anchor.diff:  { stdenv, fetchFromGitHub, pkgconfig, autoconf, automake
  -, ruby, file, xdg_utils, gettext, expat, qt5, boost
  +, drake, ruby, file, xdg_utils, gettext, expat, qt5, boost
   , libebml, zlib, libmatroska, libogg, libvorbis, flac
   , withGUI ? true
   }:
  
positive.code:   ] ++ optional withGUI qt5.qtbase;
  
    preConfigure = "./autogen.sh; patchShebangs .";
    buildPhase   = "./drake -j $NIX_BUILD_CORES";
    installPhase = "./drake install -j $NIX_BUILD_CORES";
  
    configureFlags = [
      "--enable-magic"
  
negative.code: 
  stdenv.mkDerivation rec {
    name = "mkvtoolnix-${version}";
    version = "9.8.0";
  
    src = fetchFromGitHub {
      owner = "mbunkus";
      repo = "mkvtoolnix";
      rev = "release-${version}";
      sha256 = "1hnk92ksgg290q4kwdl8jqrz7vzlwki4f85bb6kgdgzpjkblw76n";
    };
  
    nativeBuildInputs = [ pkgconfig autoconf automake gettext drake ruby ];
  
    buildInputs = [
      expat file xdg_utils boost libebml zlib libmatroska libogg
  