How to play MIDI with AudioKit's new AKSequencer

Question

I'm on AudioKit 4.9.1 and can't manage to play a MIDI file with the new AKSequencer (replacing AKAppleSequencer). No sound playing. Assume that MIDI file AND samples are loaded correctly since they previously worked with AKAppleSequencer. Background audio mode capability is also enabled.

Here's the relevant code: (I've also tried both AKSampler and AKAppleSampler but same result)

class MIDIPlayer {
    var sampler: AKSampler
    var legacySampler: AKAppleSampler
    var sequencer: AKSequencer

    init(withSfz sfz: String, orSf2 sf2: String, andMidiFile midiFile: String) {

        self.sampler = AKSampler()
        self.legacySampler = AKAppleSampler()
        try? legacySampler.loadSoundFont(sf2, preset: 0, bank: 0)
        sampler.loadSFZ(url: Bundle.main.url(forResource: sfz, withExtension: "sfz")!)

        AudioKit.output = sampler
        try? AudioKit.start()

        sequencer = AKSequencer(targetNode: sampler)
        // sequencer = AKSequencer(targetNode: legacySampler)

        let midi = AKMIDIFile(url: Bundle.main.url(forResource: midiFile, withExtension: "mid")!)
        sequencer.load(midiFile: midi)
    }

    func play() {
        sequencer.playFromStart()
    } 

Is there some difference in how to set up the signal chain that I'm missing?

Answer 1

With the new sequencer, it has to be part of the signal chain. So, do something like

let mixer = AKMixer
sampler >>> mixer
for track in sequencer.tracks { track >>> mixer }
AudioKit.output = mixer

and it should work. Sorry for the delay in seeing this on Github issues.