anchor.diff:   *
    * Not packaged:
    *   aacplus avisynth cdio-paranoia crystalhd libavc1394 libiec61883
  - *   libmxf libnut libquvi nvenc opencl opencore-amr openh264 oss shine twolame
  + *   libmxf libnut libquvi opencl opencore-amr openh264 oss shine twolame
    *   utvideo vo-aacenc vo-amrwbenc xvmc zvbi blackmagic-design-desktop-video
    *
    * Not supported:
  
positive.code: assert libxcbshmExtlib -> xorg.libxcb != null;
  assert libxcbxfixesExtlib -> xorg.libxcb != null;
  assert libxcbshapeExtlib -> xorg.libxcb != null;
  assert openglExtlib -> mesa != null;
  assert opensslExtlib -> gnutls == null && openssl != null && nonfreeLicensing;
  assert x11grabExtlib -> xorg.libX11 != null && xorg.libXv != null;
  
negative.code: , libxcbxfixesExtlib ? true # X11 grabbing mouse rendering
  , libxcbshapeExtlib ? true # X11 grabbing shape rendering
  , lzma ? null # xz-utils
  , nvenc ? false # NVIDIA NVENC support
    , nvidia-video-codec-sdk ? null
  , openal ? null # OpenAL 1.1 capture support
  #, opencl ? null # OpenCL code
  #, opencore-amr ? null # AMR-NB de/encoder & AMR-WB decoder
  