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Parameters

Declare typed parameters, stable IDs, metadata, and host automation.

Declare a collection

#[derive(Params)] generates indexed handle access without searching strings during processing.

Rust
#[derive(Params)]struct FilterParams {    cutoff: FloatParam,    resonance: FloatParam,    bypass: BoolParam,}impl Default for FilterParams {    fn default() -> Self {        Self {            cutoff: FloatParam::new("cutoff", "Cutoff", 20.0, 20_000.0, 1_000.0)                .with_unit("Hz"),            resonance: FloatParam::new("resonance", "Resonance", 0.1, 12.0, 0.7),            bypass: BoolParam::new("bypass", "Bypass", false).with_bypass(true),        }    }}

The string ID is a persistent project contract. Do not rename it after release unless you also provide a migration strategy.

Resolve handles once

Rust
struct FilterKernel {    cutoff: ParamHandle,    resonance: ParamHandle,}fn create_kernel(&self, _init: KernelInit) -> FilterKernel {    FilterKernel {        cutoff: self.params.resolve_or_invalid("cutoff"),        resonance: self.params.resolve_or_invalid("resonance"),    }}

An invalid handle safely returns None; it does not panic through host initialization.

Sample-accurate automation

Use the parameter events carried by ProcessContext when the algorithm needs exact offsets. The adapter preserves the previous block value until the first event, orders points by sample offset, and commits the final value after processing.

For a coefficient that can change less frequently, combine event handling with a preallocated smoother instead of recalculating expensive state every sample.

Generate the manifest

Bash
vesty param-manifest \  --specs params.specs.json \  --out vesty-parameters.jsonvesty param-manifest \  --specs params.specs.json \  --out vesty-parameters.json \  --check

Commit the manifest. Packaging copies it into the VST3 bundle, and strict validation checks that it still matches the parameter specifications.