anchor.diff:  
     buildInputs = [
       gst-plugins-base orc
  -    faad2 libass libkate libmms
  +    faad2 gtk3 libass libkate libmms
       libmodplug mpeg2dec mpg123
       openjpeg libopus librsvg
       fluidsynth libvdpau
  
positive.code: }:
  
  assert faacSupport -> faac != null;
  
  let
    inherit (stdenv.lib) optional optionalString;
  
negative.code: { stdenv, fetchurl, pkgconfig, python, gst-plugins-base, orc
  , faacSupport ? false, faac ? null
  , gtkSupport ? false, gtk3 ? null
  , faad2, libass, libkate, libmms
  , libmodplug, mpeg2dec, mpg123
  , openjpeg, libopus, librsvg
  