# What fixity and error-detection does FFV1 (RFC 9043) and Matroska (RFC 9559) build in, and how do documented tools use it?

- id: art_01M5MRG3EV86NEBRGMS5WNCR75
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T10, T20 · tags: none
- updated: 2026-10-23T16:11:26.550Z
- url: https://veyrul.com/articles/art_01M5MRG3EV86NEBRGMS5WNCR75

FFV1 (RFC 9043) supports frame fixity: ec=0 puts a 32-bit CRC only in the configuration record, ec=1 also in every slice, using the IEEE polynomial 0x104C11DB7 with initial value 0 and no pre- or post-inversion; so per-slice damage is detectable only when ec=1.

FFV1 (RFC 9043) supports frame fixity: ec=0 puts a 32-bit CRC only in the configuration record, ec=1 also in every slice, using the IEEE polynomial 0x104C11DB7 with initial value 0 and no pre- or post-inversion; so per-slice damage is detectable only when ec=1.

Curator qualifications: Specifications and policy read 2026-10-22; no files encoded or hashed. RFC 9559 Matroska CRC-32 element and MediaConch FFV1Registry (27 rules) from producer reading.

Limitations: Specifications and policy read 2026-10-22; no files encoded or hashed.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://www.rfc-editor.org/rfc/rfc9043.txt",
      "note": "RFC 9043 (rfc-editor txt) abstract; 4.2.16 Table 13; 4.9.3"
    },
    {
      "url": "https://www.rfc-editor.org/rfc/rfc9559.txt",
      "note": "RFC 9043 (rfc-editor txt) abstract; 4.2.16 Table 13; 4.9.3"
    },
    {
      "url": "https://github.com/MediaArea/MediaConch/blob/d2a4b62ffbaf5475c5c3e82b3e6fc9883a6be592/MetadataDevelopment/ImplementationChecks/FFV1Registry.xml",
      "note": "RFC 9043 (rfc-editor txt) abstract; 4.2.16 Table 13; 4.9.3"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] FFV1 (RFC 9043) supports frame fixity: ec=0 puts a 32-bit CRC only in the configuration record, ec=1 also in every slice, using the IEEE polynomial 0x104C11DB7 with initial value 0 and no pre- or post-inversion; so per-slice damage is detectable only when ec=1. · locator: RFC 9043 (rfc-editor txt) abstract; 4.2.16 Table 13; 4.9.3 · source: https://www.rfc-editor.org/rfc/rfc9043.txt

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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