feuerwerk/tests/editor/compressor-view.test.ts

/**
 * What the tab of a Compressor draws (#378): its curve and the handles on it, the ratio a drag of
 * the end of the curve asks for, and the level picture tinted where the compressor works.
 */
import { describe, expect, it } from 'vitest';
import {
  type CompressorNumbers,
  compressorGainDb,
  curveDbAtX,
  curveDbAtY,
  curveOutDb,
  curveX,
  curveY,
  HISTORY_SECONDS,
  LevelHistory,
  levelY,
  MAX_CURVE,
  MIN_CURVE,
  picturesLayout,
  ratioFor,
  ratioHandle,
  reductionOf,
  reductionShapes,
  thresholdHandle,
} from '../../src/editor/soundfx/compressorView';

const numbers: CompressorNumbers = {
  threshold: -24,
  knee: 0,
  ratio: 4,
  attack: 0.003,
  release: 0.25,
  makeup: 0,
  autoGain: false,
};
const RATIO = { min: 1, max: 20, step: 0.1 };

describe('the curve of a Compressor', () => {
  it('leaves a level below the threshold as it is and squeezes one above it by the ratio', () => {
    expect(curveOutDb(-40, -24, 0, 4)).toBeCloseTo(-40, 6);
    // 24 dB over a threshold of -24 come out 6 dB over it at a ratio of 4.
    expect(curveOutDb(0, -24, 0, 4)).toBeCloseTo(-18, 1);
  });

  it('spans -60 to 0 dB on both axes, level out going up', () => {
    expect(curveX(-60, 300)).toBe(0);
    expect(curveX(0, 300)).toBe(300);
    expect(curveY(0, 300)).toBe(0);
    expect(curveDbAtX(150, 300)).toBe(-30);
    expect(curveDbAtY(100, 300)).toBe(-20);
  });

  it('has the threshold where it starts to bend and the ratio at its end', () => {
    expect(thresholdHandle(numbers, 300)).toEqual({ x: 180, y: 120 });
    const end = ratioHandle(numbers, 300);
    expect(end.x).toBe(300);
    expect(curveDbAtY(end.y, 300)).toBeCloseTo(-18, 1);
  });

  it('finds the ratio whose end is where it is dragged to, held to the range', () => {
    expect(ratioFor(-18, numbers, RATIO)).toBe(4);
    expect(ratioFor(-12, numbers, RATIO)).toBe(2);
    expect(ratioFor(5, numbers, RATIO)).toBe(1);
    expect(ratioFor(-40, numbers, RATIO)).toBe(20);
    // With a knee the curve ends lower than the straight line would, and the ratio found still lands there.
    const kneed = { ...numbers, knee: 6 };
    const ratio = ratioFor(-16, kneed, RATIO);
    expect(curveOutDb(0, -24, 6, ratio)).toBeCloseTo(-16, 0);
  });

  it('counts the makeup, and the auto-gain on top of it where it is on, as the gain after it', () => {
    expect(compressorGainDb({ ...numbers, makeup: 6 })).toBe(6);
    // -18 dB in comes out at -22.5: auto-gain gives the 4.5 dB back.
    expect(compressorGainDb({ ...numbers, makeup: 6, autoGain: true })).toBeCloseTo(10.5, 3);
  });
});

describe('the level picture of a Compressor', () => {
  it('spans +6 to -60 dB top to bottom, silence at the bottom', () => {
    expect(levelY(6, 660)).toBe(0);
    expect(levelY(-60, 660)).toBe(660);
    expect(levelY(-Infinity, 660)).toBe(660);
    expect(levelY(0, 660)).toBe(60);
  });

  it('keeps the readings of the last seconds and knows when all of them are silent', () => {
    const history = new LevelHistory();
    history.push(0, { in: -6, out: -9 }, 0);
    history.push(1, null, 0);
    expect(history.heard).toBe(true);
    history.push(1 + HISTORY_SECONDS, null, 0);
    expect(history.all.map((p) => p.t)).toEqual([1, 1 + HISTORY_SECONDS]);
    expect(history.heard).toBe(false);
  });

  it('takes away what came in less what went out, the gain after it left out', () => {
    expect(reductionOf({ in: -6, out: -12 }, 0)).toBe(6);
    expect(reductionOf({ in: -6, out: -6 }, 6)).toBe(6);
    expect(reductionOf({ in: -30, out: -29 }, 0)).toBe(0);
    expect(reductionOf({ in: -Infinity, out: -Infinity }, 0)).toBe(0);
  });

  it('tints from the level coming in down by what is taken away, one shape per stretch', () => {
    const points = [
      { t: 0, in: -6, out: -12, gain: 0 },
      { t: 1, in: -6, out: -12, gain: 0 },
      { t: 2, in: -30, out: -30, gain: 0 },
      { t: 3, in: 0, out: -3, gain: 0 },
      { t: 4, in: 0, out: -3, gain: 0 },
    ];
    const shapes = reductionShapes(points, 4, 400, 660);
    expect(shapes).toHaveLength(2);
    // Along the level coming in, then back along it less what is taken away.
    expect(shapes[0]).toEqual([0, 120, 100, 120, 100, 180, 0, 180]);
    expect(shapes[1]).toEqual([300, 60, 400, 60, 400, 90, 300, 90]);
  });

  it('reads every reading by the gain after the compressing as it was then', () => {
    // Raised by 20 dB until a second ago, by 0 since: the same 6 dB taken away both times.
    const history = new LevelHistory();
    history.push(0, { in: -24, out: -10 }, 20);
    history.push(1, { in: -24, out: -10 }, 20);
    history.push(2, { in: -24, out: -30 }, 0);
    history.push(3, { in: -24, out: -30 }, 0);
    const shapes = reductionShapes(history.all, 3, 300, 660);
    expect(shapes).toHaveLength(1);
    expect(shapes[0]).toHaveLength(16);
    expect(shapes[0]!.filter((_, i) => i % 2 === 1)).toEqual([300, 300, 300, 300, 360, 360, 360, 360]);
  });
});

describe('the pictures in the space of the tab', () => {
  it('lets the levels fill the height and keeps the curve square, centred up and down', () => {
    const at = picturesLayout(1600, 1000, 8);
    expect(at.curve).toEqual({ x: 1600 - MAX_CURVE, y: (1000 - MAX_CURVE) / 2, side: MAX_CURVE });
    expect(at.levels).toEqual({ w: 1600 - MAX_CURVE - 8, h: 1000 });
  });

  it('grows the curve with a lower tab, and holds it at its least in a narrow one', () => {
    expect(picturesLayout(1600, 250, 8).curve).toEqual({ x: 1350, y: 0, side: 250 });
    expect(picturesLayout(500, 400, 8).curve.side).toBe(200);
    expect(picturesLayout(300, 400, 8).curve.side).toBe(MIN_CURVE);
  });
});