anchor.diff:      ++ optional bluraySupport      libbluray
       ++ optional jackaudioSupport   libjack2
       ++ optional pulseSupport       libpulseaudio
  -    ++ optional stdenv.isDarwin    libiconv
  -    ++ optionals stdenv.isDarwin (with darwin.apple_sdk.frameworks; [
  -       Cocoa CoreAudio ])
       ++ optional rubberbandSupport  rubberband
       ++ optional screenSaverSupport libXScrnSaver
       ++ optional vdpauSupport       libvdpau
  
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:   buildInputs = [
      ffmpeg_3_2 freetype libass libpthreadstubs
      lua lua5_sockets libuchardet
    ] ++ optionals stdenv.isDarwin (with darwin.apple_sdk.frameworks; [
         libiconv Cocoa CoreAudio ])
      ++ optional alsaSupport        alsaLib
      ++ optional xvSupport          libXv
      ++ optional theoraSupport      libtheora
      ++ optional xineramaSupport    libXinerama
  