BB.AudioSequencer

Defined in: src/BB.AudioSequencer.js:10

The Web Audio API exposes access to the audio subsystem’s hardware clock ( the “audio clock” via .currentTime ). This is used for precisely scheduling parameters and events, much more precise than the JavaScript clock ( ie. Date.now(), setTimeout() ). However, once scheduled audio parameters and events can not be modified ( ex. you can’t change the tempo or pitch when something has already been scheduled... even if it hasn't started playing ). the BB.AudioSequencer is a collaboration between the audio clock and JavaScript clock based on Chris Wilson’s article, A Tale of Two Clocks - Scheduling Web Audio with Precision which solves this problem.

Index

Properties

Methods

Constructor

BB.AudioSequencer
(
  • config
)

Defined in src/BB.AudioSequencer.js:10

Parameters:

  • config Object

    A config object to initialize the Sequencer, use keys "whole", "half", "quarter", "sixth", "eighth" and "sixteenth" to schedule events at those times in a measure additional (optional) config parameters include:  {
        multitrack: false, // play only once sample at a given beat
        noteResolution: 1, // play only 8th notes (see below)
        scheduleAheadTime: 0.2 // schedule 200ms ahead (see below)
        tempo: 150, // 150 beats per minute
     }

Example:

the BB.AudioSequencer only handles scheduling ( it doesn't create any AudioNodes ), but it does require a BB.Audio.context because it uses the context.currentTime to property schedule events
 BB.Audio.init();

 // create AudioSequencer ( with optional parameters )
 // assuming drum is an instanceof BB.AudioSampler
 var track = new BB.AudioSequencer({
   tempo: 140, // in bpm

   whole: function( time ){
     drum.play('kick', time );
   },
   quarter: function( time ){
     drum.play('snare', time );
   },
   sixteenth: function( time ){
     drum.play('hat', time );
   }
 });

view basic BB.AudioSequencer example

Properties

bars Number default:1

Defined in src/BB.AudioSequencer.js:87

how many measures per sequence

current16thNote Number

Defined in src/BB.AudioSequencer.js:109

returns the current note

currentBar Number

Defined in src/BB.AudioSequencer.js:95

current measure being played

isPlaying Boolean default:false

Defined in src/BB.AudioSequencer.js:101

whether or not sequencer is playing

multitrack Boolean default:true

Defined in src/BB.AudioSequencer.js:137

whether or not to play more than one sample at a given beat

noteResolution Number default:0

Defined in src/BB.AudioSequencer.js:126

0: play all 16th notes, 1: play only 8th notes, 2: play only quarter notes

scheduleAheadTime Number default:0.1

Defined in src/BB.AudioSequencer.js:118

how far ahead to schedule the audio (seconds), adjust for sweet spot ( smaller the better/tighter, but the buggier/more demanding)

tempo Number default:120

Defined in src/BB.AudioSequencer.js:79

tempo in beats per minute

There are no properties that match your current filter settings. You can change your filter settings in the index section on this page. index

Methods

nextNote () protected

Defined in src/BB.AudioSequencer.js:265

advance current note and time by a 16th note

scheduleNote () protected

Defined in src/BB.AudioSequencer.js:235

schedules appropriate note based on noteResolution && beatNumber ( ie current16thNote )

toggle
(
  • [type]
)

Defined in src/BB.AudioSequencer.js:184

toggles play/stop or play/pause

Parameters:

  • [type] String optional

    toggles play/pause instead of default play/stop

Example:

 // toggles start/stop (ie. starts from beginning each time)
 track.toggle();
 // toggles play/pause (ie. starts from where last puased )
 track.toggle("pause");

update ()

Defined in src/BB.AudioSequencer.js:211

advances to the next note ( when it's time )

Example:

 // in update loop
 if(track.isPlaying) track.update();

There are no methods that match your current filter settings. You can change your filter settings in the index section on this page. index