anchor.diff:  
     buildInputs = [
       SDL2
  -    ffmpeg_3
  +    ffmpeg
       glew
       libzip
       qtbase
  
positive.code: { SDL2
  , cmake
  , fetchFromGitHub
  , ffmpeg_3
  , glew
  , lib
  , libzip
  , mkDerivation
  , pkg-config
  , python3
  , qtbase
  
negative.code:     repo = pname;
      rev = "v${version}";
      fetchSubmodules = true;
      sha256 = "sha256-vfp/vacIItlPP5dR7jzDT7oOUNFnjvvdR46yi79EJKU=";
    };
  
    postPatch = ''
  