anchor.diff:  
     sourceRoot = "source/src";
   
  -  nativeBuildInputs = [ pkg-config cmake ];
  +  nativeBuildInputs = [ pkg-config cmake makeWrapper ];
   
  -  buildInputs = [ glew glfw3 leptonica tesseract3 zlib ] ++ lib.optional (!stdenv.isLinux) libiconv;
  +  buildInputs = [ zlib ]
  +    ++ lib.optional (!stdenv.isLinux) libiconv
  +    ++ lib.optionals enableOcr [ leptonica tesseract4 ffmpeg ];
   
  -  meta = {
  +  cmakeFlags = lib.optionals enableOcr [ "-DWITH_OCR=on" "-DWITH_HARDSUBX=on" ];
  +
  +  postInstall = lib.optionalString enableOcr ''
  +    wrapProgram "$out/bin/ccextractor" \
  +      --set TESSDATA_PREFIX "${tesseract4}/share/"
  +  '';
  +
  +  meta = with lib; {
       homepage = "https://www.ccextractor.org";
       description = "Tool that produces subtitles from closed caption data in videos";
       longDescription = ''
  
positive.code: { lib, stdenv, fetchFromGitHub, pkg-config, cmake
  , glew, glfw3, leptonica, libiconv, tesseract3, zlib }:
  
  with lib;
  stdenv.mkDerivation rec {
    pname = "ccextractor";
    version = "0.91";
  
negative.code:       It works on Linux, Windows, and OSX.
      '';
      platforms = platforms.unix;
      # undefined reference to `png_do_expand_palette_rgba8_neon'
      # undefined reference to `png_riffle_palette_neon'
      # undefined reference to `png_do_expand_palette_rgb8_neon'
      # undefined reference to `png_init_filter_functions_neon'
      # during Linking C executable ccextractor
      broken = stdenv.isAarch64;
      license = licenses.gpl2Only;
      maintainers = with maintainers; [ titanous ];
    };
  }
  