anchor.diff:      "LIBREM_PATH=${librem}"
       ''PREFIX=$(out)''
       "USE_VIDEO=1"
  +    "CCACHE_DISABLE=1"
   
       "USE_ALSA=1" "USE_AMR=1" "USE_CAIRO=1" "USE_CELT=1" 
       "USE_CONS=1" "USE_EVDEV=1" "USE_FFMPEG=1"  "USE_GSM=1" "USE_GST=1" 
  
positive.code:     "USE_SPEEX_AEC=1" "USE_SPEEX_PP=1" "USE_SPEEX_RESAMP=1" "USE_SRTP=1" 
      "USE_STDIO=1" "USE_SYSLOG=1" "USE_UUID=1" "USE_V4L2=1" "USE_X11=1"
  
      "USE_BV32=" "USE_COREAUDIO=" "USE_G711=" "USE_G722=" "USE_G722_1=" 
      "USE_ILBC=" "USE_OPUS=" "USE_SILK=" 
    ]
    ++ stdenv.lib.optional (stdenv.cc.cc != null) "SYSROOT_ALT=${stdenv.cc.cc}"
  
negative.code: {stdenv, fetchurl, zlib, openssl, libre, librem, pkgconfig
  , cairo, mpg123, gstreamer, gst_ffmpeg, gst_plugins_base, gst_plugins_bad
  , gst_plugins_good, alsaLib, SDL, libv4l, celt, libsndfile, srtp, ffmpeg
  , gsm, speex, portaudio, spandsp, libuuid, ccache
  }:
  stdenv.mkDerivation rec {
    version = "0.4.20";
  