Practice and rhythm tools

Practice can change how you hear a phrase without changing what is written. Score editing changes the source itself. This chapter separates the two and shows what the native engine can do with rhythm, tempo and repeated music.

Availability: the examples can be edited and engraved on this website. The practice projections and structured rhythm edits described below are native engine capabilities for applications to expose. The browser editor does not yet provide controls for all of them. Building an integration requires source access.

Practise at a different tempo

A phrase may carry tempo changes, a range or a metric modulation. Keep that musical information when practising slowly:

• Scale the tempo: apply a rational multiplier to the whole reading. A scale of 3/4 turns quarter = 120 into 90 and quarter = 80 into 60. Their relationship remains intact.
• Set the opening rate: choose a starting beat and rate while retaining the relationships to later tempo changes.
• Use one uniform rate: rehearse the whole passage at a chosen beat and rate. This overrides changes for that reading; it does not erase them from the source.

meter 4/4
tempo {q=120, m2 q=80}
4G4 A B C | 2D C

Original canonical spelling

meter 4/4

tempo {q=120, m2 q=80}

4G4 A B C | 2D C

A rate always names its beat value. Dotted quarter = 60 in 6/8 is not the same speed as quarter = 60. Written tempo ranges play from their first number unless a practice setting changes the reading. See tempo and metric modulation.

A host opens one native position-clock reading and uses its returned performance, beat grid and occurrence table together. At a fermata or caesura, arrival and release can differ; estimating a rest or beat from the nearest sounding note loses that information.

Hear the beat inside a subdivision

Two native practice options answer different musical questions:

A pulse can follow each selected part's native grouping or use an explicit valid grouping. Its subdivision has a count and a named sound template. The engine owns their timing, including silent beats; the application plays the returned strikes. These are separate from the authored notes.

For 6/8, begin by hearing the two dotted-quarter groups, then add the three subdivisions within each group:

meter 6/8
tempo q.=60
8G4 A B C D E | D C B A G F

Original canonical spelling

meter 6/8
tempo q.=60

8G4 A B C D E | D C B A G F

A hearing projection and a pulse overlay cannot be combined in one reading. A missing or ambiguous sound template, a grouping that does not fit the meter, and unsupported meters receive a refusal. They do not silently turn into another practice pattern.

Follow repeats and returns

A straight-through reading visits the written bars once. A written-navigation reading follows supported repeats, numbered endings, D.C., D.S., Fine and Coda instructions. Applications choose that traversal explicitly; ordinary performance output does not imply repeat-aware playback.

|: 4C5 D E F | [1..] 1G :| [2..] C, |||

Original canonical spelling

|: 4C5 D E F | [1..] 1G :| [2..] C, |||

Each performed visit retains its original written bar and event addresses. The second visit to a bar is another occurrence of that bar, not a newly written measure. A cursor or selection can therefore distinguish “m1, second visit” from “m1, first visit”. A uniform practice rate retains these source addresses as well.

An application must ask which occurrence it means when a position repeats. Ambiguous temporal spans across jumps and enabled expressive-navigation combinations are refused. See repeats and navigation for the written instructions.

Build a rhythm from beat figures

The native rhythm builder accepts a meter, tempo, beat lengths and figures. It writes a ScoreScript document with independently addressable bars, so the same document can then be edited by beat, event or bar. A figure can contain:

• an ordinary or accented attack;
• a rest;
• a hold continuing the preceding event;
• equal subdivisions, unequal weights or a tuplet;
• explicit R/L sticking, or a hit with no hand assigned.

An unassigned hand stays unassigned. The engine does not invent alternating R/L strokes. A second voice may add an evenly spaced counter-rhythm while preserving the main line.

Here is ordinary authored source for a two-against-three rhythm. The voices occupy the same bar; they are not successive passages:

meter 3/4
parts { snare-drum }
snare-drum {
  staff-lines 1
  m1 {
    v1[4B4 B B]
    v2[4.B4 B]
  }
}

Original canonical spelling

meter 3/4

parts {
  snare-drum
}

snare-drum {
  staff-lines 1

  m1 {
    v1 [ 4B4 B B ]
    v2 [ 4.B4 B ]
  }
}

The builder is scorescript_entry::bar_ops::rhythm::build, a Rust API, not a new source keyword or a browser menu. Beat lengths must fill their meter exactly. Empty requests, figures that do not fit, and requests over its 128-bar or 8,192-event bounds are refused before a document is returned.

Change the grouping, figure or beat length

These are three different musical edits:

For example, a beat containing two eighths can become a dotted-quarter beat containing two dotted eighths. In an otherwise four-quarter bar the new lengths are 2+3+2+2 eighths. The following bar restores its own meter.

meter {4/4, m2 2+3+2+2/8, m3 4/4}
m1 { 4B4 8B(>) B(.) 4B r }
m2 { 4B4 8.B(>) B(.) 4B r }
m3 { 1r }

Original canonical spelling

meter {4/4, m2 2+3+2+2/8, m3 4/4}


m1 {
  4B4 (>)8B (.)B 4B r
}

m2 {
  4B4 (>)8.B (.)B 4B r
}

m3 {
  r
}

Grouping alone does not change 4/4 into 9/8. Changing a beat's length does. See Beaming for automatic groups, recursive trees, beam connections, cross-staff membership and feathering.

The same native bar operations can add, replace or remove a counter-rhythm; change a meter or tempo for one bar or until the next stated change; insert, duplicate or remove a bar; and adjust a pickup. A pickup adjustment must respect the music already occupying each voice. Unsupported figures and changes that would damage unselected music are refused.

Keep edits bound to the music you selected

Structured edits use the source revision and exact snapshot they were read from. If the score changes before the edit is applied, the caller must refresh the selection and request again. A stale request cannot overwrite newer music, even when the replacement text would otherwise be a no-op.

Native applications use scorescript_entry::step_grid, bar_ops and part_pan with the document session. Hosts should expose their native refusals and revision checks. These are not extra methods on the browser's CompiledDocument class. See integration for the actual WASM methods and projects for linked-source boundaries.

Different meters at once

Polymeter gives parts separate meters and exact alignment rules. It is more than a counter-rhythm inside one shared meter. The primary part owns the section's bar range and tempo; each follower states either a bar ratio or an equality between beat values. The engine derives each part's clock.

See Polymeter for complete examples, local bar numbering and section limits. It currently refuses practice pulse overlays, hearing/expression projections, uniform tempo and written-navigation playback. Independent barline engraving remains reserved. Those boundaries are separate from the accepted source and timing model.