Function keyTimelineFromNotes

keyTimelineFromNotes(
notes: readonly NoteEvent[],
opts?: KeyTimelineOptions,
): KeyRegion[]
Infer where the key changes from raw notes.

The span is examined in minKeyBeats slots. Each slot's pitch-class distribution is correlated against all 24 major and minor key profiles, and the run of keys that best explains the piece is chosen, paying a cost per modulation that rises with the distance travelled around the circle of fifths and falls on strong beats. Adjacent slots agreeing on a key become one region.

The metric accents that discount a modulation follow the signature in force at the beat in question, so a piece that changes meter is read in the meter it is actually in. The first downbeat is beat 0, so a pickup is written at negative beats and its notes argue for the key like any others rather than falling outside the span.

Pivot chords are not reported here: naming one requires knowing which chord sounded at the boundary, which raw notes do not say. Use detectModulations when a chord timeline is in hand.
Parameters
- notes: readonly NoteEvent[]
  The notes to analyze (any number of tracks, flattened).
- opts: KeyTimelineOptions = {}
  Analysis options; see KeyTimelineOptions.
Returns KeyRegion[]
The key regions in time order; empty when nothing sounds.
Example
```
import { keyTimelineFromNotes } from '@libraz/libcantus';
const notes = [
  { pitch: 60, startBeat: 0, durationBeat: 4 },
  { pitch: 64, startBeat: 4, durationBeat: 4 },
];
const regions = keyTimelineFromNotes(notes);
regions[0]?.key; // the key in force at the start
```
- Defined in src/analyze/keys/index.ts:683

Function keyTimelineFromNotes

Parameters

Returns KeyRegion[]

Example

Settings