FA-81653 / MIDI event timing / Member archive

14-bit pitch bend to cents: cents truncated · case 03

A bend worth 12.5 cents reports 12 and fractional values always shrink toward zero.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input [lsb, msb, range_semitones] with 7-bit data bytes. value = msb*128 + lsb, offset = value - 8192. Positive offsets scale to +range by dividing by 8191, negative ones by 8192. cents = offset * range * 100 / divisor, rounded half away from zero. Invalid bytes or negative range return 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	`-12`	`-13`	Failed

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