more to signal my blessings to this?

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

https://discourse.nixos.org/t/prs-ready-for-review/3032/427

I can see no reason not to have this. Let's land, thank you :)