Presets Reference

Complete reference for all configurable presets in MIDI Sketch Bach.

Reading these tables

ID and String are API values. Voices, meter, raw natural bars, key, and character are musical structure choices. If those terms are new, keep the Music Primer for Engineers open while reading this page.

Forms Reference

All 10 Forms

ID	Name	String	Category	Default Instrument	Voices	Meter	Raw Natural Bars	Short Output Bars
0	Fugue	"fugue"	Organ	Organ	3	4/4	42	44
1	Prelude and Fugue	"prelude_and_fugue"	Organ	Organ	3	4/4	24	24
2	Trio Sonata	"trio_sonata"	Organ	Organ	3	4/4	16	16
3	Chorale Prelude	"chorale_prelude"	Organ	Organ	3	4/4	16	16
4	Toccata and Fugue	"toccata_and_fugue"	Organ	Organ	3	4/4	32	32
5	Passacaglia	"passacaglia"	Organ	Organ	3	3/4	24	24
6	Fantasia and Fugue	"fantasia_and_fugue"	Organ	Organ	3	4/4	32	32
7	Cello Prelude	"cello_prelude"	Solo	Cello	1	4/4	8	8
8	Chaconne	"chaconne"	Solo	Violin	2	3/4	16	16
9	Goldberg Variations	"goldberg_variations"	Variation	Harpsichord	3	4/4	20	20

Bar counts

"Raw Natural Bars" is the form's base length before snapping. scale multiplies that value (~1x/2x/3x/4x), then the result snaps to the form's bar grid. Fugue's raw 42 bars therefore produce 44 bars with scale: "short". targetBars overrides scale, and every form caps at 128 output bars.

Natural bars are not seconds

A bar count is musical length, not wall-clock duration. Playback time also depends on bpm and meter. A 44-bar fugue at 80 BPM lasts longer than the same 44 bars at 140 BPM.

Form Selection Flowchart

Organ System (Forms 0--6)

The seven organ forms cover the major genres of Bach's organ repertoire. All default to organ registration and use three voices.

Solo Instrument System (Forms 7--8)

The two solo forms generate music for unaccompanied string instruments. The cello prelude is a single continuous line; the chaconne pairs a ground bass with an upper line. Implied polyphony emerges through register shifts, arpeggiation, and chordal writing.

Variation System (Form 9)

The Goldberg Variations form is a theme-and-variations cycle over an immutable bass, defaulting to harpsichord.

BWV References by Form

Form	Notable Bach Works
Fugue	BWV 578 (G minor "Little" Fugue), BWV 542/2
Prelude and Fugue	BWV 532, 541, 548, 846--893 (Well-Tempered Clavier)
Trio Sonata	BWV 525--530 (Six Trio Sonatas)
Chorale Prelude	BWV 599--644 (Orgelbüchlein), BWV 651--668
Toccata and Fugue	BWV 565 (D minor), BWV 540
Passacaglia	BWV 582 (C minor)
Fantasia and Fugue	BWV 537, 542, 561
Cello Prelude	BWV 1007--1012 (Cello Suites)
Chaconne	BWV 1004/5 (Partita No. 2 in D minor)
Goldberg Variations	BWV 988

Instruments Reference

ID	Name	String	GM Program	Sound	Accepted by
0	Organ	"organ"	19	Church Organ	Organ forms (0--6)
1	Harpsichord	"harpsichord"	6	Harpsichord	Goldberg Variations (9)
2	Piano	"piano"	0	Acoustic Grand Piano	Goldberg Variations (9)
3	Violin	"violin"	40	Violin	Chaconne (8)
4	Cello	"cello"	42	Cello	Cello Prelude (7)
5	Guitar	"guitar"	24	Nylon Guitar	--

Instrument does not decide the composition

The instrument selects MIDI sound, playable range, and ornament density. It does not change voice count, meter, form layout, or validator rules; those come from form.

The form fixes the instrument

Every form except the Goldberg Variations accepts exactly one instrument — the one it was written for. Requesting another throws an incompatible-instrument error rather than transcribing the piece. The Goldberg Variations is the one form that offers a choice, between harpsichord and piano.

Subject Characters

ID	Name	String	Effect
0	Severe	"severe"	Strict, intellectually rigorous (default)
1	Playful	"playful"	Light, agile, rhythmically lively
2	Noble	"noble"	Stately, broad, dignified
3	Restless	"restless"	Driving, chromatic, dramatically charged

INFO

The character parameter affects the melodic profile of the fugue subject or primary thematic material. It has the most noticeable effect on fugal forms, where the subject defines the character of the entire piece. Two combinations are forbidden and throw: chorale_prelude rejects playful/restless, and toccata_and_fugue rejects noble.

Scale Modes

scale multiplies the form's natural length. targetBars overrides it.

ID	Name	String	Approximate Length
0	Short	"short"	~1x natural (default)
1	Medium	"medium"	~2x natural
2	Long	"long"	~3x natural
3	Full	"full"	~4x natural

TIP

The actual output length depends on each form's natural length (see the Forms Reference table above): the same scale produces different bar counts for different forms because each scales from its own natural length. Use targetBars for precise length control; values are clamped to [form minimum, 128].

Key Reference

ID	Name	Pitch Class	Common Baroque Associations
0	C	C	Purity, simplicity, clarity
1	C# / Db	C#	Devotion, depth
2	D	D	Triumph, brilliance (D major); passion, drama (D minor)
3	D# / Eb	Eb	Heroic grandeur, nobility
4	E	E	Joy, brightness (E major); lament (E minor)
5	F	F	Pastoral, calm
6	F# / Gb	F#	Intensity, brilliance
7	G	G	Grace, simplicity (G major); seriousness (G minor)
8	G# / Ab	Ab	Solemn, devotional
9	A	A	Tenderness, elegance (A major); gentle melancholy (A minor)
10	A# / Bb	Bb	Nobility, warmth
11	B	B	Hard brilliance (B major); somber weight (B minor)

Pitch class and mode

key chooses the pitch class, such as C or D. isMinor chooses major or minor. For example, key: 2, isMinor: false is D major; key: 2, isMinor: true is D minor.

Key Associations in Baroque Music

Baroque composers associated specific keys with emotional qualities (Affektenlehre). D minor was the key of passion and drama (BWV 565 Toccata and Fugue), while C major represented purity (BWV 846 Prelude). These associations are subjective and vary by era, but they influenced Bach's choice of key for his compositions.

All keys work with both isMinor: false (major) and isMinor: true (minor).

Default Mapping

Cross-reference of form defaults (voices and meter are fixed by the form; BPM defaults to 100 unless you set it):

Form	Instrument	Voices	Meter	Short Output Bars
Fugue	Organ (0)	3	4/4	44
Prelude and Fugue	Organ (0)	3	4/4	24
Trio Sonata	Organ (0)	3	4/4	16
Chorale Prelude	Organ (0)	3	4/4	16
Toccata and Fugue	Organ (0)	3	4/4	32
Passacaglia	Organ (0)	3	3/4	24
Fantasia and Fugue	Organ (0)	3	4/4	32
Cello Prelude	Cello (4)	1	4/4	8
Chaconne	Violin (3)	2	3/4	16
Goldberg Variations	Harpsichord (1)	3	4/4	20

Programmatic Access

Use the preset enumeration functions to access these values at runtime:

import {
  init,
  getForms,
  getInstruments,
  getCharacters,
  getDefaultInstrumentForForm,
  getKeys,
  getScales,
  getVersion
} from '@libraz/midi-sketch-bach'

await init()

// List all forms
const forms = getForms()
for (const form of forms) {
  console.log(`${form.id}: ${form.display ?? form.name}`)
}
// 0: Fugue
// 1: Prelude and Fugue
// 2: Trio Sonata
// 3: Chorale Prelude
// 4: Toccata and Fugue
// 5: Passacaglia
// 6: Fantasia and Fugue
// 7: Cello Prelude
// 8: Chaconne
// 9: Goldberg Variations

// List all instruments
const instruments = getInstruments()
// [{ id: 0, name: "organ" }, ...]

// List all keys
const keys = getKeys()
// [{ id: 0, name: "C" }, { id: 1, name: "C#" }, ...]

// Look up a form's default instrument ID
const celloPreludeInstrument = getDefaultInstrumentForForm(7)
// 4 (cello)

TIP

These functions are useful for building UI components like dropdowns or form selectors. The demo on this site uses them to populate the form selection interface.

getDefaultInstrumentForForm(formId: number): number accepts form IDs 0--9. Invalid or out-of-range values return 0 (organ).