Seedance 2.5

About

Seedance 2.5 is ByteDance's mainline video generation model, served through BytePlus ModelArk. It renders 4 to 30 second clips at a fixed 24 fps and generates native audio in the same pass.

Its Reference to Video workspace now exposes three explicit modes. Create makes a new clip from loose references. Edit transforms @Video1 while preserving everything you do not ask to change; the output follows the source video's duration and aspect. Extend continues @Video1 after its ending; the aspect follows the source while you choose a new 4 to 30 second continuation.

Seedance 2.5 accepts up to 30 reference images, 10 reference videos, and 10 reference audio clips — 50 media parts total. Edit and Extend require a source video as @Video1, and you can still use the wider reference stack to guide identity, environment, motion, or sound.

Seedance 2.5 is an addition to the Seedance line, not a replacement. Seedance 2.0 stays the default: 2.5 doubles the maximum clip length and widens reference input, but it tops out at 720p, while 2.0 also renders 1080p and 4K. Pick 2.5 for length and references, and 2.0 when resolution decides the shot.

Prompting tips

Choose the reference mode first, then make @Video1's role explicit in the prompt.

• Create — Assign each attached image, video, or audio a role, then describe the new scene. Example: Use @Image1 for the character, @Image2 for the location, and @Video1 for camera movement.
• Edit — Start with ‘Edit @Video1.’ State exactly what should change and what must remain, such as cast, motion, framing, timing, or soundtrack.
• Extend — Start with ‘Extend @Video1 after its ending.’ Describe only the continuation, then restate the identity, lighting, camera language, pacing, and audio continuity to preserve.

In Edit and Extend, the first attached video is the source or continuation anchor. Edit inherits its duration and aspect; Extend inherits its aspect and uses the continuation duration you select.

Reference modes: Create, Edit, Extend

The mode is fixed before generation so the same reference video cannot be ambiguously interpreted after billing.

Pricing

Seedance 2.5 is a pay-as-you-go Premium Spark vendor model. Every clip uses purchased Spark, including for Sogni Unlimited members. Unlimited saves 5%; Unlimited Pro saves 10%.

Per-second Premium Spark rates: $0.300456 per second at 720p and $0.133640 per second at 480p. Totals are billed from those exact rates.

Jobs that supply a reference video — video editing and video extension — use a lower vendor rate, so they cost less per second than text-to-video.

API

One Sogni API key reaches every model in the catalog — call Seedance 2.5 with the exact model id.

import { SogniClient } from '@sogni-ai/sogni-client';

const client = await SogniClient.createInstance({
  appId: crypto.randomUUID(),
  apiKey: process.env.SOGNI_API_KEY,
  network: 'fast',
});

const project = await client.projects.create({
  type: 'video',
  modelId: 'seedance-2-5',
  positivePrompt: 'a slothicorn surfing a wave of liquid paint, slow push-in, cinematic',
  numberOfMedia: 1,
  duration: 5,
});

const [url] = await project.waitForCompletion();
console.log(url); // result link — download within 24h

curl https://api.sogni.ai/v1/creative-agent/workflows \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $SOGNI_API_KEY" \
  -d '{
    "input": {
      "title": "First render",
      "steps": [{
        "id": "step1",
        "toolName": "generate_video",
        "arguments": { "prompt": "a slothicorn surfing a wave of liquid paint, slow push-in, cinematic", "videoModel": "seedance2-5", "duration": 5 }
      }]
    },
    "confirm_cost": true
  }'

REST workflow alias: seedance2-5. Pin the exact id with the SDK. Full reference at docs.sogni.ai.