Steps & actions
Steps are the timed beats of a segment; actions are what happens during them. Everything you see on the timeline flows from this one idea.
Steps: the beats of a scene
A segment is divided into an ordered sequence of steps. Each step has a duration (as short as 0.1 seconds), and the segment's total length is simply its steps laid end to end. Step boundaries appear as vertical guides on the timeline ruler, and each interior boundary is a draggable handle, so retiming a beat is a matter of sliding its edge.
Steps give a scene its rhythm. A slow ambient piece might be three long steps; a tightly choreographed reveal might be a dozen short ones. Steps are also where gates live: a gated step reaches its end and then holds — the scene waits for a tap before the next step begins. That's how a fixed timeline becomes a performance that breathes with its audience.
Actions: what happens, and when
Actions are the verbs of Chapter Vision: reveal this model, play that video, fade this audio, fire that particle burst. Every action belongs to a step, and its timing works one of two ways:
- At step start: the action fires the instant its step begins. This is the natural home for "beat downbeats": the things that define what this moment is.
- Scheduled mid-step: the action fires at an offset into the step, for example 1.4 seconds after it begins. When you drop an action chip in the middle of a step on the timeline, Chapter Studio schedules it at that offset automatically.
You don't usually think about this distinction while working; you just drop a chip where you want it to happen. Drops that land on a step boundary become step-start actions; drops inside a step become scheduled ones. Drops snap to the nearest boundary when you're close, so hitting a downbeat exactly is easy.
Action categories
The action library groups its chips by category, and timeline sections accept matching categories, so scene chips land on scene rows, audio on audio rows, and so on:
| Category | What it covers |
|---|---|
| Scene | Entity verbs: reveal, hide, fade, move, scale, motion |
| Add | Bringing new things into the scene: primitives, text, lights, particle emitters |
| Video | Playing, stopping, and trimming video on panels |
| Audio | Playing, stopping, and fading audio on named channels |
| Effects | Instant flourishes: pulse rings, spark bursts, custom events |
Every action's parameters are editable in the inspector. The common ones (opacity, duration, volume, loop) have inline sliders and toggles right on the selected clip's card. For the full catalog of actions and their parameters, see the action reference.
Clips are derived, not drawn
Here's the mental shift that makes the timeline click: you never author a clip directly. A clip is a projection of a pair of actions:
- A reveal opens a visual clip on an entity's track; a hide (or a fade to zero) closes it.
- A play video opens a clip on its panel; a stop video closes it.
- A play audio opens a clip on its channel; a stop audio closes it.
- Anything still open when the segment ends is drawn as running to the end.
So when you drag a clip's left edge, you're retiming the opening action; the right edge, the closing action; the clip body, both together. The timeline is a live view of your action stream rendered the way a film editor expects, which means it can never drift out of sync with what actually plays, because it is what actually plays.
Note. Clip colors and glyphs reflect the action behind them: a fade clip, a move clip, and a video clip each read differently at a glance, and the clip under the playhead pulses during playback.
Moving and duplicating
Steps and actions are freely rearrangeable, and every change is one undo entry:
- Drag a clip to slide its actions in time. Cross a step boundary and the action moves into the neighboring step automatically, so you think in seconds, not in steps.
- Right-click a clip for quick moves: duplicate it slightly later, delete its opening action, or jump to it in the inspector.
- Move or duplicate whole steps from the segment inspector's step list to reorder or repeat a beat with everything it contains. Both editors, Chapter Studio and Chapter Vision, support step and action move/duplicate, and changes sync live between them.
Gates hold a step's end
When a step carries a gate, it plays to its end and then holds: animation curves freeze in pose, and the scene waits for a viewer tap or a timeout before the next step starts. Gates get a full treatment on their own page.
Tip. Scrub the ruler constantly. Clicking anywhere shows exactly what's on screen at that moment, even while stopped, so you can verify a beat without playing the whole segment.