Seedance 2 5

Seedance 2.5

Seedance 2.5 extends the Seedance 2 family to 4–30 second 480p/720p clips and larger multimodal reference sets. It is hosted; there are no local model weights in OpenMontage.

Choose a supported route

Do not invent a Replicate, HeyGen, or Higgsfield identifier when their current public API schema does not list Seedance 2.5.

Resolution note. The supported routes above expose 480p and 720p. The model generates 1080p natively on the vendor's own web platform, which is not an OpenMontage route. If a vendor blog cites 1080p or 4K, check which surface it means before promising it in a pipeline.

Reference limits

• Up to 30 reference images.
• Up to 10 reference videos.
• Up to 10 reference audio clips.
• Keep combined reference video/audio duration within the provider's documented ceiling; Runway caps it at 30 seconds.
• For Runway video-to-video, the source video consumes one video slot.

Reference inputs are provider-specific. fal.ai uses image_urls, video_urls, and audio_urls internally. Runway uses references, referenceVideos, and referenceAudio. Ark uses typed content entries with roles. Always call the OpenMontage tool instead of constructing a provider payload manually.

50 assets is a ceiling to use deliberately, not to max out. A cluttered reference set with competing faces, props, and locations produces a less coherent result than a smaller, chosen one. Rule: one reference per element that must stay consistent — a face, a product, a location, a style.

Prompting

Lead with the shot structure, then subject, action, camera, lighting, and audio. For multi-shot work, give each beat an explicit time range and use quoted text for dialogue. Reference each supplied asset by a stable role in the prompt. Thirty seconds is a ceiling, not a target: use a shorter generation when the scene has only one meaningful action.

Section order

One continuous block of text, broken into labeled sections. Skipping a section does not degrade the output generally — it breaks it in a specific, predictable way.

GLOBAL STYLE
  Genre, color grade, film stock or digital look, aspect ratio, shutter behavior,
  and anything that must not appear. Everything below must match this.

SCENE
  A one-line logline: what happens, where, in what mood.

CHARACTERS
  Face, hair, build, wardrobe. If a reference covers this, just name which
  reference is which character.

LOCATION
  The space and its props, separate from the people in it. A vague location is
  the single most common reason a multi-shot sequence drifts between cuts.

FIRST FRAME AND BLOCKING
  Exact starting positions: who is where, facing which direction, as the clip
  opens. Something fixed before any motion starts.

Shot 1: [shot type] [action in one or two sentences]. Hard cut.
Shot 2: [...]. Hard cut.
Shot 3: [...].
  Pacing is built here. State camera distance and framing per shot: vague
  transitions are the most common cause of a sequence collapsing.

OPTICS / CAMERA
  Focal length, camera height, handheld or dolly or crane, per shot.

PHYSICS
  Fabric, smoke, hair, liquid. Anything that would look wrong moving like a solid.

LIGHTING
  Where the light is motivated from, its direction, how it falls on faces.

AUDIO
  Ambience, specific effects, and what must not be heard. Default:
  "No music, no discernible dialogue", unless the scene needs otherwise.

The shape working prompts share: one visual rule at the top, one sound rule at the bottom, everything in between broken into shots. CHARACTERS can be short when a reference does that work; keep GLOBAL STYLE, the shot breakdown, and AUDIO regardless.

Genre, era, and lighting carry more than prose

On vendor web platforms these are UI selectors, and changing genre alone shifts pacing, contrast, and camera behavior with the scene description held identical. The API routes above expose no such selectors, so on OpenMontage tool calls that intent has to be written into GLOBAL STYLE and LIGHTING explicitly — genre, decade, grain and color response, light source and its angle, and the emotional register. Leaving them implicit is the difference between a shot that reads as noir and one that is merely dark.

Locks: continuity across cuts

Constraints do not belong in a trailing negative prompt. They go in named blocks, usually phrased positively, stating what holds.

State monotonicity. The cheapest continuity trick available: states only advance, never reset. Wetness only accumulates. The cookie only shrinks — whole, bitten, two halves, finished — and never regrows. Writing the progression shot by shot stops the model from cleaning up your character on the next cut.

One grammar per action. When an action repeats, define one way to perform it and forbid the rest, then close the list: exactly five sword actions in the piece, each with its timestamp. Same for slow motion — allow-list it to named moments and nowhere else.

Event tracks. Write ambient elements as a timestamped event list rather than as texture: each wave with its second and its spray height as a percentage of frame, at irregular intervals. Works for sea, wind, rain, traffic, and crowds.

Substitute, don't only forbid. If you forbid something, supply the concrete replacement. "No blood" is weak; "the cut edge glows orange, sparks blow out, the body crumbles to ash" is enforceable.

Assets

The piece is won or lost here, before any video generates.

Character sheet: three plates, face on only one. Full body front with the face removed, full body back, and a 3/4 close-up carrying the face in two versions, smiling and neutral. The face is stripped from the full-body plates because in a wide shot it is small and blurry and the model copies that blur; if the only face in the set is a sharp close-up, that is the one it uses. Without the smiling version the model invents teeth.

One asset per state. Variations are split into separate assets rather than noted in the prompt: clean jacket, soaked, and bloodied. Splitting is cheaper than arguing.

The rule of 10. Before accepting an asset, generate it ten times across different poses and lighting. It must stay recognizable all ten.

Locations. Do not generate a head-on still. Generate a video of the empty space with the camera moving slowly, then derive the other sides of the room from that footage. A still gives you a wall; a slow travelling gives you geometry.