FA-81684 / MIDI event timing / Member archive

Loop-region playback event firing: loop wraps to the song start · case 04

After the first pass the song position jumps to tick 0 instead of the loop start, replaying the intro.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Input [loop_start, loop_end, events, from_tick, to_tick]. Playback runs over playback ticks p in [from, to). Song position is p while p < loop_end, afterwards loop_start + (p - loop_end) mod (loop_end - loop_start). Every event whose song tick equals the song position fires as [p, event_tick]. Requires 0 <= loop_start < loop_end and 0 <= from < loop_end, else 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	`[[0, 0], [2, 2], [5, 5], [6, 0], [8, 2], [10, 0], [12, 2]]`	`[[0, 0], [2, 2], [5, 5], [6, 2], [9, 5], [10, 2], [13, 5]]`	Failed

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