fix(scene): a replay's sound plays with its pictures

quest/m0/README.md

@@ -100,7 +100,6 @@ repository.
 - [Web studio](/quest/m0/web.md) - the full studio in wasm on WebGPU and WebCodecs, served from this repository
 - [Virtual camera](/quest/m0/vcam/README.md) - the program or a published scene exposed as a system camera on Linux, Windows, and macOS
 - [Browser sources on the GPU under Mesa](/quest/m0/cef-headless.md) - shared-texture pages paint on Intel and AMD under Wayland, and a page that cannot paint fails loudly
-- [A replay's sound plays with its pictures](/quest/m0/replay-av-sync.md) - replay sources write a bus latency ahead, as media and broadcast sources do
 - [The Apple signing identity is available](/quest/m0/signing.md) - the Apple credentials packaging and the macOS camera need; Windows ships unsigned
 - [Packaging](/quest/m0/packaging.md) - a signed macOS app, a Windows installer, and a Flatpak for Linux
 - [The persistable portal restore token is pinned](/quest/m0/pin-portal-token.md) - moq-video's restore token, for Wayland sources

rs/moq-scene/src/playout.rs

@@ -9,8 +9,8 @@
 //! `moq play` holds its jitter buffer in the speaker. The bus holds only
 //! [`BUS_LATENCY`] of a source, so a [`Speaker`] holds the rest: it places each
 //! frame the playout target moq-audio's decoder estimates after it arrives,
-//! and a [`Writer`] writes it the bus's latency ahead of then. A media
-//! source's sound goes through a [`Writer`] too, so it sounds with the
+//! and a [`Writer`] writes it the bus's latency ahead of then. A media or
+//! replay source's sound goes through a [`Writer`] too, so it sounds with the
 //! pictures it shows.
 
 use std::time::Duration;

rs/moq-scene/src/publish.rs

@@ -1528,10 +1528,9 @@ mod tests {
 			};
 			let take = crate::replay::Take::new(&target, std::time::Duration::from_millis(2_500)).unwrap();
 			let feed = sources.get("replay").unwrap();
-			let begin = kio::clock::now();
 			feed.replay(take, 1.0).unwrap();
-			// The first picture is due at once, so the clock stays put while
-			// the encoder opens.
+			// The track opens before the replay begins, so the clock stays put
+			// while the encoder opens.
 			let listed = until(|| {
 				let listed = catalog.snapshot().ext.studio.sources.remove("replay");
 				listed.filter(|listed| !listed.video.renditions.is_empty())
@@ -1551,6 +1550,7 @@ mod tests {
 				.unwrap();
 			let container = moq_mux::catalog::hang::Container::try_from(config).unwrap();
 			let mut track = moq_mux::container::Consumer::new(track, container);
+			let begin = until(|| feed.run().begun).await;
 			until_time(begin + std::time::Duration::from_millis(1_500)).await;
 			let now = kio::Waiter::noop();
 			until(|| match track.poll_read(&now) {