Skip to main content

​
Overview

Audio tracks are the fundamental building blocks for working with audio in Lumix. Each audio track provides a complete signal chain including mixing, plugin processing, volume/pan control, and metering.

​
AudioTrack Class

The AudioTrack class (~/workspace/source/Lumix/Tracks/AudioTracks/AudioTrack.cs:9) extends the base Track class and provides audio-specific functionality.

​
Key Properties

PropertyTypeDescription
TrackTypeTrackTypeAlways returns TrackType.Audio
EngineTrackAudioEngineThe audio engine handling playback and processing
DraggedClipAudioFileReaderCurrently dragged audio clip (for UI operations)
NamestringTrack name
ColorVector4Track color (randomly assigned on creation)
ClipsList<Clip>Audio clips contained in this track

​
Construction

public AudioTrack(string name)
{
    Name = name;
    Vector4 trackCol = ImGuiTheme.GetRandomColor();
    Color = trackCol;
    Engine = new TrackAudioEngine(this, AudioSettings.SampleRate);
    Engine.VolumeMeasured += (sender, e) =>
    {
        _leftChannelGain = e.MaxSampleValues[0];
        _rightChannelGain = e.MaxSampleValues[1];
    };
    ArrangementView.MasterTrack.AudioEngine.AddTrack(Engine);
}

​
Audio Track Lifecycle

1

Track Creation

When an audio track is created, it:
  • Generates a random color for visual identification
  • Initializes a TrackAudioEngine with the project’s sample rate
  • Subscribes to volume metering events for gain visualization
  • Registers itself with the master track for final output routing
2

Clip Management

Audio clips can be:
  • Dragged from the file browser onto the track
  • Recorded directly into the track
  • Duplicated, moved, and edited
3

Signal Processing

Audio flows through the track’s engine:
  1. Mixer combines all playing clips
  2. Plugin chain processes the mixed signal
  3. Stereo provider applies volume and pan
  4. Metering provider measures levels
  5. Track state provider handles mute/solo

​
Track Controls

Each audio track includes the following controls (defined in base Track class):

​
Volume and Pan

  • Volume: Range from -90 dB to +6 dB
    • Converted to linear gain: float linearVolume = (float)Math.Pow(10, _volume / 20)
    • Double-click to reset to 0 dB
  • Pan: Range from -50 (left) to +50 (right)
    • Mapped to stereo provider: float mappedPan = _pan / 50f
    • Double-click to center

​
Track State

ControlDescription
Enable/DisableTurns track on/off (mute)
SoloMutes all other tracks
Arm RecordingEnables recording when playback starts

​
Gain Metering

Each track displays a real-time stereo gain meter showing:
  • Left channel level (left half of meter)
  • Right channel level (right half of meter)
  • Smoothed visualization for better readability
// Smoothing factor for gain display
float smoothingFactor = 0.1f;
_smoothLeftChannelGain = Lerp(_smoothLeftChannelGain, _leftChannelGain, smoothingFactor);
_smoothRightChannelGain = Lerp(_smoothRightChannelGain, _rightChannelGain, smoothingFactor);

​
Clip Operations

​
Adding Clips

Clips can be added to a track by:
  1. Drag and drop from file browser
  2. Recording audio input
  3. Duplicating existing clips (Ctrl+D)

​
Supported Audio Formats

Any format supported by NAudio’s AudioFileReader, including:
  • WAV
  • MP3
  • AIFF
  • And other common formats
Audio files must match the project’s sample format. If the wave format doesn’t match, you’ll see a warning dialog: “Can’t play [filename]“

​
Track Duplication

Audio tracks can be fully duplicated with all settings and clips: 
if (ImGui.MenuItem("Duplicate", "Ctrl+D"))
{
    var track = ArrangementView.NewAudioTrack(this.Name, ArrangementView.Tracks.IndexOf(this) + 1);
    
    // Copy all clips
    foreach (AudioClip clip in Clips.Cast<AudioClip>())
    {
        var copy_clip = new AudioClip(track, clip.Clip, clip.StartTick);
        track.Clips.Add(copy_clip);
    }
    
    // Copy track settings
    track._enabled = this.Enabled;
    track._volume = this.Volume;
    track._pan = this.Pan;
    track._solo = this.Solo;
    track._recordOnStart = this.RecordOnStart;
    track._color = this.Color;
    
    // Copy plugin chain
    foreach (var fxPlugin in this.Engine.PluginChainSampleProvider.FxPlugins)
    {
        // Plugin instances are recreated
    }
}

​
Time Selection

Tracks support time selection areas for:
  • Selecting multiple clips within a time range
  • Creating new MIDI clips (on MIDI tracks)
  • Visual reference during editing
Time selection is displayed in musical time format: Bars.Beats.Ticks

​
Recording Audio

When recording is armed and playback starts:
  1. Track engine creates a WaveInEvent device
  2. Audio is written to a temporary WAV file
  3. On stop, an AudioClip is created from the recorded file
  4. The clip is added to the track at the recording start position
See Audio Engine for more details on the recording process.

​
Best Practices

  • Use descriptive track names
  • Color-code related tracks for easier navigation
  • Use track reordering (arrow buttons) to group related tracks
  • Disable unused tracks to save CPU
  • Use the solo feature instead of manually muting multiple tracks
  • Monitor gain meters to avoid clipping
  • Double-click track controls to open device view
  • Use Ctrl+Click on solo to solo multiple tracks
  • Right-click for quick access to track operations
  • Base Track Class: ~/workspace/source/Lumix/Tracks/Track.cs
  • Audio Engine: ~/workspace/source/Lumix/Tracks/AudioTracks/TrackAudioEngine.cs
  • Track Types: Audio, MIDI, Group

​
Next Steps

Audio Clips

Learn about audio clip management and editing

Audio Engine

Deep dive into audio processing and playback

Build docs developers (and LLMs) love

Get started for freeTalk to us