tone/Tone/core/worklet/SingleIOProcessor.worklet.ts

A Web Audio framework for making interactive music in the browser.

import "./ToneAudioWorkletProcessor.worklet.js";
import { addToWorklet } from "./WorkletGlobalScope.js";

export const singleIOProcess = /* javascript */ `
	/**
	 * Abstract class for a single input/output processor. 
	 * has a 'generate' function which processes one sample at a time
	 */
	class SingleIOProcessor extends ToneAudioWorkletProcessor {

		constructor(options) {
			super(Object.assign(options, {
				numberOfInputs: 1,
				numberOfOutputs: 1
			}));
			/**
			 * Holds the name of the parameter and a single value of that
			 * parameter at the current sample
			 * @type { [name: string]: number }
			 */
			this.params = {}
		}

		/**
		 * Generate an output sample from the input sample and parameters
		 * @abstract
		 * @param input number
		 * @param channel number
		 * @param parameters { [name: string]: number }
		 * @returns number
		 */
		generate(){}

		/**
		 * Update the private params object with the 
		 * values of the parameters at the given index
		 * @param parameters { [name: string]: Float32Array },
		 * @param index number
		 */
		updateParams(parameters, index) {
			for (const paramName in parameters) {
				const param = parameters[paramName];
				if (param.length > 1) {
					this.params[paramName] = parameters[paramName][index];
				} else {
					this.params[paramName] = parameters[paramName][0];
				}
			}
		}

		/**
		 * Process a single frame of the audio
		 * @param inputs Float32Array[][]
		 * @param outputs Float32Array[][]
		 */
		process(inputs, outputs, parameters) {
			const input = inputs[0];
			const output = outputs[0];
			// get the parameter values
			const channelCount = Math.max(input && input.length || 0, output.length);
			for (let sample = 0; sample < this.blockSize; sample++) {
				this.updateParams(parameters, sample);
				for (let channel = 0; channel < channelCount; channel++) {
					const inputSample = input && input.length ? input[channel][sample] : 0;
					output[channel][sample] = this.generate(inputSample, channel, this.params);
				}
			}
			return !this.disposed;
		}
	};
`;

addToWorklet(singleIOProcess);