# Pastebin 3I59QjBl
  boot = {
    # use with OBS and
    # ffmpeg -listen 1 -i rtmp://127.0.0.1:1935/live -f v4l2 -vf hflip -vcodec rawvideo /dev/video2
    kernelModules = [ "v4l2loopback" ];
    extraModulePackages = [ pkgs.linuxPackages.v4l2loopback ];
    extraModprobeConfig = ''
      options v4l2loopback devices=1 video_nr=2 card_label="RTMP server" exclusive_caps=1
    '';
  };