What is first-last-frame generation? Endpoint images and intermediate motion
Understand endpoint constraints, references, interpolation, compatibility, transitions, and model support through open-close images.
Understand the concept
First-last-frame generation conditions video on starting and ending images. Endpoint control does not specify every frame or guarantee physically plausible, identity-stable transitions. Model support differs for endpoints and references. Inspect both endpoints and the entire transition rather than assume two uploads invoke one standard feature.
Endpoint images differ from ordinary references
Closed and open box images constrain endpoints while the opening motion is inferred. Appearance references need not occupy fixed times. Google Cloud specifies endpoint inputs and Runway distinguishes positioned keyframes from unpositioned references.
Models within a platform can support different combinations or mutually exclusive conditions. Check current model-interface support. No generation service was called and universal endpoint support is not claimed.
Endpoint compatibility affects transition plausibility
Large pose or viewpoint changes can lead to morphing or cuts. Text guides actions without guaranteeing a continuous physical path. Check shared subjects and whether the transition needs separate shots.
This differs from frame-rate interpolation over existing neighboring frames. Matching endpoints does not validate an invented action; inspect hands and contact through full playback.
Validate starts, ends, and intervening motion separately
Compare endpoint images and inspect turns and occlusions for disappearing or added objects. This is design without scores. Verify actual final-frame equality rather than infer pixel identity from the name.
Keep both originals and settings. Fixed closing text may suit retained layers rather than generated lettering. Supported inputs do not establish a deliverable shot without temporal checks.
Checked sources
These sources support the concepts and methods described here. Examples and test scope are labeled separately; check the version of the tools you use.