Plain-English explanation
Think of a keyframe the way an animator would: it’s a frame you commit to first, that everything else has to lead into or out of. In AI video generation, a keyframe is usually a still image (either a real photo, a generated text-to-image output, or a frame extracted from another clip) that’s designated as the exact state of the video at a specific moment, most commonly the very start or the very end of a clip.
How it's used
The simplest and most common pattern is single-keyframe generation: a single starting image is the only keyframe, and the model, as in image-to-video, has to invent everything that happens after it. A more constrained pattern supplies two keyframes (a start frame and an end frame) and asks the model to generate a plausible sequence that connects them, sometimes called “start/end frame” or “first-last frame” generation. This gives noticeably more control than a single starting image, since the model isn’t just extrapolating forward, it’s solving for a specific destination.
Some longer-form workflows chain several keyframes together, generating short segments between each consecutive pair so a longer scene stays anchored at multiple points rather than drifting the way pure autoregressive generation tends to.
Adult-AI use
Keyframing is the practical answer to a specific frustration with AI video: a single starting image gives you a great first frame and then increasingly unpredictable results after that. Supplying a second keyframe (the pose or expression you want the clip to end on) gives creators a way to specify both ends of a short scene and let the model handle the motion between them, which matters a lot when likeness and composition need to stay under control for a specific character rather than drift into something else mid-clip.
Common uses
- Start/end frame generation, where a creator supplies both the opening and closing image of a clip.
- Anchoring longer generated sequences at multiple points to limit drift.
- Extracting a frame from one generated clip to use as the keyframe for the next, chaining short clips into a longer sequence.
How it differs from frame interpolation
Keyframes and frame interpolation are two halves of the same pipeline, not competing techniques. A keyframe is a frame that’s fully specified; it exists in full detail before the in-between frames are made. Frame interpolation is the process that generates those in-between frames, given two keyframes (or two existing frames) to connect. Keyframes define what the video passes through; interpolation defines how it gets there.
Limitations and misconceptions
- Two keyframes don’t guarantee a smooth path between them. If the start and end images are very different in pose or composition, the model may produce implausible or distorted motion trying to connect them.
- Keyframe generation is not the same as manual video-editing keyframing (as in traditional animation or editing software, where a keyframe sets a property value like position or opacity): in AI video generation it specifically refers to a full anchor frame of visual content.