AudioKitService.swift

import SwiftUI
import AudioKit
import AudioKitEX
import AVFoundation
import SoundpipeAudioKit
import DunneAudioKit

class AudioEffectsConductorAudioKitService {
    private let engine = AudioEngine()
    private let leadingVocalAudioPlayer = AudioPlayer()
    private let mixer = Mixer()
    
    private var inputType: AudioEffectInputType
    
    // -------------------
    
    private var leadingVocalAudioFader: Fader!
    
    private var reverbSmallRoom: Reverb!
    private var reverbPlate: Reverb!
    
    private var reverbMediumChamber: Reverb!
    private var reverbMediumChamberDryWetMixer: DryWetMixer!
    
    private var flanger: Flanger!
    private var flangerDryWetMixer: DryWetMixer!
    
    private var highShelfFilter: HighShelfFilter!
    private var highShelfFilterDryWetMixer: DryWetMixer!
    
    private var highPassFilter: HighPassFilter!
    private var lowPassFilter: LowPassFilter!
    
    private var peakingParametricEqualizerFilter: PeakingParametricEqualizerFilter!
    private var bandRejectButterworthFilter: BandRejectButterworthFilter!
    
    private var pitchShifter: PitchShifter!
    
    private var stereoDelay: StereoDelay!
    
    private var delay: Delay!
    private var delayDryWetMixer: DryWetMixer!
    
    private var pitchCorrection: PitchCorrectionAudioKitNode!
    private var pitchCorrectionDryWetMixer: DryWetMixer!
    
    private var compressor: Compressor!
    private var compressorDryWetMixer: DryWetMixer!
    
    private var bandPassButterworth: BandPassButterworthFilter!
    private var bandPassButterworthDryWetMixer: DryWetMixer!
    
    // ------------------
    
    private var harmoniesLowPitchShiftFilter1: PitchShifter!
    private var harmoniesLowPitchShiftFilterDryWetMixer1: DryWetMixer!
    
    private var harmoniesHighPitchShiftFilter1: PitchShifter!
    private var harmoniesHighPitchShiftFilterDryWetMixer1: DryWetMixer!
    
    private var harmoniesPitchesFilterDryWetMixer1: DryWetMixer!
    private var harmoniesFinalFilterDryWetMixer1: DryWetMixer!
    
    // ------------------
    
    private var harmoniesLowPitchShiftFilter2: PitchShifter!
    private var harmoniesLowPitchShiftFilterDryWetMixer2: DryWetMixer!
    
    private var harmoniesHighPitchShiftFilter2: PitchShifter!
    private var harmoniesHighPitchShiftFilterDryWetMixer2: DryWetMixer!
    
    private var harmoniesPitchesFilterDryWetMixer2: DryWetMixer!
    private var harmoniesFinalFilterDryWetMixer2: DryWetMixer!
    
    // ------------------
    
    @Injected private var config: ConfigRepository
    @Injected private var supportService: SupportRepository
    
    // ------------------
    
    private var isInitialized = false
    private var selectedVolume: Float = 1
    private var selectedPitchCorrectionSpeed: Float = 0
    private var selectedDecibelCutoff: Float = -60
    
    // ------------------
    
    init(inputType: AudioEffectInputType) {
        self.inputType = inputType
        
        // if isLooping = false (default) seek doesn’t work properly
        leadingVocalAudioPlayer.isLooping = true
    }
    
    private func initializeEffects() {
        let inputNode = engine.input
        
        guard let inputNode else { return }
        
        guard !isInitialized else { return }
        isInitialized = true
        
        // ------------------
        
        leadingVocalAudioFader = Fader(inputNode, gain: 1)
        
        pitchCorrection = PitchCorrectionAudioKitNode(leadingVocalAudioFader)
        pitchCorrectionDryWetMixer = DryWetMixer(leadingVocalAudioFader, pitchCorrection, balance: 0)
        
        // ------------------
        
        highPassFilter = HighPassFilter(pitchCorrectionDryWetMixer)
        highPassFilter.resonance = 0
        
        // ------------------
        
        lowPassFilter = LowPassFilter(highPassFilter)
        lowPassFilter.resonance = 0
        
        // ------------------
        
        compressor = Compressor(lowPassFilter)
        compressor.masterGain = 0
        compressor.attackTime = 0.2
        compressor.releaseTime = 1.5
        
        compressorDryWetMixer = DryWetMixer(lowPassFilter, compressor, balance: 0)
        
        // ------------------
        
        peakingParametricEqualizerFilter = PeakingParametricEqualizerFilter(compressorDryWetMixer)
        peakingParametricEqualizerFilter.centerFrequency = 3000
        peakingParametricEqualizerFilter.q = 0.6
        peakingParametricEqualizerFilter.gain = 1
        
        // ------------------
        
        bandRejectButterworthFilter = BandRejectButterworthFilter(peakingParametricEqualizerFilter)
        bandRejectButterworthFilter.bandwidth = 100
        
        // ------------------
        
        bandPassButterworth = BandPassButterworthFilter(bandRejectButterworthFilter)
        bandPassButterworth.bandwidth = 4000
        bandPassButterworth.centerFrequency = 0
        
        bandPassButterworthDryWetMixer = DryWetMixer(bandRejectButterworthFilter, bandPassButterworth, balance: 0)
        
        // ------------------
        
        highShelfFilter = HighShelfFilter(bandPassButterworthDryWetMixer, gain: 0)
        highShelfFilterDryWetMixer = DryWetMixer(bandPassButterworthDryWetMixer, highShelfFilter, balance: 0)
        
        // ------------------
        
        stereoDelay = StereoDelay(highShelfFilterDryWetMixer)
        stereoDelay.feedback = 0
        stereoDelay.time = 0.5
        stereoDelay.dryWetMix = 0.8
        stereoDelay.pingPong = 1
        
        // ------------------
        
        reverbSmallRoom = Reverb(stereoDelay)
        reverbSmallRoom.dryWetMix = 0
        reverbSmallRoom.loadFactoryPreset(.smallRoom)
        
        // ------------------
        
        reverbPlate = Reverb(reverbSmallRoom)
        reverbPlate.dryWetMix = 0
        reverbPlate.loadFactoryPreset(.plate)
        
        // ------------------
        
        delay = Delay(reverbPlate)
        delay.feedback = 10
        delay.time = 0.125
        delay.dryWetMix = 0
        
        delayDryWetMixer = DryWetMixer(reverbPlate, delay, balance: 0.5)
        
        // ------------------
        
        reverbMediumChamber = Reverb(delayDryWetMixer)
        reverbMediumChamber.dryWetMix = 0
        reverbMediumChamber.loadFactoryPreset(.mediumChamber)
        
        reverbMediumChamberDryWetMixer = DryWetMixer(delayDryWetMixer, reverbMediumChamber, balance: 0)
        
        // ------------------
        
        pitchShifter = PitchShifter(reverbMediumChamberDryWetMixer)
        
        // ------------------
        
        harmoniesLowPitchShiftFilter1 = PitchShifter(pitchShifter, shift: -12)
        harmoniesLowPitchShiftFilterDryWetMixer1 = DryWetMixer(pitchShifter, harmoniesLowPitchShiftFilter1, balance: 0.7)
        
        harmoniesHighPitchShiftFilter1 = PitchShifter(pitchShifter, shift: 12)
        harmoniesHighPitchShiftFilterDryWetMixer1 = DryWetMixer(pitchShifter, harmoniesHighPitchShiftFilter1, balance: 0.3)
        
        harmoniesPitchesFilterDryWetMixer1 = DryWetMixer(harmoniesHighPitchShiftFilterDryWetMixer1, harmoniesLowPitchShiftFilterDryWetMixer1, balance: 0.5)
        harmoniesFinalFilterDryWetMixer1 = DryWetMixer(pitchShifter, harmoniesPitchesFilterDryWetMixer1, balance: 0)
        
        // ------------------
        
        harmoniesLowPitchShiftFilter2 = PitchShifter(harmoniesFinalFilterDryWetMixer1, shift: -3)
        harmoniesHighPitchShiftFilter2 = PitchShifter(harmoniesFinalFilterDryWetMixer1, shift: 8)
        
        harmoniesPitchesFilterDryWetMixer2 = DryWetMixer(harmoniesLowPitchShiftFilter2, harmoniesHighPitchShiftFilter2, balance: 0.5)
        harmoniesFinalFilterDryWetMixer2 = DryWetMixer(harmoniesFinalFilterDryWetMixer1, harmoniesPitchesFilterDryWetMixer2, balance: 0)
        
        // ------------------
        
        flanger = Flanger(harmoniesFinalFilterDryWetMixer2)
        flanger.frequency = 1
        flanger.depth = 1
        flanger.feedback = 0
        flanger.dryWetMix = 1
        
        flangerDryWetMixer = DryWetMixer(harmoniesFinalFilterDryWetMixer2, flanger)
        flangerDryWetMixer.balance = 0.5
    }
    
    func start() {
        if engine.avEngine.isRunning {
            return
        }
        
        initializeEffects()
        startMic()
    }
}

extension AudioEffectsConductorAudioKitService {
    private func startMic() {
        if engine.output == nil {
            engine.output = flangerDryWetMixer
            
            engine.input?.avAudioNode.installTap(onBus: 0, bufferSize: 8, format: nil) { [weak self] buffer, time in
                guard let self else { return }
                let decibels = buffer.calculateDecibelValue()
                
                if decibels < selectedDecibelCutoff {
                    if leadingVocalAudioFader.gain > 0.2 {
                        leadingVocalAudioFader.gain = selectedVolume < 0.2 ? selectedVolume : 0.2
                    }
                } else if leadingVocalAudioFader.gain < selectedVolume {
                    leadingVocalAudioFader.gain = selectedVolume
                }
            }
        }
        
        do {
            try engine.start()
        } catch {
            print("poop mic test Audio Engine failed to start: \(error)")
        }
    }
    
    private func stopMic() {
        engine.stop()
    }
}