test(audio-quality): record real arrival traces and grade their replay per PR

.github/workflows/audio-quality.yml

@@ -0,0 +1,63 @@
+name: Audio quality
+
+# Grades the recorded-trace replays of test/audio-quality against their exact
+# budgets on every PR that can move them. They replay the player's container
+# consumer and rings on a simulated clock, so they are deterministic and take
+# seconds, unlike the browser rows, which stay in nightly.yml.
+on:
+  pull_request:
+    paths:
+      - "js/watch/**"
+      # The container consumer decides what a replay delivers, waits for, and skips, on the
+      # groups, tracks, and signals underneath it.
+      - "js/hang/**"
+      - "js/net/**"
+      - "js/signals/**"
+      - "test/audio-quality/**"
+      - "test/lib/**"
+      - "test/justfile"
+      - ".github/workflows/audio-quality.yml"
+
+concurrency:
+  group: audio-quality-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  replay:
+    name: Replay
+    runs-on: ubuntu-24.04-arm
+    timeout-minutes: 20
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+
+      - uses: DeterminateSystems/nix-installer-action@1d87d45818068401a10cf16bdc5f00b24994a83f # main
+        with:
+          determinate: false
+          # Trust the flake's cachix substituter; see check.yml.
+          extra-conf: |
+            extra-substituters = https://kixelated.cachix.org
+            extra-trusted-public-keys = kixelated.cachix.org-1:CmFcV0lyM6KuVM2m9mih0q4SrAa0XyCsiM7GHrz3KKk=
+
+      - name: Replay
+        run: nix develop --command just test audio-quality --replays --enforce
+        shell: bash -leo pipefail {0}
+        env:
+          # Somewhere upload-artifact can reach; the harness default is under $TMPDIR.
+          MOQ_TEST_RUNS: ${{ runner.temp }}/moq-test-runs
+
+      # The harness keeps a failing run's directory: every row's samples and summary.
+      - name: Keep the failing run
+        if: ${{ failure() }}
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
+        with:
+          name: audio-quality-replay
+          path: ${{ runner.temp }}/moq-test-runs/
+          retention-days: 7
+          if-no-files-found: ignore

.github/workflows/nightly.yml

@@ -23,7 +23,9 @@ name: Nightly
 # number it grades is a timing one that moves with whatever else the runner is
 # doing. A per-PR arm would fail on unrelated load often enough to be ignored;
 # nightly it competes with nothing, and a regression surfaces a day late against
-# a budget that still means something.
+# a budget that still means something. The recorded-trace replays are the
+# exception: deterministic and seconds long, so audio-quality.yml also gates
+# PRs on them.
 #
 # A failure here lands on main rather than being caught in review, which is the
 # accepted trade. Anything that must block a merge belongs in check.yml.

js/watch/src/audio/replay.test.ts

@@ -0,0 +1,70 @@
+import { afterEach, beforeEach, describe, expect, it, type Mock, spyOn } from "bun:test";
+import type * as Catalog from "@moq/hang/catalog";
+import { Time } from "@moq/net";
+import { type Arrival, type Options, QUANTUM, replay, target } from "./replay";
+
+const RATE = 48000;
+
+/** Twenty ms frames for `seconds`, one per group, each arriving `lateness(i)` ms after it was captured. */
+function paced(seconds: number, lateness: (i: number) => number): Arrival[] {
+	return Array.from({ length: seconds * 50 }, (_, i) => ({ at: i * 20 + lateness(i), timestamp: i * 20, group: i }));
+}
+
+/** Quanta that came back short or empty while playing, once the ring had first played. */
+async function underruns(trace: Arrival[], options: Options): Promise<number> {
+	let started = false;
+	let short = 0;
+	for await (const { output, stalled } of replay(trace, options)) {
+		const filled = output.findLastIndex((v) => v !== 0) + 1;
+		if (started && !stalled && filled < QUANTUM) short++;
+		if (filled > 0) started = true;
+	}
+	return short;
+}
+
+describe.each(["shared", "post"] as const)("%s ring", (ring) => {
+	// The consumer warns on every group it skips.
+	let warn: Mock<typeof console.warn>;
+	beforeEach(() => {
+		warn = spyOn(console, "warn").mockImplementation(() => {});
+	});
+	afterEach(() => warn.mockRestore());
+
+	it("plays an evenly paced sender without a gap", async () => {
+		expect(
+			await underruns(
+				paced(10, () => 30),
+				{ ring, rate: RATE, delay: 100 },
+			),
+		).toBe(0);
+	});
+
+	it("underruns when a flush span outlasts the target, and not when it is covered", async () => {
+		// Five frames held and flushed at once: 80 ms of arrival spread.
+		const trace = paced(10, (i) => 30 + (4 - (i % 5)) * 20);
+		expect(await underruns(trace, { ring, rate: RATE, delay: 40 })).toBeGreaterThan(50);
+		expect(await underruns(trace, { ring, rate: RATE, delay: 150 })).toBe(0);
+	});
+
+	it("holds newer groups behind a missing one until the max age gives up on it", async () => {
+		const trace = paced(10, () => 30).filter((arrival) => arrival.group !== 250);
+		// The consumer delivers in group order, so the ring runs dry for longer than the missing frame
+		// while the groups behind it wait. Writing arrivals straight into the ring plays straight through.
+		const frame = Math.ceil((20 / 1000) * (RATE / QUANTUM));
+		expect(await underruns(trace, { ring, rate: RATE, delay: 100 })).toBeGreaterThan(frame);
+		expect(warn).toHaveBeenCalled();
+	});
+});
+
+describe("target", () => {
+	const config = { codec: "opus", sampleRate: RATE, numberOfChannels: 1 } as Catalog.AudioConfig;
+
+	it("sizes auto from the RTT and the rendition's jitter", async () => {
+		// 1.25 x 40 ms of RTT, plus the Opus frame and a render quantum.
+		expect(await target({ delay: "auto", config, rtt: 40 })).toBe(Time.Milli(50 + 20 + 3));
+	});
+
+	it("adds the rendition's jitter to a fixed delay", async () => {
+		expect(await target({ delay: Time.Milli(250), config })).toBe(Time.Milli(250 + 20 + 3));
+	});
+});