bind-parameter

(no submodules)

Purpose

bindParameter wires a typed MidiSource (a controller CC, note-velocity, or future hardware source) to a parameter on any AudioFxPlugin from @suaveplan/audio-fx-plugin-base. It looks the parameter up via the plugin's O(1) parameterIndex, maps the inbound 0–127 byte into the declared [min, max] range honouring the parameter's scale (linear / log / exponential), and dispatches either setParameter or setParameterCurve depending on whether a smoothingMs was supplied. The complement bindPluginPreset listens for program-change-style CCs and applies PresetSnapshots by index.

Features

Source-aware mapping: linear, logarithmic, exponential parameter scales.
Optional smoothingMs engages setParameterCurve so jittery knobs ramp.
Unknown paramId raises AUDIO_CONTROLLERS.UNKNOWN_PARAMETER.
Unbind returns a UnsubscribeFn that removes only this binding — other bindings on the same source keep firing.
Preset binding for MIDI program-change-style flows.

Usage: Basic

const off = bindParameter(eq, "lowShelfGain", { type: "cc", channel: 0, number: 7 }, {
  controller,
});
// ...
off();

Usage: Advanced

const off = bindParameter(
  eq,
  "lowShelfGain",
  { type: "cc", channel: 0, number: 7 },
  { controller, smoothingMs: 20 }
);

const offPreset = bindPluginPreset(
  eq,
  { type: "cc", channel: 0, number: 32 },
  presetSnapshots,
  { controller }
);

API Reference

bindParameter(plugin, paramId, source, { controller, smoothingMs? }) → UnsubscribeFn.
bindPluginPreset(plugin, source, presets, { controller }) → UnsubscribeFn.
MidiSource — union of cc and note-velocity shapes.
UnsubscribeFn — () => void.

Implementation Notes

The binding subscribes to the controller's raw event so it can observe even messages that have no defineMappings entry. A (channel, controller) filter inside the handler keeps the dispatch O(1). When the parameter declares scale: "log" the mapping does min * (max/min)^t, falling back to 1e-6 if min === 0 to avoid a division by zero. Preset application delegates to plugin.applyPreset, which performs Zod validation itself — any failure propagates unchanged.

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