anchor.diff:      (enableFeature (libbs2b != null) "libbs2b")
       #(enableFeature (libcaca != null) "libcaca")
       #(enableFeature (cdio-paranoia != null && gplLicensing) "libcdio")
  -    (enableFeature (if isLinux then libdc1394 != null && libraw1394 != null else false) "libdc1394")
  +    (enableFeature (libdc1394 != null && libraw1394 != null) "libdc1394")
       (enableFeature (libiconv != null) "iconv")
  -    #(enableFeature (if isLinux then libiec61883 != null && libavc1394 != null && libraw1394 != null else false) "libiec61883")
  +    #(enableFeature (libiec61883 != null && libavc1394 != null && libraw1394 != null) "libiec61883")
       #(enableFeature (libmfx != null) "libmfx")
       (enableFeature (libmodplug != null) "libmodplug")
       #(enableFeature (libnut != null) "libnut")
       (enableFeature (libopus != null) "libopus")
       (enableFeature (libssh != null) "libssh")
       (enableFeature (libtheora != null) "libtheora")
  -    (enableFeature (if isLinux then libv4l != null else false) "libv4l2")
  -    (enableFeature ((isLinux || isFreeBSD) && libva != null) "vaapi")
  +    (enableFeature (libv4l != null) "libv4l2")
  +    (enableFeature (libva != null) "vaapi")
       (enableFeature (libvdpau != null) "vdpau")
       (enableFeature (libvorbis != null) "libvorbis")
       (enableFeature (libvpx != null) "libvpx")
       (enableFeature (libwebp != null) "libwebp")
  -    (enableFeature (libX11 != null && libXv != null) "xlib")
  -    (enableFeature (libxcb != null) "libxcb")
  +    (enableFeature (xorg.libX11 != null && xorg.libXv != null) "xlib")
  +    (enableFeature (xorg.libxcb != null) "libxcb")
       (enableFeature libxcbshmExtlib "libxcb-shm")
       (enableFeature libxcbxfixesExtlib "libxcb-xfixes")
       (enableFeature libxcbshapeExtlib "libxcb-shape")
  
positive.code:  *   aacplus avisynth cdio-paranoia crystalhd libavc1394 libiec61883
   *   libmxf libnut libquvi nvenc opencl opencore-amr openh264 oss shine twolame
   *   utvideo vo-aacenc vo-amrwbenc xvmc zvbi blackmagic-design-desktop-video
   *
   * Need fixes to support Darwin:
   *   frei0r, game-music-emu, gsm, libjack2, libssh, libvpx(stable 1.3.0), openal, openjpeg_1,
   *   pulseaudio, rtmpdump, samba, vid-stab, wavpack, x265. xavs
   *
   * Not supported:
   *   stagefright-h264(android only)
  
negative.code: , libvorbis ? null # Vorbis de/encoding, native encoder exists
  , libvpx ? null # VP8 & VP9 de/encoding
  , libwebp ? null # WebP encoder
  , xorg ? null
  , libxcbshmExtlib ? true # X11 grabbing shm communication
  , libxcbxfixesExtlib ? true # X11 grabbing mouse rendering
  , libxcbshapeExtlib ? true # X11 grabbing shape rendering
  , lzma ? null # xz-utils
  #, nvenc ? null # NVIDIA NVENC support
  , openal ? null # OpenAL 1.1 capture support
  