Add pre-connect audio for use with agents (#666)

* Update protocol submodule to v1.38.0

* Basic Preconnect audio buffer implementation

* Add Participant.State and related events

* prerecording full implementation

* Fix outgoing byte datastreams incorrectly padding data

* Add pre-connect audio for use with agents

+---
+"client-sdk-android": minor
+---
+
+Add pre-connect audio for use with agents
+
+See Room.withPreconnectAudio for details.

+---
+"client-sdk-android": patch
+---
+
+Fix outgoing datastreams incorrectly padding data

+---
+"client-sdk-android": minor
+---
+
+Add Participant.State and related events

 /*
 /*
- * Copyright 2023-2024 LiveKit, Inc.
+ * Copyright 2023-2025 LiveKit, Inc.
  *
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,7 @@ import io.livekit.android.audio.AudioProcessorOptions
 import io.livekit.android.audio.AudioSwitchHandler
 import io.livekit.android.audio.AudioSwitchHandler
 import io.livekit.android.audio.NoAudioHandler
 import io.livekit.android.audio.NoAudioHandler
 import io.livekit.android.room.Room
 import io.livekit.android.room.Room
+import io.livekit.android.room.track.LocalAudioTrack
 import livekit.org.webrtc.EglBase
 import livekit.org.webrtc.EglBase
 import livekit.org.webrtc.PeerConnectionFactory
 import livekit.org.webrtc.PeerConnectionFactory
 import livekit.org.webrtc.VideoDecoderFactory
 import livekit.org.webrtc.VideoDecoderFactory
@@ -33,6 +34,7 @@ import livekit.org.webrtc.VideoEncoderFactory
 import livekit.org.webrtc.audio.AudioDeviceModule
 import livekit.org.webrtc.audio.AudioDeviceModule
 import livekit.org.webrtc.audio.JavaAudioDeviceModule
 import livekit.org.webrtc.audio.JavaAudioDeviceModule
 import okhttp3.OkHttpClient
 import okhttp3.OkHttpClient
+
 /**
 /**
  * Overrides to replace LiveKit internally used components with custom implementations.
  * Overrides to replace LiveKit internally used components with custom implementations.
  */
  */
@@ -110,6 +112,11 @@ class AudioOptions(
      * Called after default setup to allow for customizations on the [JavaAudioDeviceModule].
      * Called after default setup to allow for customizations on the [JavaAudioDeviceModule].
      *
      *
      * Not used if [audioDeviceModule] is provided.
      * Not used if [audioDeviceModule] is provided.
+     *
+     * Note: We require setting the [JavaAudioDeviceModule.Builder.setSamplesReadyCallback] to provide
+     * support for [LocalAudioTrack.addSink]. If you wish to grab the audio samples
+     * from the local microphone track, use [LocalAudioTrack.addSink] instead of setting your own
+     * callback.
      */
      */
     val javaAudioDeviceModuleCustomizer: ((builder: JavaAudioDeviceModule.Builder) -> Unit)? = null,
     val javaAudioDeviceModuleCustomizer: ((builder: JavaAudioDeviceModule.Builder) -> Unit)? = null,
 
 

+/*
+ * Copyright 2025 LiveKit, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.livekit.android.audio
+
+import android.os.SystemClock
+import io.livekit.android.audio.PreconnectAudioBuffer.Companion.DEFAULT_TOPIC
+import io.livekit.android.audio.PreconnectAudioBuffer.Companion.TIMEOUT
+import io.livekit.android.events.RoomEvent
+import io.livekit.android.events.collect
+import io.livekit.android.room.ConnectionState
+import io.livekit.android.room.Room
+import io.livekit.android.room.datastream.StreamBytesOptions
+import io.livekit.android.room.participant.Participant
+import io.livekit.android.util.LKLog
+import io.livekit.android.util.flow
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.takeWhile
+import kotlinx.coroutines.launch
+import livekit.org.webrtc.AudioTrackSink
+import java.io.ByteArrayOutputStream
+import java.nio.ByteBuffer
+import kotlin.math.min
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.seconds
+
+internal class PreconnectAudioBuffer
+internal constructor(timeout: Duration) : AudioTrackSink {
+
+    companion object {
+        const val DEFAULT_TOPIC = "lk.agent.pre-connect-audio-buffer"
+        val TIMEOUT = 10.seconds
+    }
+
+    private val outputStreamLock = Any()
+    private val outputStream by lazy {
+        ByteArrayOutputStream()
+    }
+
+    private lateinit var collectedBytes: ByteArray
+
+    private val tempArray = ByteArray(1024)
+    private var initialTime = -1L
+
+    private var bitsPerSample = 16
+    private var sampleRate = 48000 // default sampleRate from JavaAudioDeviceModule
+    private var numberOfChannels = 1 // default channels from JavaAudioDeviceModule
+
+    private var isRecording = true
+    private val timeoutMs = timeout.inWholeMilliseconds
+
+    fun startRecording() {
+        isRecording = true
+    }
+
+    fun stopRecording() {
+        synchronized(outputStreamLock) {
+            if (isRecording) {
+                collectedBytes = outputStream.toByteArray()
+                isRecording = false
+            }
+        }
+    }
+
+    fun clear() {
+        stopRecording()
+        collectedBytes = ByteArray(0)
+    }
+
+    override fun onData(
+        audioData: ByteBuffer,
+        bitsPerSample: Int,
+        sampleRate: Int,
+        numberOfChannels: Int,
+        numberOfFrames: Int,
+        absoluteCaptureTimestampMs: Long,
+    ) {
+        if (!isRecording) {
+            return
+        }
+        if (initialTime == -1L) {
+            initialTime = SystemClock.elapsedRealtime()
+        }
+
+        this.bitsPerSample = bitsPerSample
+        this.sampleRate = sampleRate
+        this.numberOfChannels = numberOfChannels
+        val currentTime = SystemClock.elapsedRealtime()
+        // Limit reached, don't buffer any more.
+        if (currentTime - initialTime > timeoutMs) {
+            return
+        }
+
+        audioData.rewind()
+
+        synchronized(outputStreamLock) {
+            if (audioData.hasArray()) {
+                outputStream.write(audioData.array())
+            } else {
+                while (audioData.hasRemaining()) {
+                    val readBytes = min(tempArray.size, audioData.remaining())
+                    audioData.get(tempArray, 0, readBytes)
+                    outputStream.write(tempArray)
+                }
+            }
+        }
+    }
+
+    suspend fun sendAudioData(room: Room, trackSid: String?, agentIdentities: List<Participant.Identity>, topic: String = DEFAULT_TOPIC) {
+        if (agentIdentities.isEmpty()) {
+            return
+        }
+
+        val audioData = outputStream.toByteArray()
+        if (audioData.size <= 1024) {
+            LKLog.i { "Audio data size too small, nothing to send." }
+            return
+        }
+
+        val sender = room.localParticipant.streamBytes(
+            StreamBytesOptions(
+                topic = topic,
+                attributes = mapOf(
+                    "sampleRate" to "${this.sampleRate}",
+                    "channels" to "${this.numberOfChannels}",
+                    "trackId" to (trackSid ?: ""),
+                ),
+                destinationIdentities = agentIdentities,
+                totalSize = audioData.size.toLong(),
+                name = "preconnect-audio-buffer",
+            ),
+        )
+
+        try {
+            sender.write(audioData)
+            sender.close()
+        } catch (e: Exception) {
+            sender.close(e.localizedMessage)
+        }
+
+        val samples = audioData.size / (numberOfChannels * bitsPerSample / 8)
+        val duration = samples.toFloat() / sampleRate
+        LKLog.i { "Sent ${duration}s (${audioData.size / 1024}KB) of audio data to ${agentIdentities.size} agent(s) (${agentIdentities.joinToString(",")})" }
+    }
+}
+
+/**
+ * Starts a pre-connect audio recording that will be sent to
+ * any agents that connect within the [timeout]. This speeds up
+ * preceived connection times, as the user can start speaking
+ * prior to actual connection with the agent.
+ *
+ * This will automatically be cleaned up when the room disconnects or the operation fails.
+ *
+ * Example:
+ * ```
+ * try {
+ *     room.withPreconnectAudio {
+ *         // Audio is being captured automatically
+ *         // Perform any other (async) setup here
+ *         val (url, token) = tokenService.fetchConnectionDetails()
+ *         room.connect(
+ *             url = url,
+ *             token = token,
+ *         )
+ *         room.localParticipant.setMicrophoneEnabled(true)
+ *     }
+ * } catch (e: Throwable) {
+ *     Log.e(TAG, "Error!")
+ * }
+ * ```
+ * @param timeout the timeout for the remote participant to subscribe to the audio track.
+ * The room connection needs to be established and the remote participant needs to subscribe to the audio track
+ * before the timeout is reached. Otherwise, the audio stream will be flushed without sending.
+ * @param topic the topic to send the preconnect audio buffer to. By default this is configured for
+ * use with LiveKit Agents.
+ * @param onError The error handler to call when an error occurs while sending the audio buffer.
+ * @param operation The connection lambda to call with the pre-connect audio.
+ *
+ */
+suspend fun <T> Room.withPreconnectAudio(
+    timeout: Duration = TIMEOUT,
+    topic: String = DEFAULT_TOPIC,
+    onError: ((e: Exception) -> Unit)? = null,
+    operation: suspend () -> T,
+) = coroutineScope {
+    isPrerecording = true
+    val audioTrack = localParticipant.getOrCreateDefaultAudioTrack()
+    val preconnectAudioBuffer = PreconnectAudioBuffer(timeout)
+
+    LKLog.v { "Starting preconnect audio buffer" }
+    preconnectAudioBuffer.startRecording()
+    audioTrack.addSink(preconnectAudioBuffer)
+    audioTrack.prewarm()
+
+    fun stopRecording() {
+        if (!isPrerecording) {
+            return
+        }
+
+        LKLog.v { "Stopping preconnect audio buffer" }
+        audioTrack.removeSink(preconnectAudioBuffer)
+        preconnectAudioBuffer.stopRecording()
+        isPrerecording = false
+    }
+
+    // Clear the preconnect audio buffer after the timeout to free memory.
+    launch {
+        delay(TIMEOUT)
+        preconnectAudioBuffer.clear()
+    }
+
+    val sentIdentities = mutableSetOf<Participant.Identity>()
+    launch {
+        suspend fun handleSendIfNeeded(participant: Participant) {
+            coroutineScope inner@{
+                engine::connectionState.flow
+                    .takeWhile { it != ConnectionState.CONNECTED }
+                    .collect()
+                val kind = participant.kind
+                val state = participant.state
+                val identity = participant.identity
+                if (sentIdentities.contains(identity) || kind != Participant.Kind.AGENT || state != Participant.State.ACTIVE || identity == null) {
+                    return@inner
+                }
+
+                stopRecording()
+                launch {
+                    try {
+                        preconnectAudioBuffer.sendAudioData(
+                            room = this@withPreconnectAudio,
+                            trackSid = audioTrack.sid,
+                            agentIdentities = listOf(identity),
+                            topic = topic,
+                        )
+                        sentIdentities.add(identity)
+                    } catch (e: Exception) {
+                        LKLog.w(e) { "Error occurred while sending the audio preconnect data." }
+                        onError?.invoke(e)
+                    }
+                }
+            }
+        }
+
+        events.collect { event ->
+            when (event) {
+                is RoomEvent.LocalTrackSubscribed -> {
+                    LKLog.i { "Local audio track has been subscribed to, stopping preconnect audio recording." }
+                    stopRecording()
+                }
+
+                is RoomEvent.ParticipantConnected -> {
+                    // agents may connect with ACTIVE state and not trigger a participant state changed.
+                    handleSendIfNeeded(event.participant)
+                }
+
+                is RoomEvent.ParticipantStateChanged -> {
+                    handleSendIfNeeded(event.participant)
+                }
+
+                is RoomEvent.Disconnected -> {
+                    cancel()
+                }
+
+                else -> {
+                    // Intentionally blank.
+                }
+            }
+        }
+    }
+
+    val retValue: T
+    try {
+        retValue = operation.invoke()
+    } catch (e: Exception) {
+        cancel()
+        throw e
+    }
+
+    return@coroutineScope retValue
+}

@@ -197,4 +197,13 @@ sealed class ParticipantEvent(open val participant: Participant) : Event() {
          */
          */
         val publication: TrackPublication?,
         val publication: TrackPublication?,
     ) : ParticipantEvent(participant)
     ) : ParticipantEvent(participant)
+
+    /**
+     * A participant's state has changed.
+     */
+    class StateChanged(
+        override val participant: Participant,
+        val newState: Participant.State,
+        val oldState: Participant.State,
+    ) : ParticipantEvent(participant)
 }
 }

@@ -271,6 +271,16 @@ sealed class RoomEvent(val room: Room) : Event() {
          */
          */
         val publication: TrackPublication?,
         val publication: TrackPublication?,
     ) : RoomEvent(room)
     ) : RoomEvent(room)
+
+    /**
+     * The state for a participant has changed.
+     */
+    class ParticipantStateChanged(
+        room: Room,
+        val participant: Participant,
+        val newState: Participant.State,
+        val oldState: Participant.State,
+    ) : RoomEvent(room)
 }
 }
 
 
 enum class DisconnectReason {
 enum class DisconnectReason {
@@ -288,6 +298,7 @@ enum class DisconnectReason {
     USER_UNAVAILABLE,
     USER_UNAVAILABLE,
     USER_REJECTED,
     USER_REJECTED,
     SIP_TRUNK_FAILURE,
     SIP_TRUNK_FAILURE,
+    CONNECTION_TIMEOUT,
 }
 }
 
 
 /**
 /**
@@ -308,6 +319,7 @@ fun LivekitModels.DisconnectReason?.convert(): DisconnectReason {
         LivekitModels.DisconnectReason.USER_UNAVAILABLE -> DisconnectReason.USER_UNAVAILABLE
         LivekitModels.DisconnectReason.USER_UNAVAILABLE -> DisconnectReason.USER_UNAVAILABLE
         LivekitModels.DisconnectReason.USER_REJECTED -> DisconnectReason.USER_REJECTED
         LivekitModels.DisconnectReason.USER_REJECTED -> DisconnectReason.USER_REJECTED
         LivekitModels.DisconnectReason.SIP_TRUNK_FAILURE -> DisconnectReason.SIP_TRUNK_FAILURE
         LivekitModels.DisconnectReason.SIP_TRUNK_FAILURE -> DisconnectReason.SIP_TRUNK_FAILURE
+        LivekitModels.DisconnectReason.CONNECTION_TIMEOUT -> DisconnectReason.CONNECTION_TIMEOUT
         LivekitModels.DisconnectReason.UNKNOWN_REASON,
         LivekitModels.DisconnectReason.UNKNOWN_REASON,
         LivekitModels.DisconnectReason.UNRECOGNIZED,
         LivekitModels.DisconnectReason.UNRECOGNIZED,
         null,
         null,

 /*
 /*
- * Copyright 2023-2024 LiveKit, Inc.
+ * Copyright 2023-2025 LiveKit, Inc.
  *
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,9 @@ import io.livekit.android.room.track.ScreenSharePresets
 import javax.inject.Inject
 import javax.inject.Inject
 import javax.inject.Singleton
 import javax.inject.Singleton
 
 
+/**
+ * @suppress
+ */
 @Singleton
 @Singleton
 class DefaultsManager
 class DefaultsManager
 @Inject
 @Inject
@@ -34,4 +37,6 @@ constructor() {
     var videoTrackPublishDefaults: VideoTrackPublishDefaults = VideoTrackPublishDefaults()
     var videoTrackPublishDefaults: VideoTrackPublishDefaults = VideoTrackPublishDefaults()
     var screenShareTrackCaptureDefaults: LocalVideoTrackOptions = LocalVideoTrackOptions(isScreencast = true, captureParams = ScreenSharePresets.ORIGINAL.capture)
     var screenShareTrackCaptureDefaults: LocalVideoTrackOptions = LocalVideoTrackOptions(isScreencast = true, captureParams = ScreenSharePresets.ORIGINAL.capture)
     var screenShareTrackPublishDefaults: VideoTrackPublishDefaults = VideoTrackPublishDefaults(videoEncoding = ScreenSharePresets.ORIGINAL.encoding)
     var screenShareTrackPublishDefaults: VideoTrackPublishDefaults = VideoTrackPublishDefaults(videoEncoding = ScreenSharePresets.ORIGINAL.encoding)
+
+    var isPrerecording: Boolean = false
 }
 }

@@ -110,7 +110,7 @@ internal constructor(
      * Reflects the combined connection state of SignalClient and primary PeerConnection.
      * Reflects the combined connection state of SignalClient and primary PeerConnection.
      */
      */
     @FlowObservable
     @FlowObservable
-    @VisibleForTesting(otherwise = VisibleForTesting.PACKAGE_PRIVATE)
+    @get:FlowObservable
     var connectionState: ConnectionState by flowDelegate(ConnectionState.DISCONNECTED) { newVal, oldVal ->
     var connectionState: ConnectionState by flowDelegate(ConnectionState.DISCONNECTED) { newVal, oldVal ->
         if (newVal == oldVal) {
         if (newVal == oldVal) {
             return@flowDelegate
             return@flowDelegate
@@ -302,7 +302,8 @@ internal constructor(
                         RELIABLE_DATA_CHANNEL_LABEL,
                         RELIABLE_DATA_CHANNEL_LABEL,
                         reliableInit,
                         reliableInit,
                     ).also { dataChannel ->
                     ).also { dataChannel ->
-                        dataChannel.registerObserver(DataChannelObserver(dataChannel))
+                        reliableDataChannelManager = DataChannelManager(dataChannel, DataChannelObserver(dataChannel))
+                        dataChannel.registerObserver(reliableDataChannelManager)
                     }
                     }
                 }
                 }
 
 
@@ -315,7 +316,8 @@ internal constructor(
                         LOSSY_DATA_CHANNEL_LABEL,
                         LOSSY_DATA_CHANNEL_LABEL,
                         lossyInit,
                         lossyInit,
                     ).also { dataChannel ->
                     ).also { dataChannel ->
-                        dataChannel.registerObserver(DataChannelObserver(dataChannel))
+                        lossyDataChannelManager = DataChannelManager(dataChannel, DataChannelObserver(dataChannel))
+                        dataChannel.registerObserver(lossyDataChannelManager)
                     }
                     }
                 }
                 }
             }
             }
@@ -1095,6 +1097,7 @@ internal constructor(
             -> {
             -> {
                 listener?.onRpcPacketReceived(dp)
                 listener?.onRpcPacketReceived(dp)
             }
             }
+
             LivekitModels.DataPacket.ValueCase.VALUE_NOT_SET,
             LivekitModels.DataPacket.ValueCase.VALUE_NOT_SET,
             null,
             null,
             -> {
             -> {

@@ -76,7 +76,7 @@ class Room
 @AssistedInject
 @AssistedInject
 constructor(
 constructor(
     @Assisted private val context: Context,
     @Assisted private val context: Context,
-    private val engine: RTCEngine,
+    internal val engine: RTCEngine,
     private val eglBase: EglBase,
     private val eglBase: EglBase,
     localParticipantFactory: LocalParticipant.Factory,
     localParticipantFactory: LocalParticipant.Factory,
     private val defaultsManager: DefaultsManager,
     private val defaultsManager: DefaultsManager,
@@ -320,6 +320,8 @@ constructor(
 
 
     private var transcriptionReceivedTimes = mutableMapOf<String, Long>()
     private var transcriptionReceivedTimes = mutableMapOf<String, Long>()
 
 
+    internal var isPrerecording by defaultsManager::isPrerecording
+
     private fun getCurrentRoomOptions(): RoomOptions =
     private fun getCurrentRoomOptions(): RoomOptions =
         RoomOptions(
         RoomOptions(
             adaptiveStream = adaptiveStream,
             adaptiveStream = adaptiveStream,
@@ -678,6 +680,15 @@ constructor(
                         )
                         )
                     }
                     }
 
 
+                    is ParticipantEvent.StateChanged -> {
+                        RoomEvent.ParticipantStateChanged(
+                            this@Room,
+                            it.participant,
+                            it.newState,
+                            it.oldState,
+                        )
+                    }
+
                     else -> {
                     else -> {
                         // do nothing
                         // do nothing
                     }
                     }
@@ -808,6 +819,17 @@ constructor(
                         ),
                         ),
                     )
                     )
 
 
+                    is ParticipantEvent.StateChanged -> {
+                        eventBus.postEvent(
+                            RoomEvent.ParticipantStateChanged(
+                                room = this@Room,
+                                participant = it.participant,
+                                newState = it.newState,
+                                oldState = it.oldState,
+                            ),
+                        )
+                    }
+
                     else -> {
                     else -> {
                         // do nothing
                         // do nothing
                     }
                     }

@@ -780,6 +780,10 @@ constructor(
             -> {
             -> {
                 LKLog.v { "empty messageCase!" }
                 LKLog.v { "empty messageCase!" }
             }
             }
+
+            LivekitRtc.SignalResponse.MessageCase.ROOM_MOVED -> {
+                // TODO
+            }
         }
         }
     }
     }
 
 

@@ -45,4 +45,7 @@ interface StreamDestination<T> {
     suspend fun close(reason: String?)
     suspend fun close(reason: String?)
 }
 }
 
 
-internal typealias DataChunker<T> = (data: T, chunkSize: Int) -> List<ByteArray>
+/**
+ * @suppress
+ */
+typealias DataChunker<T> = (data: T, chunkSize: Int) -> List<ByteArray>

@@ -24,6 +24,7 @@ import okio.Source
 import okio.source
 import okio.source
 import java.io.InputStream
 import java.io.InputStream
 import java.util.Arrays
 import java.util.Arrays
+import kotlin.math.min
 
 
 class ByteStreamSender(
 class ByteStreamSender(
     val info: ByteStreamInfo,
     val info: ByteStreamInfo,
@@ -36,7 +37,16 @@ class ByteStreamSender(
 
 
 private val byteDataChunker: DataChunker<ByteArray> = { data: ByteArray, chunkSize: Int ->
 private val byteDataChunker: DataChunker<ByteArray> = { data: ByteArray, chunkSize: Int ->
     (data.indices step chunkSize)
     (data.indices step chunkSize)
-        .map { index -> Arrays.copyOfRange(data, index, index + chunkSize) }
+        .map { index ->
+            Arrays.copyOfRange(
+                /* original = */
+                data,
+                /* from = */
+                index,
+                /* to = */
+                min(index + chunkSize, data.size),
+            )
+        }
 }
 }
 
 
 /**
 /**

@@ -67,6 +67,7 @@ import kotlinx.coroutines.suspendCancellableCoroutine
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import kotlinx.coroutines.sync.withLock
 import livekit.LivekitModels
 import livekit.LivekitModels
+import livekit.LivekitModels.AudioTrackFeature
 import livekit.LivekitModels.Codec
 import livekit.LivekitModels.Codec
 import livekit.LivekitModels.DataPacket
 import livekit.LivekitModels.DataPacket
 import livekit.LivekitModels.TrackInfo
 import livekit.LivekitModels.TrackInfo
@@ -434,7 +435,7 @@ internal constructor(
         options: AudioTrackPublishOptions = AudioTrackPublishOptions(
         options: AudioTrackPublishOptions = AudioTrackPublishOptions(
             null,
             null,
             audioTrackPublishDefaults,
             audioTrackPublishDefaults,
-        ),
+        ).copy(preconnect = defaultsManager.isPrerecording),
         publishListener: PublishListener? = null,
         publishListener: PublishListener? = null,
     ): Boolean {
     ): Boolean {
         val encodings = listOf(
         val encodings = listOf(
@@ -450,6 +451,7 @@ internal constructor(
             requestConfig = {
             requestConfig = {
                 disableDtx = !options.dtx
                 disableDtx = !options.dtx
                 disableRed = !options.red
                 disableRed = !options.red
+                addAllAudioFeatures(options.getFeaturesList())
                 source = options.source?.toProto() ?: LivekitModels.TrackSource.MICROPHONE
                 source = options.source?.toProto() ?: LivekitModels.TrackSource.MICROPHONE
             },
             },
             encodings = encodings,
             encodings = encodings,
@@ -459,7 +461,7 @@ internal constructor(
         if (publication != null) {
         if (publication != null) {
             val job = scope.launch {
             val job = scope.launch {
                 track::features.flow.collect {
                 track::features.flow.collect {
-                    engine.updateLocalAudioTrack(publication.sid, it)
+                    engine.updateLocalAudioTrack(publication.sid, it + options.getFeaturesList())
                 }
                 }
             }
             }
             jobs[publication] = job
             jobs[publication] = job
@@ -1763,6 +1765,7 @@ data class AudioTrackPublishOptions(
     override val red: Boolean = true,
     override val red: Boolean = true,
     override val source: Track.Source? = null,
     override val source: Track.Source? = null,
     override val stream: String? = null,
     override val stream: String? = null,
+    val preconnect: Boolean = false,
 ) : BaseAudioTrackPublishOptions(), TrackPublishOptions {
 ) : BaseAudioTrackPublishOptions(), TrackPublishOptions {
     constructor(
     constructor(
         name: String? = null,
         name: String? = null,
@@ -1777,6 +1780,17 @@ data class AudioTrackPublishOptions(
         source = source,
         source = source,
         stream = stream,
         stream = stream,
     )
     )
+
+    internal fun getFeaturesList(): Set<AudioTrackFeature> {
+        val features = mutableSetOf<AudioTrackFeature>()
+        if (!dtx) {
+            features.add(AudioTrackFeature.TF_NO_DTX)
+        }
+        if (preconnect) {
+            features.add(AudioTrackFeature.TF_PRECONNECT_BUFFER)
+        }
+        return features
+    }
 }
 }
 
 
 data class ParticipantTrackPermission(
 data class ParticipantTrackPermission(

@@ -93,6 +93,27 @@ open class Participant(
         @VisibleForTesting set
         @VisibleForTesting set
 
 
     /**
     /**
+     * The participant state.
+     *
+     * Changes can be observed by using [io.livekit.android.util.flow]
+     */
+    @FlowObservable
+    @get:FlowObservable
+    var state: State by flowDelegate(State.UNKNOWN) { newState, oldState ->
+        if (newState != oldState) {
+            eventBus.postEvent(
+                ParticipantEvent.StateChanged(
+                    participant = this,
+                    newState = newState,
+                    oldState = oldState,
+                ),
+                scope,
+            )
+        }
+    }
+        @VisibleForTesting set
+
+    /**
      * Changes can be observed by using [io.livekit.android.util.flow]
      * Changes can be observed by using [io.livekit.android.util.flow]
      */
      */
     @FlowObservable
     @FlowObservable
@@ -377,6 +398,7 @@ open class Participant(
             permissions = ParticipantPermission.fromProto(info.permission)
             permissions = ParticipantPermission.fromProto(info.permission)
         }
         }
         attributes = info.attributesMap
         attributes = info.attributesMap
+        state = State.fromProto(info.state)
     }
     }
 
 
     override fun equals(other: Any?): Boolean {
     override fun equals(other: Any?): Boolean {
@@ -474,6 +496,34 @@ open class Participant(
             }
             }
         }
         }
     }
     }
+
+    enum class State {
+        // websocket' connected, but not offered yet
+        JOINING,
+
+        // server received client offer
+        JOINED,
+
+        // ICE connectivity established
+        ACTIVE,
+
+        // WS disconnected
+        DISCONNECTED,
+
+        UNKNOWN;
+
+        companion object {
+            fun fromProto(proto: LivekitModels.ParticipantInfo.State): State {
+                return when (proto) {
+                    LivekitModels.ParticipantInfo.State.JOINING -> JOINING
+                    LivekitModels.ParticipantInfo.State.JOINED -> JOINED
+                    LivekitModels.ParticipantInfo.State.ACTIVE -> ACTIVE
+                    LivekitModels.ParticipantInfo.State.DISCONNECTED -> DISCONNECTED
+                    LivekitModels.ParticipantInfo.State.UNRECOGNIZED -> UNKNOWN
+                }
+            }
+        }
+    }
 }
 }
 
 
 /**
 /**

+/*
+ * Copyright 2025 LiveKit, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.livekit.android.test.mock.room.datastream.outgoing
+
+import io.livekit.android.room.datastream.outgoing.DataChunker
+import io.livekit.android.room.datastream.outgoing.StreamDestination
+
+class MockStreamDestination<T>(val chunkSize: Int) : StreamDestination<T> {
+    override var isOpen: Boolean = true
+
+    val writtenChunks = mutableListOf<ByteArray>()
+    override suspend fun write(data: T, chunker: DataChunker<T>) {
+        val chunks = chunker.invoke(data, chunkSize)
+
+        for (chunk in chunks) {
+            writtenChunks.add(chunk)
+        }
+    }
+
+    override suspend fun close(reason: String?) {
+        isOpen = false
+    }
+}

@@ -14,10 +14,10 @@
  * limitations under the License.
  * limitations under the License.
  */
  */
 
 
-package io.livekit.android.room
+package io.livekit.android.room.datastream
 
 
 import com.google.protobuf.ByteString
 import com.google.protobuf.ByteString
-import io.livekit.android.room.datastream.StreamException
+import io.livekit.android.room.RTCEngine
 import io.livekit.android.test.MockE2ETest
 import io.livekit.android.test.MockE2ETest
 import io.livekit.android.test.assert.assertIsClass
 import io.livekit.android.test.assert.assertIsClass
 import io.livekit.android.test.mock.MockDataChannel
 import io.livekit.android.test.mock.MockDataChannel
@@ -38,7 +38,7 @@ import org.junit.Test
 import java.nio.ByteBuffer
 import java.nio.ByteBuffer
 
 
 @OptIn(ExperimentalCoroutinesApi::class)
 @OptIn(ExperimentalCoroutinesApi::class)
-class RoomDataStreamMockE2ETest : MockE2ETest() {
+class RoomIncomingDataStreamMockE2ETest : MockE2ETest() {
     @Test
     @Test
     fun dataStream() = runTest {
     fun dataStream() = runTest {
         connect()
         connect()

+/*
+ * Copyright 2023-2025 LiveKit, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.livekit.android.room.datastream
+
+import com.google.protobuf.ByteString
+import io.livekit.android.room.RTCEngine
+import io.livekit.android.room.participant.Participant
+import io.livekit.android.test.MockE2ETest
+import io.livekit.android.test.mock.MockDataChannel
+import io.livekit.android.test.mock.MockPeerConnection
+import io.livekit.android.test.mock.TestData
+import io.livekit.android.util.toOkioByteString
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.launch
+import livekit.LivekitModels
+import livekit.LivekitRtc
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+@OptIn(ExperimentalCoroutinesApi::class)
+class RoomOutgoingDataStreamMockE2ETest : MockE2ETest() {
+
+    private lateinit var pubDataChannel: MockDataChannel
+
+    override suspend fun connect(joinResponse: LivekitRtc.SignalResponse) {
+        super.connect(joinResponse)
+
+        val pubPeerConnection = component.rtcEngine().getPublisherPeerConnection() as MockPeerConnection
+        pubDataChannel = pubPeerConnection.dataChannels[RTCEngine.RELIABLE_DATA_CHANNEL_LABEL] as MockDataChannel
+    }
+
+    @Test
+    fun dataStream() = runTest {
+        connect()
+
+        // Remote participant to send data to
+        wsFactory.listener.onMessage(
+            wsFactory.ws,
+            TestData.PARTICIPANT_JOIN.toOkioByteString(),
+        )
+
+        val bytesToStream = ByteArray(100)
+        for (i in bytesToStream.indices) {
+            bytesToStream[i] = i.toByte()
+        }
+        val job = launch {
+            val sender = room.localParticipant.streamBytes(
+                StreamBytesOptions(
+                    topic = "topic",
+                    attributes = mapOf("hello" to "world"),
+                    streamId = "stream_id",
+                    destinationIdentities = listOf(Participant.Identity(TestData.REMOTE_PARTICIPANT.identity)),
+                    name = "stream_name",
+                    totalSize = bytesToStream.size.toLong(),
+                ),
+            )
+            sender.write(bytesToStream)
+            sender.close()
+        }
+
+        job.join()
+
+        val buffers = pubDataChannel.sentBuffers
+
+        println(buffers)
+        assertEquals(3, buffers.size)
+
+        val headerPacket = LivekitModels.DataPacket.parseFrom(ByteString.copyFrom(buffers[0].data))
+        assertTrue(headerPacket.hasStreamHeader())
+
+        with(headerPacket.streamHeader) {
+            assertTrue(hasByteHeader())
+        }
+
+        val payloadPacket = LivekitModels.DataPacket.parseFrom(ByteString.copyFrom(buffers[1].data))
+        assertTrue(payloadPacket.hasStreamChunk())
+        with(payloadPacket.streamChunk) {
+            assertEquals(100, content.size())
+        }
+
+        val trailerPacket = LivekitModels.DataPacket.parseFrom(ByteString.copyFrom(buffers[2].data))
+        assertTrue(trailerPacket.hasStreamTrailer())
+        with(trailerPacket.streamTrailer) {
+            assertTrue(reason.isNullOrEmpty())
+        }
+    }
+}

+/*
+ * Copyright 2025 LiveKit, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.livekit.android.room.datastream.outgoing
+
+import io.livekit.android.room.datastream.ByteStreamInfo
+import io.livekit.android.test.BaseTest
+import io.livekit.android.test.mock.room.datastream.outgoing.MockStreamDestination
+import kotlinx.coroutines.launch
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Test
+import kotlin.math.roundToInt
+
+class ByteStreamSenderTest : BaseTest() {
+
+    companion object {
+        val CHUNK_SIZE = 2048
+    }
+
+    @Test
+    fun sendsSmallBytes() = runTest {
+        val destination = MockStreamDestination<ByteArray>(CHUNK_SIZE)
+        val sender = ByteStreamSender(
+            info = createInfo(),
+            destination = destination,
+        )
+
+        val job = launch {
+            sender.write(ByteArray(100))
+            sender.close()
+        }
+
+        job.join()
+
+        assertFalse(destination.isOpen)
+        assertEquals(1, destination.writtenChunks.size)
+        assertEquals(100, destination.writtenChunks[0].size)
+    }
+
+    @Test
+    fun sendsLargeBytes() = runTest {
+        val destination = MockStreamDestination<ByteArray>(CHUNK_SIZE)
+        val sender = ByteStreamSender(
+            info = createInfo(),
+            destination = destination,
+        )
+
+        val bytes = ByteArray((CHUNK_SIZE * 1.5).roundToInt())
+
+        val job = launch {
+            sender.write(bytes)
+            sender.close()
+        }
+
+        job.join()
+
+        assertFalse(destination.isOpen)
+        assertEquals(2, destination.writtenChunks.size)
+        assertEquals(CHUNK_SIZE, destination.writtenChunks[0].size)
+        assertEquals(bytes.size - CHUNK_SIZE, destination.writtenChunks[1].size)
+    }
+
+    fun createInfo(): ByteStreamInfo = ByteStreamInfo(id = "stream_id", topic = "topic", timestampMs = 0, totalSize = null, attributes = mapOf(), mimeType = "", name = null)
+}

+/*
+ * Copyright 2025 LiveKit, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.livekit.android.room.datastream.outgoing
+
+import io.livekit.android.room.datastream.TextStreamInfo
+import io.livekit.android.test.BaseTest
+import io.livekit.android.test.mock.room.datastream.outgoing.MockStreamDestination
+import kotlinx.coroutines.launch
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNotEquals
+import org.junit.Test
+
+class TextStreamSenderTest : BaseTest() {
+
+    companion object {
+        val CHUNK_SIZE = 20
+    }
+
+    @Test
+    fun sendsSingle() = runTest {
+        val destination = MockStreamDestination<String>(CHUNK_SIZE)
+        val sender = TextStreamSender(
+            info = createInfo(),
+            destination = destination,
+        )
+
+        val text = "abcdefghi"
+        val job = launch {
+            sender.write(text)
+            sender.close()
+        }
+
+        job.join()
+
+        assertFalse(destination.isOpen)
+        assertEquals(1, destination.writtenChunks.size)
+        assertEquals(text, destination.writtenChunks[0].decodeToString())
+    }
+
+    @Test
+    fun sendsChunks() = runTest {
+        val destination = MockStreamDestination<String>(CHUNK_SIZE)
+        val sender = TextStreamSender(
+            info = createInfo(),
+            destination = destination,
+        )
+
+        val text = with(StringBuilder()) {
+            for (i in 1..CHUNK_SIZE) {
+                append("abcdefghi")
+            }
+            toString()
+        }
+
+        val job = launch {
+            sender.write(text)
+            sender.close()
+        }
+
+        job.join()
+
+        assertFalse(destination.isOpen)
+        assertNotEquals(1, destination.writtenChunks.size)
+
+        val writtenString = with(StringBuilder()) {
+            for (chunk in destination.writtenChunks) {
+                append(chunk.decodeToString())
+            }
+            toString()
+        }
+
+        assertEquals(text, writtenString)
+    }
+
+    fun createInfo(): TextStreamInfo = TextStreamInfo(
+        id = "stream_id",
+        topic = "topic",
+        timestampMs = 0,
+        totalSize = null,
+        attributes = mapOf(),
+        operationType = TextStreamInfo.OperationType.CREATE,
+        version = 0,
+        replyToStreamId = null,
+        attachedStreamIds = listOf(),
+        generated = false,
+    )
+}

 /*
 /*
- * Copyright 2023-2024 LiveKit, Inc.
+ * Copyright 2023-2025 LiveKit, Inc.
  *
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * you may not use this file except in compliance with the License.
@@ -58,7 +58,7 @@ class ParticipantTest {
         assertEquals(INFO.name, participant.name)
         assertEquals(INFO.name, participant.name)
         assertEquals(Participant.Kind.fromProto(INFO.kind), participant.kind)
         assertEquals(Participant.Kind.fromProto(INFO.kind), participant.kind)
         assertEquals(INFO.attributesMap, participant.attributes)
         assertEquals(INFO.attributesMap, participant.attributes)
-
+        assertEquals(Participant.State.fromProto(INFO.state), participant.state)
         assertEquals(INFO, participant.participantInfo)
         assertEquals(INFO, participant.participantInfo)
     }
     }
 
 
@@ -151,6 +151,23 @@ class ParticipantTest {
     }
     }
 
 
     @Test
     @Test
+    fun setStateChangedEvent() = runTest {
+        val eventCollector = EventCollector(participant.events, coroutineRule.scope)
+        participant.state = Participant.State.JOINED
+
+        val events = eventCollector.stopCollecting()
+
+        assertEquals(1, events.size)
+        assertEquals(true, events[0] is ParticipantEvent.StateChanged)
+
+        val event = events[0] as ParticipantEvent.StateChanged
+
+        assertEquals(participant, event.participant)
+        assertEquals(Participant.State.JOINED, event.newState)
+        assertEquals(Participant.State.UNKNOWN, event.oldState)
+    }
+
+    @Test
     fun addTrackPublication() = runTest {
     fun addTrackPublication() = runTest {
         val audioPublication = TrackPublication(TRACK_INFO, null, participant)
         val audioPublication = TrackPublication(TRACK_INFO, null, participant)
         participant.addTrackPublication(audioPublication)
         participant.addTrackPublication(audioPublication)
@@ -197,6 +214,7 @@ class ParticipantTest {
             .setName("name")
             .setName("name")
             .setKind(LivekitModels.ParticipantInfo.Kind.STANDARD)
             .setKind(LivekitModels.ParticipantInfo.Kind.STANDARD)
             .putAttributes("attribute", "value")
             .putAttributes("attribute", "value")
+            .setState(LivekitModels.ParticipantInfo.State.JOINED)
             .build()
             .build()
 
 
         val TRACK_INFO = LivekitModels.TrackInfo.newBuilder()
         val TRACK_INFO = LivekitModels.TrackInfo.newBuilder()

--Subproject commit 02ee5e6947593443d0dfc90cae0b27ce03b6c1fe
++Subproject commit 499c17c48063582ac2af0a021827fab18356cc29