A plugin to analyse audio level for 100ms local peer.

AnalyserAudioPlugin.js

import { HMSAudioPluginType } from "@100mslive/react-sdk";

export class AnalyserPlugin {
  name = "analyser-plugin";
  onChange = () => {};
  analyserNode = undefined;

  constructor(onChange) {
    this.onChange = onChange;
  }

  checkSupport() {
    return { isSupported: true };
  }

  async processAudioTrack(ctx, source) {
    if (!ctx) {
      throw new Error("Audio context is not created");
    }
    if (!source) {
      throw new Error("source is not defined");
    }
    this.analyserNode = ctx.createAnalyser();
    source.connect(this.analyserNode);
    this.calculateAudioLevel();
    return source;
  }

  calculateAudioLevel = () => {
    if (!this.analyserNode) {
      return;
    }

    const data = new Uint8Array(this.analyserNode.fftSize);
    this.analyserNode.getByteTimeDomainData(data);
    const lowest = 0.009;
    let max = lowest;
    for (const frequency of data) {
      max = Math.max(max, (frequency - 128) / 128);
    }
    const normalized = (Math.log(lowest) - Math.log(max)) / Math.log(lowest);
    const percent = Math.ceil(Math.min(Math.max(normalized * 100, 0), 100));
    this.onChange(percent);
    requestAnimationFrame(this.calculateAudioLevel);
  };

  init() {}

  getName() {
    return this.name;
  }

  getPluginType() {
    return HMSAudioPluginType.ANALYZE;
  }

  stop() {
    this.analyserNode?.disconnect();
    this.analyserNode = undefined;
  }
}