Timeline overview

The timeline is the heart of Chapter Studio — a full-width, film-editor-style surface where every segment of your chapter becomes tracks, clips, and beats you can see, scrub, and rearrange.

Where it lives

The timeline spans the entire width of the Chapter Studio window, sitting below the main editing area. A draggable horizontal divider separates it from the 3D viewport above. Pull the divider up when you're deep in timing work, or down when you want a bigger stage. The timeline always shows one segment at a time; a chapter is a set of segments, and each segment is a run of timed steps.

From top to bottom, the timeline stacks five strips:

1. Segment tabs. One tab per segment in the chapter, with a + button to add a new segment and zoom controls at the end of the strip. Click a tab to switch the whole timeline to that segment.

2. The action library. A horizontal strip of draggable action chips, grouped by category, with search and collapsible groups. See adding actions.

3. The time ruler. Tick marks, step boundaries, and gate flags, plus click-to-seek and drag-to-scrub. The ruler stays pinned while the lanes scroll, and step-boundary handles live only here, so a clip drag can never resize a step by accident.

4. The backdrop lane. A pinned lane holding the segment's backdrop, drawn as a cue bar you can right-click or open in the Source Previewer.

5. The tracks. Scene, Audio, and Effects sections holding one track per asset, channel, or effect. Related tracks can fold into track groups.

The timeline's own tools sit in its header: Blade B, Hand H and Zoom Z, next to the snap control. Zooming keeps the time under your pointer fixed, so you dive toward the thing you're looking at rather than losing it off-screen.

The time ruler

The ruler shows second ticks, labeled every second when you're zoomed in and every five seconds when zoomed out. Accent-colored vertical guides mark each step boundary, and those guides continue faintly down through every lane so you can see exactly which step a clip belongs to. Steps that wait for the viewer carry a yellow gate flag on the ruler; clicking a flag selects the source step and opens its gate settings in the inspector.

Click anywhere on the ruler to seek the playhead to that time; press and drag to scrub continuously. Interior step boundaries are themselves draggable handles; see editing clips for retiming steps.

Tracks: everything anchors to an asset

Each track is anchored to one thing: a scene asset, an audio channel, or an effect type. A track owns one or more primary lanes (the asset's own on-stage ranges) plus shorter attached lanes nested directly beneath, holding the modifiers (fades, moves, scales, motion) that target that asset. Modifiers never live on a separate effects row somewhere else; they always sit under the thing they change, so a glance at a track tells you the asset's whole story.

When two clips on the same track overlap in time, they pack into stacked sub-lanes instead of painting over each other. Tracks appear in order of first use in the segment, so the first asset to come on stage gets the top row. When a segment grows past a dozen tracks, fold related ones into named track groups.

Three sections are always rendered, even when empty: Scene, Audio, and Effects. An empty section shows a dashed dropzone so you can drag an action into a brand-new segment without anything existing there first.

Clips are derived, not drawn

You never create a clip directly. Clips are projections of pairs of actions in your steps: a Reveal opens a visual clip and a Hide (or a fade to zero) closes it; Play Video and Stop Video bracket a video clip; Play Audio and Stop Audio bracket an audio clip. Anything still open when the segment ends simply runs to the end. Playing a video also surfaces its panel on the Scene section automatically, so a step that only plays a video still shows the panel's clip.

Each clip is tinted by its track's section color and modulated by subtype: show, reveal, fade, scale, move, motion, video, audio, and effect clips each get a distinct shade and a small glyph inside the clip, so you can read a dense timeline without selecting anything. The full mapping is in the actions reference.

Keyframe lanes

An asset that carries segment-level animation gets one more lane in its track: a keyframe lane showing diamond markers at every keyed time, spanned by a soft band across the animated range, with a badge for the animated channels. Drag diamonds to move keys; double-click one to delete it. For the full animation workflow, see the animation overview and keyframes & auto-key.

Playback and scrubbing

During playback, the clip currently under the playhead pulses gently so your eye tracks the live beat; clips that have already finished dim to half opacity. When playback is stopped, the timeline renders statically — no distracting motion.

Scrubbing works even while stopped. Clicking a step, a clip, or a spot on the ruler updates the viewport to show exactly what's on stage at that moment (which assets are visible, which video panels are up). That "what's on stage at this step" preview is what makes the timeline feel like a film editor rather than a static outline: you can walk a whole segment beat by beat without ever pressing play.

The same timeline model appears in Chapter Vision as a floating panel, so edits made on the headset and on the Mac read identically; see the spatial timeline.