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Overview

MIDI tracks in Lumix enable music composition and sequencing using MIDI data. They support VST instruments, MIDI event playback, and real-time recording from virtual or hardware keyboards.

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Creating MIDI Tracks

MIDI tracks can be created through the arrangement view. Each track has its own MIDI engine for processing MIDI events and routing them to VST instruments. 
public class MidiTrack : Track
{
    public override TrackType TrackType => TrackType.Midi;
    
    public MidiTrack(string name = "")
    {
        Name = name;
        Vector4 trackCol = ImGuiTheme.GetRandomColor();
        Color = trackCol;
        Engine = new TrackMidiEngine(this, AudioSettings.SampleRate);
        // ...
    }
}

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Key Features

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MIDI Clip Management

Create MIDI clips by double-clicking on the track timeline: 
public void CreateMidiClip(long time)
{
    var clip = new MidiClip(this, time);
    Clips.Add(clip);
}

public void CreateMidiClip(TimeSelection time)
{
    var clip = new MidiClip(this, time);
    Clips.Add(clip);
}

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Volume Metering

MIDI tracks feature real-time volume metering for monitoring output levels: 
Engine.VolumeMeasured += (sender, e) =>
{
    // Get the maximum peak across all channels
    _leftChannelGain = e.MaxSampleValues[0];
    _rightChannelGain = e.MaxSampleValues[1];
};

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MIDI Engine

The TrackMidiEngine handles MIDI event processing and VST instrument communication.

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Sending MIDI Events

public void SendNoteOnEvent(int channel, SevenBitNumber noteNumber, SevenBitNumber velocity)
{
    var vstPlugin = PluginChainSampleProvider.PluginInstrument?.GetPlugin<VstPlugin>();
    vstPlugin?.SendNoteOn(channel, noteNumber, velocity);
}

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MIDI File Playback

The engine supports playback of MIDI files with real-time event processing: 
public override void Fire(MidiFile midiFile, float offset, float endOffset)
{
    _playback?.Dispose();
    
    _playback = midiFile.GetPlayback();
    _playback.TrackProgram = true;
    _playback.TrackNotes = true;
    _playback.TrackControlValue = true;
    _playback.TrackPitchValue = true;
    _playback.PlaybackStart = new MetricTimeSpan(TimeSpan.FromSeconds(offset));
    _playback.Speed = TopBarControls.Bpm / 120f;
    
    // Event handling
    _playback.EventPlayed += (sender, e) =>
    {
        if (e.Event is NoteOnEvent noteOn)
        {
            SendNoteOnEvent(0, noteOn.NoteNumber, noteOn.Velocity);
        }
        else if (e.Event is NoteOffEvent noteOff)
        {
            SendNoteOffEvent(0, noteOff.NoteNumber, noteOff.Velocity);
        }
        else if (e.Event is ControlChangeEvent ccEvent)
        {
            // Handle CC events (sustain, volume, etc.)
        }
    };
    
    _playback.Start();
}

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Supported MIDI Events

  • Note On: Triggers when a note starts playing
  • Note Off: Triggers when a note stops playing
  • Includes velocity information (0-127)
  • CC 64: Sustain pedal on/off
  • CC 7: Volume control
  • CC 10: Pan control
  • Other CC messages for modulation, expression, etc.
  • Switch between instrument patches
  • Tracked automatically during playback
  • Smooth pitch modulation
  • Tracked in real-time during playback

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Integration with VST Instruments

MIDI tracks seamlessly integrate with VST instruments through the plugin chain: 
PluginChainSampleProvider = new PluginChainSampleProvider(Mixer);
The plugin chain processes MIDI events and generates audio output, which is then routed through the track’s effects chain and mixer.

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Track Properties

PropertyTypeDescription
TrackTypeTrackTypeAlways TrackType.Midi for MIDI tracks
EngineTrackMidiEngineMIDI processing engine
ClipsList<Clip>Collection of MIDI clips on this track
ColorVector4Track color for visual identification
EnabledboolWhether the track is active
RecordOnStartboolEnable recording from virtual keyboard
MIDI tracks require at least one VST instrument to produce sound. Add a VST instrument from the plugin browser to start making music.

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Best Practices

Organize Your Tracks

Use descriptive names and colors to keep your project organized as you add more MIDI tracks.

Monitor Levels

Watch the track meters to avoid clipping and maintain proper gain staging.

Use Automation

Automate MIDI CC parameters for dynamic, expressive performances.

Bounce to Audio

Render MIDI tracks to audio to save CPU when using heavy VST instruments.

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See Also

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