anchor.diff:    useFdk ? false, fdk_aac ? null
   }:
   
  -assert stdenv.isDarwin -> AudioToolbox != null
  -       && Foundation != null
  -       && libobjc != null
  -       && VideoToolbox != null;
  -
   stdenv.mkDerivation rec {
     pname = "handbrake";
     version = "1.3.3";
  
positive.code:     ffmpeg-full libogg libtheora x264 x265 libvpx dav1d
      libopus lame libvorbis a52dec speex libsamplerate
      libiconv fribidi fontconfig freetype libass jansson libxml2 harfbuzz
      libdvdread libdvdnav libdvdcss libbluray lzma numactl
    ] ++ lib.optionals useGtk [
      glib gtk3 libappindicator-gtk3 libnotify
      gst_all_1.gstreamer gst_all_1.gst-plugins-base dbus-glib udev
      libgudev hicolor-icon-theme
  
negative.code: # Upstream distributes HandBrake with bundle of according versions of libraries
  # and patches to them. This derivation patches HandBrake to use Nix closure
  # dependencies.
  #
  # NOTE: 2019-07-19: This derivation does not currently support the native macOS
  # GUI--it produces the "HandbrakeCLI" CLI version only. In the future it would
  