fix(tracks): dispose video source and stop transceiver on unpublish

LocalVideoTrack.dispose() left its VideoSource undisposed, leaking the
source's native memory for the lifetime of the process; only the track
and capturer were released. Unpublishing a video track removed the track
from its sender but never stopped the transceiver, which is created fresh
on every publish, so transceivers accumulated until the connection closed.

Author: adrian-niculescu

.changeset/video-track-publish-unpublish-leaks.md

@@ -0,0 +1,5 @@
+---
+"client-sdk-android": patch
+---
+
+Fix native memory leaks on video track publish/unpublish cycles (#521). `LocalVideoTrack.dispose()` now disposes its backing `VideoSource`, which was previously left undisposed and leaked for the lifetime of the process (only the track and capturer were released). Unpublishing a video track now also stops its `RtpTransceiver`; since a new transceiver is created on every publish, removing the track from its sender alone left the transceiver retained until the connection closed.

livekit-android-sdk/src/main/java/io/livekit/android/room/RTCEngine.kt

@@ -1498,6 +1498,16 @@ internal constructor(
         }
     }
 
+    internal fun stopTransceiver(transceiver: RtpTransceiver) {
+        runBlocking {
+            publisher?.withPeerConnection {
+                if (!transceiver.isStopped) {
+                    transceiver.stopInternal()
+                }
+            }
+        }
+    }
+
     @VisibleForTesting
     fun getPublisherPeerConnection() =
         publisher!!.peerConnection

livekit-android-sdk/src/main/java/io/livekit/android/room/participant/LocalParticipant.kt

@@ -953,6 +953,15 @@ internal constructor(
 
         if (engine.connectionState == ConnectionState.CONNECTED) {
             engine.removeTrack(track.rtcTrack)
+
+            // A new transceiver is created for each publish. Removing the track from its sender
+            // doesn't release the transceiver, so it would otherwise be retained until the
+            // connection closes. Stopping it releases the native resources and frees the SDP
+            // m-section for reuse. Limited to video, which is where this leak is significant.
+            if (track is LocalVideoTrack) {
+                track.transceiver?.let { engine.stopTransceiver(it) }
+                track.transceiver = null
+            }
         }
         if (stopOnUnpublish) {
             track.stop()

livekit-android-sdk/src/main/java/io/livekit/android/room/track/LocalVideoTrack.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2025 LiveKit, Inc.
+ * Copyright 2023-2026 LiveKit, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -141,6 +141,7 @@ constructor(
     override fun dispose() {
         super.dispose()
         capturer.dispose()
+        source.dispose()
         closeableManager.close()
     }
 

livekit-android-test/src/main/java/io/livekit/android/test/mock/MockVideoSource.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 LiveKit, Inc.
+ * Copyright 2023-2026 LiveKit, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,4 +18,7 @@ package io.livekit.android.test.mock
 
 import livekit.org.webrtc.VideoSource
 
-class MockVideoSource(nativeSource: Long = 100) : VideoSource(nativeSource)
+class MockVideoSource(nativeSource: Long = 100) : VideoSource(nativeSource) {
+    override fun dispose() {
+    }
+}

livekit-android-test/src/test/java/io/livekit/android/room/participant/LocalParticipantMockE2ETest.kt

@@ -219,6 +219,28 @@ class LocalParticipantMockE2ETest : MockE2ETest() {
         assertEquals(publishOptions.stream, sentRequest.addTrack.stream)
     }
 
+    @Test
+    fun unpublishStopsVideoTransceiver() = runTest {
+        connect()
+        val videoTrack = createLocalTrack()
+        room.localParticipant.publishVideoTrack(videoTrack)
+
+        val transceiver = getPublisherPeerConnection().transceivers.first()
+        room.localParticipant.unpublishTrack(videoTrack)
+
+        Mockito.verify(transceiver).stopInternal()
+    }
+
+    @Test
+    fun disposeDisposesVideoSource() {
+        val source = mock(VideoSource::class.java)
+        val videoTrack = createLocalTrack(source = source)
+
+        videoTrack.dispose()
+
+        Mockito.verify(source).dispose()
+    }
+
     @Test
     fun updateMetadata() = runTest {
         connect()
@@ -292,9 +314,14 @@ class LocalParticipantMockE2ETest : MockE2ETest() {
         )
     }
 
-    private fun createLocalTrack(width: Int = 1280, height: Int = 720, isScreencast: Boolean = false) = LocalVideoTrack(
+    private fun createLocalTrack(
+        width: Int = 1280,
+        height: Int = 720,
+        isScreencast: Boolean = false,
+        source: VideoSource = mock(VideoSource::class.java),
+    ) = LocalVideoTrack(
         capturer = MockVideoCapturer(),
-        source = mock(VideoSource::class.java),
+        source = source,
         name = "",
         options = LocalVideoTrackOptions(
             isScreencast = isScreencast,