/
InputSignalTracker.swift
112 lines (88 loc) · 3.03 KB
/
InputSignalTracker.swift
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import AVFoundation
public enum InputSignalTrackerError: Error {
case inputNodeMissing
}
final class InputSignalTracker: SignalTracker {
weak var delegate: SignalTrackerDelegate?
var levelThreshold: Float?
private let bufferSize: AVAudioFrameCount
private var audioChannel: AVCaptureAudioChannel?
private let captureSession = AVCaptureSession()
private var audioEngine: AVAudioEngine?
private let session = AVAudioSession.sharedInstance()
private let bus = 0
var peakLevel: Float? {
return audioChannel?.peakHoldLevel
}
var averageLevel: Float? {
return audioChannel?.averagePowerLevel
}
var mode: SignalTrackerMode {
return .record
}
// MARK: - Initialization
required init(bufferSize: AVAudioFrameCount = 2048,
delegate: SignalTrackerDelegate? = nil) {
self.bufferSize = bufferSize
self.delegate = delegate
setupAudio()
}
// MARK: - Tracking
func start() throws {
try session.setCategory(AVAudioSession.Category.playAndRecord)
// check input type
let currentRoute = session.currentRoute
if currentRoute.outputs.count != 0 {
for description in currentRoute.outputs {
if (description.portType != AVAudioSession.Port.headphones) { // input from speaker if port is not headphones
try session.overrideOutputAudioPort(AVAudioSession.PortOverride.speaker)
} else { // input from default (headphones)
try session.overrideOutputAudioPort(.none)
}
}
}
audioEngine = AVAudioEngine()
guard let inputNode = audioEngine?.inputNode else {
throw InputSignalTrackerError.inputNodeMissing
}
let format = inputNode.outputFormat(forBus: bus)
inputNode.installTap(onBus: bus, bufferSize: bufferSize, format: format) { buffer, time in
guard let averageLevel = self.averageLevel else { return }
let levelThreshold = self.levelThreshold ?? -1000000.0
if averageLevel > levelThreshold {
DispatchQueue.main.async {
self.delegate?.signalTracker(self, didReceiveBuffer: buffer, atTime: time)
}
} else {
DispatchQueue.main.async {
self.delegate?.signalTrackerWentBelowLevelThreshold(self)
}
}
}
try audioEngine?.start()
captureSession.startRunning()
guard captureSession.isRunning == true else {
throw InputSignalTrackerError.inputNodeMissing
}
}
func stop() {
guard audioEngine != nil else {
return
}
audioEngine?.stop()
audioEngine?.reset()
audioEngine = nil
captureSession.stopRunning()
}
private func setupAudio() {
do {
let audioDevice = AVCaptureDevice.default(for: AVMediaType.audio)
let audioCaptureInput = try AVCaptureDeviceInput(device: audioDevice!)
captureSession.addInput(audioCaptureInput)
let audioOutput = AVCaptureAudioDataOutput()
captureSession.addOutput(audioOutput)
let connection = audioOutput.connections[0]
audioChannel = connection.audioChannels[0]
} catch {}
}
}