Method

Scan essence match

Scan type vs essence reconciliation

What we measure and how

Reconciles the DECLARED scan (the container `field_order` tag that `scan_type` reads) against the MEASURED scan (ffmpeg `idet` statistics on the decoded essence). Catches the classic progressive-essence-in-an-interlaced-wrapper export (e.g. from Adobe Premiere) where `scan_type` passes on the metadata tag and `combing` independently reads progressive, leaving two contradictory green verdicts. FAILs when the metadata tag disagrees with the essence AND the spec mandates a single scan type; skips (not-applicable) when idet has no usable stats, no field_order is declared, the measured scan is ambiguous, or the spec doesn't mandate a scan type.

Method identifier: scan_essence_match