{
  "slug": "dvd-pi-sum8",
  "term": "DVD PI Sum8",
  "aliases": [
    "PI Sum 8"
  ],
  "definition": "DVD PI Sum8 counts parity-inner rows containing errors over eight consecutive ECC blocks before correction.",
  "note": "The NIST studies describe a threshold of 280 PI errors in this eight-block window [nist2004]. The denominator is not seconds, and the count is neither uncorrectable files nor CD BLER. Record the aggregation window with the value; an unspecified PI count cannot be compared reliably.",
  "status": "unknown",
  "advantages": [],
  "limitations": [],
  "related": [
    "optical-archival",
    "optical-bler"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-15",
  "citations": [
    {
      "id": "nist2004",
      "title": "Slattery, Lu, Zheng, Byers and Tang. Stability Comparison of Recordable Optical Discs: A Study of Error Rates in Harsh Conditions. J. Res. NIST 109(5), 517-524 (2004), sections 2-4.",
      "url": "https://nvlpubs.nist.gov/nistpubs/jres/109/5/j95sla.pdf",
      "accessed": "2026-10-15"
    },
    {
      "id": "analysis",
      "title": "Hesela: optical-disc lifetime estimates, error thresholds and uncertainty",
      "url": "https://hesela.com/analyses/optical-disc-lifetime-estimates/",
      "accessed": "2026-10-15"
    }
  ]
}