youtube-music/plugins/visualizer/visualizers/butterchurn.js

const butterchurn = require('butterchurn');
const butterchurnPresets = require('butterchurn-presets');

const presets = butterchurnPresets.getPresets();

class ButterchurnVisualizer {
  constructor(
    audioContext,
    audioSource,
    visualizerContainer,
    canvas,
    audioNode,
    stream,
    options,
  ) {
    this.visualizer = butterchurn.default.createVisualizer(
      audioContext,
      canvas,
      {
        width: canvas.width,
        height: canvas.height,
      },
    );

    const preset = presets[options.preset];
    this.visualizer.loadPreset(preset, options.blendTimeInSeconds);

    this.visualizer.connectAudio(audioNode);

    this.renderingFrequencyInMs = options.renderingFrequencyInMs;
  }

  resize(width, height) {
    this.visualizer.setRendererSize(width, height);
  }

  render() {
    const renderVisualizer = () => {
      requestAnimationFrame(() => renderVisualizer());
      this.visualizer.render();
    };

    setTimeout(renderVisualizer(), this.renderingFrequencyInMs);
  }
}

module.exports = ButterchurnVisualizer;