Tone.js/Tone/core/context/Offline.ts
Yotam Mann f17249691d feat: updating all examples
now in the form Tone.Something instead of using `import { Something } from "tone"`. It makes the example runner on the docs page work much faster
2020-04-16 22:24:18 -04:00

65 lines
2.3 KiB
TypeScript

import { getContext, setContext } from "../Global";
import { Seconds } from "../type/Units";
import { OfflineContext } from "./OfflineContext";
import { ToneAudioBuffer } from "./ToneAudioBuffer";
/**
* Generate a buffer by rendering all of the Tone.js code within the callback using the OfflineAudioContext.
* The OfflineAudioContext is capable of rendering much faster than real time in many cases.
* The callback function also passes in an offline instance of [[Context]] which can be used
* to schedule events along the Transport.
* @param callback All Tone.js nodes which are created and scheduled within this callback are recorded into the output Buffer.
* @param duration the amount of time to record for.
* @return The promise which is invoked with the ToneAudioBuffer of the recorded output.
* @example
* // render 2 seconds of the oscillator
* Tone.Offline(() => {
* // only nodes created in this callback will be recorded
* const oscillator = new Tone.Oscillator().toDestination().start(0);
* }, 2).then((buffer) => {
* // do something with the output buffer
* console.log(buffer);
* });
* @example
* // can also schedule events along the Transport
* // using the passed in Offline Transport
* Tone.Offline(({ transport }) => {
* const osc = new Tone.Oscillator().toDestination();
* transport.schedule(time => {
* osc.start(time).stop(time + 0.1);
* }, 1);
* // make sure to start the transport
* transport.start(0.2);
* }, 4).then((buffer) => {
* // do something with the output buffer
* console.log(buffer);
* });
* @category Core
*/
export async function Offline(
callback: (context: OfflineContext) => Promise<void> | void,
duration: Seconds,
channels = 2,
sampleRate: number = getContext().sampleRate,
): Promise<ToneAudioBuffer> {
// set the OfflineAudioContext based on the current context
const originalContext = getContext();
const context = new OfflineContext(channels, duration, sampleRate);
setContext(context);
// invoke the callback/scheduling
await callback(context);
// then render the audio
const bufferPromise = context.render();
// return the original AudioContext
setContext(originalContext);
// await the rendering
const buffer = await bufferPromise;
// return the audio
return new ToneAudioBuffer(buffer);
}