26 lines
1.2 KiB
TypeScript
26 lines
1.2 KiB
TypeScript
import { test, expect } from "bun:test";
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import { mixStemsScaled } from "../../src/audio/mix.ts";
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import type { Audio } from "../../src/core/types.ts";
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test("mixStemsScaled: scaled stems sum to mix; scale is the normalisation factor", () => {
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const mk = (n: number, amp: number): Audio => {
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const x = Float32Array.from({ length: n }, (_, i) => amp * Math.sin(i / 7));
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return { sampleRate: 44100, channels: [x, x.slice()] };
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};
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const a = mk(1000, 0.9), b = mk(700, 0.8);
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const { mix, scaled, scale } = mixStemsScaled([{ audio: a, gainDb: 0 }, { audio: b, gainDb: -3 }]);
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// unnormalised peak
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const gb = Math.pow(10, -3 / 20);
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let peak = 0;
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for (let i = 0; i < 1000; i++) peak = Math.max(peak, Math.abs(a.channels[0]![i]! + (i < 700 ? b.channels[0]![i]! * gb : 0)));
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expect(peak).toBeGreaterThan(1);
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expect(Math.abs(scale - Math.pow(10, -1 / 20) / peak)).toBeLessThan(1e-6);
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expect(scaled.length).toBe(2);
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let maxDiff = 0;
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for (let c = 0; c < 2; c++) for (let i = 0; i < 1000; i++) {
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const s = scaled[0]!.channels[c]![i]! + scaled[1]!.channels[c]![i]!;
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maxDiff = Math.max(maxDiff, Math.abs(s - mix.channels[c]![i]!));
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}
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expect(maxDiff).toBeLessThan(1e-6);
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});
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