avoid background noise and audio echo in AvAudioEngine Swift

Question

I am trying to send audio with using AudioEngine (getting over iPhone microphone) to another listening device via GCDAsyncUdpSocket, and I get audio in another ios device and I can listen auido in below getComingAudio method , but audio comes with background noise and echo, How can I avoid background noise and audio echo? ,thanks.

func setupAudio () {
    self.audioEngine = AVAudioEngine()
    self.mixer = AVAudioMixerNode()
    self.mixer.volume = 0
    self.audioEngine.attach(mixer)
    
    self.socket = GCDAsyncUdpSocket(delegate: self, delegateQueue: DispatchQueue.main)
    audioFormat = AVAudioFormat(standardFormatWithSampleRate: Double(sampleRate), channels: 1)
}

//Sending Audio
    func sendAudio {
    try! AVAudioSession.sharedInstance().setCategory(AVAudioSession.Category.playAndRecord)
    try! AVAudioSession.sharedInstance().setActive(true)
    
    let format = AVAudioFormat(commonFormat: AVAudioCommonFormat.pcmFormatInt16,
        sampleRate: 44100.0,
        channels: 1,
        interleaved: true)
    
    self.audioEngine.connect(self.audioEngine.inputNode, to: self.mixer, format: format)
    self.audioEngine.connect(self.mixer, to: self.audioEngine.mainMixerNode, format: format)

try! self.audioEngine.inputNode.setVoiceProcessingEnabled(true)

    DispatchQueue.global(qos: .background).async { [weak self] in
        guard let self = self else { return }
        do {
            self.socket.setIPv4Enabled(true)
            self.socket.setIPv6Enabled(false)
            try self.socket.connect(toHost:"235.10.10.100" ?? "", onPort: 4646 ?? 0)
            try self.socket.beginReceiving()
            print("Socket started")
        } catch {
            print("Socket Started Error: \(error)")
        }
    }
    
    self.mixer.installTap(onBus: 0, bufferSize: 2048, format: format, block: { (buffer: AVAudioPCMBuffer!, time: AVAudioTime!) -> Void in
        
        let data = Data(bytes: (buffer.int16ChannelData![0]), count: Int(buffer.frameLength))
        print(buffer)
        
        DispatchQueue.global(qos: .background).async { [weak self] in
            guard let self = self else { return }
            do {
                self.socket.send(data, withTimeout: 0, tag: 0)

            } catch {
                print("Socket send Error: \(error)")
            }
        }
    })
    
    audioEngine.prepare()
    do {
        try audioEngine.start()
    } catch {
        print("Can't start the engine: \(error)")
    }
    }

// Listening Audio

func udpSocket(_ sock: GCDAsyncUdpSocket, didReceive data: Data, fromAddress address: Data, withFilterContext filterContext: Any?) {
    audioPlayer.scheduleBuffer(getComingAudio(with: data), completionHandler: nil)
}

func getComingAudio(with data: Data) -> AVAudioPCMBuffer {
    let audioBuffer = AVAudioPCMBuffer(pcmFormat: audioFormat, frameCapacity: UInt32(data.count) / 2)!
    data.withUnsafeBytes { (bufferPointer: UnsafeRawBufferPointer) in
        let int16Array = Array(bufferPointer.bindMemory(to: Int16.self))
        let floatArray = int16Array.map { Float($0) / Float(Int16.max) }
        floatArray.withUnsafeBufferPointer { audioBuffer.floatChannelData!.pointee.assign(from: $0.baseAddress!, count: floatArray.count) }
    }
    audioBuffer.frameLength = audioBuffer.frameCapacity
    return audioBuffer
}

Answer 1

The very short answer is to turn on voice processing:

try audioEngine.inputNode.setVoiceProcessingEnabled(true)

For more information (and you'll likely want more information because these things can be tricky at times), see WWDC2019/510 What's New in AVAudioEngine and the relevant sample code, Using Voice Processing.