# Peak limiter
Make quiet audio louder without clipping: boost the player's audio and keep its peaks under a ceiling with a lookahead limiter.
Tip: open your browser's developer console and use the `player` and `THEOplayer` variables to interact with this demo.
| Boost | 18 | +18 dB |
| ------- | -- | ------ |
| Ceiling | -1 | -1 dB |
\[x]Limiter on
Output peak`-∞ dB`
Turn the limiter off to hear the boosted audio clip: in loud scenes, the output peak goes above 0 dB and the meter turns red.
The Web Audio API has no built-in peak limiter. Its `DynamicsCompressorNode` adds makeup gain automatically, so it can't guarantee that peaks stay under a ceiling. This example uses [`@synthlet/lookahead-limiter`](https://www.npmjs.com/package/@synthlet/lookahead-limiter), an open source (MIT) limiter that runs in an `AudioWorklet`. It looks 2 ms ahead, so it lowers the gain before a peak arrives, and it also catches peaks between samples (true peaks).
```js
import { registerLookaheadLimiterWorklet, LookaheadLimiter } from '@synthlet/lookahead-limiter';
const context = new AudioContext();
await registerLookaheadLimiterWorklet(context);
const source = player.audio.createAudioSourceNode(context);
const limiter = LookaheadLimiter(context, {
gain: 12, // boost in dB, applied before limiting
threshold: -1, // ceiling in dB
});
source.connect(limiter).connect(context.destination);
```
The limiter delays the audio by about 2 ms. Browsers start an `AudioContext` in the `suspended` state until the viewer interacts with the page, so call `context.resume()` when playback starts. See the [Web Audio API](https://docs-preview.optiview.dolby.com/pr-913/theoplayer/examples/playback/web-audio-api.md) example for more about routing the player's audio.
Code
demo.html
```html
Peak limiter
```