anchor.diff:      "--enable-avresample"
       "--enable-runtime-cpudetect"
     ]
  +    ++ stdenv.lib.optional subtitleSupport "--enable-libass"
       ++ stdenv.lib.optional mp3Support "--enable-libmp3lame"
       ++ stdenv.lib.optional speexSupport "--enable-libspeex"
       ++ stdenv.lib.optional theoraSupport "--enable-libtheora"
  
positive.code:     ++ stdenv.lib.optional gnutlsSupport "--enable-gnutls";
  
    buildInputs = [ pkgconfig lame yasm zlib bzip2 alsaLib texinfo perl ]
      ++ stdenv.lib.optional mp3Support lame
      ++ stdenv.lib.optional speexSupport speex
      ++ stdenv.lib.optional theoraSupport libtheora
  
negative.code: { stdenv, fetchurl, config, pkgconfig, yasm, zlib, bzip2, alsaLib, texinfo, perl
  , lame, speex, libass, libtheora, libvorbis, libvpx, x264, xvidcore, libopus
  , libvdpau, libva, faac, libdc1394, libXext, libXfixes, SDL
  , freetype, fontconfig, fdk_aac, gnutls
  }:
  