Transition Compositions

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Transition compositions make a timeline transition editable as a linked composition while preserving the source clips’ real timing.

Mapped-v3 Source Layout

A mapped-v3 composition normally has one full-duration outgoing source clip and one full-duration incoming source clip. Both span the complete transition composition; they are not split into coverage segments at the cut. Multi-panel templates replace either source with full-duration, editable panel slices; generated overlays may add further layers.

Each source uses TransitionSourceMap v2, which keeps three time domains separate:

• source media time for decoding;
• original parent-clip animation time for the user’s transforms, effects, masks, speed curves, reverse playback, holds, and keyframes;
• composition-local recipe time for generated transition animation.

The mapped animation combines the original and generated edits without reinterpreting the source. Invalid v2 data fails closed: the affected layer is omitted and stale mask texture state is removed rather than inventing a time or animation.

Transition Templates

There are 74 active runtime transitions. The generic compiler materializes 73 of them from their recipes; Light Leak uses its dedicated mapped builder for its outgoing, masked incoming, and light-streak layers.

The generic compiler is templateVersion 4; Light Leak is templateVersion 3. These are recipe-template revisions, not the sourceLayout: mapped-v3 format name.

Recipes materialize normal editable layers: opacity, transforms, effects, masks, overlays, and blend windows. Procedural, pattern, and clock masks retain semantic transitionRender.progress state instead of being flattened. Cross and star reveals use distinct mask shapes. Scene-3D transitions materialize 3D layers, and recipe rotations are converted into the timeline’s degree domain. Blend changes are resolved in composition-local, half-open windows.

Runtime Parity

Preview, live runtime, paused-frame sync, mask-texture updates, and export all resolve the same source map and mapped animation. Before a transition has been opened or saved as a composition, preview and export build that same mapped-v3 scene transiently; no project state is created just to render it. Holds stay on their mapped frame; reverse or variable-speed source playback keeps its signed timing. The nested transition composition is the transition rendered by the parent timeline.

Dynamic nested video sources are recollected within a timeline frame instead of reusing a same-time nested texture, so a late decoded source frame updates the mapped composite without a separate transition renderer.

Editing

Double-click a transition body to open its linked composition.

Troubleshooting And Verification

Mapped-v3 compositions normally show one full-duration source clip per side; multi-panel templates show full-duration panel slices instead, and generated layers remain separately editable.

Mapped continuity keeps the source owners alive across the transition instead of handing off between segments. For a playback investigation, refresh, wait 5 seconds, then use the AI bridge’s getStats, getStatsHistory, and getPlaybackTrace around the transition.