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Waveform Playlist

Inspired byAudacity,this project is a multiple track playlist editor written in ES2015 using theWeb 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 differentaudio fade typesin the project.

• See examples in action
• Try out the waveform editor!

(code for picture shown can be found in ghpages/_examples/04stemtracks.html)

(code for picture shown can be found in ghpages/_examples/13annotations.html)

Browser Support

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

Installation

npm install waveform-playlist --save

Hate npm? Check Unpkg:https://unpkg.com/browse/waveform-playlist/

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

Basic Usage

https://github.com/naomiaro/waveform-playlist/blob/main/examples/basic-html/

https://github.com/naomiaro/waveform-playlist/tree/main/examples/basic-express/

importWaveformPlaylistfrom"waveform-playlist";

varplaylist=WaveformPlaylist({
samplesPerPixel:3000,
mono:true,
waveHeight:70,
container:document.getElementById("playlist"),
state:"cursor",
colors:{
waveOutlineColor:"#E0EFF1",
timeColor:"grey",
fadeColor:"black",
},
controls:{
show:false,
width:150,
},
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

varoptions={
// 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,

// whether to render the widget or not in the controls panel.
widgets:{
// Mute & solo button widget
muteOrSolo:true,

// Volume slider
volume:true,

// Stereo pan slider
stereoPan:true,

// Collapse track button
collapse:true,

// Remove track button
remove:true,
},
},

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,

// width in pixels of waveform bars.
barWidth:1,

// spacing in pixels between waveform bars.
barGap:0,

// 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],

// Whether to automatically scroll the waveform while playing
isAutomaticScroll:false,

// configuration object for the annotations add on.
annotationList:{
// Array of annotations in [Aeneas](https://github.com/readbeyond/aeneas) JSON format
annotations:[],

// Whether the annotation texts will be in updateable contenteditable html elements
editable:false,

// User defined functions which can manipulate the loaded annotations
controls:[
{
// class names for generated <i> tag separated by '.'
class:"fa.fa-minus",

// title attribute for the generated <i> tag
title:"Reduce annotation end by 0.010s",

// function which acts on the given annotation row
// when the corresponding <i> is clicked.
action:(annotation,i,annotations,opts)=>{
// @param Object annotation - current annotation
// @param Number i - index of annotation
// @param Array annotations - array of annotations in the playlist
// @param Object opts - configuration options available
// - opts.linkEndpoints
},
},
],

// If false when clicking an annotation id segment
// playback will stop after segment completion.
isContinuousPlay:false,

// If true annotation endpoints will remain linked when dragged
// if they were the same value before dragging started.
linkEndpoints:false,

// pass a custom function which will receive the mastergainnode for this playlist and the audio context's destination.
// if you pass a function, you must connect these two nodes to hear sound at minimum.
// if you need to clean something up when the graph is disposed, return a cleanup function. Waveform Playlist will cleanup the nodes passed as arguments.
effects:function(masterGainNode,destination,isOffline){
// analyser nodes don't work offline.
if(!isOffline)masterGainNode.connect(analyser);
masterGainNode.connect(destination);

// return function cleanup() {
// // if you create webaudio nodes that need to be cleaned up do that here
// // see the track effects example.
// };
},
},
};

Track Options

{
// a media path for XHR, a Blob, a File, or an AudioBuffer 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,
},

// value from -1 (full left pan) to 1 (full right pan)
stereoPan:0,

// pass a custom function which will receive the last graphnode for this track and the mastergainnode.
// if you pass a function, you must connect these two nodes to hear sound at minimum.
// if you need to clean something up when the graph is disposed, return a cleanup function. Waveform Playlist will cleanup the nodes passed as arguments.
effects:function(graphEnd,masterGainNode,isOffline){
varreverb=newTone.Reverb(1.2);

Tone.connect(graphEnd,reverb);
Tone.connect(reverb,masterGainNode);

returnfunctioncleanup(){
reverb.disconnect();
reverb.dispose();
}
}
}

Playlist Events

Waveform Playlist uses an instance ofevent-emitterto send & receive messages from the playlist.

importEventEmitterfrom"event-emitter";
importWaveformPlaylistfrom"waveform-playlist";

varplaylist=WaveformPlaylist(
{
container:document.getElementById("playlist"),
},

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

// retrieves the event emitter the playlist is using.
varee=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 secondsstartandendto play just an audio segment.startcan be passed without anendto 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 arrayzoomLevels.
zoomout	none	Changes zoom level to the next largest entry (if one exists) from the arrayzoomLevels.
trim	none	Trims currently active track to the cursor selection.
statechange	cursor/select/fadein/fadeout/shift	Changes interaction state to the state given.
fadetype	logarithmic/linear/sCurve/exponential	Changes playlist default fade type.
newtrack	File	LoadsFileobject into the playlist.
volumechange	volume, track	Set volume oftracktovolume(0-100)
mastervolumechange	volume	Set a new master volumevolume(0-100)
select	start, end, track:optional	Seek to the start time or start/end selection optionally with active tracktrack.
startaudiorendering	wav/buffer	Request for a downloadable file or web Audio buffer that represent the current work
automaticscroll	true/false	Change propertyisAutomaticScroll.
continuousplay	true/false	Change propertyisContinuousPlay.
linkendpoints	true/false	Change propertylinkEndpoints.
annotationsrequest	none	Requests to download the annotations to a json file.
stereopan	panvalue, track	Set pan value oftracktopanvalue(-1-1)

Events to Listen to

event	arguments	description
select	start, end, track	Cursor selection has occurred fromstarttoendwith active Tracktrack.
timeupdate	playbackPosition	Sends current position of playoutplaybackPositionin seconds.
scroll	scrollLeft	Sends current position of scrollscrollLeftin seconds.
statechange	state	Sends current interaction statestate.
shift	deltaTime, track	SendsdeltaTimein seconds change for Tracktrack
mute	track	Mute button has been pressed fortrack
solo	track	Solo button has been pressed fortrack
removeTrack	track	Remove button has been pressed fortrack
changeTrackView	track, opts	Collapse button has been pressed fortrack
volumechange	volume, track	Volume oftrackhas changed tovolume(0-100)
mastervolumechange	volume	Master volume of the playlist has changed tovolume(0-100)
audiorequeststatechange	state, src	Loading audiosrc(stringorFile) is now in statestate(Number)
loadprogress	percent, src	Loading audiosrchas loaded percentpercent(0-100)
audiosourcesloaded	none	Audio decoding has finished for all tracks
audiosourcesrendered	none	Tracks are rendered to the playlist
audiosourceserror	err	Error thrown while loading tracks
finished	none	Event fired when cursor ( while playing ) reaches the end (maximum duration)
audiorenderingstarting	offlineCtx, setUpPromiseArray	Event fired after the OfflineAudioContext is created before any rendering begins. If any setup is async before offline redering, push a promise to the setUpPromiseArray.
audiorenderingfinished	type, data	Return the result of the rendering in the desired format.typecan bebufferorwavand can be used to dertermine thedatatype. Whentypeiswav,data is ablobobject that represent the wav file.
stereopan	panvalue, track	Pan value oftrackhas been changed topanvalue

Tests

npm test

Development without example changes

npm install && npm start

This will install dependencies and start the webpack server.

Development with example changes

gem install jekyll

Jekyll is needed if changes to the example pages will be done.

npm install && npm run dev

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

Credits

Originally created for theAirtimeproject atSourcefabric

The annotation plugin has been sponsored by a fond Italian TED volunteer transcriber hoping to make the transcription process of TEDx talks easier and more fun.

Books

Currently writing:Mastering Tone.js.Get notified by Leanpub when I publish.

License

MIT License