anchor.diff:  
     buildInputs = [
       a52dec
  -    amrnb
  -    amrwb
  +    #amrnb
  +    #amrwb
       glib
       gst-plugins-base
       gstreamer
  
positive.code:     libcdio
      libdvdread
      libmad
      mpeg2dec
      orc
      x264
    ];
  
negative.code: , libcdio
  , libdvdread
  , libmad
  , libmpeg2
  , orc
  , x264
  }:
  