Audio Recording

The StreamChat framework ships with tools that enable you to record audio files.

An instance of AudioRecording is responsible for handling all recording related operations and acts as a thin abstraction layer between your app and the AVAudioRecorder system.

The StreamAudioRecorder that ships with the SDK and implements the AudioRecording protocol, can take care of the following responsibilities, additional to recording audio:

• Request any required permissions.
• Configure the AVAudioSession for recording.
• React on the application’s state changes(move to background or foreground).

StreamAudioRecorder follows a subscription model where in order to receive updates for a recording, we need to subscribe on the recorder. Once subscribed we will start receiving events about the state of the recording.

Configuration

The StreamAudioRecorder records audio in audio/aac format (.aac), with 12000 sample rate, using 1 audio channel on high quality. If you need to customize any of those values you can do so by sub-classing StreamAudioRecorder and provide your own configuration like below.:

final class MyAppAudioRecorder: StreamAudioRecorder {

    override required convenience init() {
        self.init(configuration: .init(
            audioRecorderSettings: [
                AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
                AVSampleRateKey: 44100,
                AVNumberOfChannelsKey: 1,
                AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
            ]
            ...
        ))
    }
}

By doing so, you can customize other parts of the StreamAudioRecorder like:

• The path where audio files will be stored.
• The name and extension of the currently recording file.
• The interval that will be used to observe and receive updates on the duration of the recording audio file.
• The interval that will be used to observe and receive updates from the recorder’s meters.

Actions

StreamAudioRecorder and any instance that conforms to the AudioRecording protocol has the following actions that we can call on them:

func beginRecording(_ completionHandler: @escaping (() -> Void))

Instructs the recorder to begin recording. The StreamAudioRecorder will perform the following operations prior to begin recording:

1. Activate the AVAudioSession for recording.
2. Request recording permission (if it hasn’t been requested before).

func stopRecording()

It will stop the current recording and inform the AVAudioSession that recording capability is not needed any more.

func pauseRecording() & func resumeRecording()

They will pause and resume respectively, the current recording.

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: AudioRecordingDelegate) we are subscribing to receive updates from the AudioRecording instance. Those updates include information about:

• Active recording and its properties (for example its duration, state and average power)
• Successfully finished recording and the location of the audio file.
• Errors that occurred during any part of the recording flow.

Errors

Errors thrown by StreamAudioRecorder are instances of the AudioRecorderError error class and you can see references to all of them below:

noRecordPermission

During the beginRecording flow, the recorder failed to obtain permission to record. That may occur if the user of your app didn’t allow recording and access

failedToBegin

Error thrown when the recorder fails to begin recording.

failedToResume

Error thrown when the recorder fails to resume an already paused recording.

failedToSave

Error thrown when the recorder fails to save the audio file of a stopped recording.

unknown

Generic error thrown in cases where the recorder failed but no error was provided.