Set left and right headphone volume using two different sliders - ios

Question

I am generating a wave sound for different frequencies and user should hear this wave sound using headphones only and he/she will set left and right headphone volumes using two different sliders. To achieve wave sound I wrote below code which works perfect.
But problem is: From last 5 days I am trying to set volume for left and right headphones separately, but no luck.
class Synth {
// MARK: Properties
public static let shared = Synth()
public var volume: Float {
set {
audioEngine.mainMixerNode.outputVolume = newValue
}
get {
audioEngine.mainMixerNode.outputVolume
}
}
public var frequencyRampValue: Float = 0
public var frequency: Float = 440 {
didSet {
if oldValue != 0 {
frequencyRampValue = frequency - oldValue
} else {
frequencyRampValue = 0
}
}
}
private var audioEngine: AVAudioEngine
private lazy var sourceNode = AVAudioSourceNode { _, _, frameCount, audioBufferList in
let ablPointer = UnsafeMutableAudioBufferListPointer(audioBufferList)
let localRampValue = self.frequencyRampValue
let localFrequency = self.frequency - localRampValue
let period = 1 / localFrequency
for frame in 0..<Int(frameCount) {
let percentComplete = self.time / period
let sampleVal = self.signal(localFrequency + localRampValue * percentComplete, self.time)
self.time += self.deltaTime
self.time = fmod(self.time, period)
for buffer in ablPointer {
let buf: UnsafeMutableBufferPointer<Float> = UnsafeMutableBufferPointer(buffer)
buf[frame] = sampleVal
}
}
self.frequencyRampValue = 0
return noErr
}
private var time: Float = 0
private let sampleRate: Double
private let deltaTime: Float
private var signal: Signal
// MARK: Init
init(signal: #escaping Signal = Oscillator.square) {
audioEngine = AVAudioEngine()
let mainMixer = audioEngine.mainMixerNode
let outputNode = audioEngine.outputNode
let format = outputNode.inputFormat(forBus: 0)
sampleRate = format.sampleRate
deltaTime = 1 / Float(sampleRate)
self.signal = signal
let inputFormat = AVAudioFormat(commonFormat: format.commonFormat,
sampleRate: format.sampleRate,
channels: 1,
interleaved: format.isInterleaved)
audioEngine.attach(sourceNode)
audioEngine.connect(sourceNode, to: mainMixer, format: inputFormat)
audioEngine.connect(mainMixer, to: outputNode, format: nil)
mainMixer.outputVolume = 0
audioEngine.mainMixerNode.pan = 100 // this does not work,
//audioEngine.mainMixerNode.pan = 1.0 // this also does not work
do {
try audioEngine.start()
} catch {
print("Could not start engine: \(error.localizedDescription)")
}
}
//This function will be called in view controller to generate sound
public func setWaveformTo(_ signal: #escaping Signal) {
self.signal = signal
}
}
With the above code I can hear the wave sound as normal in left and right headphone.
I tried to use audioEngine.mainMixerNode.pan for value 100 and -100 also -1.0 and 1.0 but this did not make any change.

Answer 1

I tried to use audioEngine.mainMixerNode.pan for value 100 and -100 but this did not make any change.
The allowable range for the pan value is {-1.0, 1.0}. The values that you say you used are outside that range, so it's not surprising that they had no effect. Try 0.75 or -0.75 instead.