feuerwerk/tests/viewport/spectrum.test.ts

/**
 * The taps of the spectrum (#374): a voice's tap feeds the analyser of its side only while its node
 * is listened to, and once that stops – or the voice does – nothing feeds one any more.
 */
import { describe, expect, it } from 'vitest';
import type { FxTap } from '../../src/core/soundfx/nodes';
import { SpectrumTaps } from '../../src/viewport/spectrum';

/** A node that remembers what it is linked to. */
class FakeNode {
  readonly links = new Set<FakeNode>();
  fftSize = 0;
  frequencyBinCount = 4;
  constructor(readonly context: FakeContext) {}
  connect(to: FakeNode): FakeNode {
    this.links.add(to);
    return to;
  }
  disconnect(to?: FakeNode): void {
    if (!to) this.links.clear();
    else if (!this.links.delete(to)) throw new Error('not linked');
  }
  getFloatFrequencyData(data: Float32Array): void {
    data.fill(this.context.made.length);
  }
  /** What the analyser heard last: `wave`, at the end of `data` like the newest samples. */
  wave: number[] = [];
  getFloatTimeDomainData(data: Float32Array): void {
    data.fill(0);
    data.set(this.wave, data.length - this.wave.length);
  }
}

class FakeContext {
  readonly sampleRate = 48000;
  readonly made: FakeNode[] = [];
  private make(): FakeNode {
    const node = new FakeNode(this);
    this.made.push(node);
    return node;
  }
  createGain(): FakeNode {
    return this.make();
  }
  createAnalyser(): FakeNode {
    return this.make();
  }
}

const tap = (id: string, at: FxTap['at']): FxTap => ({ kind: 'tap', id, at });

describe('the taps of the spectrum', () => {
  it('feed nothing and make nothing before their node is listened to', () => {
    const context = new FakeContext();
    const taps = new SpectrumTaps();
    taps.hold(tap('fx:eq', 'in'), new FakeNode(context) as never);
    expect(taps.info()).toEqual({ listened: '', held: 1, feeding: 0 });
    expect(context.made).toHaveLength(0);
    expect(taps.read('fx:eq')).toBeNull();
  });

  it('feed the analyser of their side while listened to, a voice started before as well', () => {
    const context = new FakeContext();
    const taps = new SpectrumTaps();
    const before = new FakeNode(context);
    taps.hold(tap('fx:eq', 'in'), before as never);
    taps.listen('fx:eq');
    const after = new FakeNode(context);
    taps.hold(tap('fx:eq', 'out'), after as never);
    const other = new FakeNode(context);
    taps.hold(tap('fx:other', 'out'), other as never);
    expect(taps.info()).toEqual({ listened: 'fx:eq', held: 3, feeding: 2 });
    // Two sums, each into its analyser: the in side made first.
    const [sumIn, , sumOut] = context.made;
    expect([...before.links]).toEqual([sumIn]);
    expect([...after.links]).toEqual([sumOut]);
    expect(other.links.size).toBe(0);
    expect(taps.read('fx:eq')?.binHz).toBeCloseTo(48000 / 8192, 9);
  });

  it('let go of the analysers once nobody listens, or once the voice stops', () => {
    const context = new FakeContext();
    const taps = new SpectrumTaps();
    taps.listen('fx:eq');
    const voice = new FakeNode(context);
    const stopVoice = taps.hold(tap('fx:eq', 'in'), voice as never);
    const bus = new FakeNode(context);
    taps.hold(tap('fx:eq', 'out'), bus as never);
    stopVoice();
    stopVoice();
    expect(voice.links.size).toBe(0);
    expect(taps.info()).toEqual({ listened: 'fx:eq', held: 1, feeding: 1 });
    taps.stop();
    expect(bus.links.size).toBe(0);
    expect(taps.info()).toEqual({ listened: '', held: 1, feeding: 0 });
    expect(taps.read('fx:eq')).toBeNull();
  });

  it('listen to two nodes at once, and let one go without the other (#378)', () => {
    const context = new FakeContext();
    const taps = new SpectrumTaps();
    const eq = new FakeNode(context);
    const compressor = new FakeNode(context);
    taps.hold(tap('fx:eq', 'in'), eq as never);
    taps.hold(tap('fx:comp', 'in'), compressor as never);
    taps.listen('fx:eq');
    taps.listen('fx:comp');
    expect(taps.info()).toEqual({ listened: 'fx:eq fx:comp', held: 2, feeding: 2 });
    expect(eq.links.size).toBe(1);
    expect(compressor.links.size).toBe(1);
    taps.stop('fx:eq');
    expect(eq.links.size).toBe(0);
    expect(compressor.links.size).toBe(1);
    expect(taps.info()).toEqual({ listened: 'fx:comp', held: 2, feeding: 1 });
    expect(taps.read('fx:comp')).not.toBeNull();
  });

  it('give the loudest sample of the last stretch on each side, in dB (#378)', () => {
    const context = new FakeContext();
    const taps = new SpectrumTaps();
    expect(taps.levels('fx:comp', 0.01)).toBeNull();
    taps.listen('fx:comp');
    taps.hold(tap('fx:comp', 'in'), new FakeNode(context) as never);
    const [, analyserIn, , analyserOut] = context.made;
    // A peak of 1 long ago, then 0.5: a window of 10 ms (480 samples) only sees the 0.5.
    analyserIn!.wave = [1, ...new Array<number>(1000).fill(0), -0.5, 0.25];
    analyserOut!.wave = [];
    const levels = taps.levels('fx:comp', 0.01);
    expect(levels?.in).toBeCloseTo(20 * Math.log10(0.5), 9);
    expect(levels?.out).toBe(-Infinity);
    expect(taps.levels('fx:comp', 1)?.in).toBeCloseTo(0, 9);
  });

  it('read the side in front as late as the node is, so a peak is met by what it became (#397)', () => {
    const context = new FakeContext();
    const taps = new SpectrumTaps();
    taps.listen('fx:lim');
    taps.hold(tap('fx:lim', 'in'), new FakeNode(context) as never);
    const [, analyserIn, , analyserOut] = context.made;
    // A peak of 1 that came in 5 ms (240 samples) before the newest sample, and the sound at 0.125 since.
    analyserIn!.wave = [1, ...new Array<number>(240).fill(0.125)];
    analyserOut!.wave = [0.5];
    const window = 1 / 480;
    expect(taps.levels('fx:lim', window)?.in).toBeCloseTo(20 * Math.log10(0.125), 9);
    const late = taps.levels('fx:lim', window, 0.005);
    expect(late?.in).toBeCloseTo(0, 9);
    expect(late?.out).toBeCloseTo(20 * Math.log10(0.5), 9);
  });
});