A seed is the number. A seed-lock is the habit of not letting it float. Leave the field blank and the tool picks a new starting noise every run, which is correct while you are hunting. The moment a frame is almost right — the face, the product angle, the light — copy that seed and pin it. Now a wording change is a wording change, not a wording change plus a different universe.
The lock is only as honest as the rest of the inputs. Same seed, same prompt, same model, same duration, same ratio, same reference stack. Change the model version and the mapping from noise to picture is different, so yesterday's lock is just a number again. Neighbouring seeds are not neighbours on screen: 41 and 42 are as far apart as 41 and 900,000. You lock one value; you do not 'nudge' it.
Extend-retake is where the lock earns its keep on video. A continuation that re-rolls the seed will not match the parent clip's grain, face, or set. A retake of a marked span with the seed floating is a recast, not a fix. Capture the seed on the take you are extending before you ask for more seconds.
In practice
- Explore with the seed unlocked; lock it the moment a result is close enough to iterate.
- Write the seed down with the prompt. A locked UI field you never copied is gone when the tab closes.
- Do not carry a lock across models or model versions and expect the same picture.
The mistake to avoid
Changing the prompt and the seed together, then attributing the difference to the wording. You moved two controls.
Where you will run into it
- AI Video Generator — Text-to-video, image-to-video, and story chaining in one studio.
- Text to Image Generator — One prompt. Catalog image models. One studio.
Related terms
Seed
Seed meaning: the number that sets the random starting noise so the same seed and settings can reproduce the same output.
Prompt
Prompt meaning: the written instruction a generative model reads to decide what to make. The one input almost every model needs.
Extend retake
An extend-retake regenerates one continuation or a marked span of a clip while keeping the rest, rather than re-rolling the whole generate.
CFG scale
CFG scale meaning: how strictly a model obeys your prompt, trading obedience against the model's sense of a natural image.
Negative prompt
Negative prompt meaning: a list of what you do not want in the output, steering generation away from those terms.
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