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Tone.js is a Web Audio framework for creating interactive music in the browser. The architecture of Tone.js aims to be familiar to both musicians and audio programmers creating web-based audio applications. On the high-level, Tone offers common DAW (digital audio workstation) features like a global transport for synchronizing and scheduling events as well as prebuilt synths and effects. Additionally, Tone provides high-performance building blocks to create your own synthesizers, effects, and complex control signals.

• API
• Examples

There are two ways to incorporate Tone.js into a project. First, it can be installed locally into a project usingnpm:

npm install tone      // Install the latest stable versionnpm install tone@next // Or, alternatively, use the'next' version

Add Tone.js to a project using the JavaScriptimport syntax:

import*asTonefrom"tone";

Tone.js is also hosted at unpkg.com. It can be added directly within an HTML document, as long as it precedes any project scripts.See the example here for more details.

<scriptsrc="http://unpkg.com/tone"></script>

//create a synth and connect it to the main output (your speakers)constsynth=newTone.Synth().toDestination();//play a middle 'C' for the duration of an 8th notesynth.triggerAttackRelease("C4","8n");

Tone.Synth is a basic synthesizer with a single oscillator and an ADSR envelope.

triggerAttack starts the note (the amplitude is rising), andtriggerRelease is when the amplitude is going back to 0 (i.e.note off).

constsynth=newTone.Synth().toDestination();constnow=Tone.now();// trigger the attack immediatelysynth.triggerAttack("C4",now);// wait one second before triggering the releasesynth.triggerRelease(now+1);

triggerAttackRelease is a combination oftriggerAttack andtriggerRelease

The first argument to the note which can either be a frequency in hertz (like440) or as "pitch-octave" notation (like"D#2").

The second argument is the duration that the note is held. This value can either be in seconds, or as atempo-relative value.

The third (optional) argument oftriggerAttackRelease iswhen along the AudioContext time the note should play. It can be used to schedule events in the future.

constsynth=newTone.Synth().toDestination();constnow=Tone.now();synth.triggerAttackRelease("C4","8n",now);synth.triggerAttackRelease("E4","8n",now+0.5);synth.triggerAttackRelease("G4","8n",now+1);

Web Audio has advanced, sample accurate scheduling capabilities. The AudioContext time is what the Web Audio API uses to schedule events, starts at 0 when the page loads and counts up inseconds.

Tone.now() gets the current time of the AudioContext.

setInterval(()=>console.log(Tone.now()),100);

Tone.js abstracts away the AudioContext time. Instead of defining all values in seconds, any method which takes time as an argument can accept a number or a string. For example"4n" is a quarter-note,"8t" is an eighth-note triplet, and"1m" is one measure.

Read about Time encodings.

IMPORTANT: Browsers will not playany audio until a user clicks something (like a play button). Run your Tone.js code only after callingTone.start() from a event listener which is triggered by a user action such as "click" or "keydown".

Tone.start() returns a promise, the audio will be ready only after that promise is resolved. Scheduling or playing audio before the AudioContext is running will result in silence or incorrect scheduling.

//attach a click listener to a play buttondocument.querySelector("button")?.addEventListener("click",async()=>{awaitTone.start();console.log("audio is ready");});

Tone.getTransport() returns the main timekeeper. Unlike the AudioContext clock, it can be started, stopped, looped and adjusted on the fly. You can think of it like the arrangement view in a Digital Audio Workstation.

Multiple events and parts can be arranged and synchronized along the Transport.Tone.Loop is a simple way to create a looped callback that can be scheduled to start and stop.

// create two monophonic synthsconstsynthA=newTone.FMSynth().toDestination();constsynthB=newTone.AMSynth().toDestination();//play a note every quarter-noteconstloopA=newTone.Loop((time)=>{synthA.triggerAttackRelease("C2","8n",time);},"4n").start(0);//play another note every off quarter-note, by starting it "8n"constloopB=newTone.Loop((time)=>{synthB.triggerAttackRelease("C4","8n",time);},"4n").start("8n");// all loops start when the Transport is startedTone.getTransport().start();// ramp up to 800 bpm over 10 secondsTone.getTransport().bpm.rampTo(800,10);

Since Javascript callbacks arenot precisely timed, the sample-accurate time of the event is passed into the callback function.Use this time value to schedule the events.

There are numerous synths to choose from includingTone.FMSynth,Tone.AMSynth andTone.NoiseSynth.

All of these instruments aremonophonic (single voice) which means that they can only play one note at a time.

To create apolyphonic synthesizer, useTone.PolySynth, which accepts a monophonic synth as its first parameter and automatically handles the note allocation so you can pass in multiple notes. The API is similar to the monophonic synths, excepttriggerRelease must be given a note or array of notes.

constsynth=newTone.PolySynth(Tone.Synth).toDestination();constnow=Tone.now();synth.triggerAttack("D4",now);synth.triggerAttack("F4",now+0.5);synth.triggerAttack("A4",now+1);synth.triggerAttack("C5",now+1.5);synth.triggerAttack("E5",now+2);synth.triggerRelease(["D4","F4","A4","C5","E5"],now+4);

Sound generation is not limited to synthesized sounds. You can also load a sample and play that back in a number of ways.Tone.Player is one way to load and play back an audio file.

constplayer=newTone.Player("https://tonejs.github.io/audio/berklee/gong_1.mp3").toDestination();Tone.loaded().then(()=>{player.start();});

Tone.loaded() returns a promise which resolves whenall audio files are loaded. It's a helpful shorthand instead of waiting on each individual audio buffer'sonload event to resolve.

Multiple samples can also be combined into an instrument. If you have audio files organized by note,Tone.Sampler will pitch shift the samples to fill in gaps between notes. So for example, if you only have every 3rd note on a piano sampled, you could turn that into a full piano sample.

Unlike the other synths, Tone.Sampler is polyphonic so doesn't need to be passed into Tone.PolySynth

constsampler=newTone.Sampler({urls:{C4:"C4.mp3","D#4":"Ds4.mp3","F#4":"Fs4.mp3",A4:"A4.mp3",},release:1,baseUrl:"https://tonejs.github.io/audio/salamander/",}).toDestination();Tone.loaded().then(()=>{sampler.triggerAttackRelease(["Eb4","G4","Bb4"],4);});

In the above examples, the sources were always connected directly to theDestination, but the output of the synth could also be routed through one (or more) effects before going to the speakers.

constplayer=newTone.Player({url:"https://tonejs.github.io/audio/berklee/gurgling_theremin_1.mp3",loop:true,autostart:true,});//create a distortion effectconstdistortion=newTone.Distortion(0.4).toDestination();//connect a player to the distortionplayer.connect(distortion);

The connection routing is flexible, connections can run serially or in parallel.

constplayer=newTone.Player({url:"https://tonejs.github.io/audio/drum-samples/loops/ominous.mp3",autostart:true,});constfilter=newTone.Filter(400,"lowpass").toDestination();constfeedbackDelay=newTone.FeedbackDelay(0.125,0.5).toDestination();// connect the player to the feedback delay and filter in parallelplayer.connect(filter);player.connect(feedbackDelay);

Multiple nodes can be connected to the same input enabling sources to share effects.Tone.Gain is useful utility node for creating complex routing.

Like the underlying Web Audio API, Tone.js is built with audio-rate signal control over nearly everything. This is a powerful feature which allows for sample-accurate synchronization and scheduling of parameters.

Signal properties have a few built in methods for creating automation curves.

For example, thefrequency parameter onOscillator is a Signal so you can create a smooth ramp from one frequency to another.

constosc=newTone.Oscillator().toDestination();// start at "C4"osc.frequency.value="C4";// ramp to "C2" over 2 secondsosc.frequency.rampTo("C2",2);// start the oscillator for 2 secondsosc.start().stop("+3");

Tone.js creates an AudioContext when it loads and shims it for maximum browser compatibility usingstandardized-audio-context. The AudioContext can be accessed atTone.getContext. Or set your own AudioContext usingTone.setContext(audioContext).

To use MIDI files, you'll first need to convert them into a JSON format which Tone.js can understand usingMidi.

Tone.js makes extensive use of the native Web Audio Nodes such as the GainNode and WaveShaperNode for all signal processing, which enables Tone.js to work well on both desktop and mobile browsers.

This wiki article has some suggestions related to performance for best practices.

Tone.js runs an extensive test suite usingmocha andchai with nearly 100% coverage. Passing builds on the 'dev' branch are published on npm astone@next.

There are many ways to contribute to Tone.js. Check outthis wiki if you're interested.

• Many of Chris Wilson's Repositories
• Many of Mohayonao's Repositories
• The Spec
• Sound on Sound - Synth Secrets
• Miller Puckette - Theory and Techniques of Electronic Music
• standardized-audio-context