audio stuff on macOS

audio.swift

//
//  File.swift
//  AudioSwitcher
//
//  Created by Masakazu Ohtsuka on 2017/09/22.
//  Copyright © 2017 maaash.jp. All rights reserved.
//

import Foundation
import Cocoa
import CoreAudio
import AVFoundation
import AudioUnit

enum InOut {
    case In, Out
}

// CustomStringConvertible is defined elsewhere
extension AudioObjectPropertySelector {
    var description :String {
        get {
            switch self {
            case kAudioObjectPropertyName:
                return "name"
            case kAudioObjectPropertyManufacturer:
                return "manufacturer"
            case kAudioObjectPropertyModelName:
                return "modelName"
            case kAudioObjectPropertyClass:
                return "class"
            case kAudioObjectPropertyOwner:
                return "owner"
            case kAudioObjectPropertyCreator:
                return "creator"
            case kAudioObjectPropertyElementName:
                return "elementName"
            case kAudioObjectPropertyElementCategoryName:
                return "elementCategoryName"
            case kAudioObjectPropertyElementNumberName:
                return "elementNumberName"
            case kAudioObjectPropertySerialNumber:
                return "serialNumber"
            case kAudioObjectPropertyFirmwareVersion:
                return "firmwareVersion"
            default:
                return "unknown"
            }
        }
    }
}

enum Property :String {
    case name, manufacturer, modelName, klass, owner, creator, elementName, elementCategoryName, elementNumberName, serialNumber, firmwareVersion

    func audioObjectPropertyName() -> AudioObjectPropertySelector {
        switch self {
        case .name:
            return kAudioObjectPropertyName
        case .manufacturer:
            return kAudioObjectPropertyManufacturer
        case .modelName:
            return kAudioObjectPropertyModelName
        case .klass:
            return kAudioObjectPropertyClass
        case .owner:
            return kAudioObjectPropertyOwner
        case .creator:
            return kAudioObjectPropertyCreator
        case .elementName:
            return kAudioObjectPropertyElementName
        case .elementNumberName:
            return kAudioObjectPropertyElementNumberName
        case .elementCategoryName:
            return kAudioObjectPropertyElementCategoryName
        case .serialNumber:
            return kAudioObjectPropertySerialNumber
        case .firmwareVersion:
            return kAudioObjectPropertyFirmwareVersion
        }
    }

    static func all() -> [Property] {
        return [.name, .manufacturer, .modelName, .klass, .owner, .creator, .elementName, .elementCategoryName, .elementNumberName, .serialNumber, .firmwareVersion]
    }
}

struct AudioDevice {
    let id :AudioObjectID
    let inOut :InOut
    let selected :Bool
    let properties :[String:String]

    init(id :AudioObjectID, inOut :InOut, selected :Bool) {
        self.id = id
        self.inOut = inOut
        self.selected = selected

        var p = [String:String]()
        // other properties fails to access
        [Property]([.name, .manufacturer]).forEach { property in
            if let val = getProperty(of: id, selector: property.audioObjectPropertyName()) {
                p[ property.rawValue ] = val
            }
        }
        self.properties = p
    }
}

func selectedAudioObject(inOut :InOut) -> AudioObjectID? {
    var deviceID:AudioObjectID = AudioObjectID(0)
    var size:UInt32 = UInt32(MemoryLayout<AudioObjectID>.size)
    var address:AudioObjectPropertyAddress = AudioObjectPropertyAddress()
    if inOut == .In {
        address.mSelector = kAudioHardwarePropertyDefaultInputDevice
    }
    else {
        address.mSelector = kAudioHardwarePropertyDefaultOutputDevice
    }
    address.mScope = kAudioObjectPropertyScopeGlobal
    address.mElement = kAudioObjectPropertyElementMaster
    let err1 = AudioObjectGetPropertyData(AudioObjectID(kAudioObjectSystemObject), &address, 0, nil, &size, &deviceID)
    if err1 != 0 {
        print("error: \(err1)")
        return nil
    }
    return deviceID
}

func currentAudioDevices() -> [AudioDevice] {
    let ins = currentAudioObjects(inOut: .In)
    let outs = currentAudioObjects(inOut: .Out)
    let selectedIn = selectedAudioObject(inOut: .In)
    let selectedOut = selectedAudioObject(inOut: .Out)
    let inDevices = ins.flatMap { (id) -> AudioDevice? in
        return AudioDevice(id: id, inOut: .In, selected: id == selectedIn)
    }
    let outDevices = outs.flatMap { (id) -> AudioDevice? in
        return AudioDevice(id: id, inOut: .Out, selected: id == selectedOut)
    }
    return inDevices + outDevices
}

func currentAudioObjects(inOut :InOut) -> [AudioObjectID] {
    var deviceIDs:[AudioObjectID]
    var size:UInt32 = UInt32(MemoryLayout<[AudioObjectID]>.size)
    var address:AudioObjectPropertyAddress = AudioObjectPropertyAddress()
    address.mSelector = kAudioHardwarePropertyDevices
    if inOut == .In {
        address.mScope = kAudioObjectPropertyScopeInput
    }
    else {
        address.mScope = kAudioObjectPropertyScopeOutput
    }
    address.mElement = kAudioObjectPropertyElementMaster
    let err1 = AudioObjectGetPropertyDataSize(AudioObjectID(kAudioObjectSystemObject), &address, 0, nil, &size)
    if err1 != 0 {
        print("error: \(err1)")
        return []
    }
    deviceIDs = [AudioObjectID](repeating: 0, count: Int(size/UInt32(MemoryLayout<AudioObjectID>.size)))
    let err2 = AudioObjectGetPropertyData(AudioObjectID(kAudioObjectSystemObject), &address, 0, nil, &size, &deviceIDs)
    if err2 != 0 {
        print("error: \(err2)")
        return []
    }
    return deviceIDs
}

func getProperty(of id :AudioObjectID, selector :AudioObjectPropertySelector) -> String? {
    var address:AudioObjectPropertyAddress = AudioObjectPropertyAddress()
    address.mSelector = selector
    address.mScope = kAudioObjectPropertyScopeGlobal
    address.mElement = kAudioObjectPropertyElementMaster

    var deviceName :CFString? = nil
    var size = UInt32(MemoryLayout<String>.size)
    let err1 = AudioObjectGetPropertyData(id, &address, 0, nil, &size, &deviceName)
    if err1 != 0 {
        print("failed to get property: \(selector.description), error: \(err1)")
        return nil
    }
    return deviceName as String?
}

Thank you very much!