fix(nests): T13 reset Opus decoder on publisher boundary in NestPlayer
The reissuing-subscribe wrapper splices fresh-publisher frames into the
same `SharedFlow` that NestPlayer consumes, so across a JWT-refresh
hot-swap (speaker side) or a cliff-detector recycle (listener side)
the decoder receives a discontinuous frame stream while keeping its
Opus predictor state. Result: an audible warble at every publisher
cycle. Single-stream tests don't catch it because they never present
two distinct publishers.
Detect the boundary via `MoqObject.trackAlias` — the underlying
`MoqLiteSession.subscribe` assigns a fresh subscribeId per SUBSCRIBE,
which the listener wrapper surfaces verbatim as `trackAlias` on every
emitted object. A change between consecutive objects = new publisher.
Add an optional `decoderFactory: (() -> OpusDecoder)?` to NestPlayer.
When non-null, NestPlayer tracks `lastTrackAlias` and on a change
releases the current decoder and rebuilds via the factory. The
default `null` preserves the legacy single-decoder behaviour so
existing tests / callers that don't care about boundaries stand
unchanged.
NestViewModel.openSubscription wires the factory: a closure capturing
the catalog-derived `channelCount` so a rebuild reuses the SAME
channel layout — without that capture, a rebuild after a stereo-
publisher cycle would default to mono and silently downmix.
Two new NestPlayerTest cases pin the behaviour:
- `publisher_boundary_rebuilds_decoder_when_factory_provided`:
factory invoked twice (initial + boundary), first decoder
released on boundary, second released on stop.
- `publisher_boundary_no_op_when_factory_is_null`: legacy path
holds onto the same decoder across trackAlias changes (unchanged
semantics).
NestPlayer's first constructor parameter is now `initialDecoder`
(was `decoder`); positional-arg call sites are unchanged but the
named-arg call sites in the test suite are updated accordingly.
https://claude.ai/code/session_014JfZJHSTvyYYWJbC9VbB47
This commit is contained in:
Claude
+95
-5
@@ -232,7 +232,7 @@ class NestPlayerTest {
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val sut =
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NestPlayer(
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decoder = decoder,
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initialDecoder = decoder,
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player = player,
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scope = this,
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prerollFrames = 3,
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@@ -289,7 +289,7 @@ class NestPlayerTest {
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val sut =
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NestPlayer(
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decoder = decoder,
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initialDecoder = decoder,
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player = player,
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scope = this,
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prerollFrames = 5,
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@@ -326,7 +326,7 @@ class NestPlayerTest {
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val sut =
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NestPlayer(
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decoder = decoder,
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initialDecoder = decoder,
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player = player,
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scope = this,
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prerollFrames = 3,
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@@ -340,17 +340,107 @@ class NestPlayerTest {
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sut.stop()
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}
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@Test
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fun publisher_boundary_rebuilds_decoder_when_factory_provided() =
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runTest {
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// Two distinct decoders so we can prove the factory was
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// invoked. After the trackAlias change, frames should
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// route through `decoderB`, NOT `decoderA`.
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val decoderA =
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FakeOpusDecoder {
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byteArrayOf(0x0A) + it
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ShortArray(it.size) { _ -> 0xAA.toShort() }
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}
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val decoderB =
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FakeOpusDecoder {
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byteArrayOf(0x0B) + it
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ShortArray(it.size) { _ -> 0xBB.toShort() }
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}
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val factoryCallCount = atomicIntZero()
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val factory: () -> OpusDecoder = {
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if (factoryCallCount.getAndIncrement() == 0) decoderA else decoderB
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}
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val player = FakeAudioPlayer()
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val objects =
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flowOf(
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// First subscription cycle: trackAlias = 7
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moqObject(byteArrayOf(0x01), trackAlias = 7L),
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moqObject(byteArrayOf(0x02), trackAlias = 7L),
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// Wrapper re-issued — new SUBSCRIBE produces a
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// different trackAlias. Decoder MUST be rebuilt
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// before the next decode runs.
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moqObject(byteArrayOf(0x03), trackAlias = 8L),
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moqObject(byteArrayOf(0x04), trackAlias = 8L),
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)
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val sut =
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NestPlayer(
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initialDecoder = factory(),
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player = player,
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scope = this,
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decoderFactory = factory,
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)
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sut.play(objects)
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testScheduler.advanceUntilIdle()
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assertEquals(2, factoryCallCount.value, "factory invoked twice: initial + boundary")
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assertEquals(1, decoderA.releaseCount, "decoderA released on the boundary")
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assertEquals(0, decoderB.releaseCount, "decoderB still alive (released on stop)")
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sut.stop()
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assertEquals(1, decoderB.releaseCount, "decoderB released on stop")
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}
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@Test
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fun publisher_boundary_no_op_when_factory_is_null() =
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runTest {
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// Without a factory, NestPlayer keeps the same decoder
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// across trackAlias changes — backwards-compat path.
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val decoder = FakeOpusDecoder { byteToShorts(it) }
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val player = FakeAudioPlayer()
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val objects =
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flowOf(
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moqObject(byteArrayOf(0x01), trackAlias = 7L),
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moqObject(byteArrayOf(0x02), trackAlias = 8L),
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)
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val sut = NestPlayer(decoder, player, this)
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sut.play(objects)
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testScheduler.advanceUntilIdle()
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assertEquals(0, decoder.releaseCount, "no boundary-driven release without a factory")
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sut.stop()
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assertEquals(1, decoder.releaseCount, "released exactly once on stop")
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}
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// -- helpers -----------------------------------------------------------
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private fun moqObject(payload: ByteArray): MoqObject =
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private fun moqObject(
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payload: ByteArray,
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trackAlias: Long = 1L,
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): MoqObject =
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MoqObject(
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trackAlias = 1,
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trackAlias = trackAlias,
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groupId = 0,
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objectId = 0,
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publisherPriority = 0x80,
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payload = payload,
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)
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/**
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* Tiny stand-in for AtomicInteger that's available in commonMain
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* (kotlin.test scope). Used by the boundary-rebuild test to count
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* factory invocations across the test scope's coroutine
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* dispatcher.
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*/
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private class IntBox {
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var value: Int = 0
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fun getAndIncrement(): Int = value++
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}
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private fun atomicIntZero(): IntBox = IntBox()
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private fun byteToShorts(b: ByteArray): ShortArray = ShortArray(b.size) { b[it].toShort() }
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private class FakeOpusDecoder(
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