Flux 3 Extend versus a new generate

Extend continues a shot. A new generate resets identity. That is the decision. Everything else is commentary on when the last frame is good enough to inherit, and when the idea is wrong enough that inheritance is the bug.

Flux 3 Extend Video is not a longer duration slider on the same prompt. It takes an existing clip and keeps going from the final frame — motion, room, audio bed. A fresh Flux 3 Text to Video call starts a new plate. The face, the wardrobe, the camera, the room tone all sample again. If you liked the take, that resampling is the loss. If you did not like the take, that resampling is the point.

This post is the routing rule. The mechanic, the source-clip limits, and the walkthrough live in Flux 3 Extend: continuing shots. Do not treat that review as a reason to extend every clip. Treat this page as the reason not to.

The two failures, named

You regenerated a good plate to make it longer. The eight-second hero was working. You wanted twelve. You re-ran the prompt at a longer duration. You now have a twelve-second cousin: same brief, different person, camera that forgot it was mid-push. You paid twice and threw the keeper away. That job was extend.

You extended a bad hook. The first two seconds were already wrong — the product drifted, the face melted, the line didn't land. Extend read that tail as ground truth and built more of it. You now have a longer wrong take. That job was a new generate, or a different still, or a different prompt. Length is not a repair.

The general version of extend versus regen is the same fork on any model that offers both. Flux 3 is the catalog row where the fork is explicit: extend is its own endpoint, with a video input, not a checkbox on text-to-video.

Use extend when the camera should keep moving

Extend is for velocity you do not want to throw away. A push that is mid-move at the cut. A pour that is still pouring. A walk that has not arrived. A still has no velocity. A new generate has no memory of the last camera vector. Only a clip does.

So the test is: is the last frame good, and is the next beat the same shot?

Last frame good, next beat same shot, camera still travelling → extend.
Last frame good, next beat a different room or a different lens → new generate, then cut.
Last frame bad → do not extend. Trim back to a clean frame or throw the take out.
The idea is wrong — wrong product, wrong line, wrong staging → new generate. Extend cannot change the brief. It can only continue it.

"Same shot" is literal. Same room, same wardrobe, same lens family. Asking extend to "now they are in the car" is a new generate wearing an extend button. You will get a warp at the seam and call it a model failure.

What a new generate is for

A new generate is the cheap way to change your mind. Identity, staging, and prompt intent all reset. That is correct when:

The first take taught you the prompt was underspecified.
You want a different performer, a different angle, a different time of day.
You need a second shot in the sequence, not more of shot one.
The keeper you have is a still, not a clip. Extend requires a video. A still is image-to-video or first-last-frame, not extend.

Teams waste credits by treating generate as "make it longer" and extend as "make it better." They are opposite operations. Generate explores. Extend commits.

If you are still exploring, stay on generate. If you have committed to a plate and the only complaint is that it stops, extend once. Do not extend the extension as a habit. Each pass conditions on the previous pass's ending, so drift compounds in the place you stop watching — usually the audio bed.

The practical gate

Before you click either button, scrub the last second of the clip you have.

If that second is a keeper — anatomy holds, product holds, the move is still alive — extend, and prompt only the new beat. Do not re-describe the shot you already have. The clip is the description.

If that second is a problem, you do not have an extend job. You have an edit (trim to the last clean frame) or a regen (the idea or the take is wrong). Sending a broken tail into Flux 3 Extend is how a small defect becomes the entire next clip.

Source clip still has to be an MP4, under 50 MB, under 15 seconds. Those limits are a statement of purpose: extend continues a chosen hero, not an arbitrary reel. If the file fails that spec, you are not in this decision yet.

FAQ

Does extend keep the same person, or just the same vibe?

It continues the clip you uploaded. Identity, wardrobe, room and audio state come from those pixels and that soundtrack, not from a text reminder of them. A new generate has none of that state. If sameness is the requirement, extend. If sameness is the problem, generate.

Can I extend a clip that did not come from Flux 3?

Yes. The requirement is the file spec, not the parent model. Any qualifying MP4 can go in. The review covers the input limits; this page only cares that you are continuing a specific plate rather than rolling a new one.

When is a new generate cheaper even if I like the shot?

When you do not actually need that shot to continue. A second angle, a cutaway, a different line, a different product face — those are new files. Extending a plate you are about to cut away from is paying for continuity you will throw out at the edit.

Should I extend to fix a weak first two seconds?

No. Extend inherits the tail, not the complaint. A weak hook is a regen or a recut. Making a weak hook longer is the expensive way to confirm it was weak.