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Adding loop functionality to Sampler (#1310) #1350

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5fd18ca
Adding loop functionality to Sampler (#1310)
Caden-Hornyak Jun 4, 2025
2631c37
Addressed nits and fixed linting errors
Caden-Hornyak Jun 22, 2025
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93 changes: 93 additions & 0 deletions Tone/instrument/Sampler.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ import { CompareToFile } from "../../test/helper/CompareToFile.js";
import { InstrumentTest } from "../../test/helper/InstrumentTests.js";
import { atTime, Offline } from "../../test/helper/Offline.js";
import { ToneAudioBuffer } from "../core/context/ToneAudioBuffer.js";
import { getContext } from "../core/Global.js";
import { Sampler } from "./Sampler.js";

describe("Sampler", () => {
Expand Down Expand Up @@ -56,6 +57,7 @@ describe("Sampler", () => {
{
attack: 0.2,
release: 0.3,
loop: true
}
);
expect(sampler.attack).to.equal(0.2);
Expand Down Expand Up @@ -267,6 +269,97 @@ describe("Sampler", () => {
});
});

context("Looping", () => {

it("can be set to loop", () => {
const sampler = new Sampler();
sampler.loop = true;
expect(sampler.loop).to.be.true;
sampler.dispose();
});

it("can set the loop points", () => {
const sampler = new Sampler();
sampler.loopStart = 0.2;
expect(sampler.loopStart).to.equal(0.2);
sampler.loopEnd = 0.7;
expect(sampler.loopEnd).to.equal(0.7);
sampler.setLoopPoints(0, 0.5);
expect(sampler.loopStart).to.equal(0);
expect(sampler.loopEnd).to.equal(0.5);
sampler.dispose();
});

it("loops the audio", async () => {
const buff = await Offline(() => {
const sampler = new Sampler({
urls: {
A4: A4_buffer
}
});
sampler.loop = true;
sampler.toDestination();
sampler.triggerAttack("A4");
}, A4_buffer.duration * 1.5);
expect(buff.getRmsAtTime(0)).to.be.above(0);
expect(buff.getRmsAtTime(A4_buffer.duration * 0.5)).to.be.above(0);
expect(buff.getRmsAtTime(A4_buffer.duration)).to.be.above(0);
expect(buff.getRmsAtTime(A4_buffer.duration * 1.2)).to.be.above(0);
});

it("setting the loop multiple times has no affect", async () => {
const buff = await Offline(() => {
const sampler = new Sampler({
urls: {
A4: A4_buffer
}
});
sampler.loop = true;
sampler.loop = true;
sampler.toDestination();
sampler.triggerAttack("A4");
}, A4_buffer.duration * 1.5);
expect(buff.getRmsAtTime(0)).to.be.above(0);
expect(buff.getRmsAtTime(A4_buffer.duration * 0.5)).to.be.above(0);
expect(buff.getRmsAtTime(A4_buffer.duration)).to.be.above(0);
expect(buff.getRmsAtTime(A4_buffer.duration * 1.2)).to.be.above(0);
});

it("loops the audio when loop is set after start", async () => {
const buff = await Offline(() => {
const sampler = new Sampler({
urls: {
A4: A4_buffer
}
});
sampler.toDestination();
sampler.triggerAttack("A4");
sampler.loop = true;
}, A4_buffer.duration * 1.5);
expect(buff.getRmsAtTime(0)).to.be.above(0);
expect(buff.getRmsAtTime(A4_buffer.duration * 0.5)).to.be.above(0);
expect(buff.getRmsAtTime(A4_buffer.duration)).to.be.above(0);
expect(buff.getRmsAtTime(A4_buffer.duration * 1.2)).to.be.above(0);
});

it("starts buffers at loopStart when set to loop", async () => {
const testSample =
A4_buffer.toArray(0)[Math.floor(0.1 * getContext().sampleRate)];
const buff = await Offline(() => {
const sampler = new Sampler({
urls: {
A4: A4_buffer
}
});
sampler.loopStart = 0.1;
sampler.loop = true;
sampler.toDestination();
sampler.triggerAttack("A4");
}, 0.05);
expect(buff.toArray()[0][0]).to.equal(testSample);
});
});

context("add samples", () => {
it("can add a note with its midi value", async () => {
const buffer = await Offline(() => {
Expand Down
134 changes: 131 additions & 3 deletions Tone/instrument/Sampler.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -10,9 +10,9 @@ import {
Note,
Time,
} from "../core/type/Units.js";
import { assert } from "../core/util/Debug.js";
import { assert, assertRange } from "../core/util/Debug.js";
import { timeRange } from "../core/util/Decorator.js";
import { optionsFromArguments } from "../core/util/Defaults.js";
import { defaultArg, optionsFromArguments } from "../core/util/Defaults.js";
import { noOp } from "../core/util/Interface.js";
import { isArray, isNote, isNumber } from "../core/util/TypeCheck.js";
import { Instrument, InstrumentOptions } from "../instrument/Instrument.js";
Expand All @@ -34,6 +34,9 @@ export interface SamplerOptions extends InstrumentOptions {
baseUrl: string;
curve: ToneBufferSourceCurve;
urls: SamplesMap;
loop: boolean;
loopEnd: number;
loopStart: number;
}

/**
Expand Down Expand Up @@ -70,6 +73,26 @@ export class Sampler extends Instrument<SamplerOptions> {
*/
private _activeSources: Map<MidiNote, ToneBufferSource[]> = new Map();

/**
* The list of all provided midi notes
*/
private _providedMidiNotes: MidiNote[] = [];

/**
* if the buffer should loop once its over
*/
private _loop: boolean;

/**
* if 'loop' is true, the loop will start at this position
*/
private _loopStart: Time;

/**
* if 'loop' is true, the loop will end at this position
*/
private _loopEnd: Time;

/**
* The envelope applied to the beginning of the sample.
* @min 0
Expand Down Expand Up @@ -144,6 +167,9 @@ export class Sampler extends Instrument<SamplerOptions> {
this.attack = options.attack;
this.release = options.release;
this.curve = options.curve;
this._loop = options.loop;
this._loopStart = options.loopStart;
this._loopEnd = options.loopEnd;

// invoke the callback if it's already loaded
if (this._buffers.loaded) {
Expand All @@ -161,6 +187,9 @@ export class Sampler extends Instrument<SamplerOptions> {
onerror: noOp,
release: 0.1,
urls: {},
loop: false,
loopEnd: 0,
loopStart: 0,
});
}

Expand Down Expand Up @@ -197,6 +226,7 @@ export class Sampler extends Instrument<SamplerOptions> {
if (!Array.isArray(notes)) {
notes = [notes];
}
const offset = defaultArg(this._loopStart, 0);
notes.forEach((note) => {
const midiFloat = ftomf(
new FrequencyClass(this.context, note).toFrequency()
Expand All @@ -210,16 +240,22 @@ export class Sampler extends Instrument<SamplerOptions> {
const playbackRate = intervalToFrequencyRatio(
difference + remainder
);
const duration = this._loop
? undefined
: buffer.duration / playbackRate;
// play that note
const source = new ToneBufferSource({
url: buffer,
context: this.context,
curve: this.curve,
fadeIn: this.attack,
fadeOut: this.release,
loop: this._loop,
loopStart: this._loopStart,
loopEnd: this._loopEnd,
playbackRate,
}).connect(this.output);
source.start(time, 0, buffer.duration / playbackRate, velocity);
source.start(time, offset, duration, velocity);
// add it to the active sources
if (!isArray(this._activeSources.get(midi))) {
this._activeSources.set(midi, []);
Expand Down Expand Up @@ -357,6 +393,98 @@ export class Sampler extends Instrument<SamplerOptions> {
return this._buffers.loaded;
}

/**
* Set the loop start and end. Will only loop if loop is set to true.
* @param loopStart The loop start time
* @param loopEnd The loop end time
* @example
* const sampler = new Tone.Sampler({
* urls: {
* A1: "https://tonejs.github.io/audio/berklee/guitar_chord4.mp3",
* },
* }).toDestination();
* // loop between the given points
* sampler.setLoopPoints(0.2, 0.3);
* sampler.loop = true;
*/
setLoopPoints(loopStart: Time, loopEnd: Time): this {
this.loopStart = loopStart;
this.loopEnd = loopEnd;
return this;
}

/**
* If loop is true, the loop will start at this position.
*/
get loopStart(): Time {
return this._loopStart;
}
set loopStart(loopStart) {
this._loopStart = loopStart;
this._providedMidiNotes.forEach((midiNote) => {
const buffer = this._buffers.get(midiNote);
if (buffer.loaded) {
assertRange(this.toSeconds(loopStart), 0, buffer.duration);
}
});
// get the current sources
this._activeSources.forEach((sourceList) => {
sourceList.forEach((source) => {
source.loopStart = loopStart;
});
});
}

/**
* If loop is true, the loop will end at this position.
*/
get loopEnd(): Time {
return this._loopEnd;
}
set loopEnd(loopEnd) {
this._loopEnd = loopEnd;
this._providedMidiNotes.forEach((midiNote) => {
const buffer = this._buffers.get(midiNote);
if (buffer.loaded) {
assertRange(this.toSeconds(loopEnd), 0, buffer.duration);
}
});
// get the current sources
this._activeSources.forEach((sourceList) => {
sourceList.forEach((source) => {
source.loopEnd = loopEnd;
});
});
}


/**
* If the buffers should loop once they are over.
* @example
* const sampler = new Tone.Sampler({
* urls: {
* A4: "https://tonejs.github.io/audio/berklee/femalevoice_aa_A4.mp3",
* },
* }).toDestination();
* sampler.loop = true;
*/
get loop(): boolean {
return this._loop;
}
set loop(loop) {
// if no change, do nothing
if (this._loop === loop) {
return;
}
this._loop = loop;
// set the loop of all of the sources
this._activeSources.forEach((sourceList) => {
sourceList.forEach((source) => {
source.loop = loop;
});
});
}

/**
* Clean up
*/
Expand Down