main.swift

//
//  main.swift
//  AggregateAudioVolumeControl
//
//  Created by Gurhan Polat on 20.12.2020.
//

import Foundation
import Cocoa
import AVFoundation

// @mode = 0 get
// @mode = 1 set n
var mode:Int = -1

var volumeToBeSet:Float = 0.0
// get current volume
if (CommandLine.arguments.count == 2 &&
    CommandLine.arguments[1] == "get") {
    mode = 0
}
// set current volume
else if (CommandLine.arguments.count == 3 &&
         CommandLine.arguments[1] == "set" &&
         Int32(CommandLine.arguments[2]) != nil &&
         Int32(CommandLine.arguments[2])! >= 0 && Int32(CommandLine.arguments[2])! <= 100) {
    mode = 1
    volumeToBeSet = Float(Int32(CommandLine.arguments[2])!) / Float(100)
}
else {
    print("usage: AggregateAudioVolumeControl <get | set n>")
    exit(-1)
}

// get default audio output device
var address:AudioObjectPropertyAddress = AudioObjectPropertyAddress(
    mSelector:AudioObjectPropertySelector(kAudioHardwarePropertyDefaultOutputDevice),
    mScope:AudioObjectPropertyScope(kAudioObjectPropertyScopeGlobal),
    mElement:AudioObjectPropertyElement(kAudioObjectPropertyElementMaster))

var audioDeviceID:AudioDeviceID = 0
var propsize:UInt32 = UInt32(MemoryLayout<AudioDeviceID>.size)
var result = AudioObjectGetPropertyData(AudioDeviceID(kAudioObjectSystemObject), &address, 0, nil, &propsize, &audioDeviceID)

if (result != 0) {
    print("kAudioHardwarePropertyDefaultOutputDevice")
    exit(-1)
}

// get default audio output device uid
address = AudioObjectPropertyAddress(
    mSelector:AudioObjectPropertySelector(kAudioDevicePropertyDeviceUID),
    mScope:AudioObjectPropertyScope(kAudioObjectPropertyScopeGlobal),
    mElement:AudioObjectPropertyElement(kAudioObjectPropertyElementMaster))

var audioDeviceUID:CFString? = nil
propsize = UInt32(MemoryLayout<CFString?>.size)
result = AudioObjectGetPropertyData(audioDeviceID, &address, 0, nil, &propsize, &audioDeviceUID)

if (result != 0) {
    print("kAudioDevicePropertyDeviceUID")
    exit(-1)
}

// get default audio output device transport type
address = AudioObjectPropertyAddress(
    mSelector:AudioObjectPropertySelector(kAudioDevicePropertyTransportType),
    mScope:AudioObjectPropertyScope(kAudioObjectPropertyScopeGlobal),
    mElement:AudioObjectPropertyElement(kAudioObjectPropertyElementMaster))
var transportType:UInt32 = 0
propsize = UInt32(MemoryLayout<UInt32>.size)
result = AudioObjectGetPropertyData(audioDeviceID, &address, 0, nil, &propsize, &transportType)

if (result != 0) {
    print("kAudioDevicePropertyTransportType")
    exit(-1)
}

// if transportType is not Aggregate then exit the tool
if (transportType != kAudioDeviceTransportTypeAggregate) {
    print("audioDeviceID: \(audioDeviceID) uid: \(audioDeviceUID as String? ?? "") transportType: \(transportType == kAudioDeviceTransportTypeAggregate)")
    print("this tool only works with a kAudioDeviceTransportTypeAggregate")
    exit(1)
}

// get the sublist of the Aggregate Audio Device
address = AudioObjectPropertyAddress(
    mSelector:AudioObjectPropertySelector(kAudioAggregateDevicePropertyActiveSubDeviceList),
    mScope:AudioObjectPropertyScope(kAudioObjectPropertyScopeGlobal),
    mElement:AudioObjectPropertyElement(kAudioObjectPropertyElementMaster))
var subDevicesID = [AudioDeviceID]()
for _ in 0..<32 {
    subDevicesID.append(AudioDeviceID())
}
propsize = UInt32(MemoryLayout<AudioDeviceID>.size * 32)
result = AudioObjectGetPropertyData(audioDeviceID, &address, 0, nil, &propsize, &subDevicesID)

if (result != 0) {
    print("kAudioAggregateDevicePropertyActiveSubDeviceList")
    exit(-1)
}

var volAvg: Float = 0.0
var subDeviceCount:Int = Int((propsize / UInt32(MemoryLayout<AudioDeviceID>.size)))

// for eah sub device
// we either set the volume or just get it according to mode argument
print("audioDeviceUID: \(audioDeviceUID as String? ?? "") subDeviceCount: \(subDeviceCount)")
for i in 0..<subDeviceCount {
    let subDevice:AudioDeviceID = subDevicesID[i]
    
    var volLeft:Float = 0.0
    var volRight:Float = 0.0
    
    address = AudioObjectPropertyAddress(
        mSelector:AudioObjectPropertySelector(kAudioDevicePropertyDeviceUID),
        mScope:AudioObjectPropertyScope(kAudioObjectPropertyScopeGlobal),
        mElement:AudioObjectPropertyElement(kAudioObjectPropertyElementMaster))

    var subDeviceUID:CFString? = nil
    propsize = UInt32(MemoryLayout<CFString?>.size)
    result = AudioObjectGetPropertyData(subDevice, &address, 0, nil, &propsize, &subDeviceUID)
    
    if (result != 0) {
        print("kAudioDevicePropertyDeviceUID subDevice")
        exit(-1)
    }
    
    address = AudioObjectPropertyAddress(
        mSelector:AudioObjectPropertySelector(kAudioDevicePropertyVolumeScalar),
        mScope:AudioObjectPropertyScope(kAudioDevicePropertyScopeOutput),
        mElement:1)
    propsize = UInt32(MemoryLayout<Float>.size)
    
    // if mode is get, get the volume of left channel otherwise set it to parameter n
    if (mode == 0) {
        result = AudioObjectGetPropertyData(subDevice, &address, 0, nil, &propsize, &volLeft)
    }
    else {
        result = AudioObjectSetPropertyData(subDevice, &address, 0, nil, propsize, &volumeToBeSet)
        volLeft = volumeToBeSet
    }
    
    if (result != 0) {
        print("kAudioDevicePropertyVolumeScalar volLeft")
        exit(-1)
    }
    
    address = AudioObjectPropertyAddress(
        mSelector:AudioObjectPropertySelector(kAudioDevicePropertyVolumeScalar),
        mScope:AudioObjectPropertyScope(kAudioDevicePropertyScopeOutput),
        mElement:2)
    propsize = UInt32(MemoryLayout<Float>.size)
    
    // if mode is get, get the volume of right channel otherwise set it to parameter n
    if (mode == 0) {
        result = AudioObjectGetPropertyData(subDevice, &address, 0, nil, &propsize, &volRight)
    }
    else {
        result = AudioObjectSetPropertyData(subDevice, &address, 0, nil, propsize, &volumeToBeSet)
        volRight = volumeToBeSet
    }
    
    if (result != 0) {
        print("kAudioDevicePropertyVolumeScalar volRight")
        exit(-1)
    }
    
    volAvg += (volLeft + volRight) / 2
    
    print("subDevice: \(subDeviceUID as String? ?? "") volLeft: \(volLeft) volLeft: \(volRight)")
}

volAvg = volAvg / Float(subDeviceCount)
print("volAvg: \(volAvg)")

// we always return current volume of the sound if no error
// if any error occurs we then return (-1):255
exit(Int32(volAvg * 100))