{
  "video_id": "sample.mp4",
  "description": "Surveillance video with activity labels",
  "activities": [
    {
      "id": 1,
      "type": "walking",
      "start_time": 0.0,
      "end_time": 5.2,
      "person_id": 1,
      "bbox": [100, 150, 200, 300]
    },
    {
      "id": 2,
      "type": "standing",
      "start_time": 5.2,
      "end_time": 8.5,
      "person_id": 1,
      "bbox": [150, 140, 250, 290]
    },
    {
      "id": 3,
      "type": "walking",
      "start_time": 8.5,
      "end_time": 12.0,
      "person_id": 2,
      "bbox": [300, 200, 400, 350]
    }
  ]
}