Seedance 2.5

Seedance 2.5 is a multimodal video generation model for coherent long-form shots, multimodal references, precise editing, video extension, and native multilingual audio. Use the AnyFast model ID seedance-2.5 with POST /v1/video/generations.

What’s new

Generate one coherent video up to 30 seconds long.
Reference up to 50 media items: 30 images, 10 videos, and 10 audio clips.
Generate from audio references alone, without an image or video reference.
Let the model choose aspect ratio and duration with ratio: "adaptive" and duration: -1.
Preserve source dimensions and timing automatically in editing, extension, and frame-guided workflows.
Generate spoken or sung audio in 11 supported languages.

Capability	Seedance 2.5 limit
Output duration	`-1` for automatic duration, or an integer from 4–30 seconds
Reference images	Up to 30
Reference videos	Up to 10; 2–30 seconds each, 30 seconds total
Reference audio	Up to 10; 2–30 seconds each, 30 seconds total
Audio-only reference	Supported
Resolution	480p or 720p
Aspect ratio	21:9, 16:9, 4:3, 1:1, 3:4, 9:16, or adaptive
Synchronized audio	Supported
Web search	Supported for text-to-video
Return final frame	Supported
Draft/sample mode	Not supported

Capability examples

A time-coded prompt can divide one continuous story into several acts. This example moves from a brass clock and mechanical city to an ocean voyage and a moonlit ridge, then returns to the opening clock face.

Reference image for the 30-second steampunk narrative — Reference image

30-second output

This advertising example uses one product image and six motion/composition videos. In the prompt, @image1 defines the product while @video1 through @video6 assign composition, camera movement, impact, rhythm, typography, and final framing.

Product reference image for the multimodal advertising example — Product reference image

View the six reference videos

Reference video 1 — composition

Reference video 2 — movement

Reference video 3 — impact

Reference video 4 — rhythm

Reference video 5 — typography

Reference video 6 — final framing

Combined multimodal output

The prompt removes background people while preserving the main subject. With ratio: "adaptive" and duration: -1, the result keeps the input video’s 5:4 ratio and approximately 16-second duration.

Input video (MOV)

Edited output (MOV)

Task types and classification

Seedance 2.5 classifies each request from the media role values and the prompt intent. It supports five task families.

Task	How it is detected	Aspect ratio	Duration
Text-to-video	Text prompt without reference media	Explicit ratio or `adaptive`	`-1` or 4–30
Reference-to-video	One or more `reference_image`, `reference_video`, or `reference_audio` items	Explicit ratio or `adaptive`	`-1` or 4–30
Video editing	Reference media plus editing intent such as add, remove, replace, modify, or repair	Must be `adaptive`	Must be `-1`
Video extension	Reference media plus extension intent such as extend forward/backward, continue, or carry on	Must be `adaptive`	`-1` or 4–30
First/last-frame generation	An image with `first_frame`, optionally followed by `last_frame`	Must be `adaptive`	`-1` or 4–30

Editing, extension, and frame-guided restrictions are checked after the model classifies the task. The create request can initially return a task ID and then fail asynchronously with InvalidParameter.TaskTypeConstraint. If several parameters are invalid, the asynchronous error may list them together.

For ordinary reference generation, avoid editing or extension phrases unless that is the intended workflow. Such phrases can cause the model to classify the request as editing or extension and apply the stricter parameter rules.

Smarter duration and aspect ratio control

Set ratio to adaptive and duration to -1 to let Seedance 2.5 choose output dimensions and timing. Editing, extension, and first-frame/first-and-last-frame tasks have special behavior.

Video editing

For editing, ratio defaults to and only accepts adaptive. The output follows the aspect ratio of the video selected for editing. duration defaults to and only accepts -1, so the result stays close to the source duration. The output can have a fractional duration and may be up to 0.4 seconds shorter than the source because of input-frame processing.

Video extension

For extension, ratio defaults to and only accepts adaptive. The output follows the aspect ratio of the video being extended. Set duration to -1 for automatic timing or choose an integer from 4–30.

First-frame and first-and-last-frame generation

For frame-guided generation, ratio defaults to and only accepts adaptive. The output follows the first frame’s aspect ratio. Set duration to -1 or an integer from 4–30.

Text and reference generation

For text-to-video and ordinary reference-to-video, adaptive selects the best ratio from 21:9, 16:9, 4:3, 1:1, 3:4, and 9:16. With duration: -1, the model selects an integer duration from 4–30 seconds.

Create a task

Text to video
Multimodal reference
Edit video
Extend video
First and last frame

cURL

curl --request POST \
  --url https://www.anyfast.ai/v1/video/generations \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "model": "seedance-2.5",
    "content": [{
      "type": "text",
      "text": "A 20-second cinematic tracking shot through a miniature steampunk city at golden hour"
    }],
    "generate_audio": true,
    "resolution": "720p",
    "ratio": "16:9",
    "duration": 20
  }'

Use @image1, @video1, and @audio1 to reference media by type and order. The text prompt is optional for reference generation.

cURL

curl --request POST \
  --url https://www.anyfast.ai/v1/video/generations \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "model": "seedance-2.5",
    "content": [
      {"type":"text","text":"@image1 performs the motion from @video1, paced to @audio1"},
      {"type":"image_url","image_url":{"url":"https://example.com/character.jpg"},"role":"reference_image"},
      {"type":"video_url","video_url":{"url":"https://example.com/motion.mp4"},"role":"reference_video"},
      {"type":"audio_url","audio_url":{"url":"https://example.com/music.mp3"},"role":"reference_audio"}
    ],
    "generate_audio": true,
    "ratio": "16:9",
    "duration": 15
  }'

See the Multimodal references capability example above for all six inputs and the generated output.

Editing requires ratio: "adaptive" and duration: -1 so the result follows the source video.

cURL

curl --request POST \
  --url https://www.anyfast.ai/v1/video/generations \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "model": "seedance-2.5",
    "content": [
      {"type":"text","text":"Edit @video1: remove every background pedestrian while preserving the main subject"},
      {"type":"video_url","video_url":{"url":"https://example.com/source.mov"},"role":"reference_video"}
    ],
    "generate_audio": true,
    "ratio": "adaptive",
    "duration": -1
  }'

See the Video editing capability example above for the input/output comparison.

Extension requires ratio: "adaptive". Set duration to -1 or an integer from 4–30.

cURL

curl --request POST \
  --url https://www.anyfast.ai/v1/video/generations \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "model": "seedance-2.5",
    "content": [
      {"type":"text","text":"Extend @video1: the camera passes through the open window into a quiet gallery"},
      {"type":"video_url","video_url":{"url":"https://example.com/source.mp4"},"role":"reference_video"}
    ],
    "generate_audio": true,
    "ratio": "adaptive",
    "duration": 11
  }'

See the Video extension capability example above for all three inputs and the output.

Frame-guided generation requires ratio: "adaptive"; the output follows the first frame’s aspect ratio.

cURL

curl --request POST \
  --url https://www.anyfast.ai/v1/video/generations \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "model": "seedance-2.5",
    "content": [
      {"type":"text","text":"The subject smiles at the camera while it makes a smooth 360-degree orbit"},
      {"type":"image_url","image_url":{"url":"https://example.com/first.jpg"},"role":"first_frame"},
      {"type":"image_url","image_url":{"url":"https://example.com/last.jpg"},"role":"last_frame"}
    ],
    "generate_audio": true,
    "ratio": "adaptive",
    "duration": 5
  }'

See the First and last frames capability example above for both frame inputs and the output.

Additional workflows

Audio-only reference
Web search
Watermark and final frame

Seedance 2.5 can generate a video from an audio reference without any image or video input. The text prompt is optional; when included, use @audio1 to describe how the audio should guide the scene.

cURL

curl --request POST \
  --url https://www.anyfast.ai/v1/video/generations \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "model": "seedance-2.5",
    "content": [
      {"type":"text","text":"Create a night-market performance paced to @audio1"},
      {"type":"audio_url","audio_url":{"url":"https://example.com/performance.mp3"},"role":"reference_audio"}
    ],
    "generate_audio": true,
    "ratio": "16:9",
    "duration": -1
  }'

Text-to-video tasks can let the model search for current information such as products, events, or weather before generation.

cURL

curl --request POST \
  --url https://www.anyfast.ai/v1/video/generations \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "model": "seedance-2.5",
    "content": [{"type":"text","text":"Create a short travel video using today’s weather in Tokyo"}],
    "tools": [{"type":"web_search"}],
    "generate_audio": true,
    "ratio": "16:9",
    "duration": 8
  }'

Use watermark to add the AI-generated mark and return_last_frame to request the final frame alongside the video result.

{
  "watermark": true,
  "return_last_frame": true
}

Advanced request controls

Field	Behavior
`execution_expires_after`	Maximum queued/running lifetime in seconds; default `172800`.
`priority`	Task execution priority; default `0`.
`safety_identifier`	Stable end-user identifier for safety tracing.
`seed`	Random seed; `-1` chooses a random value.
`service_tier`	Task service tier; default `default`.

A task becomes expired when it remains queued or running beyond execution_expires_after.

Output specifications

Resolution and pixel dimensions

resolution defaults to 720p. Seedance 2.5 supports 480p and 720p; it does not support 1080p or 4K output.

Resolution	Ratio	Pixel dimensions
480p	16:9	854×480
480p	4:3	752×560
480p	1:1	640×640
480p	3:4	560×752
480p	9:16	480×854
480p	21:9	992×432
720p	16:9	1280×720
720p	4:3	1112×834
720p	1:1	960×960
720p	3:4	834×1112
720p	9:16	720×1280
720p	21:9	1470×630

MOV playback support varies. VLC, mpv, and ffplay support it on macOS and Windows; IINA supports it on macOS. Browser playback may not work, so download the file and use a compatible player when necessary.

Audio, watermark, and final frame

generate_audio defaults to true and enables synchronized dialogue, sound effects, and music.
watermark defaults to false. Set it to true to add an AI-generated mark in the lower-right corner.
return_last_frame defaults to false. Enable it when you need the generated video’s final frame.

Input requirements

Do not directly upload reference images or videos containing real-person faces unless your workflow and account are authorized to use that material.

Images

Property	Requirement
Input methods	Public URL, Base64 data URI, or asset ID
Formats	JPEG, PNG, WebP, BMP, TIFF, GIF, HEIC, HEIF
Aspect ratio	Width/height from 0.4–2.5
Dimensions	Each side from 300–6000 px
File size	Less than 30 MB per image
Count	1 first frame; 2 first/last frames; 1–30 reference images

Videos

Property	Requirement
Input methods	Public URL or asset ID
Containers	MP4 or MOV
Video codecs	H.264/AVC or H.265/HEVC
Audio codecs	AAC or MP3
Resolution	480p or 720p
Duration	2–30 seconds each; no more than 30 seconds total
Aspect ratio	Width/height from 0.4–2.5
Dimensions	Each side from 300–6000 px
Total pixels	409,600–8,295,044 pixels per frame
File size	Up to 200 MB per video
Frame rate	24–60 FPS
Count	Up to 10 reference videos

Audio

Property	Requirement
Input methods	Public URL, Base64 data URI, or asset ID
Formats	WAV or MP3
Duration	2–30 seconds each; no more than 30 seconds total
File size	Up to 15 MB per audio clip
Count	Up to 10 reference audio clips

The complete request body must not exceed 64 MB. Avoid Base64 for large files.

Native multilingual generation

Seedance 2.5 accepts prompts and generates spoken audio in Chinese, English, Spanish, Indonesian, Malay, Thai, Arabic, Portuguese, Vietnamese, Japanese, and Korean. See the Native languages capability example above for its reference image and generated output.

Prompting tips

Organize prompts as subject + action/event + scene/environment + visual style + camera/editing + sound. Omit parts you do not need.
Refer to media as @image1, @video1, and @audio1, and state what each item should and should not contribute.
Distinguish audio intent with punctuation: music in (), sound effects in <>, dialogue in {}, and subtitles in 【】.
For non-Chinese dialogue, state the language before the dialogue.
Use timestamps such as [0–10s], [10–20s], and [20–30s] to structure a long narrative.

Query and retain the result

The create endpoint returns an asynchronous task ID. Poll GET /v1/video/generations/{task_id} until the task reaches SUCCESS, then read result_url.

Task records can be queried for 7 days after submission.
Generated video URLs remain available for 24 hours and allow up to 100 downloads.
Download or transfer the result promptly after success.

Seedance 2.5 API Reference

View every request field and open Try it.

Query a Seedance task

Poll task status and retrieve the generated video.

Source: Volcengine Seedance 2.5 tutorial

Getting started

Model Introduction

Resources

What’s new

Capability examples

Task types and classification

Smarter duration and aspect ratio control

Video editing

Video extension

First-frame and first-and-last-frame generation

Text and reference generation

Create a task

Additional workflows

Advanced request controls

Output specifications

Resolution and pixel dimensions

Audio, watermark, and final frame

Input requirements

Images

Videos

Audio

Native multilingual generation

Prompting tips

Query and retain the result

Seedance 2.5 API Reference

Query a Seedance task

​What’s new

​Capability examples

​Task types and classification

​Smarter duration and aspect ratio control

​Video editing

​Video extension

​First-frame and first-and-last-frame generation

​Text and reference generation

​Create a task

​Additional workflows

​Advanced request controls

​Output specifications

​Resolution and pixel dimensions

​Audio, watermark, and final frame

​Input requirements

​Images

​Videos

​Audio

​Native multilingual generation

​Prompting tips

​Query and retain the result

Seedance 2.5 API Reference

Query a Seedance task

What’s new

Capability examples

Task types and classification

Smarter duration and aspect ratio control

Video editing

Video extension

First-frame and first-and-last-frame generation

Text and reference generation

Create a task

Additional workflows

Advanced request controls

Output specifications

Resolution and pixel dimensions

Audio, watermark, and final frame

Input requirements

Images

Videos

Audio

Native multilingual generation

Prompting tips

Query and retain the result