Gibberish Audio Driver

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driver.js gibberish.js waa.js context.js compatibility.js debug.js midi.js random.js stdlib.js index.js process.js utils.js vm.js

¶

Gibberish Audio Driver
```
import { AudioDriver } from "./driver"
```

This driver uses Gibberish both for scheduling and sounds

/**
 * Create a VM plugin to add the audio driver
 * @return {Function} a VM plugin
 */
export default function init (Gibberish, options = {}) {
  if (!Gibberish.context) Gibberish.init()
  const audio = new GibberishDriver(Gibberish, options.bpm || 120)
  audio.addInstruments(createInstruments(Gibberish))
  return audio
}

class GibberishDriver extends AudioDriver {
  constructor (Gibberish, bpm) {
    super(bpm, Gibberish.context.sampleRate)
    this.Gibberish = Gibberish
  }

¶

Start a VM
```
  start (vm) {
    super.start(vm)
```

convert bmp to beats per audio sample

    const bpm2bpa = 1 / (60 * this.sampleRate)

tick is binded to this

    this.tick = () => vm.resume(this.bpm * bpm2bpa)
    this.Gibberish.sequencers.push({ tick: this.tick })
  }
}

¶

Instruments

Create a trigger function for a percussion instrument

const perc = (inst, gain) => (ctx) => {
  inst.amp = gain * ctx.get("amp")
  inst.note()
}

Create a trigger function for a tuned percussion instrument

const pitched = (inst, gain) => (ctx) => {
  inst.amp = gain * ctx.get("amp")
  inst.pitch = ctx.get("freq")
  inst.note()
}

¶

Create the basic instruments using Gibberish
```
function createInstruments (Gibberish) {
```

The actual instruments

  const kick = new Gibberish.Kick({ decay: 0.2 }).connect()
  const snare = new Gibberish.Snare({ snappy: 1.5 }).connect()
  const hat = new Gibberish.Hat({ amp: 1.5 }).connect()
  const conga = new Gibberish.Conga({ amp: 0.25, freq: 400 }).connect()
  const tom = new Gibberish.Tom({ amp: 0.25, freq: 400 }).connect()
  const pluck = new Gibberish.PolyKarplusStrong({maxVoices: 32}).connect()
  const bass = new Gibberish.MonoSynth({
    attack: 44,
    decay: Gibberish.Time.beats(0.25),
    filterMult: 0.25,
    octave2: 0,
    octave3: 0
  }).connect()
  const sampleRate = Gibberish.sampleRate

The instrument trigger functions

  return {
    kick: perc(kick, 0.5),
    snare: perc(snare, 0.25),
    hat: perc(hat, 1),
    conga: pitched(conga, 0.25),
    tom: pitched(tom, 0.25),
    pluck: (ctx) => {
      const amp = ctx.get("amp")
      const freq = ctx.get("freq")
      if (freq > 0) {

¶

this is not in any way accurate, just a hack to make @set-dur do something semi-meaningful
```
        pluck.damping = 1 - (-6 / Math.log(freq / sampleRate))
```

pluck by default seem too quiet:

        pluck.note(freq, amp * amp * 2)
      }
    },
    bass: (ctx) => {
      const velocity = ctx.get("amp")
      const freq = ctx.get("freq")
      if (freq > 0) bass.note(freq, velocity)
    }
  }
}