ADOFAIRenderer/Util/Audio/AudioSyncCalculator.cs

using System;

namespace ADOFAIRenderer.Util.Audio;

internal class AudioSyncCalculator
{
    private readonly long _sampleRate;
    private readonly (long Numerator, long Denominator) _fpsRational;

    // ReSharper disable once NotAccessedField.Local
    private long _currentSample;
    private long _remainder;
        
    public AudioSyncCalculator(long sampleRate, double fps)
    {
        _sampleRate = sampleRate;
        _fpsRational = RationalUtil.Double2MaxPrecisionInt(fps);
    }

    public void Reset()
    {
        _currentSample = 0;
        _remainder = 0;
    }

    public int GetNextFrameSamples()
    {
        var numerator = _sampleRate * _fpsRational.Denominator + _remainder;
        var samplesNeeded = numerator / _fpsRational.Numerator;

        _remainder = numerator % _fpsRational.Numerator;
        _currentSample += samplesNeeded;
        return (int)samplesNeeded;
    }
}