GodotRhythmGameToolbox.cs

using Godot;
using System;

public static class Rhythmer
{
    static double ASPTimeSec(AudioStreamPlayer ASP)
    {
        return ASP.GetPlaybackPosition() + GetPlayLatency();
    }
    
    static double ASPTimeSec(AudioStreamPlayer ASP, bool isScaled = false)
    {
        return ASPTimeSec(ASP) / (isScaled ? ASP.PitchScale : 1);
    }

    static double Beat2Sec(double beat, double bpm)
    {
        return beat * 60 / bpm;
    }

    static double Beat2Sec(double beat, double bpm, float timeScale = 1)
    {
        return beat * 60 / bpm * timeScale;
    }
    
    static double Sec2Beat(double sec, double bpm)
    {
        return sec * bpm / 60;
    }

    static double Sec2Beat(double sec, double bpm, float timeScale = 1)
    {
        return sec * bpm / 60 * timeScale;
    }

    static double GetPlayLatency()
    {
        return AudioServer.GetTimeSinceLastMix() - AudioServer.GetOutputLatency();
    }

    static double GetOffsetTimeSec(double playbackTimeSec, double missionTimeSec,
                                   AudioStreamPlayer ASPMusic, AudioStreamPlayer ASPSlave)
    {
        return ((missionTimeSec - playbackTimeSec - AudioServer.GetOutputLatency())
                * ASPSlave.PitchScale
                + AudioServer.GetTimeSinceLastMix()) / ASPMusic.PitchScale;
    }

    static double GetOffsetTimeSec(double playbackTimeSec, double missionTimeSec,
                                   float musicPitchScale, float slavePitchScale)
    {
        return ((missionTimeSec - playbackTimeSec - AudioServer.GetOutputLatency())
                * slavePitchScale
                + AudioServer.GetTimeSinceLastMix()) / musicPitchScale;
    }

    static double GetOffsetTimeSec(double playbackTimeSec, double missionTimeSec)
    {
        return missionTimeSec - playbackTimeSec + GetPlayLatency();
    }
}