anchor.diff:  { stdenv
   , autoreconfHook
  -, fetchzip
  +, fetchFromGitHub
   , lib
   
   , ffmpeg
  
positive.code:     ffmpeg
      zlib
    ];
  
    configureFlags = [
      "--disable-debug"
  
negative.code: }:
  
  let
    version = "2017-11-21";
  in
  stdenv.mkDerivation rec {
    name = "ffms-${version}";
  
    src = fetchFromGitHub {
      version = 4;
      owner = "ffms";
      repo = "ffms2";
      rev = "c71cade921072bce46289635ed0780e5ce01beab";
      sha256 = "3cddcca60423fa7ba0b293e888632b541940ac63a4e14a3703acfa6f904aab77";
    };
  
    nativeBuildInputs = [
  