Seedance family

ByteDance’s video generation models, four in total, called through the OfoxAI video endpoint POST /v1/videos. Tasks run asynchronously: creating a task returns a task ID, which you then use to query the result.

Choosing a model

Key pointChoose 2.0 when you need 4K output; choose 2.5 when you need 30-second duration or a 21:9 aspect ratio; choose Mini or Fast for batch generation of 480p and 720p videos.

Model	Resolutions (default)	Duration	Aspect ratios
Seedance 2.5	`480p` `720p` `1080p` (`720p`)	4–30 s	`21:9` `16:9` `4:3` `1:1` `3:4` `9:16` `adaptive`
Seedance 2.0	`480p` `720p` `1080p` `4k` (`1080p`)	4–15 s	`16:9` `9:16` `1:1` `adaptive`
Seedance 2.0 Fast	`480p` `720p` (`720p`)	4–15 s	Same as 2.0
Seedance 2.0 Mini	`480p` `720p` (`720p`)	4–15 s	Same as 2.0

All four support text-to-video, image-to-video, and video reference, and can generate a synchronized audio track (generate_audio defaults to true). adaptive keeps the input image’s aspect ratio.

Model IDs (copy them exactly)

Seedance 2.5bytedance/seedance-2.530 s, 21:9

Seedance 2.0bytedance/seedance-2.04K

Seedance 2.0 Fastbytedance/seedance-2.0-fast480p, 720p

Seedance 2.0 Minibytedance/seedance-2.0-mini480p, 720p

The table above matches the video_attributes returned by the Models API; if model capabilities change, the API response takes precedence. Billing is per second, and the actual charge is usage.video_cost in the task result. For prices, see the model page .

Pass resolution and duration explicitly. If omitted, 2.0 defaults to 1080p; cost is calculated by resolution tier and is higher than at 720p.

Examples

Key pointAll five generation modes share one endpoint. The mode is determined by the input fields you send; no mode parameter is needed.

The examples below show only the request that creates the task. For the full flow of querying status and downloading the result after creation, see Video API · Quickstart.

Text to video

Send only prompt.

Terminal


curl -X POST https://api.ofox.ai/v1/videos \
  -H "Authorization: Bearer $OFOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "bytedance/seedance-2.0-mini",
    "prompt": "A fox running through the snow, the camera following it",
    "duration": 5,
    "resolution": "720p",
    "aspect_ratio": "16:9"
  }'

Image to video

Pass one first_frame in frame_images; the video uses that image as its first frame. The aspect ratio can be set to adaptive to keep the image’s ratio.

Terminal


curl -X POST https://api.ofox.ai/v1/videos \
  -H "Authorization: Bearer $OFOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "bytedance/seedance-2.0",
    "prompt": "The dog in the frame runs toward the camera",
    "duration": 5,
    "resolution": "720p",
    "aspect_ratio": "adaptive",
    "frame_images": [
      { "type": "image_url", "image_url": { "url": "https://example.com/dog.jpg" }, "frame_type": "first_frame" }
    ]
  }'

First & last frame

Pass first_frame and last_frame in frame_images to generate the transition between the two frames. Sending only last_frame returns 400.

Terminal


curl -X POST https://api.ofox.ai/v1/videos \
  -H "Authorization: Bearer $OFOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "bytedance/seedance-2.0",
    "prompt": "A flower bud slowly opens into a rose in full bloom",
    "duration": 5,
    "resolution": "720p",
    "frame_images": [
      { "type": "image_url", "image_url": { "url": "https://example.com/bud.jpg" }, "frame_type": "first_frame" },
      { "type": "image_url", "image_url": { "url": "https://example.com/rose.jpg" }, "frame_type": "last_frame" }
    ]
  }'

Image reference

Pass images in input_references (up to 9) to keep a person, product, or style consistent; they are not used as fixed frames. Refer to each image in the prompt as “image 1”, “image 2”, and so on.

Terminal


curl -X POST https://api.ofox.ai/v1/videos \
  -H "Authorization: Bearer $OFOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "bytedance/seedance-2.5",
    "prompt": "The girl in image 1 holds the cup from image 2 and smiles by a café window",
    "duration": 5,
    "resolution": "720p",
    "input_references": [
      { "type": "image_url", "image_url": { "url": "https://example.com/girl.jpg" } },
      { "type": "image_url", "image_url": { "url": "https://example.com/cup.jpg" } }
    ]
  }'

Audio/video reference

input_references can mix images, audio (up to 3 clips, each no longer than 15 seconds), and video (up to 1 clip). When video is used as input, billed seconds may include the input video’s duration.

Terminal


curl -X POST https://api.ofox.ai/v1/videos \
  -H "Authorization: Bearer $OFOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "bytedance/seedance-2.0",
    "prompt": "The character speaks in the tone of this voiceover, with camera style based on this video",
    "duration": 5,
    "resolution": "720p",
    "input_references": [
      { "type": "image_url", "image_url": { "url": "https://example.com/character.jpg" } },
      { "type": "audio_url", "audio_url": { "url": "https://example.com/voice.mp3" } },
      { "type": "video_url", "video_url": { "url": "https://example.com/style-ref.mp4" } }
    ]
  }'

frame_images and input_references cannot be sent together; sending both returns 400 references_conflict.
Images can be public URLs or strings starting with data:image/...;base64,.
Pass "generate_audio": false when you do not need an audio track.
For the full field structure, see Create video task.

Real-person reference images

Key pointWhen calling through OfoxAI, you do not need to complete Seedance’s asset library verification; just add real_person: true at the top level of the request.

ByteDance’s official Seedance API does not allow direct upload of reference images or videos containing real human faces. The official BytePlus Seedance 2.0 documentation requires authorized real-person portrait assets, and the Volcano Engine Ark real-person portrait library guide lists steps such as sending an invitation, identity verification and authorization, uploading assets, and receiving authorization to obtain an asset ID.

Step	Calling the official Seedance API directly	Calling through OfoxAI
Before the first request	Create an asset group, complete real-person verification and authorization, upload and validate assets, obtain an asset ID	No advance enrollment on the provider’s platform
Passing reference images	Use an active authorized asset `asset://<asset_id>`	Pass an image URL or `data:` URI in `frame_images` or `input_references`
Request switch	Switch to the approved asset URI	Add `"real_person": true` at the top level of the request


{
  "model": "bytedance/seedance-2.0",
  "prompt": "The person in the frame walks through a cinematic night market",
  "duration": 5,
  "resolution": "720p",
  "real_person": true,
  "input_references": [
    { "type": "image_url", "image_url": { "url": "https://example.com/person.jpg" } }
  ]
}

OfoxAI applies privacy preprocessing to reference images before submission. This can reduce false rejections by upstream anti-deepfake review, but cannot guarantee upstream acceptance; tasks rejected upstream are not charged.
real_person is a processing instruction, not proof of authorization. Only submit images you are legally entitled and authorized to use.
For how to adjust images that are still rejected and for preprocessing error codes, see Real-person reference images.

Pin a provider

Key pointSeedance is served by two providers with different moderation strictness; if none is specified, the gateway distributes requests by weight.

Provider	Description	Content moderation
`volcengine`	Volcano Engine Ark, ByteDance’s platform for mainland China	Standard moderation
`byteplus`	BytePlus, ByteDance’s platform outside mainland China	Allows not-for-all-audiences (NSFW) content

To pin a provider, add this at the top level of the request:


"provider": { "type": "byteplus" }

To generate not-for-all-audiences content, you must explicitly specify byteplus. Otherwise the request may be routed to volcengine and rejected by content moderation. Once a provider is specified, the request will not switch automatically if that provider is unavailable.

An invalid provider.type value returns 400 invalid_provider_type; a specified provider that does not serve the model returns 400 provider_type_unavailable. For general details, see Video provider routing.

Common errors

Key pointParameter validation errors are returned at creation time; no task is created and nothing is charged. The error message lists the allowed values.

HTTP · code	Error message	Cause	Fix
400 `unsupported_parameter`	`duration 3 out of range [4, 15]`	Duration outside the model’s range	4–15 s for the 2.0 series, 4–30 s for 2.5
400 `unsupported_parameter`	`resolution "1080p" not supported; allowed: [480p 720p]`	Fast and Mini do not support 1080p	Use `720p`, or switch to 2.0 / 2.5
400 `unsupported_parameter`	`resolution "4k" not supported; allowed: [480p 720p 1080p]`	Only 2.0 supports 4K	Switch to `bytedance/seedance-2.0`
400 `unsupported_parameter`	`aspect_ratio "21:9" not supported; allowed: [16:9 9:16 1:1 adaptive]`	The 2.0 series does not support 21:9	Switch to 2.5, or use a supported ratio
400 `references_conflict`	`frame_images and input_references are mutually exclusive`	Both input fields were sent	Use only one of them; see Examples
400 `invalid_request`	`frame_images: last_frame requires a first_frame`	Only the last frame was sent	Add a `first_frame`
400 `too_many_references`	`input_references over limit: images 10/9, audios 0/3, videos 0/1`	Reference inputs exceed the limit	Up to 9 images, 3 audio clips, and 1 video
400 `invalid_request`	`real_person requires at least one image reference`	`real_person` is enabled but no image was sent	Add an image, or remove `real_person`
400 `invalid_request`	`cannot unmarshal string into Go struct field CreateVideoRequest.duration of type int`	`duration` was sent as a string, e.g. `"5s"`	Use an integer, e.g. `5`
400 `invalid_callback_url`	`callback_url must be a public HTTPS URL`	The callback address is not HTTPS, or is an internal address	Use a public HTTPS address
404 `model_not_found`	`model not found`	Model ID misspelled, e.g. `bytedance/seedance-2`	Copy the model ID from this page
402 `insufficient_credits`	—	Balance is insufficient for the estimated cost (no task is created)	Top up and retry

If a task is created successfully but fails during generation, the query result is status: "failed", with the reason in the error field; a timeout corresponds to error.code: "expired". For the full list of error codes, see Video API error codes.

Official docs

FAQ

How do I make a first/last-frame video with Seedance?

Pass two images in frame_images, one with frame_type first_frame and one with last_frame. Sending only last_frame returns 400 last_frame requires a first_frame. frame_images cannot be sent together with input_references.

Does Seedance 2.0 support 4K?

Only bytedance/seedance-2.0 supports 4k. 2.5 goes up to 1080p, and Fast and Mini up to 720p. An unsupported resolution returns 400, and the error message lists the allowed values.

What is the maximum length Seedance can generate?

Seedance 2.5 generates 4 to 30 seconds per task; 2.0, 2.0 Fast, and 2.0 Mini generate 4 to 15 seconds. Values outside the range return 400 duration out of range.

Does Seedance support 21:9?

Only Seedance 2.5 supports 21:9. The 2.0 series supports only 16:9, 9:16, 1:1, and adaptive.

What should I do if a Seedance reference image with a real person returns an error?

Calling the official API directly requires identity verification in the asset library first. Through OfoxAI, add real_person: true at the top level of the request and pass the image directly; OfoxAI applies privacy preprocessing first. If the upstream still rejects it, you are not charged; adjust the image following the advice on the real-person reference images page and retry.

How many reference images can Seedance take at once?

input_references accepts up to 9 images, 3 audio clips (each no longer than 15 seconds), and 1 video. Exceeding this returns 400 too_many_references.

How long is the Seedance video URL valid after generation?

Prefer mirror_urls. If only unsigned_urls is returned, it is a temporary upstream address that may expire after 24 hours, so download and save it promptly.