anchor.diff:      "--enable-nls"
       "--enable-rpath"
       "--disable-fatal-warnings"
  +    "--disable-extra-checks"
       "--disable-debug"
       "--disable-profiling"
       "--disable-valgrind"
  
positive.code: };
  
  stdenv.mkDerivation rec {
    name = "gst-plugins-ugly-1.6.3";
  
    src = fetchurl {
      url = "http://gstreamer.freedesktop.org/src/gst-plugins-ugly/${name}.tar.xz";
      sha256 = "0r6h3ys5n90jv3c06crxzcac561z07s4h04hy5i8ybw8qyvzgv1g";
    };
  
    nativeBuildInputs = [
  
negative.code:     (enFlag "lame" (lame != null) null)
      (enFlag "mad" (libmad != null) null)
      (enFlag "mpeg2dec" (libmpeg2 != null) null)
      (enFlag "mpg123" (mpg123 != null) null)
      #(enFlag "sidplay" (sidplay != null) null)
      #(enFlag "twolame" (twolame != null) null)
      (enFlag "x264" (x264 != null) null)
  