FA-78449 / Broadcast timecode arithmetic / Member archive

Drop-frame label increment: second carry · case 04

Labels with a seconds field of 60 appear.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Given a valid drop-frame label at rate "29.97" (nominal 30, drop 2) or "59.94" (nominal 60, drop 4), return the next label: frames carry into seconds at the nominal rate, seconds into minutes, minutes into hours (wrapping at 24); on entering a new minute not divisible by 10 the first drop labels are skipped.

Why this case matters

Timecode arithmetic errors misplace edits, commercial breaks and captions against the broadcast clock.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: second carry	`"23:59:60;00"`	`"00:00:00;00"`	Failed

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