anchor.diff:  { stdenv
  +, fetchgit
   , fetchurl
   , lib
  -, yasm
  +, nasm
   
   , enable10bit ? false
   }:
  +
  +# NOTE: the videolan autogenerated tarballs do not contain the latest sources.
   
   let
     version = "20170926";
  
positive.code:     "--disable-lsmash"
    ];
  
    meta = with lib; {
      description = "Library for encoding h.264/AVC video streams";
      homepage = https://www.videolan.org/developers/x264.html;
  
negative.code:   name = "x264-${version}";
  
    src = fetchurl {
      url = "http://x264.tar.xz";
      multihash = "QmfTkaU5QeiP5jc47RTB34sakdtHEHhAEznWUfo6qeUabX";
      sha256 = "04a61a93d53476fbd21fad6dcb1271ec2b80a1ece203f120414d4588d0867d87";
    };
  
    nativeBuildInputs = [
      nasm
    ];
  
    postPatch = ''
  