Sound player helper

Sources/LiveKit/Audio/AudioSessionEngineObserver.swift

@@ -48,17 +48,40 @@ public class AudioSessionEngineObserver: AudioEngineObserver, Loggable, @uncheck
         set { _state.mutate { $0.isSpeakerOutputPreferred = newValue } }
     }
 
+    public struct SessionRequirement: Sendable {
+        public static let none = Self(isPlayoutEnabled: false, isRecordingEnabled: false)
+        public static let playbackOnly = Self(isPlayoutEnabled: true, isRecordingEnabled: false)
+        public static let recordingOnly = Self(isPlayoutEnabled: false, isRecordingEnabled: true)
+        public static let playbackAndRecording = Self(isPlayoutEnabled: true, isRecordingEnabled: true)
+
+        public let isPlayoutEnabled: Bool
+        public let isRecordingEnabled: Bool
+
+        public init(isPlayoutEnabled: Bool = false, isRecordingEnabled: Bool = false) {
+            self.isPlayoutEnabled = isPlayoutEnabled
+            self.isRecordingEnabled = isRecordingEnabled
+        }
+    }
+
     struct State: Sendable {
         var next: (any AudioEngineObserver)?
 
         var isAutomaticConfigurationEnabled: Bool = true
-        var isPlayoutEnabled: Bool = false
-        var isRecordingEnabled: Bool = false
         var isSpeakerOutputPreferred: Bool = true
+
+        //
+        var sessionRequirements: [UUID: SessionRequirement] = [:]
+
+        // Computed
+        var isPlayoutEnabled: Bool { sessionRequirements.values.contains(where: \.isPlayoutEnabled) }
+        var isRecordingEnabled: Bool { sessionRequirements.values.contains(where: \.isRecordingEnabled) }
     }
 
     let _state = StateSync(State())
 
+    // Session requirement id for this object
+    private let sessionRequirementId = UUID()
+
     public var next: (any AudioEngineObserver)? {
         get { _state.next }
         set { _state.mutate { $0.next = newValue } }
@@ -83,6 +106,10 @@ public class AudioSessionEngineObserver: AudioEngineObserver, Loggable, @uncheck
         }
     }
 
+    public func set(requirement: SessionRequirement, for id: UUID) {
+        _state.mutate { $0.sessionRequirements[id] = requirement }
+    }
+
     @Sendable func configure(oldState: State, newState: State) {
         let session = LKRTCAudioSession.sharedInstance()
 
@@ -92,6 +119,8 @@ public class AudioSessionEngineObserver: AudioEngineObserver, Loggable, @uncheck
             log("AudioSession activationCount: \(session.activationCount), webRTCSessionCount: \(session.webRTCSessionCount)")
         }
 
+        log("configure isRecordingEnabled: \(newState.isRecordingEnabled), isPlayoutEnabled: \(newState.isPlayoutEnabled)")
+
         if (!newState.isPlayoutEnabled && !newState.isRecordingEnabled) && (oldState.isPlayoutEnabled || oldState.isRecordingEnabled) {
             do {
                 log("AudioSession deactivating...")
@@ -123,10 +152,8 @@ public class AudioSessionEngineObserver: AudioEngineObserver, Loggable, @uncheck
     }
 
     public func engineWillEnable(_ engine: AVAudioEngine, isPlayoutEnabled: Bool, isRecordingEnabled: Bool) -> Int {
-        _state.mutate {
-            $0.isPlayoutEnabled = isPlayoutEnabled
-            $0.isRecordingEnabled = isRecordingEnabled
-        }
+        let requirement = SessionRequirement(isPlayoutEnabled: isPlayoutEnabled, isRecordingEnabled: isRecordingEnabled)
+        set(requirement: requirement, for: sessionRequirementId)
 
         // Call next last
         return _state.next?.engineWillEnable(engine, isPlayoutEnabled: isPlayoutEnabled, isRecordingEnabled: isRecordingEnabled) ?? 0
@@ -136,10 +163,8 @@ public class AudioSessionEngineObserver: AudioEngineObserver, Loggable, @uncheck
         // Call next first
         let nextResult = _state.next?.engineDidDisable(engine, isPlayoutEnabled: isPlayoutEnabled, isRecordingEnabled: isRecordingEnabled)
 
-        _state.mutate {
-            $0.isPlayoutEnabled = isPlayoutEnabled
-            $0.isRecordingEnabled = isRecordingEnabled
-        }
+        let requirement = SessionRequirement(isPlayoutEnabled: isPlayoutEnabled, isRecordingEnabled: isRecordingEnabled)
+        set(requirement: requirement, for: sessionRequirementId)
 
         return nextResult ?? 0
     }

Sources/LiveKit/Audio/SoundPlayer.swift

@@ -0,0 +1,190 @@
+/*
+ * Copyright 2025 LiveKit
+ *
+ * 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.
+ */
+
+@preconcurrency import AVFAudio
+
+public class SoundPlayer: Loggable, @unchecked Sendable {
+    private let engine = AVAudioEngine()
+    private let playerNodes = AVAudioPlayerNodePool()
+    public let outputFormat: AVAudioFormat
+
+    // Session requirement id for this object
+    private let sessionRequirementId = UUID()
+
+    private struct State {
+        var sounds: [String: AVAudioPCMBuffer] = [:]
+    }
+
+    private let _state = StateSync(State())
+
+    public init() {
+        outputFormat = engine.outputNode.outputFormat(forBus: 0)
+        playerNodes.attach(to: engine)
+    }
+
+    public func startEngine() async throws {
+        guard !engine.isRunning else {
+            log("Engine already running", .info)
+            return
+        }
+        log("Starting audio engine...")
+
+        playerNodes.connect(to: engine, node: engine.mainMixerNode, format: outputFormat)
+
+        // Request
+        #if os(iOS) || os(visionOS) || os(tvOS)
+        AudioManager.shared.audioSession.set(requirement: .playbackOnly, for: sessionRequirementId)
+        #endif
+
+        try engine.start()
+        log("Audio engine started")
+    }
+
+    public func stopEngine() {
+        guard engine.isRunning else {
+            log("Engine already stopped", .info)
+            return
+        }
+        log("Stopping audio engine...")
+
+        playerNodes.stop()
+        engine.stop()
+
+        #if os(iOS) || os(visionOS) || os(tvOS)
+        AudioManager.shared.audioSession.set(requirement: .none, for: sessionRequirementId)
+        #endif
+
+        log("Audio engine stopped")
+    }
+
+    public func prepare(url: URL, withId id: String) throws {
+        // Prepare audio file
+        let audioFile = try AVAudioFile(forReading: url)
+        // Prepare buffer
+        guard let readBuffer = AVAudioPCMBuffer(pcmFormat: audioFile.processingFormat, frameCapacity: AVAudioFrameCount(audioFile.length)) else {
+            throw NSError(domain: "Audio", code: 2, userInfo: [NSLocalizedDescriptionKey: "Cannot allocate buffer"])
+        }
+        // Read all into buffer
+        try audioFile.read(into: readBuffer, frameCount: AVAudioFrameCount(audioFile.length))
+        // Compute required convert buffer capacity
+        let outputBufferCapacity = AudioConverter.frameCapacity(from: readBuffer.format, to: outputFormat, inputFrameCount: readBuffer.frameLength)
+        // Create converter
+        guard let converter = AudioConverter(from: readBuffer.format, to: outputFormat, outputBufferCapacity: outputBufferCapacity) else {
+            throw NSError(domain: "Audio", code: 2, userInfo: [NSLocalizedDescriptionKey: "Cannot create converter"])
+        }
+        // Convert to suitable format for audio engine
+        let convertedBuffer = converter.convert(from: readBuffer)
+        // Register
+        _state.mutate {
+            $0.sounds[id] = convertedBuffer
+        }
+    }
+
+    public func play(id: String) async throws {
+        guard engine.isRunning else {
+            throw NSError(domain: "Audio", code: 2, userInfo: [NSLocalizedDescriptionKey: "Engine not running"])
+        }
+        guard let audioBuffer = _state.read(\.sounds[id]) else {
+            throw NSError(domain: "Audio", code: 2, userInfo: [NSLocalizedDescriptionKey: "Sound not prepared"])
+        }
+        try playerNodes.scheduleBuffer(audioBuffer)
+    }
+}
+
+// Support scheduling buffer to play concurrently
+class AVAudioPlayerNodePool: @unchecked Sendable, Loggable {
+    let poolSize: Int
+    private let mixerNode = AVAudioMixerNode()
+
+    private struct State {
+        var playerNodes: [AVAudioPlayerNode]
+    }
+
+    private let audioCallbackQueue = DispatchQueue(label: "audio.playerNodePool.queue")
+
+    private let _state: StateSync<State>
+
+    init(poolSize: Int = 10) {
+        self.poolSize = poolSize
+        let playerNodes = (0 ..< poolSize).map { _ in AVAudioPlayerNode() }
+        _state = StateSync(State(playerNodes: playerNodes))
+    }
+
+    func attach(to engine: AVAudioEngine) {
+        let playerNodes = _state.read(\.playerNodes)
+        // Attach playerNodes
+        for playerNode in playerNodes {
+            engine.attach(playerNode)
+        }
+        // Attach mixerNode
+        engine.attach(mixerNode)
+    }
+
+    func connect(to engine: AVAudioEngine, node: AVAudioNode, format: AVAudioFormat? = nil) {
+        let playerNodes = _state.read(\.playerNodes)
+        for playerNode in playerNodes {
+            engine.connect(playerNode, to: mixerNode, format: format)
+        }
+        engine.connect(mixerNode, to: node, format: format)
+    }
+
+    func detach(from engine: AVAudioEngine) {
+        let playerNodes = _state.read(\.playerNodes)
+        // Detach playerNodes
+        for playerNode in playerNodes {
+            playerNode.stop()
+            engine.detach(playerNode)
+        }
+        // Detach mixerNode
+        engine.detach(mixerNode)
+    }
+
+    func scheduleBuffer(_ buffer: AVAudioPCMBuffer) throws {
+        guard let node = nextAvailablePlayerNode() else {
+            throw NSError(domain: "Audio", code: 2, userInfo: [NSLocalizedDescriptionKey: "No available player nodes"])
+        }
+        log("Next node: \(node)")
+
+        node.scheduleBuffer(buffer, completionCallbackType: .dataPlayedBack) { [weak self, weak node] _ in
+            guard let self else { return }
+            audioCallbackQueue.async { [weak node] in
+                guard let node else { return }
+                node.stop() // Stop the node
+            }
+        }
+        node.play()
+    }
+
+    // Stops all player nodes
+    func stop() {
+        for node in _state.read(\.playerNodes) {
+            node.stop()
+        }
+    }
+
+    private func nextAvailablePlayerNode() -> AVAudioPlayerNode? {
+        // Find first available node
+        guard let node = _state.read({ $0.playerNodes.first(where: { !$0.isPlaying }) }) else {
+            return nil
+        }
+
+        // Ensure node settings
+        node.volume = 1.0
+        node.pan = 0.0
+
+        return node
+    }
+}

Sources/LiveKit/Support/Audio/AudioConverter.swift

@@ -28,10 +28,10 @@ final class AudioConverter: Sendable {
         let inputSampleRate = inputFormat.sampleRate
         let outputSampleRate = outputFormat.sampleRate
         // Compute the output frame capacity based on sample rate ratio
-        return AVAudioFrameCount(Double(inputFrameCount) * (outputSampleRate / inputSampleRate))
+        return AVAudioFrameCount(ceil(Double(inputFrameCount) * (outputSampleRate / inputSampleRate)))
     }
 
-    init?(from inputFormat: AVAudioFormat, to outputFormat: AVAudioFormat, outputBufferCapacity: AVAudioFrameCount = 9600) {
+    init?(from inputFormat: AVAudioFormat, to outputFormat: AVAudioFormat, outputBufferCapacity: AVAudioFrameCount = 1024 * 10) {
         guard let converter = AVAudioConverter(from: inputFormat, to: outputFormat),
               let buffer = AVAudioPCMBuffer(pcmFormat: outputFormat, frameCapacity: outputBufferCapacity)
         else {

Sources/LiveKit/Support/AudioPlayerRenderer.swift

@@ -29,6 +29,7 @@ public class AudioPlayerRenderer: AudioRenderer, Loggable, @unchecked Sendable {
     }
 
     public func start() async throws {
+        guard !engine.isRunning else { return }
         log("Starting audio engine...")
 
         let format = engine.outputNode.outputFormat(forBus: 0)
@@ -41,6 +42,7 @@ public class AudioPlayerRenderer: AudioRenderer, Loggable, @unchecked Sendable {
     }
 
     public func stop() {
+        guard engine.isRunning else { return }
         log("Stopping audio engine...")
 
         playerNode.stop()