MIDI Concepts

Ticks and Time

A tick represents the lowest-level resolution of a MIDI track. MIDI files use relative (delta) ticks by default — each event’s tick is the offset from the previous event, not an absolute time.

To convert between relative and absolute ticks, use make_ticks_abs() and make_ticks_rel().

Resolution and Tempo

Two values determine how ticks map to wall-clock time:

Resolution (PPQ): Pulses Per Quarter note. Set once per file in resolution. Typically 220 or 480.
Tempo: Beats Per Minute. Set via SetTempoEvent. Internally stored as microseconds per quarter note (MPQN).

The conversion:

# 120 BPM → 500,000 µs per beat
mpqn = 60_000_000 / bpm

# With resolution=1000, one tick = 500 µs = 0.5 ms
tick_us = mpqn / resolution

Time Signatures

TimeSignatureEvent encodes the time signature (e.g. 4/4, 3/4, 6/8). Time signatures affect notation but do not change the tempo.