---
title: Filter
description: "A filter as a device you can plug in: a type, a cutoff and a resonance as a state, a panel with a handle on the curve and a live spectrum, a Web Audio engine and the tools an agent drives it with."
component: true
base: base
---

<ComponentPreview styleName="base-nova" name="block-filter" />

Takes part of the spectrum out: a low-pass, high-pass, band-pass or notch. Drag the handle on the curve across for the cutoff and up for the resonance; pass a spectrum to the panel to see what comes out behind it. It is a device like the [compressor](/docs/components/compressor): a state, a panel that draws it, an engine that plays it and tools an agent calls, each its own file.

## Installation

<CodeTabs>

<TabsList>
  <TabsTrigger value="cli">CLI</TabsTrigger>
  <TabsTrigger value="manual">Manual</TabsTrigger>
</TabsList>

<TabsContent value="cli">

```bash component
npx shadcn@latest add @audio-ui/block-filter
```

</TabsContent>

<TabsContent value="manual">

<Steps>

<Step>Install the packages:</Step>

```bash
npm install @audio-ui/react @audio-ui/core
```

<Step>Add the pieces you want. All of them, or only the state and the panel if your engine is elsewhere:</Step>

```bash
npx shadcn@latest add @audio-ui/filter-device @audio-ui/filter-panel @audio-ui/filter-engine
```

<Step>Copy and paste the demo that wires them, if you want it.</Step>

<ComponentSource
  styleName="base-nova"
  name="block-filter"
  title="components/examples/block-filter.tsx"
/>

</Steps>

</TabsContent>

</CodeTabs>

## Usage

```tsx
import { FilterPanel } from "@/components/audio-ui/devices/filter/panel";
import { filterDevice } from "@/components/audio-ui/devices/filter/device";

const [state, setState] = useState(() => filterDevice.defaults());

<FilterPanel onValueChange={setState} value={state} />;
```

The state is a plain object keyed by parameter id, so a host stores it, saves it with its project and sends it where it likes. `filterCurve(state)` is the curve the panel draws and `filterSettings(state)` what goes on the node.

## The engine

```ts
import { createFilterEngine } from "@/components/audio-ui/devices/filter/engine";

const engine = createFilterEngine(ctx, state);
source.connect(engine.input);
engine.output.connect(ctx.destination);
engine.update(nextState); // parameters ramp: no click
engine.dispose();
```

The node is the filter the curve draws. A low-pass and a high-pass read their resonance in decibels, so the device gives it to the node in that unit, and the curve and the sound agree.

## The tools

```ts
import { deviceTools } from "@audio-ui/core/device";
import { filterDevice } from "@/components/audio-ui/devices/filter/device";

const [set, reset] = deviceTools(filterDevice);
```

`set` and `reset` change the state, with the ranges the device enforces: a value out of range is brought in and reported, a wrong one is refused by name, and a call never throws.

## Accessibility

Every control is a native input: the knobs are sliders named after their parameter, with the value and unit as the text value, the switch is a toggle button, and everything takes the keyboard.