How to make the AKSequencer switch soundfonts? - ios

Question

I'm creating a function using the Audiokit API which the user presses music notes onto a screen and a sound comes out based on the SoundFont they chose. I then allow them to collect a host of notes and let them play it back in the order they chose.
The problem is that I am using an AKSequencer to play the notes back and when the AKSequencer plays the notes back it never sounds like the SoundFont. It makes a beep sound.
Is there code that lets me change what sound is coming out of the AKSequencer?
I'm using audio kit to do this.
Sample is an NSObject that contains midisampler, player, etc. Here's the code
class Sampler1: NSObject {
var engine = AVAudioEngine()
var sampler: AVAudioUnitSampler!
var midisampler = AKMIDISampler()
var octave = 4
let midiChannel = 0
var midiVelocity = UInt8(127)
var audioGraph: AUGraph?
var musicPlayer: MusicPlayer?
var patch = UInt32(0)
var synthUnit: AudioUnit?
var synthNode = AUNode()
var outputNode = AUNode()
override init() {
super.init()
// engine = AVAudioEngine()
sampler = AVAudioUnitSampler()
engine.attach(sampler)
engine.connect(sampler, to: engine.mainMixerNode, format: nil)
loadSF2PresetIntoSampler(5)
/* sampler2 = AVAudioUnitSampler()
engine.attachNode(sampler2)
engine.connect(sampler2, to: engine.mainMixerNode, format: nil)
*/
addObservers()
startEngine()
setSessionPlayback()
/* CheckError(NewAUGraph(&audioGraph))
createOutputNode(audioGraph: audioGraph!, outputNode: &outputNode)
createSynthNode()
CheckError(AUGraphNodeInfo(audioGraph!, synthNode, nil, &synthUnit))
let synthOutputElement: AudioUnitElement = 0
let ioUnitInputElement: AudioUnitElement = 0
CheckError(AUGraphConnectNodeInput(audioGraph!, synthNode, synthOutputElement,
outputNode, ioUnitInputElement))
CheckError(AUGraphInitialize(audioGraph!))
CheckError(AUGraphStart(audioGraph!))
loadnewSoundFont()
loadPatch(patchNo: 0)*/
setUpSequencer()
}
func createOutputNode(audioGraph: AUGraph, outputNode: UnsafeMutablePointer<AUNode>) {
var cd = AudioComponentDescription(
componentType: OSType(kAudioUnitType_Output),
componentSubType: OSType(kAudioUnitSubType_RemoteIO),
componentManufacturer: OSType(kAudioUnitManufacturer_Apple),
componentFlags: 0,componentFlagsMask: 0)
CheckError(AUGraphAddNode(audioGraph, &cd, outputNode))
}
func loadSF2PresetIntoSampler(_ preset: UInt8) {
guard let bankURL = Bundle.main.url(forResource: "Arachno SoundFont - Version 1.0", withExtension: "sf2") else {
print("could not load sound font")
return
}
let folder = bankURL.path
do {
try self.sampler.loadSoundBankInstrument(at: bankURL,
program: preset,
bankMSB: UInt8(kAUSampler_DefaultMelodicBankMSB),
bankLSB: UInt8(kAUSampler_DefaultBankLSB))
try midisampler.loadSoundFont(folder, preset: 0, bank: kAUSampler_DefaultBankLSB)
// try midisampler.loadPath(bankURL.absoluteString)
} catch {
print("error loading sound bank instrument")
}
}
func createSynthNode() {
var cd = AudioComponentDescription(
componentType: OSType(kAudioUnitType_MusicDevice),
componentSubType: OSType(kAudioUnitSubType_MIDISynth),
componentManufacturer: OSType(kAudioUnitManufacturer_Apple),
componentFlags: 0,componentFlagsMask: 0)
CheckError(AUGraphAddNode(audioGraph!, &cd, &synthNode))
}
func setSessionPlayback() {
let audioSession = AVAudioSession.sharedInstance()
do {
try
audioSession.setCategory(AVAudioSession.Category.playback, options:
AVAudioSession.CategoryOptions.mixWithOthers)
} catch {
print("couldn't set category \(error)")
return
}
do {
try audioSession.setActive(true)
} catch {
print("couldn't set category active \(error)")
return
}
}
func startEngine() {
if engine.isRunning {
print("audio engine already started")
return
}
do {
try engine.start()
print("audio engine started")
} catch {
print("oops \(error)")
print("could not start audio engine")
}
}
func addObservers() {
NotificationCenter.default.addObserver(self,
selector:"engineConfigurationChange:",
name:NSNotification.Name.AVAudioEngineConfigurationChange,
object:engine)
NotificationCenter.default.addObserver(self,
selector:"sessionInterrupted:",
name:AVAudioSession.interruptionNotification,
object:engine)
NotificationCenter.default.addObserver(self,
selector:"sessionRouteChange:",
name:AVAudioSession.routeChangeNotification,
object:engine)
}
func removeObservers() {
NotificationCenter.default.removeObserver(self,
name: NSNotification.Name.AVAudioEngineConfigurationChange,
object: nil)
NotificationCenter.default.removeObserver(self,
name: AVAudioSession.interruptionNotification,
object: nil)
NotificationCenter.default.removeObserver(self,
name: AVAudioSession.routeChangeNotification,
object: nil)
}
private func setUpSequencer() {
// set the sequencer voice to storedPatch so we can play along with it using patch
var status = NewMusicSequence(&musicSequence)
if status != noErr {
print("\(#line) bad status \(status) creating sequence")
}
status = MusicSequenceNewTrack(musicSequence!, &track)
if status != noErr {
print("error creating track \(status)")
}
// 0xB0 = bank select, first we do the most significant byte
var chanmess = MIDIChannelMessage(status: 0xB0 | sequencerMidiChannel, data1: 0, data2: 0, reserved: 0)
status = MusicTrackNewMIDIChannelEvent(track!, 0, &chanmess)
if status != noErr {
print("creating bank select event \(status)")
}
// then the least significant byte
chanmess = MIDIChannelMessage(status: 0xB0 | sequencerMidiChannel, data1: 32, data2: 0, reserved: 0)
status = MusicTrackNewMIDIChannelEvent(track!, 0, &chanmess)
if status != noErr {
print("creating bank select event \(status)")
}
// set the voice
chanmess = MIDIChannelMessage(status: 0xC0 | sequencerMidiChannel, data1: UInt8(0), data2: 0, reserved: 0)
status = MusicTrackNewMIDIChannelEvent(track!, 0, &chanmess)
if status != noErr {
print("creating program change event \(status)")
}
CheckError(MusicSequenceSetAUGraph(musicSequence!, audioGraph))
CheckError(NewMusicPlayer(&musicPlayer))
CheckError(MusicPlayerSetSequence(musicPlayer!, musicSequence))
CheckError(MusicPlayerPreroll(musicPlayer!))
}
func loadnewSoundFont() {
var bankURL = Bundle.main.url(forResource: "Arachno SoundFont - Version 1.0", withExtension: "sf2")
CheckError(AudioUnitSetProperty(synthUnit!, AudioUnitPropertyID(kMusicDeviceProperty_SoundBankURL), AudioUnitScope(kAudioUnitScope_Global), 0, &bankURL, UInt32(MemoryLayout<URL>.size)))
}
func loadPatch(patchNo: Int) {
let channel = UInt32(0)
var enabled = UInt32(1)
var disabled = UInt32(0)
patch = UInt32(patchNo)
CheckError(AudioUnitSetProperty(
synthUnit!,
AudioUnitPropertyID(kAUMIDISynthProperty_EnablePreload),
AudioUnitScope(kAudioUnitScope_Global),
0,
&enabled,
UInt32(MemoryLayout<UInt32>.size)))
let programChangeCommand = UInt32(0xC0 | channel)
CheckError(MusicDeviceMIDIEvent(self.synthUnit!, programChangeCommand, patch, 0, 0))
CheckError(AudioUnitSetProperty(
synthUnit!,
AudioUnitPropertyID(kAUMIDISynthProperty_EnablePreload),
AudioUnitScope(kAudioUnitScope_Global),
0,
&disabled,
UInt32(MemoryLayout<UInt32>.size)))
// the previous programChangeCommand just triggered a preload
// this one actually changes to the new voice
CheckError(MusicDeviceMIDIEvent(synthUnit!, programChangeCommand, patch, 0, 0))
}
func play(number: UInt8) {
sampler.startNote(number, withVelocity: 127, onChannel: 0)
}
func stop(number: UInt8) {
sampler.stopNote(number, onChannel: 0)
}
func musicPlayerPlay() {
var status = noErr
var playing:DarwinBoolean = false
CheckError(MusicPlayerIsPlaying(musicPlayer!, &playing))
if playing != false {
status = MusicPlayerStop(musicPlayer!)
if status != noErr {
print("Error stopping \(status)")
CheckError(status)
return
}
}
CheckError(MusicPlayerSetTime(musicPlayer!, 0))
CheckError(MusicPlayerStart(musicPlayer!))
}
var avsequencer: AVAudioSequencer!
var sequencerMode = 1
var sequenceStartTime: Date?
var noteOnTimes = [Date] (repeating: Date(), count:128)
var musicSequence: MusicSequence?
var midisequencer = AKSequencer()
// var musicPlayer: MusicPlayer?
let sequencerMidiChannel = UInt8(1)
var midisynthUnit: AudioUnit?
//track is the variable the notes are written on
var track: MusicTrack?
var newtrack: AKMusicTrack?
func setupSequencer(name: String) {
self.avsequencer = AVAudioSequencer(audioEngine: self.engine)
let options = AVMusicSequenceLoadOptions.smfChannelsToTracks
if let fileURL = Bundle.main.url(forResource: name, withExtension: "mid") {
do {
try avsequencer.load(from: fileURL, options: options)
print("loaded \(fileURL)")
} catch {
print("something screwed up \(error)")
return
}
}
avsequencer.prepareToPlay()
}
func playsequence() {
if avsequencer.isPlaying {
stopsequence()
}
avsequencer.currentPositionInBeats = TimeInterval(0)
do {
try avsequencer.start()
} catch {
print("cannot start \(error)")
}
}
func creatnewtrck(){
let sequencelegnth = AKDuration(beats: 8.0)
newtrack = midisequencer.newTrack()
}
func addnotestotrack(){
// AKMIDISampler
}
func stopsequence() {
avsequencer.stop()
}
func setSequencerMode(mode: Int) {
sequencerMode = mode
switch(sequencerMode) {
case SequencerMode.off.rawValue:
print(mode)
// CheckError(osstatus: MusicPlayerStop(musicPlayer!))
case SequencerMode.recording.rawValue:
print(mode)
case SequencerMode.playing.rawValue:
print(mode)
default:
break
}
}
/* func noteOn(note: UInt8) {
let noteCommand = UInt32(0x90 | midiChannel)
let base = note - 48
let octaveAdjust = (UInt8(octave) * 12) + base
let pitch = UInt32(octaveAdjust)
CheckError(MusicDeviceMIDIEvent(self.midisynthUnit!,
noteCommand, pitch, UInt32(self.midiVelocity), 0))
}
func noteOff(note: UInt8) {
let channel = UInt32(0)
let noteCommand = UInt32(0x80 | channel)
let base = note - 48
let octaveAdjust = (UInt8(octave) * 12) + base
let pitch = UInt32(octaveAdjust)
CheckError(MusicDeviceMIDIEvent(self.midisynthUnit!,
noteCommand, pitch, 0, 0))
}*/
func noteOn(note: UInt8) {
if sequencerMode == SequencerMode.recording.rawValue {
print("recording sequence note")
noteOnTimes[Int(note)] = Date()
} else {
print("no notes")
}
}
func noteOff(note: UInt8, timestamp: Float64, sequencetime: Date) {
if sequencerMode == SequencerMode.recording.rawValue {
let duration: Double = Date().timeIntervalSince(noteOnTimes[Int(note)])
let onset: Double = noteOnTimes[Int(note)].timeIntervalSince(sequencetime)
//the order of the notes in the array
var beat: MusicTimeStamp = 0
CheckError(MusicSequenceGetBeatsForSeconds(musicSequence!, onset, &beat))
var mess = MIDINoteMessage(channel: sequencerMidiChannel,
note: note,
velocity: midiVelocity,
releaseVelocity: 0,
duration: Float(duration) )
CheckError(MusicTrackNewMIDINoteEvent(track!, timestamp, &mess))
}
}
}
The code that plays the collection of notes
_ = sample.midisequencer.newTrack()
let sequencelegnth = AKDuration(beats: 8.0)
sample.midisequencer.setLength(sequencelegnth)
sample.sequenceStartTime = format.date(from: format.string(from: NSDate() as Date))
sample.midisequencer.setTempo(160.0)
sample.midisequencer.enableLooping()
sample.midisequencer.play()
This is the code that changes the soundfont
func loadSF2PresetIntoSampler(_ preset: UInt8) {
guard let bankURL = Bundle.main.url(forResource: "Arachno SoundFont - Version 1.0", withExtension: "sf2") else {
print("could not load sound font")
return
}
let folder = bankURL.path
do {
try self.sampler.loadSoundBankInstrument(at: bankURL,
program: preset,
bankMSB: UInt8(kAUSampler_DefaultMelodicBankMSB),
bankLSB: UInt8(kAUSampler_DefaultBankLSB))
try midisampler.loadSoundFont(folder, preset: 0, bank: kAUSampler_DefaultBankLSB)
// try midisampler.loadPath(bankURL.absoluteString)
} catch {
print("error loading sound bank instrument")
}
}
The midisampler is an AKMidisampler.

Answer 1

At minimum, you need to connect an AKSequencer to some kind of output to get it to make sounds. With the older version (now called AKAppleSequencer), if you don't explicitly set the output, you will hear the default (beepy) sampler.
For example, on AKAppleSequencer (in AudioKit 4.8, or AKSequencer for earlier version)
let track = seq.newTrack()
track!.setMIDIOutput(sampler.midiIn)
on the new AKSequencer
let track = seq.newTrack() // for the new AKSequencer, in AudioKit 4.8
track!.setTarget(node: sampler)
Also, make sure that you have allowed audio background mode in your project's Capabilities, as missing this step this will also get you the default sampler.
You've included a massive amount of code (and I haven't tried to absorb all of what is going on here) but the fact that you are using instances of both MusicSequence and AKSequencer (which I suspect is the older version, now called AKAppleSequencer, which is merely a wrapper around MusicSequence) is something of a red flag.