{
  "disc_number": {
    "old": "4"
  },
  "disc_title": {
    "new": "Disk 4"
  },
  "legacy": {
    "cdtext_performer": {
      "new": "Portal 2"
    },
    "cdtext_title": {
      "new": "Portal 2 Volume 4"
    },
    "track_performer": {
      "new": "Portal 2"
    },
    "track_title": {
      "new": "Still Alive (J.C. Mix)"
    }
  }
}