anchor.diff:      (enableFeature (fribidi != null) "libfribidi")
       (enableFeature (game-music-emu != null) "libgme")
       (enableFeature (gnutls != null) "gnutls")
  -    (enableFeature (gsm != null) "libgsm")
  +    #(enableFeature (gsm != null) "libgsm")
       #(enableFeature (ilbc != null) "libilbc")
       (enableFeature (ladspaH !=null) "ladspa")
       (enableFeature (lame != null) "libmp3lame")
  
positive.code: , optimizationsDeveloper ? true
  , extraWarningsDeveloper ? false
  , strippingDeveloper ? false
  }:
  
  /* Maintainer notes:
  
negative.code: 
  stdenv.mkDerivation rec {
    name = "ffmpeg-full-${version}";
  
    inherit (ffmpeg) src version;
  
    postPatch = ''
      patchShebangs .
      sed -i libavcodec/libvpxenc.c \
        -e '/VP8E_UPD_ENTROPY/d' \
        -e '/VP8E_USE_REFERENCE/d' \
        -e '/VP8E_UPD_REFERENCE/d' \
        -e '/VP8D_USE_REFERENCE/d'
    '';
  
    configureFlags = [
      /*
  