ditty

Schedule a looped sequence of Web Audio events using bopper clock source.

You can pipe the output through soundbank-trigger if you want to use with soundbank.

BREAKING CHANGES: The API has changed significantly in the version 2 release. Now supports multiple loop channels with differing lengths.

Install via npm

$ npm install ditty

API

var Ditty = require('ditty')
var ditty = Ditty()

Ditty()

Creates a realtime-transform stream. Pipe in schedule events and stream out the looped events added to the input schedule.time.

var Bopper = require('bopper')
var audioContext = new AudioContext()
var scheduler = Bopper(audioContext)

schedule.pipe(ditty).on('data', function(data){
  // data: id, event (start or stop), time, position, args
  if (data.event == 'start'){
    noteOn(data.id, data.time)
  } else if (data.event == 'stop'){
    noteOff(data.id, data.time)
  }
})

Input:

{
  from: 0,
  to: 1.0,
  time: audioContext.currentTime,
  beatLength: tempo / 60
}

Output:

{
  id: 'C',
  position: 0.5, // preserved from ditty.set
  event: 'start', // or 'stop' for the off note
  time: schedule.time + delta
}

ditty.set(id, events[, loopLength=8])

Schedule a set of start/stop events for the given id. This will override any loop already set on this id.

events is an array of arrays:

[
  [beatPosition, length, args...],
  [beatPosition, length, args...],
  ...
]

// schedule a C -> F -> G -> F midi sequence

ditty.set(60, [ // midi C
  [0, 0.9], [1, 0.9]
], 8)

ditty.set(65, [ // midi F
  [2.0, 0.9], [3.0, 0.9], [5.5, 0.4], [6.5, 0.4], [7.0, 0.4], [7.5, 0.4],
], 8)

ditty.set(67, [ // midi G
  [4.0, 0.4], [5.0, 0.4]
], 8)

ditty.get(id)

Returns the event sequence as set.

ditty.getLength(id)

Returns the loopLength as specified for set.

ditty.getDescriptors()

Returns an array of objects describing the state of all loops.

ditty.update(descriptor)

Push a loop descriptor in to restore the state of the given loop at descriptor.id.

ditty.on('change', function(descriptor))

Whenever a loop is updated, the 'change' event is emitted with the new loop descriptor (id, events, length).

Example

To run the example npm install && npm install --global beefy then beefy example.js and navigate to http://localhost:9966/

mmckegg/ditty