O1Library Docs
Fall 2026
Docs API

# Sequencer

o1.sound.midi.Sequencer
object Sequencer

This object is an interface to the underlying MIDI sequencer. It is a thin Scala wrapper around the sequencer in the Java MIDI API.

## Attributes

Graph
Supertypes
  class Object
  trait Matchable
  class Any
Self type
  Sequencer.type

## Members list

### Value members

#### Concrete methods

def close(): Unit

Frees up resources associated with the sequencer’s Java peer.

Frees up resources associated with the sequencer’s Java peer.

## Attributes

def open(): Unit

Prepares the sequencer for use. This method needs to be called before calling start for the first time.

Prepares the sequencer for use. This method needs to be called before calling start for the first time.

## Attributes

def start(music: Music, initialDelay: Long = ...): Unit

Starts playing the given musical sequence.

Starts playing the given musical sequence.

You must call open once before playing any music with this method, or an `IllegalStateException` will be thrown.

## Parameters

initialDelay

  an initial delay, in milliseconds, to allow for the synthesizer’s latency. Defaults to `Synthesizer.latency / 1000`.

music

  the music to play

## Attributes

#### Concrete fields

lazy val peer: Sequencer

the underlying Java MIDI sequencer

the underlying Java MIDI sequencer

## Attributes