AudioStreaming

An AudioPlayer/Streaming library for iOS written in Swift, allows playback of online audio streaming, local file as well as gapless queueing.

Under the hood AudioStreaming uses AVAudioEngine and CoreAudio for playback and provides an easy way of applying real-time audio enhancements.

Supported audio

• Online streaming (Shoutcast/ICY streams) with metadata parsing
• AIFF, AIFC, WAVE, CAF, NeXT, ADTS, MPEG Audio Layer 3, AAC audio formats
• M4A

As of 1.2.0 version, there’s support for non-optimized M4A, please report any issues

Known limitations:
- As described above non-optimised M4A files are not supported this is a limitation of AudioFileStream Services

Requirements

• iOS 13.0+
• Swift 5.x

Using AudioStreaming

Playing an audio source over HTTP

Note: You need to keep a reference to the AudioPlayer object

let player = AudioPlayer()
player.play(url: URL(string: "https://your-remote-url/to/audio-file.mp3")!)

Playing a local file

let player = AudioPlayer()
player.play(url: URL(fileURLWithPath: "your-local-path/to/audio-file.mp3")!)

Queueing audio files

let player = AudioPlayer()
// when you want to queue a single url
player.queue(url: URL(string: "https://your-remote-url/to/audio-file.mp3")!)

// or if you want to queue a list of urls use
player.queue(urls: [
    URL(fileURLWithPath: "your-local-path/to/audio-file.mp3")!,
    URL(fileURLWithPath: "your-local-path/to/audio-file-2.mp3")!
])

Adjusting playback properties

let player = AudioPlayer()
player.play(url: URL(fileURLWithPath: "your-local-path/to/audio-file.mp3")!)
// adjust the playback rate
player.rate = 2.0

// adjusting the volume
player.volume = 0.5

// mute/unmute the audio
player.mute = true

// pause the playback
player.pause()

// resume the playback
player.resume()

// stop the playback
player.stop()

// seeking to to a time (in seconds)
player.seek(to: 10)

Audio playback properties

let player = AudioPlayer()
player.play(url: URL(fileURLWithPath: "your-local-path/to/audio-file.mp3")!)

// To get the audio file duration
let duration = player.duration

// To get the progress of the player
let progress = player.progress

// To get the state of the player, for possible values view the `AudioPlayerState` enum
let state = player.state

// To get the stop reason of the player, for possible values view the `AudioPlayerStopReason` enum
let state = player.stopReason

AudioPlayer Delegate

You can inspect various callbacks by using the delegate property of the AudioPlayer to get informed about the player state, errors etc.
View the AudioPlayerDelegate for more details

let player = AudioPlayer()
player.play(url: URL(fileURLWithPath: "your-local-path/to/audio-file.mp3")!)

player.delegate = self // an object conforming to AudioPlayerDelegate

// observing the audio player state, provides the new and previous state of the player.
func audioPlayerStateChanged(player: AudioPlayer, with newState: AudioPlayerState, previous: AudioPlayerState) {}

Adding custom audio nodes to AudioPlayer

AudioStreaming provides an easy way to attach/remove AVAudioNode(s).
This provides a powerful way of adjusting the playback audio with various enhancements

let reverbNode = AVAudioUnitReverb()
reverbNode.wetDryMix = 50 

let player = AudioPlayer()
// attach a single node
player.attach(node: reverbNode)

// detach a single node
player.detach(node: reverbNode)

// detach all custom added nodes
player.detachCustomAttachedNodes()

The example project shows an example of adding a custom AVAudioUnitEQ node for adding equaliser to the AudioPlayer

Adding custom frame filter for recording and observation of audio data

AudioStreaming allow for custom frame filters to be added so that recording or other observation for audio that’s playing.

You add a frame filter by using the AudioPlayer’s property frameFiltering.

let player = AudioPlayer()
let format = player.mainMixerNode.outputFormat(forBus: 0)

let settings = [
    AVFormatIDKey: kAudioFormatMPEG4AAC,
    AVSampleRateKey: format.sampleRate,
    AVNumberOfChannelsKey: format.channelCount
] as [String : Any]

var audioFile = try? AVAudioFile(
        forWriting: outputUrl,
        settings: settings,
        commonFormat: format.commonFormat,
        interleaved: format.isInterleaved)

let record = FilterEntry(name: "record") { buffer, when in
    try? audioFile?.write(from: buffer)
}

player.frameFiltering.add(entry: record)

See the FrameFiltering protocol for more ways of adding and removing frame filters.
The callback in which you observe a filter will be run on a thread other than the main thread.

Under the hood the concrete class for frame filters, FrameFilterProcessor installs a tap on the mainMixerNode of AVAudioEngine in which all the added filter will be called from.

Note since the mainMixerNode is publicly exposed extra care should be taken to not install a tap directly and also use frame filters, this result in an exception because only one tap can be installed on an output node, as per Apple’s documentation.

Installation

Swift Package Manager

On Xcode 11.0+ you can add a new dependency by going to File / Swift Packages / Add Package Dependency…
and enter package repository URL https://github.com/dimitris-c/AudioStreaming.git, then follow the instructions.

Licence

AudioStreaming is available under the MIT license. See the LICENSE file for more info.

Attributions

This library takes inspiration on the already battled-tested streaming library, StreamingKit.
Big 🙏 to Thong Nguyen (@tumtumtum) and Matt Gallagher (@mattgallagher) for AudioStreamer