Rebuild a shot with actors

What you need

• The Rebuild a shot setup: ComfyUI v0.39.0, with its models and the three extras (Set up ComfyUI). A 16 GB GPU with 32 GB of system RAM and a pagefile of about 32 GB or more. Close Chrome, OBS, games and other heavy apps while it generates.
• An image model for the design pictures, or for the picture of the new place (FLUX.2, Krea 2 Turbo or Qwen Image 2.1).
• The episode’s subtitles, if anyone in the shot speaks.

1. List and cut the shots

As in Capture and mark your shot:

• Only the shots with the thing you’re changing, picked by eye. Split at every cut.
• Keep shots with on-screen text original (credits, captions, signs burned into the picture), or start your segment after the credits. A full redraw rewrites the text as garbled names.
• Parts within a cut, up to about 7–8 seconds each (tested), at the episode’s exact frames, with the sound. Part length didn’t matter between 0.8 and 7.5 s in our tests (17 shots on two shows): failures were 1.6–4.7 s long, and the four longest shots (5.1–7.5 s) all came out right on the first try. The shot type is what matters.
• Size: 1024 × 576 (16:9) or 1024 × 768 (4:3).

2. Make the pictures

• The new creature or effect: a main picture plus two more views of the same design, cut out on grey (as in Rebuild a shot).
• Face crops: required for a new place (4.1), and optional for a new creature.
  • New creature: the actors aren’t greyed, so their faces come from the reference video. To hold them better, use the 6-picture version (step 5) and give each actor a face crop as Pictures 4–6. That’s how the confirmed creature segment was made: 3 creature views + 3 explorer face crops.
  • New place (4.1): give each visible actor a face crop (face, or face and upper body) from a close still of the episode, as Pictures 2–3. In our 9-shot build, the actors vanished in 5 shots that had no face crops and only a generic “the people in <Video 1>” line.

3. Get the lines (if the actors speak)

• The words come from the subtitles, and the timing from your part’s own sound (how), as in Swap a person. No subtitle file? Download an SRT for your episode. They’re easy to find for almost every show.

4. Mark what you’re replacing (for the grey reference)

The workflow greys this out in the reference video only, so the model doesn’t copy the old design. The result is still a full new generation: nothing is pasted back onto your shot.

• A creature or effect: the mask workflow (seamless-effects-mask.16gb.json). Download the mask workflow
  • In What to mark, its word (dinosaur); Grow 12. If one word misses a part, use the two- or four-word version (seamless-effects-mask-2words.json, -4words.json) and add the second word in What to mark 2 (sauropod as well as dinosaur). Fill every ‘What to mark’ slot: repeat your first word in any slot you don’t need. A blank slot adds the whole nearest person to the mask. 2 words 4 words
  • Keep its Mask video (white = replace).
• A new place (4.1): the people masks workflow for your number of people (seamless-people-masks-2.json …). 1 person 2 people 3 people up to 6 people
  • One word per actor. Fill every word slot: if you have fewer words than slots, repeat your first word in the spare slots. A blank slot marks the whole person.
  • Keep background.mp4 (white = regenerate): everything except the actors.
• Step through the mask: what you’re replacing is white on every frame where it shows, and no actor is white.
• Grey only clean, solid shapes. If the mask breaks into small scattered pieces (a color mask catching a fading glow, say), the model draws those grey patches as pale shapes: in one test they showed on an actor’s chest. Drop tiny fragments, and end the mask on the frames where the element is gone. With that, a second try had no pale patches, rims or flicker.

5. Run the workflow

Download the workflow (16:9) 4:3
seamless-upgrade-effects-fullframe-actors-blank-reference.16gb.json · …16gb-4x3.json

With room for actors’ face crops (3+ actors, or a creature + actors): 6-picture version (16:9) 6 pictures, 4:3
seamless-upgrade-effects-fullframe-actors-blank-reference-6pics.16gb.json · …-6pics.16gb-4x3.json. It adds Picture 4/5/6: face crop of an actor who stays (or Picture 2 again).

• Leave the rest: 8 steps with the Turbo v4 LoRA, control strength 1.5, control end 0.5, reference size match. For a new place (4.1), set the control end in the Control (strength 1.5, end 0.5; …) node to 0.6 for medium shots and shots where a person fills much of the frame, and to 0.25 for close-ups and two-shots.
• Inside the graph: the masked area becomes flat grey (“Reference with the element greyed out”) in both the reference video and the control’s source, and the depth of your shot still carries the motion.
• In our test: on a shot of people with an old CG creature, the creature came out modern; the people stayed themselves and in front of it, with no outline or seam.

Replace every {…} before you run: ComfyUI drops the braces when it queues the prompt, so a leftover placeholder goes in as plain words.

Prompt: the blank-reference file’s template. It starts with “In the source video the element to replace is hidden under a flat grey shape; the new element stands and moves exactly where that shape is.” Then one line per actor who stays:

• “<Subject 3> is {who, by clothing and action} shown in <Picture 4>, exactly as in <Video 1>: same face, hair, clothes and movements” (one line per actor, each tied to their own picture number, e.g. “<Subject 3> is the man in a hat shown in <Picture 4>, exactly as in <Video 1>”);
• their lines in <d>[English]…</d> with their timing, if they speak;
• the new element, its look only from the pictures;
• “Nobody is added.” Never write “no people”.

Prompt rules from a 12-shot real-episode test (5 of 12 were right at once; the per-shot scene lines and the framing fix were confirmed in a second try):

• Write the scene line per shot, with only what’s in that shot. One line for the whole sequence (“a rocky forest hillside, a gorge and open blue sky”) put hills, trees and a gorge into shots that showed only sky.
• Say how many: “exactly one {CREATURE}”. Otherwise a second one can appear. Even with it, one shot in our test still got a second creature: keep the original for that shot.
• Energy effects: say how long they last (“one short bolt, a fraction of a second”). Without it, a beam was held for about 9 frames; with it, about 6 (the original’s was 2). It helps, but doesn’t get all the way to the original’s length.
• Describe the framing of each shot: “close-up; the man fills the left of the frame; the creature passes behind him”. In our test a fast close-up became a wide shot, and in a low-angle shot the creature took over the foreground and the actor shrank. The tested fix: a framing line plus control end 0.8, which kept the close-up and the low-angle shot with the actor in front.

Run it: about 6 minutes per 124-frame part at 1024 × 768 on a 16 GB card, with 3 or 6 pictures. Uses almost all of 32 GB RAM. Close other apps (game launchers, browsers) before you run it, or ComfyUI can be killed partway through. Split long shots into parts of about 124 frames; very long parts can run out of memory on a 32 GB machine.

6. Finish

The finish workflow (seamless-finish.json): your shot’s frame count, the episode’s rate, the Start still’s size, and the original sound back (Finish and conform). Download the finish workflow

7. Check

• Look at every face in the result. The automatic check compares with your source, and can pass a recast face that moves the same way.
• Faces, by eye: step through it next to your source. Every actor is still themselves; nobody added, missing or turned into a look-alike. Small figures far away are the ones that disappear. For a new place, check every shot for missing actors: the flicker check doesn’t show someone who’s gone.
• The new element: it follows the original’s path and timing, and doesn’t look like the old design.
• The mask covers the thing on every frame of the shot. Where it finds nothing on some frames, those frames keep the old one in the reference, and it pops from old to new mid-shot (in an outfit test, the sleeves stayed old). Step through the mask before you run.
• Lips: if they speak, the mouth moves with the words at normal speed.
• The flicker check (how): red on faces or scenery is a problem.

When it doesn’t work