parameters

(no submodules)

Purpose

Declares the parameter surface the SpessaSynthPlugin exposes to the host chain: 16 GM channels × 5 controls (volume, pan, program, reverbSend, chorusSend) plus a master gain, for a total of 81 parameters. Each is described as a PluginParameter from @suaveplan/audio-fx-plugin-base so the host chain's automation lanes, parameter-curve scheduler, and preset snapshot machinery treat them uniformly with every other plugin in the chain.

Parameter ids follow the deterministic channel/<n>/<kind> pattern (and the singleton master/gain) so external systems — control surfaces, OSC bridges, MIDI-learn UIs — can address any control by literal string without consulting a runtime registry.

Features

buildParameterDeclarations() — emits 81 PluginParameter records in deterministic order.
channelParameterId(channel, kind) / parseChannelParameterId(id) — symmetric id encode / decode.
assertChannel(channel) — throws SPESSASYNTH.INVALID_CHANNEL for non-integer or out-of-range channels.
CHANNEL_COUNT, CHANNEL_PARAM_KINDS, MASTER_GAIN_ID — closed-enum constants.
All ratios use [0, 1] for sends and volume, [-1, 1] for pan, [0, 127] for program selection, [0, 4] for master gain.
Every parameter except program is marked automatable: true (program-change is a discrete enum jump and shouldn't be interpolated).

Usage: Basic

import {
    buildParameterDeclarations,
    channelParameterId,
} from "@suaveplan/audio-fx-plugin-spessasynth/parameters";

const parameters = buildParameterDeclarations();
console.log(channelParameterId(0, "volume")); // "channel/0/volume"

Usage: Advanced

import {
    parseChannelParameterId,
    MASTER_GAIN_ID,
    assertChannel,
} from "@suaveplan/audio-fx-plugin-spessasynth/parameters";

function applyAutomation(id: string, value: number) {
    if (id === MASTER_GAIN_ID) {
        processor.setMasterGain(value);
        return;
    }
    const decoded = parseChannelParameterId(id);
    if (!decoded) return;
    assertChannel(decoded.channel);
    routeToChannel(decoded.channel, decoded.kind, value);
}

API Reference

CHANNEL_COUNT: 16, MAX_CHANNEL_INDEX: 15.
CHANNEL_PARAM_KINDS: ReadonlyArray<"volume" | "pan" | "program" | "reverbSend" | "chorusSend">.
channelParameterId(channel: number, kind: ChannelParamKind): string.
parseChannelParameterId(id: string): { channel, kind } | undefined.
buildParameterDeclarations(): ReadonlyArray<PluginParameter>.
assertChannel(channel: number): void.
MASTER_GAIN_ID: "master/gain".

Implementation Notes

program is declared automatable: false because the host chain's parameter-schedule evaluator interpolates linearly; an in-flight ramp between two program numbers would emit non-integer program values to the underlying synth, which has no defined semantics. Treating program-change as a discrete setParameter write keeps the contract clean. volume is [0, 1] to match MIDI CC #7 semantics — callers that need pre-master headroom should drive master/gain (which goes to 4×) rather than over-driving channel volume. The parameter order — channels in numeric order, kinds in declaration order, master last — is deterministic so snapshots and UI iteration produce stable byte-for-byte output.

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