Ensure audio frame when publishing

.nanpa/publish-audio-check-frames.kdl

@@ -0,0 +1 @@
+patch type="changed" "Ensure audio frames are being generated when publishing audio"

Sources/LiveKit/Participant/LocalParticipant.swift

@@ -501,7 +501,7 @@
 
 private extension LocalParticipant {
     @discardableResult
     internal func _publish(track: LocalTrack, options: TrackPublishOptions? = nil) async throws -> LocalTrackPublication {
         log("[publish] \(track) options: \(String(describing: options ?? nil))...", .info)
 
         try checkPermissions(toPublish: track)
@@ -687,6 +687,12 @@
                 }
             }()
 
+            // At this point at least 1 audio frame should be generated to continue
+            if let track = track as? LocalAudioTrack {
+                log("[Publish] Waiting for audio frame...")
+                try await track.frameWatcher.wait()
+            }
+
             if track is LocalVideoTrack {
                 if let firstCodecMime = trackInfo.codecs.first?.mimeType,
                    let firstVideoCodec = VideoCodec.from(mimeType: firstCodecMime)

Sources/LiveKit/Support/AsyncCompleter.swift

@@ -132,12 +132,12 @@ final class AsyncCompleter<T: Sendable>: @unchecked Sendable, Loggable {
     }
 
     public func resume(returning value: T) {
-        log("\(label)")
+        log("\(label)", .trace)
         resume(with: .success(value))
     }
 
     public func resume(throwing error: Error) {
-        log("\(label)")
+        log("\(label)", .error)
         resume(with: .failure(error))
     }
 

Sources/LiveKit/Track/Local/LocalAudioTrack.swift

@@ -27,6 +27,7 @@ internal import LiveKitWebRTC
 public class LocalAudioTrack: Track, LocalTrack, AudioTrack, @unchecked Sendable {
     /// ``AudioCaptureOptions`` used to create this track.
     let captureOptions: AudioCaptureOptions
+    let frameWatcher = AudioFrameWatcher()
 
     init(name: String,
          source: Track.Source,
@@ -41,6 +42,13 @@ public class LocalAudioTrack: Track, LocalTrack, AudioTrack, @unchecked Sendable
                    source: source,
                    track: track,
                    reportStatistics: reportStatistics)
+
+        // Listen for frames
+        add(audioRenderer: frameWatcher)
+    }
+
+    deinit {
+        remove(audioRenderer: frameWatcher)
     }
 
     public static func createTrack(name: String = Track.microphoneName,
@@ -93,6 +101,10 @@ public class LocalAudioTrack: Track, LocalTrack, AudioTrack, @unchecked Sendable
             throw error
         }
     }
+
+    override func stopCapture() async throws {
+        frameWatcher.reset()
+    }
 }
 
 public extension LocalAudioTrack {
@@ -109,3 +121,23 @@ public extension LocalAudioTrack {
         AudioManager.shared.remove(localAudioRenderer: audioRenderer)
     }
 }
+
+// MARK: - Internal
+
+final class AudioFrameWatcher: AudioRenderer, Loggable {
+    private let completer = AsyncCompleter<Void>(label: "Frame watcher", defaultTimeout: 5)
+
+    func wait() async throws {
+        try await completer.wait()
+    }
+
+    func reset() {
+        completer.reset()
+    }
+
+    // MARK: - AudioRenderer
+
+    func render(pcmBuffer _: AVAudioPCMBuffer) {
+        completer.resume(returning: ())
+    }
+}