FA-81479 / MIDI event timing / Member archive

Tick to microsecond conversion through a tempo map: first tempo applied from tick zero · case 04

Material before the first tempo event is timed at that later tempo instead of the default 120 BPM.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Input [ppq, changes, tick] where changes are [tick, microseconds_per_quarter] in any order (a later entry at the same tick overrides an earlier one). Before the first change the tempo is 500000. Each tempo applies from its tick onward. Sum the exact time of each segment and floor once at the end. Invalid ppq or negative tick 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 0	`1500000`	`1750000`	Failed

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