anchor.diff:  , fetchurl
   , intltool
   , pkgconfig
  -, gtk3
   , portaudio
   , SDL2
   , ffmpeg
  
positive.code:   nativeBuildInputs = [
      intltool
      pkgconfig
      wrapGAppsHook
    ];
  
    buildInputs = [
      SDL2
      alsaLib
      ffmpeg
      gtk3
      libusb1
      libv4l
      portaudio
      udev
      gsl
    ] ++ stdenv.lib.optional pulseaudioSupport libpulseaudio;
  
    meta = with stdenv.lib; {
      description = "A simple interface for devices supported by the linux UVC driver";
  
negative.code: , libv4l
  , alsaLib
  , gsl
  , libpng
  , sfml
  , pulseaudioSupport ? config.pulseaudio or stdenv.isLinux
  , libpulseaudio ? null
  , useQt ? false
  , qt5 ? null
  , wrapQtAppsHook ? null
  # can be turned off if used as a library
  , useGtk ? true
  , gtk3 ? null
  , wrapGAppsHook ? null
  }:
  
  assert pulseaudioSupport -> libpulseaudio != null;
  