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Stardust

MIDI Learn

Click a parameter, move a control, you’re mapped.

📋 Planned · v0.6.0

What it does

MIDI Learn is the interactive way to map physical controls (knobs, faders, footswitches, expression pedals) to plugin parameters and Stardust actions.

The flow:

  1. In Program mode, click the “MIDI Learn” button next to any parameter (e.g. Reverb Mix)
  2. Modal appears: “Move a control…”
  3. Turn a knob, move the expression pedal, press a footswitch
  4. Stardust detects the MIDI message (source, channel, CC/note number)
  5. Confirms mapping with detected device name and message detail
  6. (Optional) Set range, curve, min/max
  7. Save mapping

That’s it. No reading documentation, no manually typing CC numbers.

What can be mapped

Plugin parameters — anything the plugin exposes (volume, filter cutoff, reverb mix, etc.)

Stardust actions:

  • Advance/previous patch
  • Jump to specific patch (1–9)
  • Advance/previous Song
  • Trigger panic
  • Toggle Performance Lock
  • Send named MIDI message out (for forScore page turns, etc.)
  • Toggle UI widget visibility
  • Open plugin GUI

Built-in effect parameters — EQ bands, reverb decay, compressor threshold, etc.

Smart defaults via device profiles

When a known device is plugged in (e.g. Roland RD-2000), Stardust pre-applies the device’s known control labels:

  • Faders 1-9 labeled
  • Knobs 1-9 labeled
  • S1/S2 buttons labeled
  • Modulation lever, pitch bend, sustain pedal already recognized

So during MIDI Learn, when you move a control, the modal says “Detected: Knob 1 from Roland RD-2000” not “Detected: CC 80 channel 1.” Much friendlier.

See Device Profiles.

Range capture

After the initial detection, the modal optionally enters range-capture mode — move the control through its full range. Stardust records min and max, so a pedal that physically reads 5-118 (not 0-127) gets mapped accordingly without dead zones.

Curve options

For continuous controls (expression pedals, knobs), the mapping supports curve transformation:

  • Linear (default) — 1:1 mapping
  • Exponential — slow at low end, fast at top (good for volume)
  • Logarithmic — fast at low end, slow at top
  • Custom — drawable curve editor (v0.5+)

Cascading mappings

Like all settings, MIDI mappings cascade Show → Song → Patch. You set up your common rig at the Show level once. A specific Patch can override individual mappings:

Show-level: Expression Pedal → Master Volume Patch “Strings — Verse” override: Expression Pedal → Strings Filter Cutoff

Most patches will use the inherited mapping; only patches with specific needs override.

See Cascading Settings.

Multi-device awareness

If you have multiple MIDI inputs (e.g. main keyboard + auxiliary controller), MIDI Learn correctly identifies which device sent the detected message. You can also restrict a mapping to a specific device — useful if two devices both send CC 7 but you only want one of them mapped.

Roland sustain-slot footswitch handling

A specific quirk we explicitly handle:

Roland keyboards’ sustain jack sends CC 64 127/0 (sustain on/off). A common workaround is to plug a momentary footswitch (e.g. Boss FS-5U) into the sustain jack and use it as a patch-advance trigger. The catch: contact bounce or a sustained CC 64 = 127 produces multi-patch-advance bugs in most hosts.

Stardust handles this when you label the device:

  • Apply debounce (default 150 ms minimum between activations)
  • Provide “minimum interval between patch advances” setting (default 200 ms, per-Show)
  • Detect “stuck high” CC 64 and treat as a single edge, not continuous re-trigger

See Device Profiles for related quirks.

MIDI activity indicator

In Perform mode, a row of small dots shows real-time MIDI activity per device. Lets you confirm at a glance that your controls are talking. If something stops working mid-show, the dots tell you instantly whether the issue is hardware (no signal) or software (signal but no action).

See Widget Registry.

Storage format

Mappings stored in the Show file as JSON:

"midi_mappings": [
  {
    "source": { "device": "Roland RD-2000", "cc": 7, "channel": 1 },
    "target": { "type": "plugin_param", "plugin_id": "keyscape", "param": "volume" },
    "range_min": 5,
    "range_max": 118,
    "curve": "exponential"
  }
]

See Data Model.

Phase status

PhaseWhat’s available
v0.2Basic MIDI input + manual mapping in code (no UI)
v0.4Full MIDI Learn UI with device profiles, ranges, curves, cascading
v0.5+Custom curve editor, bidirectional MIDI (v1.0+)