refactor: extract pcm audio helpers

2026-05-19 13:56:36 +07:00
parent 7f5db953fa
commit f48f62893d
3 changed files with 60 additions and 27 deletions
@@ -0,0 +1,30 @@
+import { describe, expect, it } from "vitest";
+import { rmsDb, upsample24kMonoTo48kStereo } from "../../src/audio/pcm";
+
+describe("PCM helpers", () => {
+  it("upsamples 24kHz mono s16le to 48kHz stereo s16le", () => {
+    const input = Buffer.alloc(4);
+    input.writeInt16LE(1000, 0);
+    input.writeInt16LE(-1000, 2);
+
+    const output = upsample24kMonoTo48kStereo(input);
+
+    expect(output.length).toBe(16);
+    expect(output.readInt16LE(0)).toBe(1000);
+    expect(output.readInt16LE(2)).toBe(1000);
+    expect(output.readInt16LE(4)).toBe(1000);
+    expect(output.readInt16LE(6)).toBe(1000);
+    expect(output.readInt16LE(8)).toBe(-1000);
+    expect(output.readInt16LE(10)).toBe(-1000);
+    expect(output.readInt16LE(12)).toBe(-1000);
+    expect(output.readInt16LE(14)).toBe(-1000);
+  });
+
+  it("calculates RMS dB for non-silent PCM", () => {
+    const input = Buffer.alloc(4);
+    input.writeInt16LE(32767, 0);
+    input.writeInt16LE(32767, 2);
+
+    expect(rmsDb(input)).toBeCloseTo(0, 1);
+  });
+});