Tick generator

Playback uses a timer under the hood. In DryWetMIDI this timer is called tick generator. On every tick of the timer playback looks at what objects should be played by the current time, plays them and advances position within the objects list waiting for the next tick.

To make playback smooth and correct, the precision of the timer should be ~1ms. So tick will be generated every one millisecond. By default, DryWetMIDI uses HighPrecisionTickGenerator which is the best option in terms of CPU usage, memory usage and precision.

Important

HighPrecisionTickGenerator is supported for Windows and macOS only at the moment.

You can also use RegularPrecisionTickGenerator which uses standard Timer and thus provides precision about 16ms on Windows. But this tick generator is cross-platform.

Tick generator can be specified via playbackSettings parameter of Playback's constructors or GetPlayback extension methods within PlaybackUtilities:

var playback = midiFile.GetPlayback(new PlaybackSettings
{
    ClockSettings = new MidiClockSettings
    {
        CreateTickGeneratorCallback = () => new RegularPrecisionTickGenerator()
    }
});

Custom tick generator

All built-in tick generators extend the abstract TickGenerator class so you can create your own and use it for Playback and PlaybackCurrentTimeWatcher.

As an example we create a simple loop tick generator working in a separate thread. The code is:

private sealed class ThreadTickGenerator : TickGenerator
{
    private Thread _thread;
    private bool _isRunning;
    private bool _disposed;

    protected override void Start(TimeSpan interval)
    {
        if (_thread != null)
            return;

        _thread = new Thread(() =>
        {
            var stopwatch = new Stopwatch();
            var lastMs = 0L;

            stopwatch.Start();
            _isRunning = true;

            while (_isRunning)
            {
                var elapsedMs = stopwatch.ElapsedMilliseconds;
                if (elapsedMs - lastMs >= interval.TotalMilliseconds)
                {
                    GenerateTick();
                    lastMs = elapsedMs;
                }
            }
        });

        _thread.Start();
    }

    protected override void Dispose(bool disposing)
    {
        if (_disposed)
            return;

        if (disposing)
        {
            _isRunning = false;
        }

        _disposed = true;
    }
}

And then use it:

var playback = midiFile.GetPlayback(new PlaybackSettings
{
    ClockSettings = new MidiClockSettings
    {
        CreateTickGeneratorCallback = () => new ThreadTickGenerator()
    }
});

Of course this tick generator will use a lot of CPU due to infinite loop but it's for demo purposes only.

Manual ticking

Also you can tick playback's internal clock manually without a tick generator via the TickClock method of Playback. For example, you can use manual ticking within every frame update in Unity.

To use only manual ticking you should return null in CreateTickGeneratorCallback:

var playback = midiFile.GetPlayback(new PlaybackSettings
{
    ClockSettings = new MidiClockSettings
    {
        CreateTickGeneratorCallback = () => null
    }
});

and then call

playback.TickClock();

when needed.

You also can use manual ticking in conjunction with a tick generator.