anchor.diff:    buildInputs = [
       ffmpeg_3_2 freetype libass libpthreadstubs
       lua lua5_sockets libuchardet
  -  ] ++ optional alsaSupport        alsaLib
  +  ] ++ optionals stdenv.isDarwin (with darwin.apple_sdk.frameworks; [
  +       libiconv Cocoa CoreAudio ])
  +    ++ optional alsaSupport        alsaLib
       ++ optional xvSupport          libXv
       ++ optional theoraSupport      libtheora
       ++ optional xineramaSupport    libXinerama
  
positive.code: , libpngSupport      ? true,  libpng        ? null
  , youtubeSupport     ? true,  youtube-dl    ? null
  , vaapiSupport       ? true,  libva         ? null
  , drmSupport         ? true,  libdrm        ? null
  , vapoursynthSupport ? false, vapoursynth   ? null
  , jackaudioSupport   ? false, libjack2      ? null
  
  
negative.code:     ++ optional bluraySupport      libbluray
      ++ optional jackaudioSupport   libjack2
      ++ optional pulseSupport       libpulseaudio
      ++ optional rubberbandSupport  rubberband
      ++ optional screenSaverSupport libXScrnSaver
      ++ optional vdpauSupport       libvdpau
  