feat(hang)!: name the container producer's timeline break discontinuity()

js/hang/src/container/consumer.test.ts

@@ -161,7 +161,7 @@ test("Legacy Producer omits a reordered group's presentation endpoint marker", a
 		producer.encode(new Uint8Array([1]), timestamp as Time.Micro, index === 0);
 	}
 	producer.encode(new Uint8Array([1]), 160_000 as Time.Micro, true);
-	producer.cut(200_000 as Time.Micro);
+	producer.discontinuity(200_000 as Time.Micro);
 	producer.close();
 	const group = await subscriber.recvGroup();
 	expect(group).toBeDefined();
@@ -199,14 +199,14 @@ test("Legacy Producer estimates the tail from the current cadence", async () =>
 	expect(end).toBe(131_000);
 });
 
-test("Legacy Producer rejects a backwards cut without closing the group", async () => {
+test("Legacy Producer rejects a backwards discontinuity without closing the group", async () => {
 	const track = new Track.Producer("test");
 	const subscriber = track.subscribe({ maxAge: Time.Milli(30_000) });
 	const producer = new LegacyProducer(track, new LegacyFormat("video"));
 	producer.encode(new Uint8Array([1]), 20_000 as Time.Micro, true);
-	expect(() => producer.cut(10_000 as Time.Micro)).toThrow();
+	expect(() => producer.discontinuity(10_000 as Time.Micro)).toThrow();
 	producer.encode(new Uint8Array([2]), 30_000 as Time.Micro, false);
-	producer.cut(35_000 as Time.Micro);
+	producer.discontinuity(35_000 as Time.Micro);
 	producer.close();
 	const group = await subscriber.recvGroup();
 	const timestamps = [];
@@ -245,14 +245,14 @@ async function readGroups(subscriber: Track.Subscriber, last: number) {
 	}
 }
 
-test("Legacy Producer cut marks the break with one empty frame at the live edge", async () => {
+test("Legacy Producer discontinuity marks the break with one empty frame at the live edge", async () => {
 	const track = new Track.Producer("test");
 	const subscriber = replay(track);
 	const producer = new LegacyProducer(track, new LegacyFormat("audio"));
 	producer.encode(new Uint8Array([1]), 0 as Time.Micro, true);
 	producer.encode(new Uint8Array([1]), 20_000 as Time.Micro, true);
-	producer.cut();
-	producer.cut(); // nothing new to mark
+	producer.discontinuity();
+	producer.discontinuity(); // nothing new to mark
 	producer.encode(new Uint8Array([1]), 5_000_000 as Time.Micro, true);
 	producer.close();
 
@@ -264,12 +264,12 @@ test("Legacy Producer cut marks the break with one empty frame at the live edge"
 	]);
 });
 
-test("Legacy Producer cut marks the break at the caller's end", async () => {
+test("Legacy Producer discontinuity marks the break at the caller's end", async () => {
 	const track = new Track.Producer("test");
 	const subscriber = replay(track);
 	const producer = new LegacyProducer(track, new LegacyFormat("video"));
 	producer.encode(new Uint8Array([1]), 0 as Time.Micro, true);
-	producer.cut(33_000 as Time.Micro);
+	producer.discontinuity(33_000 as Time.Micro);
 	producer.close();
 
 	expect(await readGroups(subscriber, 1)).toEqual([
@@ -284,26 +284,26 @@ test("Legacy Producer cut marks the break at the caller's end", async () => {
 	]);
 });
 
-test("Legacy Producer cut marks nothing on a data track or before any frame", async () => {
+test("Legacy Producer discontinuity marks nothing on a data track or before any frame", async () => {
 	const data = new Track.Producer("data");
 	const producer = new LegacyProducer(data, new LegacyFormat("data"));
 	producer.encode(new Uint8Array([1]), 0 as Time.Micro, true);
-	producer.cut();
+	producer.discontinuity();
 	expect(data.appendGroup().sequence).toBe(1);
 
 	const empty = new Track.Producer("empty");
-	new LegacyProducer(empty, new LegacyFormat("video")).cut();
+	new LegacyProducer(empty, new LegacyFormat("video")).discontinuity();
 	expect(empty.appendGroup().sequence).toBe(0);
 });
 
 // A group's reach runs to its successor's first frame, so without the marker the group before a
 // pause would stretch across the whole gap and read as live to anyone joining after the resume.
-test("Legacy Producer cut keeps pre-pause media from reading as live", async () => {
+test("Legacy Producer discontinuity keeps pre-pause media from reading as live", async () => {
 	const track = new Track.Producer("test");
 	const producer = new LegacyProducer(track, new LegacyFormat("video"));
 	producer.encode(new Uint8Array([1]), 0 as Time.Micro, true);
 	producer.encode(new Uint8Array([1]), 33_000 as Time.Micro, false);
-	producer.cut();
+	producer.discontinuity();
 	producer.encode(new Uint8Array([1]), 5_000_000 as Time.Micro, true);
 	producer.close();
 
@@ -1530,12 +1530,12 @@ test("live duration marker follows an immediately delivered video frame", async
 	track.close();
 });
 
-test("audio cut writes no duration marker", async () => {
+test("audio discontinuity writes no duration marker", async () => {
 	const track = new Track.Producer("test");
 	const subscriber = track.subscribe();
 	const producer = new LegacyProducer(track, new LegacyFormat("audio"));
 	producer.encode(new Uint8Array([1]), 0 as Time.Micro, true);
-	producer.cut(15_000 as Time.Micro);
+	producer.discontinuity(15_000 as Time.Micro);
 	const group = await subscriber.recvGroup();
 	expect(await group?.readFrame()).toBeDefined();
 	expect(await group?.readFrame()).toBeUndefined();

js/hang/src/container/legacy.ts

@@ -84,7 +84,7 @@ export class Producer {
 	#liveEdge?: Time.Micro;
 	// Gap between consecutive timestamps, used to close the last group when no successor exists.
 	#interval?: Time.Micro;
-	// A cut's marker is the newest group, so another one would say nothing new.
+	// A discontinuity's marker is the newest group, so another one would say nothing new.
 	#marked = false;
 
 	/** Wrap a track to publish legacy-container frames into it. */
@@ -138,7 +138,7 @@ export class Producer {
 	 * joiner lands on. Data tracks only close the group, since an empty payload is data. No marker
 	 * is written until a frame follows the last one. Throws if `end` precedes the last video frame.
 	 */
-	cut(end?: Time.Micro) {
+	discontinuity(end?: Time.Micro) {
 		this.#close(end);
 		// Nothing is measured across the break.
 		this.#interval = undefined;

js/publish/src/audio/encoder.ts

@@ -270,7 +270,7 @@ export class Encoder {
 		});
 
 		// When demand disappears, end the epoch with a discontinuity marker (see
-		// Container.Legacy.Producer.cut) so a later subscriber resumes on the same track without the
+		// Container.Legacy.Producer.discontinuity) so a later subscriber resumes on the same track without the
 		// pre-gap frames reading as live. Its empty payload marks where the submitted media ends.
 		effect.run((effect) => {
 			const track = effect.get(rendition.track);

js/publish/src/video/encoder.test.ts

@@ -90,9 +90,9 @@ test("encoding tracks encoder config in its child effect", async () => {
 	}
 });
 
-test("a demand gap cuts the group and leaves the broadcast-owned track open for resume", async () => {
+test("a demand gap marks a discontinuity and leaves the broadcast-owned track open for resume", async () => {
 	using _videoEncoder = installFakeVideoEncoder();
-	const cut = spyOn(Container.Legacy.Producer.prototype, "cut");
+	const discontinuity = spyOn(Container.Legacy.Producer.prototype, "discontinuity");
 
 	const track = new Moq.Track.Producer("video").accept({ priority: 60 });
 	const live = new Signal<Moq.Track.Producer | undefined>(track);
@@ -119,20 +119,20 @@ test("a demand gap cuts the group and leaves the broadcast-owned track open for
 		live.set(undefined);
 		await settle();
 		expect(track.closed.peek()).toBeUndefined();
-		expect(cut).toHaveBeenCalledTimes(1);
+		expect(discontinuity).toHaveBeenCalledTimes(1);
 
 		live.set(track);
 		await settle();
 		expect(track.closed.peek()).toBeUndefined();
 
-		cut.mockClear();
+		discontinuity.mockClear();
 		track.close();
 		encoder.close();
-		expect(cut).not.toHaveBeenCalled();
+		expect(discontinuity).not.toHaveBeenCalled();
 	} finally {
 		encoder.close();
 		track.close();
-		cut.mockRestore();
+		discontinuity.mockRestore();
 	}
 });
 

js/publish/src/video/encoder.ts

@@ -237,12 +237,12 @@ export class Encoder {
 		this.#lastCaptureWall = performance.now();
 
 		const producer = new Container.Legacy.Producer(track, new Container.Legacy.Format("video"));
-		// The broadcast owns this static track across demand gaps. When demand disappears, cut the
+		// The broadcast owns this static track across demand gaps. When demand disappears, close the
 		// current group, marking the break so a later subscriber resumes on the same track without
 		// the pre-gap group reading as live. A fatal encoder error still aborts the track through
 		// producer.close(err) below.
 		effect.cleanup(() => {
-			if (track.closed.peek() === undefined) producer.cut();
+			if (track.closed.peek() === undefined) producer.discontinuity();
 		});
 
 		let lastKeyframe: Time.Micro | undefined;

quest/m2/README.md

@@ -27,7 +27,6 @@ upstream release waits in [m4](/quest/m4/README.md).
 - [Audio loss recovery](/quest/m2/audio-loss-recovery.md) - prove a useful Opus recovery policy before exposing another option
 - [Opus implementation](/quest/m2/audio-opus-backend.md) - compare current codec quality, CPU, and optional build costs
 - [Latency ledger](/quest/m2/latency-ledger.md) - a session reports where its end-to-end audio delay went, stage by stage
-- [JS discontinuity](/quest/m2/js-discontinuity.md) - JS names its timeline break `discontinuity()` like Rust, so `cut` means the same group close in both
 - [Synced data playback](/quest/m2/watch-data-sync.md) - js/watch releases JSON and binary payloads on the media playhead, and a slow data track holds media back
 - [Media Foundation decode](/quest/m2/audio-decode-mediafoundation.md) - Windows decodes HE-AAC, multichannel AAC, and what else the MFTs offer
 - [Media Foundation encode](/quest/m2/audio-encode-mediafoundation.md) - Windows encodes AAC-LC