anchor.diff:  , libusb ? null, usbSupport ? false
   , samba ? null, sambaSupport ? true
   # TODO: would be nice to have nfsSupport (needs libnfs library)
  +# TODO: librtmp
   , libvdpau ? null, vdpauSupport ? true
  +, pulseaudio ? null, pulseSupport ? false
   }:
   
   assert dbusSupport  -> dbus_libs != null;
  
positive.code: { stdenv, lib, fetchurl, makeWrapper
  , pkgconfig, cmake, gnumake, yasm, python
  , boost
  , gettext, pcre, yajl, fribidi
  , openssl, gperf, tinyxml2, taglib, libssh, swig, jre
  , libX11, xproto, inputproto
  
negative.code:       ffmpeg libmpeg2 libsamplerate libmad
        libogg libvorbis flac
        lzo libcdio libmodplug libass
        sqlite mysql nasm avahi libdvdcss lame
        curl bzip2 zip unzip glxinfo xdpyinfo
      ]
      ++ lib.optional dbusSupport dbus_libs
      ++ lib.optional udevSupport udev
      ++ lib.optional usbSupport libusb
      ++ lib.optional sambaSupport samba
      ++ lib.optional vdpauSupport libvdpau
      ++ lib.optional pulseSupport pulseaudio;
  
      dontUseCmakeConfigure = true;
  
  