anchor.diff:      (enableFeature ((isLinux || isFreeBSD) && libva != null) "vaapi")
       (enableFeature (libvdpau != null) "vdpau")
       (enableFeature (libvorbis != null) "libvorbis")
  +    (enableFeature (libvmaf != null && version3Licensing) "libvmaf")
       (enableFeature (libvpx != null) "libvpx")
       (enableFeature (libwebp != null) "libwebp")
       (enableFeature (libX11 != null && libXv != null && libXext != null) "xlib")
  
positive.code:  *  Licensing options (yes some are listed twice, filters and such are not listed)
   */
  , gplLicensing ? true # GPL: fdkaac,openssl,frei0r,cdio,samba,utvideo,vidstab,x265,x265,xavs,avid,zvbi,x11grab
  , version3Licensing ? true # (L)GPL3: opencore-amrnb,opencore-amrwb,samba,vo-aacenc,vo-amrwbenc
  , nonfreeLicensing ? false # NONFREE: openssl,fdkaac,blackmagic-design-desktop-video
  /*
   *  Build options
  
negative.code: , libv4l ? null # Video 4 Linux support
  , libva ? null # Vaapi hardware acceleration
  , libvdpau ? null # Vdpau hardware acceleration
  , libvmaf ? null # Netflix's VMAF (Video Multi-Method Assessment Fusion)
  , libvorbis ? null # Vorbis de/encoding, native encoder exists
  , libvpx ? null # VP8 & VP9 de/encoding
  , libwebp ? null # WebP encoder
  