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fix: skip duplicate backup codec publish instead of throwing #1010

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Merged
davidliu merged 1 commit into from
Sep 16, 2026
Merged

fix: skip duplicate backup codec publish instead of throwing #1010

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5 changes: 5 additions & 0 deletions .changeset/idempotent-add-simulcast-track.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
"client-sdk-android": patch
---

Fix crash when a duplicate SubscribedQualityUpdate requests a backup codec that is already added. addSimulcastTrack now skips the duplicate instead of throwing IllegalStateException ("VP8 already added!"), matching the JS SDK behavior.
5 changes: 4 additions & 1 deletion livekit-android-sdk/src/main/java/io/livekit/android/room/participant/LocalParticipant.kt
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Expand Up @@ -1273,7 +1273,10 @@ internal constructor(
return
}
val (newOptions, newEncodings) = result
val simulcastTrack = track.addSimulcastTrack(codec, newEncodings)
// A duplicate SubscribedQualityUpdate can request a codec that is already being
// published (or mid-publish, before the sender is attached). Treat it as a no-op
// instead of throwing, so a repeated update doesn't crash the session.
val simulcastTrack = track.addSimulcastTrack(codec, newEncodings) ?: return

val transceiverInit = RtpTransceiverInit(
RtpTransceiver.RtpTransceiverDirection.SEND_ONLY,
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5 changes: 3 additions & 2 deletions livekit-android-sdk/src/main/java/io/livekit/android/room/track/LocalVideoTrack.kt
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Expand Up @@ -430,9 +430,10 @@ constructor(
return newCodecs
}

internal fun addSimulcastTrack(codec: VideoCodec, encodings: List<RtpParameters.Encoding>): SimulcastTrackInfo {
internal fun addSimulcastTrack(codec: VideoCodec, encodings: List<RtpParameters.Encoding>): SimulcastTrackInfo? {
if (this.simulcastCodecs.containsKey(codec)) {
throw IllegalStateException("$codec already added!")
LKLog.w { "$codec already added, skipping." }
return null
}
val simulcastTrackInfo = SimulcastTrackInfo(
codec = codec.codecName,
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30 changes: 30 additions & 0 deletions ...oid-test/src/test/java/io/livekit/android/room/participant/LocalParticipantMockE2ETest.kt
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Expand Up @@ -340,6 +340,36 @@ class LocalParticipantMockE2ETest : MockE2ETest() {
assertEquals(4, getPublisherPeerConnection().transceivers.size)
}

@Test
fun addSimulcastTrackForAlreadyAddedCodecIsNoOp() = runTest {
val videoTrack = createLocalTrack()

val first = videoTrack.addSimulcastTrack(VideoCodec.VP8, emptyList())
val second = videoTrack.addSimulcastTrack(VideoCodec.VP8, emptyList())

assertNotNull(first)
assertNull(second)
}

@Test
fun duplicateSubscribedQualityUpdateDoesNotRepublishBackupCodec() = runTest {
room.videoTrackPublishDefaults = room.videoTrackPublishDefaults.copy(
videoCodec = VideoCodec.VP9.codecName,
scalabilityMode = "L3T3",
backupCodec = BackupVideoCodec(codec = VideoCodec.VP8.codecName),
)

connect()
val videoTrack = createLocalTrack()
room.localParticipant.publishVideoTrack(videoTrack)

val trackSid = room.localParticipant.videoTrackPublications.first().first.sid
receiveSubscribedQualityUpdate(trackSid)
receiveSubscribedQualityUpdate(trackSid)

assertEquals(2, getPublisherPeerConnection().transceivers.size)
}
Comment on lines +355 to +371

@MaxHeimbrock MaxHeimbrock Sep 14, 2026

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This test already passes on main today, so it is not testing the fix of your issue. Can you please remove it?

@davidliu davidliu Sep 15, 2026

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Looks like there's a pretty specific hard to test window to get the original situation to pass, and the test is a reasonable guard to have overall anyways, so I'm going to keep this one and merge.


@Test
fun disposeDisposesVideoSource() {
val source = mock(VideoSource::class.java)
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