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Session: Tracks, Clips, and Scenes

Intermediate Composer

Capture parameter snapshots as Clips, organize them into Tracks, and launch coordinated Scenes for live performance.

What you'll build

A two-track live performance session: one track for drums, one for a synth. Each track holds two named Clips (snapshots of its params), and a Scene launches both tracks together. You'll switch between clips mid-performance and trigger scene changes with beat-quantized timing.

Open the AV Performance example (graphs/session/av_performance.json) as a starting point — it already has a drum chain and a synth chain wired up. Or use any graph you've already built.

Concepts covered

Concept Description
Track A named group of graph nodes whose params are managed together
Clip A named snapshot of a track's parameter values, recalled on demand
Scene A row that assigns one clip per track; launching a scene fires all assignments at once
Dirty indicator A dot (•) on the track header when live params differ from the active clip
Quantize Defers a launch to the next beat, bar, or 4-bar boundary for rhythmic alignment

Step 1: Open the session strip

Press V (or use View → Session). A horizontal strip appears at the bottom of the graph editor. It starts with one empty track column and one empty scene row.

Step 2: Assign nodes to the first track

  1. In the graph, click to select all the drum nodes (DrumSequencer, DrumKick, DrumSnare, DrumHiHat, Mixer, Reverb — anything that belongs to the drum chain).
  2. Right-click the track header → Assign Selected. The selected nodes now belong to this track. Their graph borders light up in the track's color.
  3. Double-click the track header to rename it — type "Drums" and press Enter.

Step 3: Save your first clip

The drum pattern is currently live. Dial in an "Intro" feel — maybe a sparse hi-hat-only pattern, low reverb.

Click the + button in the track header. A dialog prompts for a name. Type "Intro" and confirm. The clip cell appears in the grid.

The track now has one clip, "Intro", shown as active (colored background).

Step 4: Create a second clip

Change the drum params: toggle more steps in the sequencer, increase reverb mix, bring the kick in. This is your "Drop".

Click + again in the track header. Name it "Drop".

You now have two clips. The "Drop" clip is active; "Intro" is stored.

Step 5: Switch between clips

Click the Intro cell. The drum nodes' params snap back to the Intro snapshot instantly.

Click Drop. Params snap to the Drop state.

Tweak any param on the drum nodes. Notice the • (dirty dot) appears on the track header — the live state has drifted from the active clip. Click + to save a new clip or right-click the active cell → Update Clip to overwrite it.

Step 6: Add a second track

Click the + in the session header to add a new track column.

Select your synth nodes in the graph (ChordProgression, WavetableOsc, VoiceMixer, etc.). Right-click the new track header → Assign Selected. Rename it "Synth".

Save two clips for this track the same way: dial in a "Verse" state (click +, name it "Verse"), then adjust the synth params and save a "Chorus" clip.

Step 7: Create a scene

You now have two tracks, each with two clips. A Scene captures one clip per track and launches them together.

Right-click the scene row header → Update. This captures the currently active clip from each track into that scene. Name it "Intro".

Set the second scene: click the Intro clip on Drums and the Verse clip on Synth to make them active. Right-click the second scene row → Update. Name it "Verse".

Step 8: Launch scenes

Click ▶ on the "Intro" scene row. Both tracks' nodes snap to their assigned clips at once.

Click ▶ on the "Verse" scene. Both tracks switch simultaneously.

Step 9: Quantized launches

The quantize selector in the session header reads Instant by default. Change it to Bar.

Now when you click a scene, nothing changes yet — the switch waits for the next bar boundary and then fires. You hear the current state play out cleanly before the new clips kick in.

Try 4Bar for longer, DJ-style transitions.

What's happening

Session
├── Track "Drums"  → [Clip "Intro"]  [Clip "Drop"]
│       ↕ owns → DrumSequencer, DrumKick, Mixer, Reverb
└── Track "Synth"  → [Clip "Verse"]  [Clip "Chorus"]
        ↕ owns → ChordProgression, WavetableOsc, VoiceMixer

Scene "Intro"  → Drums/Intro  +  Synth/Verse
Scene "Chorus" → Drums/Drop   +  Synth/Chorus

Clips store a flat map of param → value for every parameter on every node the track owns. Launching a clip calls set_param on each node — the same as dragging a knob, just done all at once.

Scenes are a lookup table: each scene row holds one clip ID per track. Launching a scene iterates the table and launches each track's assigned clip.

Quantization defers the param writes until the next beat boundary. The session watches the graph metronome (or a designated Clock's beat_phase) and fires the buffered launch when the boundary arrives.

Session state persists when you save the graph (Cmd+S). Tracks, clips, scene assignments, and which clip is active all round-trip through the JSON.

Next steps