v0.18.0 - Sequencer

[danigb]

Sequencer

A timing-correct, multi-track Sequencer that delegates audio scheduling to instruments
via instrument.start({ note, time }).

import { Sequencer, SplendidGrandPiano } from "smplr";

const seq = new Sequencer(context, { bpm: 120, loop: true });
seq.addTrack(piano, [
  { note: "C4", at: "1:1", duration: "4n" },
  { note: "E4", at: "1:2", duration: "4n" },
]);
seq.loopEnd = "2:1";
seq.start();

Features:

• Multi-track: addTrack(instrument, notes) / removeTrack / clearTracks
• Musical time notation: "4n", "8n", "1m", "2:1", "1:1:48", dotted ("4n.")
• Playback: start / pause / stop with seamless resume
• Live BPM changes: set bpm mid-playback with no rescheduling needed
• Seek: set position to jump to any bar/beat/tick while playing
• Loop: configurable loopStart / loopEnd / progress
• Pattern API: scheduleRepeat(callback, interval) for programmatic patterns
• Events: beat, bar, loop, end, start, stop, pause
• Humanize: optional random timing/velocity offsets

Sequencer noteOn / noteOff events

The Sequencer emits noteOn and noteOff events driven by the instrument's own
onStart / onEnded callbacks — they fire at actual playback time, not at scheduling time:

seq.on("noteOn", (event) => highlight(event.noteId));
seq.on("noteOff", (event) => unhighlight(event.noteId));

The event (NoteEvent) contains noteId, trackIndex, noteIndex, and the original
SequencerNote. Notes can have a custom id field; otherwise noteId defaults to the
array index.

AudioWorklet graceful degradation

Reverb now checks for context.audioWorklet before calling addModule(). On iPad Safari
over HTTP (non-secure context), audioWorklet is undefined — the reverb now degrades
gracefully (no effect, no crash) instead of throwing.