> ## Documentation Index
> Fetch the complete documentation index at: https://docs.crun.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Seedance 2.0 Fast - Reference to Video
> Generate videos from reference images, videos, and audio powered by Bytedance's advanced Seedance 2.0 Fast model
[//]: # "## Custom Uploaded Assets"
[//]: #
[//]: # "Seedance 2.0 Fast reference-to-video supports your own uploaded image, video, and audio assets."
[//]: #
[//]: # "1. Upload the source material through [Seedance Asset Upload API](/models/seedance/asset-upload)"
[//]: # "2. Query [Seedance Asset Info API](/models/seedance/asset-info) until `Status` becomes `Active`"
[//]: # "3. Pass the returned `AssetId` into `reference_images`, `reference_videos`, or `reference_audios`"
[//]: #
[//]: # ""
[//]: # " These fields also support normal public URLs. For uploaded image, video, and audio materials, only URL upload is supported and Base64 is not supported. "
[//]: # " If your reference images or videos contain real faces, it is recommended that you upload them to the material library for review first to improve the success rate of generation."
[//]: # ""
[//]: #
[//]: # "## Request Example Using Uploaded Assets"
[//]: #
[//]: # "```json"
[//]: # "{"
[//]: # " \"model\": \"bytedance/seedance2-0-fast-r2v\","
[//]: # " \"callback_url\": \"https://your-domain.com/api/callback\","
[//]: # " \"input\": {"
[//]: # " \"prompt\": \"[Image1] the boy wearing glasses and a blue T-shirt and the corgi from [Image2] sit on the lawn from [Image3] in a 3D cartoon style, with background audio based on [Audio1].\","
[//]: # " \"reference_images\": ["
[//]: # " \"asset://asset-20260224185115-jtzz8\","
[//]: # " \"asset://asset-20260224185203-r8k2m\","
[//]: # " \"asset://asset-20260224185221-q6w7n\""
[//]: # " ],"
[//]: # " \"reference_audios\": ["
[//]: # " \"asset://asset-20260224185411-k3n6x\""
[//]: # " ],"
[//]: # " \"resolution\": \"720p\","
[//]: # " \"aspect_ratio\": \"16:9\","
[//]: # " \"duration\": 8,"
[//]: # " \"audio\": true,"
[//]: # " \"return_last_frame\": false"
[//]: # " }"
[//]: # "}"
[//]: # "```"
## Query Task Status
After submitting a task, use the unified query endpoint to check progress and retrieve results:
Learn how to query task status and retrieve generation results
For production use, we recommend using the `callback_url` parameter to receive automatic notifications when generation completes, rather than polling the status endpoint.
## Related Resources
Upload custom assets before using them in Seedance requests
Wait until uploaded assets become active
Explore all available models
Check credits and account usage
## OpenAPI
````yaml models/seedance/2-0-fast/reference-to-video.json post /api/v1/client/job/CreateTask
openapi: 3.0.0
info:
title: Crun Seedance API
description: crun.ai Seedance API Documentation
version: 1.0.0
contact:
name: Technical Support
email: support@crun.ai
servers:
- url: https://api.crun.ai
description: API Server
security:
- ApiKeyAuth: []
paths:
/api/v1/client/job/CreateTask:
post:
summary: Generate video using seedance2.0 fast
operationId: bytedance/seedance2-0-fast-r2v
requestBody:
required: true
content:
application/json:
schema:
type: object
required:
- model
- input
properties:
model:
type: string
enum:
- bytedance/seedance2-0-fast-r2v
description: |-
The model name to use for generation. Required field.
- Must be `bytedance/seedance2-0-fast-r2v` for this endpoint
callback_url:
type: string
format: uri
description: >-
Optional. Callback URL for receiving task completion
notifications.
- System will POST task status and results to this URL when
generation completes
- Callback payloads structure is consistent with the `data`
object returned by the task status query
- Your callback endpoint should accept POST requests with
JSON payload containing results
- It returns an HTTP 200 status code upon successful receipt
example: https://your-domain.com/api/callback
input:
type: object
description: >-
Input parameters for the reference-to-video generation task
(Seedance 2.0 Fast). At least one of `reference_images` or
`reference_videos` must be provided.
properties:
prompt:
type: string
description: >-
Text prompt describing the target scene, motion, and how
the references should be used. You can explicitly refer
to uploaded assets in natural language with placeholders
such as `[Image1]` / `[图1]`, `[Video1]` / `[视频1]`, and
`[Audio1]` / `[音频1]`. Example: `[Image1] the boy wearing
glasses and a blue T-shirt and the corgi from [Image2]
sit on the lawn from [Image3] in a 3D cartoon style,
with background audio based on [Audio1].`
minLength: 1
maxLength: 5000
example: >-
Create a fashion commercial shot that preserves the
model's appearance from the reference images, follows
the walking rhythm of the reference video, and matches
the mood of the reference audio.
reference_images:
type: array
description: >-
Optional reference images used to guide subject
identity, style, costume, or scene details. Each item
must be either a public image URL or an uploaded AssetId
whose status is Active. Use [Seedance Asset Upload
API](/models/seedance/asset-upload) to upload custom
assets and [Seedance Asset Info
API](/models/seedance/asset-info) to query asset status.
Each image must meet these requirements:
- Input method: public URL or active uploaded AssetId
only
- Base64 is not supported
- Formats: jpeg, png, webp, bmp, tiff, gif, heic, heif
- Aspect ratio (width/height): greater than 0.4 and less
than 2.5
- Width and height: 300 to 6000 px
- File size: less than 30 MB per image
items:
type: string
format: uri
example: https://example.com/reference-image-1.png
maxItems: 9
example:
- https://example.com/reference-image-1.png
- https://example.com/reference-image-2.png
reference_videos:
type: array
description: >-
Optional reference videos used to guide motion, pacing,
or shot language. Each item must be either a public
video URL or an uploaded AssetId whose status is Active.
Use [Seedance Asset Upload
API](/models/seedance/asset-upload) to upload custom
assets and [Seedance Asset Info
API](/models/seedance/asset-info) to query asset status.
Each video must meet these requirements:
- Input method: public URL or active uploaded AssetId
only
- Base64 is not supported
- Formats: mp4, mov
- Resolution: 480p or 720p
- Duration: 2 to 15 seconds per video
- Up to 3 reference videos; total reference video
duration must not exceed 15 seconds
- Aspect ratio (width/height): 0.4 to 2.5
- Width and height: 300 to 6000 px
- Total pixel count (width x height): 409600 to 927408
- File size: up to 50 MB per video
- Frame rate: 24 to 60 FPS
items:
type: string
format: uri
example: https://example.com/reference-video-1.mp4
maxItems: 3
example:
- https://example.com/reference-video-1.mp4
reference_audios:
type: array
description: >-
Optional reference audios used to guide rhythm or sound
design. To receive audio in the final result, set the
audio field to true. Each item must be either a public
audio URL or an uploaded AssetId whose status is Active.
Use [Seedance Asset Upload
API](/models/seedance/asset-upload) to upload custom
assets and [Seedance Asset Info
API](/models/seedance/asset-info) to query asset status.
Each audio clip must meet these requirements:
- Input method: public URL or active uploaded AssetId
only
- Base64 is not supported
- Formats: wav, mp3
- Duration: 2 to 15 seconds per clip
- Up to 3 reference audios; total reference audio
duration must not exceed 15 seconds
- File size: up to 15 MB per clip
items:
type: string
format: uri
example: https://example.com/reference-audio-1.mp3
maxItems: 3
example:
- https://example.com/reference-audio-1.mp3
return_last_frame:
type: boolean
deprecated: true
description: Whether to return the last frame of the generated video
default: false
example: false
audio:
type: boolean
description: >-
Whether to generate synchronized audio for the output
video
default: false
example: true
resolution:
type: string
description: Output video resolution
enum:
- 480p
- 720p
default: 720p
example: 720p
aspect_ratio:
type: string
description: Aspect ratio of the generated video
enum:
- '1:1'
- '9:16'
- '16:9'
- '3:4'
- '4:3'
- '21:9'
- auto
default: auto
example: '16:9'
duration:
type: integer
description: >-
Video duration in seconds. Supports any integer from 4
to 15
minimum: 4
maximum: 15
default: 5
example: 8
required:
- prompt
anyOf:
- required:
- reference_images
- required:
- reference_videos
example:
model: bytedance/seedance2-0-fast-r2v
callback_url: https://your-domain.com/api/callback
input:
prompt: >-
[Image1] the boy wearing glasses and a blue T-shirt and the
corgi from [Image2] sit on the lawn from [Image3] in a 3D
cartoon style, with background audio based on [Audio1].
reference_images:
- https://example.com/reference-image-1.png
- https://example.com/reference-image-2.png
- https://example.com/reference-image-3.png
reference_audios:
- https://example.com/reference-audio-1.mp3
resolution: 720p
aspect_ratio: '16:9'
duration: 8
audio: true
return_last_frame: false
responses:
'200':
description: Request successful
content:
application/json:
schema:
allOf:
- $ref: '#/components/schemas/ApiResponse'
- type: object
properties:
data:
type: object
properties:
task_id:
type: string
description: >-
Task ID, can be used with Get Task Details
endpoint to query task status
example: task_12345678
example:
code: 200
message: success
data:
task_id: task_12345678
'422':
description: Validation Error
content:
application/json:
schema:
allOf:
- $ref: '#/components/schemas/ApiResponse'
- type: object
properties:
errors:
type: array
description: Detailed validation error messages
items:
type: string
example:
- specific error field message
example:
code: 422
message: Missing Params or Type Error
errors:
- specific error field message
'500':
$ref: '#/components/responses/Error'
components:
schemas:
ApiResponse:
type: object
properties:
code:
type: integer
enum:
- 200
- 401
- 402
- 404
- 422
- 429
- 455
- 500
- 501
- 505
description: >-
Response status code
- **200**: Success - Request has been processed successfully
- **401**: Unauthorized - Authentication credentials are missing or
invalid
- **402**: Insufficient Credits - Account does not have enough
credits to perform the operation
- **404**: Not Found - The requested resource or endpoint does not
exist
- **422**: Validation Error - The request parameters failed
validation checks
- **429**: Rate Limited - Request limit has been exceeded for this
resource
- **455**: Service Unavailable - System is currently undergoing
maintenance
- **500**: Server Error - An unexpected error occurred while
processing the request
- **501**: Generation Failed - Content generation task failed
- **505**: Feature Disabled - The requested feature is currently
disabled
message:
type: string
description: Response message, error description when failed
example: success
responses:
Error:
description: Server Error
securitySchemes:
ApiKeyAuth:
type: apiKey
in: header
name: x-api-key
description: >-
All APIs require authentication via API Key.
Get API Key:
1. Visit [API Key Management Page](https://crun.ai/user-api-key) to get
your API Key
Usage:
Add to request header:
x-api-key: YOUR_API_KEY
Note:
- Keep your API Key secure and do not share it with others
- If you suspect your API Key has been compromised, reset it immediately
in the management page
````