Sunday, May 7, 2017

Modified Version of AudioKit's Microphone Analysis Example without using the Storyboard

The code below is modified from AudioKit's Microphone Analysis example. The UI components are written programmatically without using the storyboard. The code is developed with Xcode 8.3.2 (Swift 3.1) and iOS 10.

1. Use CocoaPods to include the AudioKit framework by add this line to the Podfile:

pod 'AudioKit'

2. Enable the microphone by adding NSMicrophoneUsageDescription and a request string such as "This app needs microphone access." to Info.plist.

Your Info.plist should be like this:


When app is run at the first time, this message should be displayed:



Without this modification, you'll see error like this:


This app has crashed because it attempted to access privacy-sensitive data without a usage description. The app's Info.plist must contain an NSMicrophoneUsageDescription key with a string value explaining to the user how the app uses this data.

3. Modify ViewController.swift as below

import UIKit
import AudioKit

class ViewController: UIViewController {
    
    var labelFrequencyValue : UILabel!
    var labelAmplitudeValue : UILabel!
    var labelSharpValue : UILabel!
    var labelFlatValue : UILabel!
    let mic = AKMicrophone()
    var tracker : AKFrequencyTracker!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        let labelSing = UILabel(frame: CGRect(x: 0, y: 28, width: view.frame.width, height: 50))
        labelSing.text = "Sing into the Microphone"
        labelSing.textAlignment = .center
        labelSing.font = UIFont.systemFont(ofSize: 24, weight: UIFontWeightBold) //System Font Bold
        labelSing.textColor = UIColor.white
        labelSing.backgroundColor = UIColor(red: 2/255, green: 181/255, blue: 31/255, alpha: 1.0)
        view.addSubview(labelSing)
        
        let labelFrequency = UILabel(frame: CGRect(x: 16, y: 86, width: 85.5, height: 20.5))
        labelFrequency.text = "Frequency:"
        view.addSubview(labelFrequency)
        
        labelFrequencyValue = UILabel(frame: CGRect(x: view.frame.width-70, y: 86, width: 50, height: 20.5))
        labelFrequencyValue.text = "0"
        labelFrequencyValue.textAlignment = .right
        view.addSubview(labelFrequencyValue)
        
        let labelAmplitude = UILabel(frame: CGRect(x: 16, y: 114.5, width: 85.5, height: 20.5))
        labelAmplitude.text = "Amplitude:"
        view.addSubview(labelAmplitude)
        
        labelAmplitudeValue = UILabel(frame: CGRect(x: view.frame.width-70, y: 114.5, width: 50, height: 20.5))
        labelAmplitudeValue.text = "0"
        labelAmplitudeValue.textAlignment = .right
        view.addSubview(labelAmplitudeValue)
        
        let labelSharp = UILabel(frame: CGRect(x: 16, y: 142, width: 111.5, height: 20.5))
        labelSharp.text = "Note (Sharps):"
        view.addSubview(labelSharp)
        
        labelSharpValue = UILabel(frame: CGRect(x: view.frame.width-70, y: 142, width: 50, height: 20.5))
        labelSharpValue.text = "C4"
        labelSharpValue.textAlignment = .right
        view.addSubview(labelSharpValue)
        
        let labelFlat = UILabel(frame: CGRect(x: 16, y: 170.5, width: 94, height: 20.5))
        labelFlat.text = "Note (Flats):"
        view.addSubview(labelFlat)
        
        labelFlatValue = UILabel(frame: CGRect(x: view.frame.width-70, y: 170.5, width: 50, height: 20.5))
        labelFlatValue.text = "F4"
        labelFlatValue.textAlignment = .right
        view.addSubview(labelFlatValue)
        
        let labelPlot = UILabel(frame: CGRect(x: 0, y: 199, width: view.frame.width, height: 21.5))
        labelPlot.text = "Audio Input Plot"
        labelPlot.textAlignment = .center
        view.addSubview(labelPlot)
        

        tracker = AKFrequencyTracker.init(mic)
        let silence = AKBooster(tracker, gain: 0)
        AudioKit.output = silence
        AudioKit.start()
        
        setupPlot()
        
        Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(updateUI), userInfo: nil, repeats: true)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
    
    func setupPlot() {
        let audioInputPlot = EZAudioPlot(frame: CGRect(x: 0, y: view.center.y, width: view.frame.width, height: 200))
        
        let plot = AKNodeOutputPlot(mic, frame: audioInputPlot.bounds)
        plot.plotType = .rolling
        plot.shouldFill = true
        plot.shouldMirror = true
        plot.color = UIColor.blue
        audioInputPlot.addSubview(plot)
        view.addSubview(audioInputPlot)
    }
    
    func updateUI() {
        
        let noteFrequencies = [16.35,17.32,18.35,19.45,20.6,21.83,23.12,24.5,25.96,27.5,29.14,30.87]
        let noteNamesWithSharps = ["C", "C","D","D","E","F","F","G","G","A","A","B"]
        let noteNamesWithFlats = ["C", "D","D","E","E","F","G","G","A","A","B","B"]
        
        if tracker.amplitude > 0.1 {
            labelFrequencyValue.text = String(format: "%0.1f", tracker.frequency)
        
            var frequency = Float(tracker.frequency)
            while (frequency > Float(noteFrequencies[noteFrequencies.count-1])){
                frequency = frequency / 2.0
            }
            while (frequency < Float(noteFrequencies[0])) {
                frequency = frequency * 2.0
            }
            
            var minDistance : Float = 10000.0
            var index = 0
            
            for i in 0..<noteFrequencies.count {
                let distance = fabsf(Float(noteFrequencies[i]) - frequency)
                if (distance < minDistance) {
                    index = i
                    minDistance = distance
                }
            }
            let octave = Int(log2f(Float(tracker.frequency) / frequency))
            labelSharpValue.text = "\(noteNamesWithSharps[index])\(octave)"
            labelFlatValue.text = "\(noteNamesWithFlats[index])\(octave)"
        }
        labelAmplitudeValue.text = String(format: "%0.2f", tracker.amplitude)
    }

}

4. Result:



Related Information

AudioKit
Beethoven (Pitch Detection)

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