anchor.diff:      ++ stdenv.lib.optional xvidSupport "--enable-libxvid"
       ++ stdenv.lib.optional vdpauSupport "--enable-vdpau"
       ++ stdenv.lib.optional faacSupport "--enable-libfaac --enable-nonfree"
  -    ++ stdenv.lib.optional dc1394Support "--enable-libdc1394";
  +    ++ stdenv.lib.optional dc1394Support "--enable-libdc1394"
  +    ++ stdenv.lib.optional x11grabSupport "--enable-x11grab";
   
     buildInputs = [ pkgconfig lame yasm zlib bzip2 ]
       ++ stdenv.lib.optional mp3Support lame
  
positive.code: , vdpauSupport ? true, libvdpau ? null
  , faacSupport ? false, faac ? null
  , dc1394Support ? false, libdc1394 ? null
  }:
  
  assert speexSupport -> speex != null;
  
negative.code: assert xvidSupport -> xvidcore != null;
  assert vdpauSupport -> libvdpau != null;
  assert faacSupport -> faac != null;
  assert x11grabSupport -> libXext != null && libXfixes != null;
  
  stdenv.mkDerivation rec {
    name = "ffmpeg-0.11.1";
  