FA-81538 / MIDI event timing / Member archive

Bar, beat and tick position with meter changes: segment length measured from bar zero · case 03

With three meters, the middle segment is treated as starting from bar 0, so positions after the last change land in the wrong bar.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input [ppq, signatures, tick]. signatures is a list of [bar_index, numerator, denominator] sorted by bar, the first at bar 0; each takes effect at the start of its bar. A beat lasts ppq*4/denominator ticks. Return [bar (1-based), beat (1-based), tick within beat]; invalid input returns None.

Why this case matters

MIDI sequencers, file readers and synth drivers depend on exact event ordering and tick/time arithmetic.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
oracle 7	`[4, 3, 200]`	`[4, 2, 200]`	Failed

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