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RESTAudio Playback
The StreamChat framework ships with tools that enable you to playback any (supported) audio file.
Audio Playback, using an instance of AudioPlaying, is available since version 4.32.0.
An instance of AudioPlaying is responsible for handling all audio playback related operations and acts as a thin abstraction layer between your app and the AVPlayer system.
The SDK ships with 2 audio players out of the box, 1. StreamAudioPlayer and 2. StreamAudioQueuePlayer. As StreamAudioQueuePlayer is a simple sub-class of StreamAudioPlayer that extends its queue management capabilities, we will focus on the StreamAudioPlayer base class for now.
The StreamAudioPlayer that ships with the SDK and implements the AudioPlaying protocol, can take care of the following responsibilities, additional to managing the audio playback of:
- Configure the
AVAudioSessionfor recording. - React on the application’s state changes(move to background or foreground).
- Fetch remote properties of remote audio files (for example its duration).
StreamAudioPlayer follows a subscription model where in order to receive updates for playback, we need to subscribe on the player. Once subscribed we will start receiving events about the state of the playback.
Actions
StreamAudioPlayer and any instance that conforms to the AudioPlaying protocol has the following actions that we can call on them:
func loadAsset(from url: URL)
Instructs the player to load the asset from the provided URL and prepare it for streaming. If the player’s current item has a URL that matches the provided one, then the player will try to play or restart the playback.
func play()
Begin the loaded asset’s playback. If no asset has been loaded, the action has no effect.
func pause()
Pauses the loaded asset’s playback. If non has been loaded or the playback hasn’t started yet the action has no effect.
func stop()
Stop the loaded asset’s playback. If non has been loaded or the playback hasn’t started yet the action has no effect.
func updateRate(_:)
Updates the loaded asset’s playback rate to the provided one.
func seek(to:)
Performs a seek in the loaded asset’s timeline at the provided time.
configure(_ audioSessionConfigurator: AudioSessionConfiguring)
The default object that interacts with the AVAudioSession, assumes that it’s the only one that manages the AVAudioSession shared instance. In scenarios where that’s not the case (for example, you have an active audio session going on because of audio/video call), you can use this method to provide a another instance that will be aware of all related features and will act as the central point of AVAudioSession configuration between Stream VoiceRecording feature and any other feature that uses the AVAudioSession.
Receiving updates
By calling subscribe(_ subscriber: AudioPlayingDelegate) we are subscribing to receive updates from the AudioPlaying instance. Those updates include information about:
- The URL for the loaded audio file.
- The duration and current playback time.
- The player’s state.
- The playback’s rate.
- A flag indicating if the player is currently seeking.
StreamAudioQueuePlayer
The StreamAudioQueuePlayer implementation is a sub-class of StreamAudioPlayer with additional queue management capabilities. It requires a data source that conforms to the AudioQueuePlayerDatasource protocol. Once the playback of an audio file finishes, the StreamAudioQueuePlayer will ask its data source for the next item to play. If the dataSource provide one, the new item will be automatically loaded to the player its playback will begin once ready.