anchor.diff:      ++ stdenv.lib.optional faacSupport faac
       ++ stdenv.lib.optional dc1394Support libdc1394
       ++ stdenv.lib.optionals x11grabSupport [ libXext libXfixes ]
  -    ++ stdenv.lib.optional playSupport SDL;
  +    ++ stdenv.lib.optional playSupport SDL
  +    ++ stdenv.lib.optional freetypeSupport freetype;
   
     enableParallelBuilding = true;
   
  
positive.code: , dc1394Support ? false, libdc1394 ? null
  , x11grabSupport ? false, libXext ? null, libXfixes ? null
  , playSupport ? true, SDL ? null
  }:
  
  assert speexSupport -> speex != null;
  
negative.code:     ++ stdenv.lib.optional faacSupport "--enable-libfaac --enable-nonfree"
      ++ stdenv.lib.optional dc1394Support "--enable-libdc1394"
      ++ stdenv.lib.optional x11grabSupport "--enable-x11grab"
      ++ stdenv.lib.optional playSupport "--enable-ffplay"
      ++ stdenv.lib.optional freetypeSupport "--enable-libfreetype";
  
    buildInputs = [ pkgconfig lame yasm zlib bzip2 alsaLib texinfo perl ]
      ++ stdenv.lib.optional mp3Support lame
  