Timeline

The Timeline is the temporal editing surface in the Video Editor. It sequences video clips, audio tracks, text overlays, stickers, and any other element that appears in the final video output, along the time axis. The presence of the Timeline is the visible difference between Video Editor and the Design Editor: a video scene has one, a design scene does not.

The Timeline is where users arrange clips on tracks, set in and out points, sync audio, time animations, and place captions. Each clip on a track occupies a time range and can be dragged, trimmed, split, and reordered independently.

A video scene has two kinds of tracks.

• Background track holds the primary video content. It accepts only video or image clips that fill the full canvas. This is the foundation of every video composition.
• Overlay tracks hold additional video clips, images, text, stickers, and audio that appear over the background. Each clip on a track occupies a time range and can be manipulated independently.

The number of overlay tracks is not fixed. The Video Editor adds tracks as needed when clips would otherwise collide on the same track.

The Timeline applies two behaviors automatically. Both matter for integrations working with the engine API directly.

Automatic collision detection. When a clip is dragged or resized into the timeline, CE.SDK automatically detects overlaps and manages track assignment to prevent collisions. Clips that would overlap each other are moved to a new or existing overlay track rather than stacking on top. This removes a class of UI logic that the integration would otherwise have to handle manually.

Time offset model. Within a track, clip positions use an implicit time offset model. Each clip’s start time is calculated automatically from its order in the track and the combined duration of all preceding clips. Absolute time positioning is reserved for overlay elements that sit outside of tracks. This matters most for code that builds or manipulates video scenes programmatically through the engine API.

• Multi-track editing. Multiple video clips, image overlays, text overlays, stickers, and audio tracks running simultaneously.
• Clip trimming. Set precise in and out points to use only the needed portion of each clip.
• Clip splitting. Divide a clip into two independently editable segments at the playhead position.
• Transitions. Visual transitions between clips on the background track.
• Audio tracks. Music, voiceover, and sound effects with independent volume control per track.
• Captions. Time-synced text overlays, importable from SRT or VTT files or created manually.
• Animation timing. Element animations are time-anchored, with duration and timing controlled on the Timeline.
• Video placeholders. Placeholder clips that define where end users insert their own video in template-based workflows, exactly as image placeholders work in the Design Editor.

Individual video and audio clips support independent speed adjustment from 0.25x to 3x, with quick-access presets (0.25x, 0.5x, 1x, 2x, 3x) and custom values. Duration can also be set in HH:MM:SS time format for precise clip timing.

These controls live in the Inspector Bar when a clip is selected on the timeline, not in the Timeline surface itself.

On mobile, the Timeline is adapted for touch interaction with the same underlying clip and track model. Drag, trim, and split gestures work with finger input.

For template-based video workflows, the Timeline is where placeholder clips live. A Creator sets up the timeline structure, places placeholder video and text blocks, and saves the template. Adopters open the same template and fill in their own clips and text on the placeholders, without rearranging the structure.

See video-composition for the overall video assembly concept, caption for the caption-specific surface, and video-editor for the Starter Kit that surfaces the Timeline.