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Audio Sessions Management

Manage audio ducking and audio session sharing between the StreamLayer iOS SDK and your host app. Implement SLROverlayDelegate methods for smooth audio transitions during Watch Party, messaging, and media playback.

Audio Sessions Management

Handling Audio Ducking

For the best user experience, certain units within the StreamLayer Element may require a decrease in the main video's audio level. For instance, a video embedded in a social feed may play with sound — if the main audio level is not reduced accordingly, the two audio streams will overlap, resulting in a poor experience. When the host app provides the SDK methods to control the application's audio session, the SDK will smoothly decrease the sound when needed.

Two SLROverlayDelegate methods handle audio ducking:

Audio Ducking Example

SLRVideoPlayer: SLROverlayDelegate {

...

  private var player: AVPlayer!

  // tracks requests for ducking
  private let volumeReduceRate: Float = 0.1
  private var playerVolumeOriginal: [Float] = []

  // tracks requests for audio sessions
  private var kTotalSessions: Int { return kGenericSessions + kGenericSessions }
  private var kGenericSessions: Int = 0
  private var kVoiceSessions: Int = 0

...
  public func requestAudioDucking() {
    lock.withLockVoid {
      if let player = player {
        let isDuckingActive = playerVolumeOriginal.last.map({ Self.streamVolume == volumeReduceRate * $0 }) ?? false
        playerVolumeOriginal.append(Self.streamVolume)
        if !isDuckingActive {
          Self.streamVolume = volumeReduceRate * Self.streamVolume
        }
        onPlayerVolumeChange?()
        if player.timeControlStatus == .playing {
          player.volume = Self.streamVolume
        }
      }
    }
  }

  public func disableAudioDucking() {
    lock.withLockVoid {
      if playerVolumeOriginal.count > 0, let player = player {
        Self.streamVolume = playerVolumeOriginal.popLast() ?? 1
        onPlayerVolumeChange?()
        if player.timeControlStatus == .playing {
          player.volume = Self.streamVolume
        }
      }
    }
  }

...


}

Audio Session Management

Audio notifications are used by the SDK for Watch Party, messaging, and other features. iOS allows only one audio session per application, so the host app and the SDK share the same audio session.

To minimize interference between the host app's and SDK's audio modes, implement the following delegate methods:

  • SLROverlayDelegate.prepareAudioSession(...)
  • SLROverlayDelegate.disableAudioSession(...)

Audio Session Example

// tracks requests for audio sessions
  fileprivate var kTotalSessions: Int { return kGenericSessions + kGenericSessions }
  fileprivate var kGenericSessions: Int = 0
  fileprivate var kVoiceSessions: Int = 0

...


  public func disableAudioSession(for type: SLRAudioSessionType) {
    switch type {
    case .voice: kVoiceSessions -= 1
    case .generic: kGenericSessions -= 1
    }

    // no sessions at all - disable
    if kTotalSessions == 0 {
      disableAudioSession()
      return
    }

    if kVoiceSessions > 0 {
      return
    }

    if type == .voice {
      enableGenericAudioSession(reactivate: false)
    }
  }

  public func prepareAudioSession(for type: SLRAudioSessionType) {
    lock.lock()
    defer {
      print("[AudioSession] prepare kVoiceSessions: \(kVoiceSessions), kGenericSessions: \(kGenericSessions)")
      lock.unlock()
    }

    switch type {
    case .voice:
      kVoiceSessions += 1
      if kVoiceSessions == 1 {
        // No specific logic here for now (WebRTC handles this)
      }

    case .generic:
      kGenericSessions += 1
      if kGenericSessions > 0, kVoiceSessions == 0 {
        let reactivate = kGenericSessions == 1
        do {
          try StreamLayer.prepareSessionForGeneralAudio(reactivate: reactivate)
        } catch let error {
          print("[RPC] Error: \(error)")
          return
        }
        return
      }
    }
  }
...


}

Related

Updated 15 days ago