{
  "nodes": [
    { "id": "ndiin",       "type": "ndiin",            "params": {} },
    { "id": "ndiout", "type": "ndiout",      "params": { "device_index": 0 } }
  ],
  "edges": [
    {
      "from": "ndiin",  "from_port": "video_flow_id",
      "to":   "ndiout",      "to_port":   "video_flow_id",
      "format": { "kind": "video", "width": 1920, "height": 1080, "fps_num": 25, "fps_den": 1 }
    }
  ]
}