Initial Commit

packages/media/audio/audio-analysis-loudness/tests/property.test.ts

@@ -0,0 +1,54 @@
+import { describe, it } from "@suaveplan/testing/runner";
+import fc from "fast-check";
+import { LoudnessMeter, samplePeakLinear, truePeakDbtp } from "../src/index.js";
+import { buildDoc, sine } from "./helpers/build-doc.js";
+
+describe("LoudnessMeter properties", () => {
+    it("LUFS is monotonic with gain on a sine", {
+        timeout: 60000,
+    }, async () => {
+        await fc.assert(
+            fc.asyncProperty(
+                fc.double({ min: 0.05, max: 0.5, noNaN: true }),
+                fc.double({ min: 0.51, max: 0.95, noNaN: true }),
+                async (a, b) => {
+                    const sr = 48000;
+                    const dur = 3.5;
+                    const meter = new LoudnessMeter();
+                    const lo = await meter.analyze(
+                        buildDoc([sine(a, 1000, sr, dur)], sr)
+                    );
+                    const hi = await meter.analyze(
+                        buildDoc([sine(b, 1000, sr, dur)], sr)
+                    );
+                    return hi.lufs >= lo.lufs - 0.5;
+                }
+            ),
+            { numRuns: 6 }
+        );
+    });
+
+    it("true peak ≥ sample peak for arbitrary blocks", {
+        timeout: 30000,
+    }, () => {
+        fc.assert(
+            fc.property(
+                fc.array(fc.double({ min: -1, max: 1, noNaN: true }), {
+                    minLength: 32,
+                    maxLength: 4096,
+                }),
+                (arr) => {
+                    const ch = Float32Array.from(arr);
+                    const sp = samplePeakLinear([ch]);
+                    // Below Float32 quantisation, sample peak cannot be
+                    // round-trip compared in dB: skip such degenerate inputs.
+                    if (sp < 1e-6) return true;
+                    const spDb = 20 * Math.log10(sp);
+                    const tpDb = truePeakDbtp([ch]);
+                    return tpDb >= spDb - 0.1;
+                }
+            ),
+            { numRuns: 25 }
+        );
+    });
+});