anchor.diff:      "-Dwpe=disabled" # required `wpe-webkit` library not packaged in nixpkgs as of writing
       "-Dzxing=disabled" # required `zxing-cpp` library not packaged in nixpkgs as of writing
     ]
  +  ++ optionals (!stdenv.isLinux) [
  +    "-Dva=disabled" # see comment on `libva` in `buildInputs`
  +  ]
     ++ optionals stdenv.isDarwin [
       "-Dbluez=disabled"
       "-Dchromaprint=disabled"
  
positive.code:     "-Ddvb=disabled"
      "-Dfbdev=disabled"
      "-Duvch264=disabled" # requires gudev
      "-Dladspa=disabled" # requires lrdf
      "-Dwebrtc=disabled" # requires libnice, which as of writing doesn't work on Darwin in nixpkgs
      "-Dwildmidi=disabled" # see dependencies above
  
negative.code:     soundtouch
      srtp
      fluidsynth
      libvdpau
      libwebp
      xvidcore
  