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 75 active runtime transitions. The generic compiler materializes recipe-backed transitions; Light Leak uses its dedicated mapped builder for outgoing, masked incoming, and light-streak layers, while Datamosh can replace its clean incoming-frame fallback with a baked codec artifact.

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.

Datamosh codec bake

Datamosh is a codec-domain transition rather than a shader approximation. Its Properties section renders the outgoing and incoming participants, encodes an MPEG-4 Part 2 stream, removes the junction I-frame, and imports the resulting H.264/MP4 playback artifact into a project-backed Datamosh media folder. The transition stores only the imported media ID and bounded bake metadata. Preview, nested composition playback, and export then use that seekable artifact in real time.

Changing transition duration or data rate marks the artifact stale and exposes Rebake Datamosh. Until a current artifact exists, the transition fails safely to the incoming frame. Export preparation resolves baked media through the normal runtime registry and does not repeat the destructive codec operation during final delivery.

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.