AudioKit iOS - receivedMIDINoteOn函数 [英] AudioKit iOS - receivedMIDINoteOn function
问题描述
我正在尝试使用receivedMIDINoteOn函数在音序器播放音符时闪烁UILabel。我尝试过使用AKMIDIListener协议但没有成功。我还制作了一个AKMIDISampler的子类，并从音序器发送midi。它播放midi但未调用receivedMIDINoteOn。
I'm trying to use the receivedMIDINoteOn function to flash a UILabel when the sequencer is playing a note. I have tried using the AKMIDIListener protocol with no success. Also I have made a sub class of AKMIDISampler and send midi to it from the sequencer. It plays the midi but the receivedMIDINoteOn is not called.
这是我在售票员的init（）中所拥有的：
This is what I have in the init() of the conductor:
init() {
[ahSampler, beeSampler, gooSampler,flasher] >>> samplerMixer
AudioKit.output = samplerMixer
AudioKit.start()
let midi = AKMIDI()
midi.createVirtualPorts()
midi.openInput("Session 1")
midi.addListener(self)
}
指挥跟随AKMIDIListener协议
The conductor follows AKMIDIListener protocol
这是函数：它永远不会被调用
this is the function: it is never called
func receivedMIDINoteOn(noteNumber: MIDINoteNumber, velocity: MIDIVelocity, channel: MIDIChannel)
{
print("got it")
}
这是AKMIDISampler的子类，它得到midi并播放正弦合成器，但是从不调用receivedMIDINoteOn。
And this is the sub class of AKMIDISampler, it gets midi and plays the sine synth, but the receivedMIDINoteOn is never called.
class Flasher: AKMIDISampler
{
override func receivedMIDINoteOn(noteNumber: MIDINoteNumber, velocity: MIDIVelocity, channel: MIDIChannel)
{
print("Flasher got it!")
}
}
编辑：我应该ave一直在使用AKCallbackInstrument类，并覆盖它的start（）函数。
edit: I should have been using the AKCallbackInstrument class instead, and overriding it's start() function.
推荐答案
Ben，
在没有看到整个项目的情况下，我猜想如果你的项目能够接收和触发MIDI音符，那么只需将其输出发送到UILabel就是一个问题。我建议使用NotificationCenter在 Conductor 类中收到MIDI事件时通知ViewController。请务必添加 DispatchQueue.main.async 代码，否则文本将不会按预期更新。这在AudioKit Google Group 此处中有所说明。
Without seeing your entire project, I would guess that if your project is able to receive and trigger MIDI notes, then it's an issue with only sending its output to the UILabel. I recommend using NotificationCenter to inform the ViewController when a MIDI event has been received in the Conductor class. Be sure to add the DispatchQueue.main.async code, or else the text won't update as expected. This was noted in the AudioKit Google Group here.
示例：
DispatchQueue.main.async(execute: {
nc.post(name: NSNotification.Name(rawValue: "outputMessage"),
object: nil,
userInfo: [
"message": self.outputMIDIMessage,
"midiSignalReceived": self.midiSignalReceived,
"midiTypeReceived": self.midiTypeReceived
])
})
我还建议如下：
移动让midi = AKMIDI（） 到Conductor类顶部的 init（）之外的实例变量中，而不是在其内部。看起来你试图在 AudioKit.start（）之后创建它。
Move let midi = AKMIDI() into an instance variable outside of the init() at the top of your Conductor class, rather than inside of it. It looks like you're attempting to create it after AudioKit.start().
我发布了一个示例项目演示了如何在通过AudioKit收到MIDI音符编号时更改UILabel的颜色：
I posted a sample project that demonstrates how you can change a UILabel's color whenever a MIDI note number has been received via AudioKit:
https://github.com/markjeschke/AKMidiReceiver
指挥类：
import AudioKit
enum MidiEventType: String {
case
noteNumber = "Note Number",
continuousControl = "Continuous Control",
programChange = "Program Change"
}
class Conductor: AKMIDIListener {
// Globally accessible
static let sharedInstance = Conductor()
// Set the instance variables outside of the init()
let midi = AKMIDI()
var demoSampler = SamplerAudioFileLoader()
var samplerMixer = AKMixer()
var outputMIDIMessage = ""
var midiSignalReceived = false
var midiTypeReceived: MidiEventType = .noteNumber
init() {
// Session settings
AKSettings.bufferLength = .medium
AKSettings.defaultToSpeaker = true
// Allow audio to play while the iOS device is muted.
AKSettings.playbackWhileMuted = true
do {
try AKSettings.setSession(category: .playAndRecord, with: [.defaultToSpeaker, .allowBluetooth, .mixWithOthers])
} catch {
AKLog("Could not set session category.")
}
// File path options are:
// "TX Brass"
// "TX LoTine81z"
// "TX Metalimba"
// "TX Pluck Bass"
demoSampler.loadEXS24Sample(filePath: "TX Brass")
// If you wish to load a wav file, comment the `loadEXS24` method and uncomment this one:
// demoSampler.loadWavSample(filePath: "Kick") // Load Kick wav file
[demoSampler] >>> samplerMixer
AudioKit.output = samplerMixer
AudioKit.start()
// MIDI Configure
midi.createVirtualInputPort(98909, name: "AKMidiReceiver")
midi.createVirtualOutputPort(97789, name: "AKMidiReceiver")
midi.openInput()
midi.openOutput()
midi.addListener(self)
}
// Capture the MIDI Text within a DispatchQueue, so that it's on the main thread.
// Otherwise, it won't display.
func captureMIDIText() {
let nc = NotificationCenter.default
DispatchQueue.main.async(execute: {
nc.post(name: NSNotification.Name(rawValue: "outputMessage"),
object: nil,
userInfo: [
"message": self.outputMIDIMessage,
"midiSignalReceived": self.midiSignalReceived,
"midiTypeReceived": self.midiTypeReceived
])
})
}
// MARK: MIDI received
// Note On Number + Velocity + MIDI Channel
func receivedMIDINoteOn(noteNumber: MIDINoteNumber, velocity: MIDIVelocity, channel: MIDIChannel) {
midiTypeReceived = .noteNumber
outputMIDIMessage = "\(midiTypeReceived.rawValue)\nChannel: \(channel+1) noteOn: \(noteNumber) velocity: \(velocity)"
print(outputMIDIMessage)
midiSignalReceived = true
captureMIDIText()
playNote(note: noteNumber, velocity: velocity, channel: channel)
}
// Note Off Number + Velocity + MIDI Channel
func receivedMIDINoteOff(noteNumber: MIDINoteNumber, velocity: MIDIVelocity, channel: MIDIChannel) {
midiTypeReceived = .noteNumber
outputMIDIMessage = "\(midiTypeReceived.rawValue)\nChannel: \(channel+1) noteOff: \(noteNumber) velocity: \(velocity)"
print(outputMIDIMessage)
midiSignalReceived = false
captureMIDIText()
stopNote(note: noteNumber, channel: channel)
}
// Controller Number + Value + MIDI Channel
func receivedMIDIController(_ controller: MIDIByte, value: MIDIByte, channel: MIDIChannel) {
// If the controller value reaches 127 or above, then trigger the `demoSampler` note.
// If the controller value is less, then stop the note.
// This creates an on/off type of "momentary" MIDI messaging.
if value >= 127 {
playNote(note: 30 + controller, velocity: 80, channel: channel)
} else {
stopNote(note: 30 + controller, channel: channel)
}
midiTypeReceived = .continuousControl
outputMIDIMessage = "\(midiTypeReceived.rawValue)\nChannel: \(channel+1) controller: \(controller) value: \(value)"
midiSignalReceived = true
captureMIDIText()
}
// Program Change Number + MIDI Channel
func receivedMIDIProgramChange(_ program: MIDIByte, channel: MIDIChannel) {
// Trigger the `demoSampler` note and release it after half a second (0.5), since program changes don't have a note off release.
triggerSamplerNote(program, channel: channel)
midiTypeReceived = .programChange
outputMIDIMessage = "\(midiTypeReceived.rawValue)\nChannel: \(channel+1) programChange: \(program)"
midiSignalReceived = true
captureMIDIText()
}
func receivedMIDISetupChange() {
print("midi setup change")
print("midi.inputNames: \(midi.inputNames)")
let listInputNames = midi.inputNames
for inputNames in listInputNames {
print("inputNames: \(inputNames)")
midi.openInput(inputNames)
}
}
func playNote(note: MIDINoteNumber, velocity: MIDIVelocity, channel: MIDIChannel) {
demoSampler.play(noteNumber: note, velocity: velocity, channel: channel)
}
func stopNote(note: MIDINoteNumber, channel: MIDIChannel) {
demoSampler.stop(noteNumber: note, channel: channel)
}
func triggerSamplerNote(_ program: MIDIByte, channel: MIDIChannel) {
playNote(note: 60 + program, velocity: 80, channel: channel)
let releaseNoteDelay = DispatchTime.now() + 0.5 // Change 0.5 to desired number of seconds
DispatchQueue.main.asyncAfter(deadline: releaseNoteDelay) {
self.stopNote(note: 60 + program, channel: channel)
self.midiSignalReceived = false
}
}
}
带有UILabel的ViewController：
import UIKit
import AudioKit
class ViewController: UIViewController {
@IBOutlet weak var outputTextLabel: UILabel!
var conductor = Conductor.sharedInstance
var midiSignalReceived = false
var midiTypeReceived: MidiEventType = .noteNumber
override func viewDidLoad() {
super.viewDidLoad()
let nc = NotificationCenter.default
nc.addObserver(forName:NSNotification.Name(rawValue: "outputMessage"), object:nil, queue:nil, using:catchNotification)
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
flashBackgroundColor()
midiSignalReceived = false
self.outputTextLabel.text = "Listening for MIDI events..."
}
@objc func catchNotification(notification:Notification) -> Void {
guard
let userInfo = notification.userInfo,
let message = userInfo["message"] as? String,
let midiSignalReceived = userInfo["midiSignalReceived"] as? Bool,
let midiTypeReceived = userInfo["midiTypeReceived"] as? MidiEventType else {
print("No userInfo found in notification")
return
}
DispatchQueue.main.async(execute: {
self.outputTextLabel.text = message
self.midiSignalReceived = midiSignalReceived
self.midiTypeReceived = midiTypeReceived
self.flashBackgroundColor()
})
}
@objc func flashBackgroundColor() {
if midiSignalReceived {
self.outputTextLabel.backgroundColor = UIColor.green
self.view.backgroundColor = UIColor.lightGray
if midiTypeReceived != .noteNumber {
self.perform(#selector(dismissFlashBackgroundColor), with: nil, afterDelay: 0.5)
}
} else {
dismissFlashBackgroundColor()
}
}
@objc func dismissFlashBackgroundColor() {
UIView.animate(withDuration: 0.5) {
self.outputTextLabel.backgroundColor = UIColor.clear
self.view.backgroundColor = UIColor.white
self.midiSignalReceived = false
self.conductor.midiSignalReceived = false
}
}
deinit {
NotificationCenter.default.removeObserver(self,
name: NSNotification.Name(rawValue: "outputMessage"),
object: nil)
}
}
SamplerAudioFileLoader.swift：
import AudioKit
class SamplerAudioFileLoader: AKMIDISampler {
internal func loadWavSample(filePath: String) {
do {
try self.loadWav("Sounds/\(filePath)")
} catch {
print("Could not locate the Wav file.")
}
}
internal func loadEXS24Sample(filePath: String) {
do {
try self.loadEXS24("Sounds/Sampler Instruments/\(filePath)")
} catch {
print("Could not locate the EXS24 file.")
}
}
}
我希望这会有所帮助。如果您对此有任何疑问，请与我们联系。
I hope this helps. Please let me know if you have any questions about this.
保重，
标记
Take care,
Mark
PS如果您克隆此 AKMidiReceiver示例，请打开工作区，Xcode项目中不会显示任何方案，请关注这些步骤在此处中找到：
P.S. If you clone this AKMidiReceiver example, open the Workspace, and no scheme appears in the Xcode project, please follow these steps that were found here:
- 点击No Scheme
- 点击Manage Scheme
- 点击立即自动创建计划
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