The model looks at two consecutive frames, works out how things moved between them, and synthesises the moment in between. Do it once and you double the frame rate; do it repeatedly and you can stretch a second of footage into slow motion that was never shot.
It is inference, not recovery. Anything that happened entirely between the two source frames — a blink, a fast hand, the moment a ball meets a bat — was never captured and cannot be reconstructed. Fast motion, occlusion and objects entering frame are where interpolation produces the characteristic smear or the briefly detached limb.
It also appears invisibly. Some generators produce a modest number of real frames and interpolate up to the frame rate they advertise, which is worth knowing when you are judging how smooth a model's motion actually is.
In practice
- Best on smooth, moderate motion; worst on fast, occluded or newly-entering objects.
- For heavy slow motion, interpolating twice at 2x usually beats one 4x pass.
- Interpolated frames add no detail — they add smoothness only.
The mistake to avoid
Using interpolation to rescue a clip that stutters because of dropped frames. It will smooth the gap, but it smooths the surviving footage too.
Where you will run into it
- Change a Video's Playback Speed — Speed ramps, slow-mo, and time-lapse — described, not keyframed.
Related terms
Frame rate
Frame rate is how many still frames make up one second of video, written as fps — 24 for a filmic look, 30 for broadcast-standard motion, 60 for smooth fast action.
Temporal consistency
Temporal consistency is how well a generated clip keeps things the same from one frame to the next — a shirt that stays the same colour, a background that stays put.
Upscaling
Upscaling raises the resolution of media you already have, inventing plausible detail rather than recovering detail that was never recorded.
Duration
Duration is how long a generated clip runs, chosen before generation from whatever lengths the model supports rather than trimmed afterwards.
Character consistency
Character consistency is whether the same person, mascot or product still looks like itself across separate generations.
The all-in-one AI studio for creators. 60+ models for video, image, voice, music and lipsync in a single app.