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Stardust

Transpose

Pitch shift a Song up or down in semitones. Essential for night-to-night vocal-health adjustments.

✅ Shipped · v0.5.0 · UI v0.8.0

What it does

Per-Song transpose in semitones (±24 range typical). Audible pitch shift happens at the MIDI level — outgoing notes from the keyboard are shifted before reaching plugins, so the plugins play the transposed key directly.

Useful for:

  • Vocal health — singer is tired, transpose down 2 semitones for the night
  • Original key vs performance key — your charts are written in C but the show is performed in B
  • Capo equivalent — guitar players use capos; keyboardists transpose
  • Multi-singer shows — different soloists need different keys for the same Song

How it works

Two implementation strategies:

  1. MIDI-level transpose (default) — every note_on / note_off shifted by N semitones before reaching plugins. The plugin plays exactly the transposed notes; pitch is mathematically exact.
  2. Audio-level pitch shift (advanced) — pitch-shift the plugin output audio. Slower, introduces artifacts, but works for sample-based plugins with specific tuning. Rarely needed.

Stardust uses MIDI-level by default. Audio-level is a future option for edge cases.

Range warnings

When you transpose, Stardust checks:

  • Are any expected notes now below the plugin’s range (e.g. piano bottom note)?
  • Are any expected notes above the plugin’s range?
  • For sample-based instruments: are we hitting the boundary where sample loops break?

If yes, surface a warning during edit. Doesn’t block save — sometimes you want it that way for effect.

Per-Song vs per-Patch

Default is per-Song transpose — the whole Song shifts together. But each Patch can override:

  • Song-level transpose: +2 (all Patches default to +2)
  • “Strings — Verse” Patch override: 0 (this Patch plays at original concert pitch)

Useful when one Patch in a Song needs to be in a different key (rare, but it happens).

See Cascading Settings.

Live Mode indicator

The transpose status shows in Live Mode (configurable widget). Common display: “Key: B (orig C, -1)” or just “Transpose: -1.”

Storage

"transpose": -2,
"transpose_strategy": "midi"  // or "audio"

Patch-level overrides use the same fields under settings_overrides.