anchor.diff:   */
   
   let
  -  inherit (stdenv) isCygwin isDarwin isFreeBSD isLinux;
  +  inherit (stdenv) isCygwin isDarwin isFreeBSD isLinux isAarch64;
     inherit (stdenv.lib) optional optionals optionalString enableFeature;
   in
   
  
positive.code:  *   libvpx(stable 1.3.0) openal openjpeg pulseaudio rtmpdump samba vid-stab
   *   wavpack x265 xavs
   *
   * Not supported:
   *   stagefright-h264(android only)
   *
  
negative.code:     (enableFeature (if isLinux then libdc1394 != null && libraw1394 != null else false) "libdc1394")
      (enableFeature (libiconv != null) "iconv")
      #(enableFeature (if isLinux then libiec61883 != null && libavc1394 != null && libraw1394 != null else false) "libiec61883")
      (enableFeature (if isLinux && !isAarch64 then libmfx != null else false) "libmfx")
      (enableFeature (libmodplug != null) "libmodplug")
      (enableFeature (libmysofa != null) "libmysofa")
      #(enableFeature (libnut != null) "libnut")
  