interactive-player/dist/interactive-player-processor.js

A front-end interactive music audio player using AudioWorklet for javascript and typescript

// src/interactive-player-processor.ts
var Fader = class {
  constructor(fadeInSamples, fadeOutSamples) {
    this.fadeInStart = 0;
    this.useFadeIn = false;
    this.fadeOutStart = 0;
    this.useFadeOut = false;
    this.fadeOutEvent = null;
    this.fadeInSamples = fadeInSamples;
    this.fadeOutSamples = fadeOutSamples;
  }
  startFadeIn(head) {
    this.fadeInStart = head;
    this.useFadeIn = true;
  }
  startFadeOut(head, event = null) {
    this.fadeOutEvent = event;
    this.fadeOutStart = head;
    this.useFadeOut = true;
  }
  getFadeInStep(head) {
    if (!this.useFadeIn) return 1;
    if (head < this.fadeInStart) return 0;
    if (this.fadeInStart + this.fadeInSamples < head) {
      this.useFadeIn = false;
      return 1;
    }
    ;
    const step = (head - this.fadeInStart) / this.fadeInSamples;
    return Math.min(step, 1);
  }
  getFadeOutStep(head, isPause) {
    if (!this.useFadeOut && !isPause) {
      if (this.fadeOutEvent !== null) {
        this.fadeOutEvent();
        this.fadeOutEvent = null;
      }
      return 1;
    }
    if (!this.useFadeOut && isPause) return 0;
    if (head < this.fadeOutStart) return 1;
    if (this.fadeOutStart + this.fadeOutSamples < head) {
      this.useFadeOut = false;
      return 0;
    }
    ;
    const step = 1 - (head - this.fadeOutStart) / this.fadeOutSamples;
    return Math.max(step, 0);
  }
};
var InteractivePlayerProcessor = class extends AudioWorkletProcessor {
  constructor() {
    super();
    this.tracks = [];
    this.start = 0;
    this.head = 0;
    this.playing = false;
    this.pause = false;
    this.current = 0;
    this.next = 0;
    this.transitions = {};
    this.fader = new Fader(440, 440);
    this.port.onmessage = ({ data }) => {
      switch (data.type) {
        case "loadMulti":
          this.tracks = data.tracks.map(
            (track) => track.map((buf) => new Float32Array(buf))
          );
          this.head = 0;
          this.start = data.start ?? 0;
          this.current = this.start;
          this.transitions = data.transitions ?? {};
          this.next = this.transitions[this.current] ?? null;
          break;
        case "play":
          if (!this.playing) this.playing = true;
          break;
        case "stop":
          if (this.playing) {
            this.playing = false;
            this.head = 0;
            this.current = this.start;
            this.next = this.transitions[this.current] ?? null;
          }
          break;
        case "pause":
          if (!this.pause) {
            this.pause = data.type === "pause";
            this.fader.startFadeOut(this.head);
          }
          break;
        case "resume":
          if (this.pause) {
            this.pause = false;
            this.fader.startFadeIn(this.head);
          }
          break;
        case "next":
          if (data.currentIs === void 0 || data.currentIs === null || data.currentIs === this.current) {
            this.next = data.next;
          }
          break;
        case "setFadeIn":
          this.fader.fadeInSamples = data.fadeInSamples;
          break;
        case "setFadeOut":
          this.fader.fadeOutSamples = data.fadeOutSamples;
          break;
      }
    };
  }
  process(_inputs, outputs) {
    const out = outputs[0];
    if ((!this.playing || this.pause || this.tracks.length === 0) && !this.fader.useFadeOut) {
      out.forEach((ch) => ch.fill(0));
      return true;
    }
    for (let i = 0; i < out[0].length; i++) {
      if (this.tracks[this.current].length > 0 && this.head >= this.tracks[this.current][0].length && !this.fader.useFadeOut) {
        this.head = 0;
        if (this.next === null || this.next === void 0) {
          this.playing = false;
          this.current = this.start;
          this.next = this.transitions[this.current] ?? null;
          out.forEach((ch) => ch[i] = 0);
          continue;
        } else {
          this.current = this.next;
          this.next = this.transitions[this.current] ?? null;
        }
      }
      const fadeInStep = this.fader.getFadeInStep(this.head);
      const fadeOutStep = this.fader.getFadeOutStep(this.head, this.pause);
      for (let ch = 0; ch < out.length; ch++) {
        out[ch][i] = this.tracks[this.current][ch][this.head] * fadeInStep * fadeOutStep;
      }
      this.head++;
    }
    return true;
  }
};
registerProcessor(
  "interactive-player-processor",
  InteractivePlayerProcessor
);
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