Common problems

Playback doesn't produce sound or events logs

Make sure an instance of Playback class is held by class field, global variable or something else that can live longer than the method where you instantiate Playback. In this case

private void StartPlayback()
{
    var playback = _midiFile.GetPlayback();
    playback.Start();
}

playback variable will "die" (will be ready to be collected by GC) after the program exits the StartPlayback method so playback won't work.

SetActive can only be called from the main thread in Unity

Sometimes you want to handle playback events or use event or note callbacks. Your code can be executed on a separate thread in these cases. It can happen because Playback's internals (like tick generator's tick handling) work on separate thread.

But UI related things like call of SetActive can be executed on UI thread only. You can use the solution from here: https://stackoverflow.com/a/56715254.

Related issues on GitHub:

• trigger object with a note in Unity