# Moving shots in Seedance

How Claudia moves and sings: Seedance 2.5 prompts written like a script, lip sync measured from the soundtrack, and the templates.


Every moving shot of her in the three films is Seedance 2.5: about 200 clips, conditioned on a Midjourney plate and,
for singing, on the exact slice of the song. Two things made the difference between dead footage and a performance:
prompts written like a script, and lip sync that is measured rather than eyeballed.

## Kinds of clip

| Kind | Inputs | Used for |
|---|---|---|
| Plate shot | her plate as the first frame, the song mix for rhythm | most shots: she walks, turns, reaches, reacts |
| Singing window | her plate, a clean vocal of only her words in that window | lip sync, 4–8 s, one phrase |
| Green-screen performance | a plate of her on chroma green | cut-outs: BLISS's desktop dancers, the cursor fight |
| Cover | the last in-sync frame of another take | the rest of a line after a take drifts |
| Extension | a real clip as a video reference | joining generated shots to real footage, frame-continuous |

## Write prompts like a script

CLODYSSEY's first round of prompts was written by planner agents and described poses: "she whispers", "he listens".
Every take came back lifeless, and about 830 credits were gone before anyone read them. The director's verdict: "these
prompts are really really bad and wasting money and need to be 10x better and super context aware of the story", and then
the rule for every prompt since:

> "EVERY prompt needs to have litearlly timestamps, extremely detailed motion descriptions / blocking descriptions, it all
> needs to be deeply integrated with the story."

So the second round was rewritten by hand, all 99 prompts, by one writer in one context:

- **the story beat** of the shot, in one sentence;
- **blocking at 0.0 s**: where she is, where he is, where the camera is;
- **timestamped beats** of action and reaction, on the song's hits (kicks, snares, risers, word onsets);
- **she always does something**: in CLODYSSEY she is seductive and persuasive, close, touching, certain; he feels the weight of it;
- **the camera tied to hits**, with a start, a direction and an end;
- **mouth rules**: singing or closed.

Finish the whole prompt book before spending anything, read it, then run a three-clip pilot before the rest. BLISS did
exactly that and wasted nothing.

## The structure

Seedance follows instructions far better as labelled sections in a fixed order (BytePlus's published Seedance 2.5 prompt
guide lays this out). The order used:

1. **Audio policy** at the top and again at the bottom: what the soundtrack is, and everything that must not be added.
2. **Generation goal:** one sentence of who, where, which moment of the story, which performance.
3. **Reference asset roles**, by upload order, each with one role: `Use @Image1 as the first frame.` as its own
   sentence, then what that frame defines.
4. **Subject:** her identity text, and "Only one Claudia appears."
5. **Timeline** in whole seconds, continuous segments (0–1 s, 1–2 s …): what the audio contains and what she does then.
   Beats come from the audio; don't timestamp individual drum hits.
6. **Camera:** shot size, angle, movement with subject, start, direction and end.
7. **Core requirements:** lip sync, voice, identity, anatomy, no on-screen text.
8. **Final acceptance criteria.**

Output settings (duration, resolution, aspect) go in the API request, never in the prompt.

## Template: a singing window

`@Image1` is her plate (PNG, downscaled to the output resolution). `@Audio1` is the clean vocal of the window: the vocal
stem with everything outside her words muted, mono, normalised. The window holds one phrase, starts about 0.3–0.7 s before
the first word, and never ends inside a word.

```prompt
【Audio Policy】 The output soundtrack is @Audio1 itself: copy @Audio1 sample for sample from the first frame to the last, with the same timing, pitch and level. Do not re-sing, re-voice or re-generate it. Do not add music, background music, score, instrumental, melody, synth, pad, drone, riser, extra vocals, harmonies, ad-libs, narration or sound effects.

【Generation Goal】 @Image1 sings @Audio1: <who, where, which moment of the story; the performance in one sentence>.

【Reference Asset Roles】
Use @Image1 as the first frame.
This first frame defines Claudia's appearance and wardrobe, her pose, the set, the light and the camera direction.
@Audio1 is Claudia's own singing voice and the complete soundtrack of this video. Her mouth follows @Audio1 exactly.

【Subject】 Claudia: a Caucasian American woman in her late twenties with pale skin and light freckles, a glossy black blunt bob with heavy bangs and one clay-orange streak, a small clay-orange eight-pointed star hair clip, a thin headset microphone, <the look as in @Image1>. Only one Claudia appears.

【Performance Timeline】 What @Audio1 contains, and what Claudia does at that moment:
0-1s: @Audio1 is silent, then her voice begins; <what she does>.
1-2s: in @Audio1 she sings "<exact words>"; her lips form each of those words exactly when it sounds in @Audio1; <one main action>.
2-3s: @Audio1 is silent; her mouth relaxes and closes; <one main action>.

【Camera】 <shot size, angle, movement with subject, start, direction and end>.

【Core Requirements】
1. Lip-sync word by word to @Audio1: mouth shapes match every syllable of @Audio1, its start and its end; no early, late or mismatched mouth movement; the mouth rests naturally closed while @Audio1 is silent.
2. Claudia's voice is @Audio1 and nothing else: she never sings, speaks or hums anything that is not in @Audio1.
3. Her head and shoulders move with the rhythm of @Audio1.
4. Keep Claudia's identity, face, hair with one clay-orange streak, star clip, headset microphone and wardrobe exactly as in @Image1 throughout; the set and light stay consistent.
5. Natural anatomy: natural neck and shoulders, hands with five fingers, no extra or fused fingers, no distorted limbs; normal eyes.
6. No subtitles, captions, lyrics, titles, signs, logos, watermarks or any on-screen text.

【Final Acceptance Criteria】 The soundtrack is @Audio1 unchanged; Claudia's lips match @Audio1 word by word; one Claudia, on-model, with natural anatomy; no on-screen text.

【Audio Policy】 The output soundtrack is @Audio1 unchanged, copied sample for sample; no music, BGM, score, instrumental, melody, synth, pad, drone, riser, extra vocals, harmonies, ad-libs, narration or sound effects.
```

Two details matter:

- **Lyrics go in plain quotes, as what the audio contains.** In Seedance's own syntax, words in braces after a speaker
  are lines for the model to voice; written that way it re-sings them in its own voice instead of copying yours. In a
  test, the brace form re-sang the line in every take; the copy-mode wording with a clean vocal copied it (normalised
  cross-correlation 0.93).
- **One phrase per window.** After a long muted gap the model tends to re-sing the next phrase, and a word cut by the
  window's end comes back mangled. Two phrases are two windows.

## Template: a motion clip

The same order, with three changes: `@Audio1` is the song for rhythm and timing only ("the output audio is @Audio1
unchanged"); a performance line says she does not sing or speak (mouth closed, or a natural smile or laugh); and the
timeline runs in stages of about one bar, each naming what her body does with the beat ("steps on every beat, a big
accent on the downbeat at 2 s"). An instrumental mix with the vocal removed works best as `@Audio1` here: nothing tempts
her mouth.

## Lip sync, measured

The fact that made it work was the director's own observation on ESCAPE VELOCITY's first test: "its perfectly synced while
in seedance, but the audio changes when it desyncs." Seedance copies the reference audio into its own soundtrack, and the
mouth follows that soundtrack. So:

1. Compare each take's own soundtrack with the real vocal (spectral match, cross-correlation over time).
2. Keep the take up to the last eighth note before the two diverge. The comparison also gives the take's lag; Seedance
   tends to drop about 0.3 s of leading silence.
3. Cover the rest with a new clip: a window that starts in the word gap before the cut, from the frame at the cut.
4. If a phrase fails three times, it becomes a cutaway or an insert.

The full method, with every constant (the clean vocal window, the per-frame match, the null threshold, the cut on the
eighth, covers and coverage), is specified in [What to build](https://claudia.gallery/wiki/toolkit/#15-the-sync-check-the-spectrogram-comparison).

![The sync check on an early ESCAPE VELOCITY test. Top: the vocal Seedance was given, with each word's time. Middle: the soundtrack Seedance returned, which the mouth follows. Below: how closely they match, and the offset.](https://claudia.gallery/record/escape-velocity/lipsync-check.webp)

Measured results: about 86% of sung seconds held in sync in ESCAPE VELOCITY, and 62% (7.4 of 11.9 s) over BLISS's six
singing windows; the edit cuts away where they diverge. The bar is "most lips", like a pop video, not every word.

**Short prompts copy, long ones re-sing.** A later test on seven singing windows found that prompt length was the
biggest lever: long timestamped screenplays made the model perform the text and re-sing the line, while a short prompt
(the words quoted, one line of framing and light, at most two timed beats, about 90 words) copied it. The mean in-sync
share per take went from 26% to 58%. Screenplays stay the rule for acting and motion clips; a singing window's one job
is to copy `@Audio1`. And keep her mouth clear on the plate: a microphone at her lips held one window at 26% whatever the
prompt.

**No lip-sync models.** Re-syncing mouths with a dedicated model (Sync, LatentSync, Wav2Lip) was tried as a fallback and
dropped: the mouths come out forced and glitchy. A gap gets a new Seedance cover or a cutaway, and a changed song means
new takes from the original stills, never re-lipped old ones.

## Inputs

- **Colour in, look in post.** ESCAPE VELOCITY's references were pre-graded to monochrome and 32 of 59 clips came back
  grey. Generate from the plate's own colour and apply any look in the edit.
- **Downscale stills** to the output resolution (≤1280×720 for 720p) and send PNG. Full-size AI stills cause
  fingerprint-like textures in grass and fabric.
- **Distinct first frames.** Two clips should never start from the same frame: use a sibling plate or the previous clip's
  last frame.
- **Drafts first.** Higgsfield's API ran 480p drafts at a lower rate that can be finalised to 1080p with the same motion.

## Providers and filters

The films used two routes to Seedance 2.5: OpenRouter (about $0.23 a second at 720p, autumn 2026) and Higgsfield's API.

- **On OpenRouter, a first frame drops the audio.** When a request carries `frame_images`, the audio reference is
  silently ignored and the take makes its own soundtrack, so nothing can sync. Singing windows and covers go in
  reference mode: the plate as an image reference (`@Image1`) and the window as an audio reference (`@Audio1`).
  First frames are for motion clips. On Higgsfield a start image keeps the audio.
- **Audio goes by HTTPS URL.** OpenRouter's video endpoint rejects `data:` URIs for audio; host the window.

Two kinds of refusal came up:

- **Face filters** decline some photoreal close-ups of her. A decline is free, and final for that reference on that
  service: never re-grade, blur or otherwise alter the image to get it through. In CLODYSSEY, OpenRouter's filter
  declined most close-ups of her, and those shots were made on Higgsfield, which accepted the same references.
- **Silent input filters** fail some jobs with no reason when they misread innocent wording ("a plug pushed deep into
  each ear" for foam earplugs). Plain rewording fixed five of six at once.

## Joining real footage

To enter or leave a real clip without a visible seam, use Seedance's video extension (forward or backward) with the real
clip as the video reference: it returns only the new frames, continuous with the real ones and aligned within a pixel or
two. An `end_image` alone is not copied exactly; the last frame gets redrawn.

## Costs, measured

| Film | Clips | Spend |
|---|---|---|
| ESCAPE VELOCITY | 47 clips + 30 continuations, 421 s at 720p | about $93 (OpenRouter) |
| CLODYSSEY | 101 clips, 189 takes | about $107 (OpenRouter) plus 2,436 Higgsfield credits |
| BLISS | 50 clips, 267 s | $182 at list price (Higgsfield API) |

Every prompt the films ran:
[ESCAPE VELOCITY](https://claudia.gallery/record/escape-velocity/prompts-seedance/) ·
[CLODYSSEY](https://claudia.gallery/record/clodyssey/prompts-seedance/) ·
[BLISS](https://claudia.gallery/record/bliss/prompts-seedance/).


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From the Claudia wiki: https://claudia.gallery/wiki/seedance/