Seedance 2.5

{BASE_URL} is https://api.uniall.ai throughout this page.

Updated: 2026-10-19

Overview

UniAll exposes Seedance 2.5 through one stable public model ID: seedance2.5. It supports text-to-video, first-frame and first-and-last-frame generation, multimodal references, video editing, video extension, reusable asset:// media, optional web search, and 480p Draft previews followed by 1080p finalization.

Capability	Required input	Key rule
Text-to-video	Prompt	Defaults to `720p` and automatic duration; explicit controls are optional.
First-frame video	One first-frame image	Omit `aspect_ratio` or use `auto`.
First-and-last-frame video	One first-frame and one last-frame image	Omit `aspect_ratio` or use `auto`.
Multimodal reference	Images, videos, or audio	Text is optional; audio-only reference requests are allowed.
Video editing	Prompt and one video	Set `omni_reference_task_type: "edit"` and use automatic duration.
Video extension	Prompt and one video	Set `omni_reference_task_type: "extend"` explicitly.
Draft to final video	Your completed Draft task ID	Create a `480p` preview, then finalize it at `1080p` within seven days using inherited settings.

Endpoints And Authentication

Action	Method	Path
Create task	`POST`	`/v1/videos`
Query task	`GET`	`/v1/videos/{task_id}`

Compatible creation and query aliases remain available to existing clients:

POST /v1/videos/generations
POST /v1/video/generations
GET  /v1/videos/generations/{task_id}
GET  /v1/video/generations/{task_id}

New integrations should use /v1/videos and /v1/videos/{task_id}.

Authorization: Bearer <UNIAI_API_KEY>
Content-Type: application/json

Request Parameters

Parameter	Type	Required	Description
`model`	string	Yes	`seedance2.5`.
`prompt`	string	Conditional	Text instruction. Required for text-only generation, editing, and extension. May be omitted with image, video, or audio references; omit when finalizing a Draft.
`resolution`	string	No	`480p`, `720p`, or `1080p`. Ordinary requests default to `720p`; Draft defaults to and requires `480p`; Draft finalization defaults to and requires `1080p`.
`duration`	integer/string	No	`"auto"`, `-1`, or an integer from `4` to `30`. Defaults to automatic duration. Editing requires automatic duration; omit when finalizing a Draft.
`aspect_ratio`	string	No	`auto`, `21:9`, `16:9`, `4:3`, `1:1`, `3:4`, or `9:16`. Frame inputs, editing, and extension require omission or `auto`. Omit when finalizing a Draft.
`content`	object[]	No	Text, image, video, or audio parts. A text part uses `{"type":"text","text":"..."}`. See media roles below.
`omni_reference_task_type`	string	No	`auto`, `reference`, `edit`, or `extend`. Set `edit` or `extend` explicitly for those workflows; omit when finalizing a Draft.
`draft`	boolean	No	`true` creates a 480p preview; defaults to `false`. Do not set `true` when finalizing a Draft.
`draft_task_id`	string	Conditional	The completed Draft's UniAI task ID, owned by the same user and created less than seven days ago. Use it to create the 1080p final video.
`output_format`	string	No	`mp4` or `mov`; defaults to `mp4`.
`generate_audio`	boolean	No	Whether to generate audio. Explicit `false` is preserved. Inherited during Draft finalization; omit it then.
`watermark`	boolean	No	Whether to add a watermark. Explicit `false` is preserved.
`return_last_frame`	boolean	No	Whether to return the generated last frame when available. Explicit `false` is preserved.
`seed`	integer	No	`-1` to `2147483647`. Omit when finalizing a Draft.
`priority`	integer	No	`0` to `9`; explicit `0` is preserved.
`execution_expires_after`	integer	No	Execution expiry in seconds, from `3600` to `259200`.
`safety_identifier`	string	No	`1` to `64` visible ASCII characters, without spaces or control characters. Use a non-sensitive identifier.
`tools`	object[]	No	Web search uses `[{"type":"web_search"}]`. Omit when finalizing a Draft.
`service_tier`	string	No	Only `default` is supported. `flex` is unavailable.
`size`	string	No	Compatibility alias for `resolution`; if both are present, they must describe the same resolution. Prefer `resolution`.
`seconds`	integer/string	No	Compatibility alias for `duration`. Prefer `duration`. Omit when finalizing a Draft.
`ratio`	string	No	Compatibility alias for `aspect_ratio`; `adaptive` is normalized to `auto`. Omit when finalizing a Draft.
`operation`	string	No	Compatible workflow selector: `reference_to_video`, `edit_video`, or `extend_video`. Prefer `omni_reference_task_type` in new examples and avoid conflicting selectors. Omit when finalizing a Draft.

Use top-level parameters. Compatible clients may use extra_body for controls; any field present both there and at the top level must have identical values. Explicit false and 0 are values, not omitted settings.

4K, frames, camera_fixed, and the flex service tier are unsupported.

Minimal Text-To-Video Request

curl -X POST "https://api.uniall.ai/v1/videos" \
  -H "Authorization: Bearer <UNIAI_API_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "seedance2.5",
    "prompt": "A mechanical bird unfolds its wings on a wooden table."
  }'

Omitting resolution and duration uses 720p and automatic duration for ordinary generation. To choose explicit output settings and advanced controls:

{
  "model": "seedance2.5",
  "prompt": "A mechanical bird unfolds its wings on a wooden table.",
  "resolution": "1080p",
  "duration": 4,
  "aspect_ratio": "16:9",
  "output_format": "mp4",
  "generate_audio": true,
  "watermark": false,
  "return_last_frame": true,
  "seed": 250628,
  "priority": 0,
  "execution_expires_after": 86400,
  "safety_identifier": "video-demo-01"
}

Media Inputs

Use content[] for new multimodal integrations. Each item carries one media type and an explicit role.

Item type	URL field	Supported roles
`text`	`text`	Generation or editing instruction
`image_url`	`image_url.url`	`first_frame`, `last_frame`, `reference_image`
`video_url`	`video_url.url`	`reference_video`
`audio_url`	`audio_url.url`	`reference_audio`

Media URLs may be public HTTP(S) URLs or valid asset:// references. HTTP(S) media must remain reachable by the UniAll service without cookies or custom request headers. See the Seedance Material Library for creating reusable asset:// inputs. Wait for available, then copy the returned uri; do not construct it from mat_*. Use the material before expires_at.

The image and audio compatibility fields image, images, audios, and last_image remain accepted. Do not send conflicting values through both content[] and compatibility fields.

For video reference, use a content[] item with type: "video_url" and role: "reference_video". Top-level video / video_url fields use editing or extension semantics and cannot directly replace a reference-video item. For editing or extension, explicitly set omni_reference_task_type to edit or extend.

Media Limits

Up to 30 images.
Up to 10 videos.
Up to 10 audio files.
Up to 50 media items in total.
A multimodal request may omit text.
An audio-only reference request is valid.

Operation Rules

Mode	`omni_reference_task_type`	`duration`	`aspect_ratio`
Text-to-video	Omit or `auto`	Omit, `"auto"`, `-1`, or integer `4..30`	Any supported value
First-frame / first-and-last-frame video	Omit or `auto`	Omit, `"auto"`, `-1`, or integer `4..30`	Omit or `auto`
Multimodal reference	`reference` when specified	Omit, `"auto"`, `-1`, or integer `4..30`	Follow the media mode; frame inputs require `auto`
Video editing	`edit` required	Omit, `"auto"`, or `-1`	Omit or `auto`
Video extension	`extend` required	Omit, `"auto"`, `-1`, or integer `4..30`	Omit or `auto`
Draft finalization	Omit; inherited	Omit; inherited	Omit; inherited

Editing and extension require both a prompt and a source video. Do not rely on prompt keywords to select the workflow. Existing operation selectors remain compatible; new examples use omni_reference_task_type.

Request Examples

First-And-Last-Frame Video

{
  "model": "seedance2.5",
  "prompt": "Move naturally from the first composition to the last while preserving the subject.",
  "resolution": "720p",
  "duration": 10,
  "aspect_ratio": "auto",
  "content": [
    {
      "type": "image_url",
      "image_url": {
        "url": "https://example.com/first.png"
      },
      "role": "first_frame"
    },
    {
      "type": "image_url",
      "image_url": {
        "url": "https://example.com/last.png"
      },
      "role": "last_frame"
    }
  ]
}

For a single first frame, send only the first_frame item. In both frame modes, fixed aspect ratios are rejected because the source frame determines the composition.

Multimodal Reference

{
  "model": "seedance2.5",
  "omni_reference_task_type": "reference",
  "resolution": "720p",
  "duration": 12,
  "content": [
    {
      "type": "image_url",
      "image_url": {
        "url": "https://example.com/product.png"
      },
      "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"
    }
  ]
}

Audio-Only Reference Without A Prompt

{
  "model": "seedance2.5",
  "resolution": "480p",
  "duration": 4,
  "content": [
    {
      "type": "audio_url",
      "audio_url": {
        "url": "https://example.com/reference.wav"
      },
      "role": "reference_audio"
    }
  ]
}

Video Editing

{
  "model": "seedance2.5",
  "prompt": "Replace the sky and preserve the subject",
  "video": "https://example.com/source.mp4",
  "omni_reference_task_type": "edit",
  "resolution": "720p",
  "duration": "auto",
  "aspect_ratio": "auto"
}

Video Extension

{
  "model": "seedance2.5",
  "prompt": "Continue the camera movement into the illuminated square.",
  "video": "asset://asset-EXAMPLE",
  "omni_reference_task_type": "extend",
  "resolution": "720p",
  "duration": 8,
  "aspect_ratio": "auto",
  "output_format": "mov"
}

Web Search

{
  "model": "seedance2.5",
  "prompt": "Create a concise visual recap of the latest public spaceflight milestone.",
  "resolution": "720p",
  "duration": 8,
  "tools": [
    {
      "type": "web_search"
    }
  ]
}

Web search can be combined with media inputs. No other tools shape is accepted.

Draft Preview To 1080p Final Video

1. Create A 480p Draft

Set draft: true. Omitting resolution selects 480p; any other explicit tier is rejected. A Draft may also use the media-reference inputs on this page.

curl -X POST "https://api.uniall.ai/v1/videos" \
  -H "Authorization: Bearer <UNIAI_API_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "seedance2.5",
    "prompt": "A mechanical bird unfolds its wings on a wooden table.",
    "draft": true,
    "duration": 4,
    "aspect_ratio": "16:9",
    "generate_audio": true,
    "seed": 250628
  }'

2. Save The UniAI Task ID And Wait For Completion

Poll using the create response's id or task_id until status is completed. Replace the placeholder task_YOUR_COMPLETED_DRAFT below with the actual UniAI task ID you received.

curl "https://api.uniall.ai/v1/videos/task_YOUR_COMPLETED_DRAFT" \
  -H "Authorization: Bearer <UNIAI_API_KEY>"

3. Create The Final Video

The parent must be a completed Seedance 2.5 Draft owned by the same UniAI user and created less than seven days ago. Pending, failed, expired, non-Draft, or another user's tasks cannot be reused.

curl -X POST "https://api.uniall.ai/v1/videos" \
  -H "Authorization: Bearer <UNIAI_API_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "seedance2.5",
    "draft_task_id": "task_YOUR_COMPLETED_DRAFT",
    "output_format": "mov",
    "watermark": false,
    "return_last_frame": true,
    "priority": 0
  }'

Finalization defaults to 1080p; you may explicitly set resolution: "1080p". Other resolutions are rejected. A successful submission returns a new final-video task ID; poll it in the same way.

The final video inherits the Draft's prompt, all media, duration, aspect ratio, seed, generate_audio, and task type. Omit these fields instead of repeating or overriding them; also omit tools, operation, and omni_reference_task_type. Do not repeat the original content or resend even generate_audio: false.

You may separately set output_format, watermark, return_last_frame, priority, execution_expires_after, and safety_identifier. Do not set draft: true.

A content array containing exactly one Draft reference is also accepted:

{
  "model": "seedance2.5",
  "content": [
    {
      "type": "draft_task",
      "draft_task": {
        "id": "task_YOUR_COMPLETED_DRAFT"
      }
    }
  ]
}

Its id must also be the public task ID returned by UniAI. Do not mix it with text or media parts. If draft_task_id is also present, both IDs must match.

Create Response And Task Lifecycle

{
  "id": "task_xxxxxxxxxxxxx",
  "task_id": "task_xxxxxxxxxxxxx",
  "object": "video.generation.job",
  "model": "seedance2.5",
  "status": "queued",
  "progress": 0,
  "created_at": 1792368000
}

Store the public id or task_id and poll GET /v1/videos/{task_id} every 2 to 5 seconds until status is completed or failed. After completion, prefer the returned video_url to download the video; compatible responses may also expose it in result.video_url or result.outputs. Do not treat result URLs as permanent storage.

Query an ordinary task in the same way:

curl "https://api.uniall.ai/v1/videos/task_YOUR_VIDEO" \
  -H "Authorization: Bearer <UNIAI_API_KEY>"

If you requested return_last_frame: true, read the returned last-frame result when available. 1080p output uses HEVC/10bit and needs a compatible player. MP4 and MOV select the output container.

Do not automatically retry Seedance 2.5 creation requests after failure, a client timeout, or an uncertain outcome. If you have a task ID, continue querying that task. If no ID was received, establish the original request's outcome first. This rule also applies to Draft finalization.

See Video Generation Overview for public status fields, completed/failed responses, and error handling. This model's no-automatic-retry rule takes precedence over general retry guidance.

Billing Notes

Use each task's actual Token usage and final settlement record; pre-deduction is only an estimate. A Draft and its final video are separate billable tasks. The Draft does not offset the final video and is not counted again as an input video for finalization. Check the current UniAll price available to your account.

Common Errors

Error	Cause	Fix
Missing input	No prompt, media, or valid Draft reference	Supply the required input for the selected workflow.
Invalid resolution	4K or a mismatched Draft/final-video tier	Use `480p`/`720p`/`1080p` for ordinary tasks, only `480p` for Drafts, and only `1080p` for finalization.
Conflicting aliases	`resolution` and `size` contain different values	Remove `size` or make the values identical.
Invalid edit duration	Editing uses an integer duration	Omit `duration` or use `"auto"`/`-1`.
Invalid aspect ratio	A frame, edit, or extension request uses a fixed ratio	Omit `aspect_ratio` or set it to `auto`.
Media limit exceeded	Per-type or total media limits were exceeded	Reduce media to the documented limits.
Media unavailable	A URL is private, expired, or unreachable from the public internet	Use a stable public URL or an available `asset://` material.
Invalid tools	`tools` is not exactly the supported web-search structure	Send `[{"type":"web_search"}]` or omit `tools`.
Unsupported field	`frames`, `camera_fixed`, or `service_tier: "flex"` was sent	Remove the unsupported field.
Invalid Draft reference	Missing, incomplete, non-Draft, expired, or another user's task	Use your completed Draft's UniAI task ID within seven days of creation.
Repeated inherited fields	Finalization resends the prompt, media, duration, ratio, seed, audio, or task type	Omit inherited fields; send the Draft ID and permitted output controls only.
Invalid parameter type or range	String booleans or out-of-range priority, seed, or expiry	Use JSON booleans and the integer ranges in the parameter table.

Overview​

Endpoints And Authentication​

Request Parameters​

Minimal Text-To-Video Request​

Media Inputs​

Media Limits​

Operation Rules​

Request Examples​

First-And-Last-Frame Video​

Multimodal Reference​

Audio-Only Reference Without A Prompt​

Video Editing​

Video Extension​

Web Search​

Draft Preview To 1080p Final Video​

1. Create A 480p Draft​

2. Save The UniAI Task ID And Wait For Completion​

3. Create The Final Video​

Create Response And Task Lifecycle​

Billing Notes​

Common Errors​

Related Pages​