anchor.diff:  , x265
   , libxml2
   , srt
  +, vo-aacenc
   }:
   
   assert faacSupport -> faac != null;
  
positive.code:     "-Dsvthevcenc=disabled" # required `SvtHevcEnc` library not packaged in nixpkgs as of writing
      "-Dteletext=disabled" # required `zvbi` library not packaged in nixpkgs as of writing
      "-Dtinyalsa=disabled" # not packaged in nixpkgs as of writing
      "-Dvoaacenc=disabled" # required `vo-aacenc` library not packaged in nixpkgs as of writing
      "-Dvoamrwbenc=disabled" # required `vo-amrwbenc` library not packaged in nixpkgs as of writing
      "-Dvulkan=disabled" # Linux-only, and we haven't figured out yet which of the vulkan nixpkgs it needs
      "-Dwasapi=disabled" # not packaged in nixpkgs as of writing / no Windows support
  
negative.code: { lib, stdenv
  , fetchurl
  , meson
  , ninja
  , gettext
  , pkg-config
  , python3
  , gst-plugins-base
  