{
  "sample": "sample_01",
  "task": "General skilled trades",
  "recorded_date": "2026-09-28",
  "country": "BR",
  "activity": "Masonry finishing (applying mortar to a brick barbecue), residential setting",
  "duration_s": 615.59,
  "capture": {
    "device": "Apple iPhone 14",
    "lens": "ultra-wide",
    "mount": "head-mounted, first-person view",
    "fov_deg": {
      "horizontal": 105.2,
      "diagonal": 117.1
    }
  },
  "video": {
    "file": "sample_01_video.mp4",
    "container": "mp4",
    "codec": "HEVC 8-bit, SDR (BT.709)",
    "resolution": "1920x1440 (4:3)",
    "fps": 30,
    "keyframe_interval_s": 1,
    "audio": "AAC",
    "frames": 18466,
    "notes": "Straight from the encoder, stream-copied into mp4, never re-encoded. No location or author metadata."
  },
  "imu": {
    "file": "sample_01_imu.csv",
    "rate_hz": 100,
    "columns": "timestamp,ax,ay,az,gx,gy,gz",
    "timestamp": "int64 microseconds from video frame 0 (a few rows before 0 and after the end are kept)",
    "accel": "m/s^2, gravity included, reads +9.81 on the up axis at rest",
    "gyro": "rad/s",
    "axes_in_image_frame": "+X = image down, +Y = image right, +Z = backward (opposite the lens)"
  },
  "frames": {
    "file": "sample_01_frames.csv",
    "columns": "frame_index,timestamp_us",
    "clock": "same clock as the IMU timestamps, one row per video frame"
  }
}