Waveform Playlist

Inspired by Audacity, this project is a multiple track playlist editor written in ES2015 using the Web Audio API.

Load tracks and set cues (track cue in, cue out), fades (track fade in, fade out) and track start/end times within the playlist. I've written up some demos on github for the different audio fade types in the project.

See examples in action

(code for picture shown can be found in dist/examples/stem-tracks.html)

Try out the waveform editor!

Browser Support

Waveform Playlist requires webaudio in the browser to function correctly: Can I Use?

Installation

npm install waveform-playlist

• If you want to download and run the already compiled website, navigate to folder /dist and run python -m SimpleHTTPServer 8000. The website will be available at localhost:8000/waveform-playlist.

Basic Usage

Starter styles can be found in the npm package download at waveform-playlist/styles/playlist.scss

var WaveformPlaylist = require('waveform-playlist');

var playlist = WaveformPlaylist.init({
  samplesPerPixel: 3000,
  mono: true,
  waveHeight: 70,
  container: document.getElementById('playlist'),
  state: 'cursor',
  colors: {
    waveOutlineColor: '#E0EFF1',
    timeColor: 'grey',
    fadeColor: 'black'
  },
  controls: {
    show: true,
    width: 200
  },
  zoomLevels: [500, 1000, 3000, 5000]
});

playlist.load([
  {
    src: 'media/audio/Vocals30.mp3',
    name: 'Vocals',
    gain: 0.5,
  },
  {
    src: 'media/audio/BassDrums30.mp3',
    name: 'Drums',
    start: 8.5,
    fadeIn: {
      duration: 0.5,
    },
    fadeOut: {
      shape: 'logarithmic',
      duration: 0.5,
    },
  },
  {
    src: 'media/audio/Guitar30.mp3',
    name: 'Guitar',
    start: 23.5,
    fadeOut: {
      shape: 'linear',
      duration: 0.5,
    },
    cuein: 15,
  }
]).then(function() {
  // can do stuff with the playlist.
});

Playlist Options

var options = {

  // webaudio api AudioContext
  ac: new (window.AudioContext || window.webkitAudioContext),

  // DOM container element REQUIRED
  container: document.getElementById('playlist'),

  // sample rate of the project. (used for correct peaks rendering)
  sampleRate: new (window.AudioContext || window.webkitAudioContext).sampleRate,

  // number of audio samples per waveform peak.
  // must be an entry in option: zoomLevels.
  samplesPerPixel: 4096,

  // whether to draw multiple channels or combine them.
  mono: true,

  // enables "exclusive solo" where solo switches between tracks
  exclSolo: false,

  // default fade curve type.
  fadeType: 'logarithmic', // (logarithmic | linear | sCurve | exponential)

  // whether or not to include the time measure.
  timescale: false,

  // control panel on left side of waveform
  controls: {
    // whether or not to include the track controls
    show: false,

    // width of controls in pixels
    width: 150,
  },

  colors: {
    // color of the wave background
    waveOutlineColor: 'white',

    // color of the time ticks on the canvas
    timeColor: 'grey',

    // color of the fade drawn on canvas
    fadeColor: 'black',
  },

  // height in pixels of each canvas element a waveform is on.
  waveHeight: 128,

  // interaction state of the playlist
  // (cursor | select | fadein | fadeout | shift)
  state: 'cursor',

  // (line | fill)
  seekStyle : 'line',

  // Array of zoom levels in samples per pixel.
  // Smaller numbers have a greater zoom in.
  zoomLevels: [512, 1024, 2048, 4096],
};

Track Options

{
  // a media path for XHR or a File object.
  src: 'media/audio/BassDrums30.mp3',

  // name that will display in the playlist control panel.
  name: 'Drums',

  // volume level of the track between [0-1]
  gain: 1,

  // whether the track should initially be muted.
  muted: false,

  // whether the track should initially be soloed.
  soloed: false,

  // time in seconds relative to the playlist
  // ex (track will start after 8.5 seconds)
  / /DEFAULT 0 - track starts at beginning of playlist
  start: 8.5,

  // track fade in details
  fadeIn: {
    // fade curve shape
    // (logarithmic | linear | sCurve | exponential)
    shape: 'logarithmic',

    // length of fade starting from the beginning of this track, in seconds.
    duration: 0.5,
  },

  // track fade out details
  fadeOut: {
    // fade curve shape
    // (logarithmic | linear | sCurve | exponential)
    shape: 'logarithmic',

    //length of fade which reaches the end of this track, in seconds.
    duration: 0.5,
  }

  // where the waveform for this track should begin from
  // ex (Waveform will begin 15 seconds into this track)
  // DEFAULT start at the beginning - 0 seconds
  cuein: 15,

  // where the waveform for this track should end
  // ex (Waveform will end at 30 second into this track)
  // DEFAULT duration of the track
  cueout: 30,

  // custom class for unique track styling
  customClass: 'vocals',

  // custom background-color for the canvas-drawn waveform
  waveOutlineColor: '#f3f3f3',

  // interaction states allowed on this track.
  // DEFAULT - all true
  states: {
    cursor: true,
    fadein: true,
    fadeout: true,
    select: true,
    shift: true,
  },

  // pre-selected section on track.
  // ONLY ONE selection is permitted in a list of tracks, will take most recently set if multiple passed.
  // This track is marked as 'active'
  selected: {
    // start time of selection in seconds, relative to the playlist
    start: 5,

    // end time of selection in seconds, relative to the playlist
    end: 15,
  },
}

Playlist Events

Waveform Playlist uses an instance of event-emitter to send & receive messages from the playlist.

var EventEmitter = require('event-emitter');
var WaveformPlaylist = require('waveform-playlist');

var playlist = WaveformPlaylist.init(
  {
    container: document.getElementById('playlist'),
  },

  // you can pass your own event emitter
  EventEmitter(),
);

// retrieves the event emitter the playlist is using.
var ee = playlist.getEventEmitter();

An example of using the event emitter to control the playlist can be found in /dist/js/examples/emitter.js

Events to Invoke

event	arguments	description
play	start:optional, end:optional	Starts playout of the playlist. Takes optional Number parameters in seconds start and end to play just an audio segment. start can be passed without an end to play to the end of the track.
pause	none	Pauses playout of the playlist.
stop	none	Stops playout of the playlist.
rewind	none	Stops playout if playlist is playing, resets cursor to the beginning of the playlist.
fastforward	none	Stops playout if playlist is playing, resets cursor to the end of the playlist.
clear	none	Stops playout if playlist is playing, removes all tracks from the playlist.
record	none	Starts recording an audio track. Begins playout of other tracks in playlist if there are any.
zoomin	none	Changes zoom level to the next smallest entry (if one exists) from the array zoomLevels.
zoomout	none	Changes zoom level to the next largest entry (if one exists) from the array zoomLevels.
trim	none	Trims currently active track to the cursor selection.
statechange	(`cursor	select
fadetype	(`logarithmic	linear
newtrack	File	Loads File object into the playlist.
volumechange	volume, track	Set volume of track to volume (0-100)
mastervolumechange	volume	Set a new master volume volume (0-100)
select	start, end, track:optional	Seek to the start time or start/end selection optionally with active track track.
startaudiorendering	(`wav	buffer`)
speedchange	speed	Change de playback speed. Minimum is 0.5x and maximum is 4x
loopnumber	number	-1 : infinite loop. number > 1 : perform number loops. 0 : disable loops

Events to Listen to

event	arguments	description
select	start, end, track	Cursor selection has occurred from start to end with active Track track.
timeupdate	playbackPosition	Sends current position of playout playbackPosition in seconds.
scroll	scrollLeft	Sends current position of scroll scrollLeft in seconds.
statechange	state	Sends current interaction state state.
shift	deltaTime, track	Sends deltaTime in seconds change for Track track
mute	track	Mute button has been pressed for track
solo	track	Solo button has been pressed for track
volumechange	volume, track	Volume of track has changed to volume (0-100)
mastervolumechange	volume	Master volume of the playlist has changed to volume (0-100)
audiorequeststatechange	state, src	Loading audio src (string or File) is now in state state (Number)
loadprogress	percent, src	Loading audio src has loaded percent percent (0-100)
audiosourcesloaded	none	Audio decoding has finished for all tracks
audiosourcesrendered	none	Tracks are rendered to the playlist
finished	none	Event fired when cursor ( while playing ) reaches the end (maximum duration)
audiorenderingfinished	type, data	Return the result of the rendering in the desired format. type can be buffer or wav and can be used to dertermine the data type. When type is wav, data is a blob object that represent the wav file.
speedchanged	speed	When speed is changed, return the value applied to tracks.
newloop	remaining	Event fired when one loop finish, and give the number of remaining loops to come

Tests

npm test

Development

npm start

http://localhost:8080/waveform-playlist/

This will build the jekyll site and startup the webpack dev server.

npm run jekyll:dev

This can be run to continuously build the jekyll pages as well if they are modified.

Credits

Originally created for the Airtime project at Sourcefabric

License

MIT License