# mixer-engine

> A mixer on the Web Audio API: a channel per track and return, with its chain, volume, constant-power pan, switch, solo, pre or post-fader sends, delay compensation and meters, into a main track

```bash
npx shadcn@latest add @audio-ui/mixer-engine
```

```ts
import { createMixer } from "@/lib/mixer-engine";
```

- Files: `lib/mixer-engine.ts`
- Depends on: nothing; npm: `@audio-ui/engine`
- Used by: `arrangement-engine`

| Export | Kind | What it is |
| --- | --- | --- |
| `StripMix` | interface | What a channel does with its sound. |
| `MixerTrack` | interface | A track as the mixer plays it. |
| `MixerReturn` | interface | A return track as the mixer plays it. |
| `MixerState` | interface |  |
| `ChainLink` | interface | A device's sound path, as a chain links it. |
| `MixerStrip` | interface | A channel of the mixer. |
| `Mixer` | interface |  |
| `createMixer` | function | A mixer on the Web Audio API: a channel for each track and each return, and the main track, which goes to `destination`. |

## Usage

`mixer-engine` is the mixing desk the engine plays through, usable on its own with sources of your own: a channel per track and per return (a track that names a `group` plays into that track's channel), each with a device chain (`setChain`), a volume, a pan, a switch and a solo, sends taken before or after the volume, pan and switch as each return asks, delay compensation from the latency each chain declares, a meter per channel, and the main track to the output. Nothing limits the main track, so a mix over full scale shows on the meters as it would in the file.

```ts
import { createMixer } from "@/lib/mixer-engine";

const mixer = createMixer(context);
mixer.update({
  main: { gain: 1 },
  returns: [{ gain: 1, id: "hall", latency: 0, on: true, pan: 0, pre: false, soloed: false }],
  tracks: [{ gain: 0.8, id: "vox", latency: 288, on: true, pan: -0.2, sends: { hall: 0.3 }, soloed: false }],
});
source.connect(mixer.strip("vox")!.input);
```