curl --request POST \
  --url https://api.evolink.ai/v1/videos/generations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "seedance-2.5-video-extend",
  "prompt": "Extend @video1 backward: the character walks out of the frame, the camera slowly pulls back to reveal the empty street",
  "video_urls": [
    "https://example.com/original.mp4"
  ],
  "duration": 12,
  "quality": "720p",
  "generate_audio": true,
  "content_filter": true
}
'

{
  "created": 1761313744,
  "id": "task-unified-1774857405-abc123",
  "model": "seedance-2.5-video-extend",
  "object": "video.generation.task",
  "progress": 0,
  "status": "pending",
  "task_info": {
    "can_cancel": true,
    "estimated_time": 165,
    "video_duration": 8
  },
  "type": "video",
  "usage": {
    "billing_rule": "per_second",
    "credits_reserved": 50,
    "user_group": "default"
  }
}

{
  "error": {
    "code": "invalid_parameter",
    "message": "Invalid request parameters",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid or expired token",
    "type": "authentication_error"
  }
}

{
  "error": {
    "code": "insufficient_quota",
    "message": "Insufficient quota. Please top up your account.",
    "type": "insufficient_quota"
  }
}

{
  "error": {
    "code": "model_access_denied",
    "message": "Token does not have access to model: seedance-2.5-video-extend",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "rate_limit_exceeded",
    "message": "Too many requests, please try again later",
    "type": "rate_limit_error"
  }
}

{
  "error": {
    "code": "internal_error",
    "message": "Internal server error",
    "type": "api_error"
  }
}

Seedance 2.5

Seedance 2.5 Video Extend

Extend an input video forward or backward
Prompt must state the extension intent (e.g. “Extend @video1 backward, the character walks out of the frame”)
Input the video to extend (required) + optional reference images (0–30) + reference videos (up to 10 in total) + reference audio (0–10)
Now supports AIGC realistic human materials
Asynchronous processing mode, use the returned task ID to query status
Generated video links are valid for 24 hours, please save them promptly

POST

videos

generations

curl --request POST \
  --url https://api.evolink.ai/v1/videos/generations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "seedance-2.5-video-extend",
  "prompt": "Extend @video1 backward: the character walks out of the frame, the camera slowly pulls back to reveal the empty street",
  "video_urls": [
    "https://example.com/original.mp4"
  ],
  "duration": 12,
  "quality": "720p",
  "generate_audio": true,
  "content_filter": true
}
'

{
  "created": 1761313744,
  "id": "task-unified-1774857405-abc123",
  "model": "seedance-2.5-video-extend",
  "object": "video.generation.task",
  "progress": 0,
  "status": "pending",
  "task_info": {
    "can_cancel": true,
    "estimated_time": 165,
    "video_duration": 8
  },
  "type": "video",
  "usage": {
    "billing_rule": "per_second",
    "credits_reserved": 50,
    "user_group": "default"
  }
}

{
  "error": {
    "code": "invalid_parameter",
    "message": "Invalid request parameters",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid or expired token",
    "type": "authentication_error"
  }
}

{
  "error": {
    "code": "insufficient_quota",
    "message": "Insufficient quota. Please top up your account.",
    "type": "insufficient_quota"
  }
}

{
  "error": {
    "code": "model_access_denied",
    "message": "Token does not have access to model: seedance-2.5-video-extend",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "rate_limit_exceeded",
    "message": "Too many requests, please try again later",
    "type": "rate_limit_error"
  }
}

{
  "error": {
    "code": "internal_error",
    "message": "Internal server error",
    "type": "api_error"
  }
}

Authorizations

Authorization

string

header

required

##All endpoints require Bearer Token authentication##

Get API Key:

Visit the API Key Management Page to obtain your API Key

Add to request header:

Authorization: Bearer YOUR_API_KEY

Body

application/json

model

enum<string>

default:seedance-2.5-video-extend

required

Video generation model name

Available options:

seedance-2.5-video-extend

Example:

"seedance-2.5-video-extend"

prompt

string

required

Text prompt describing the desired extension. Supports both Chinese and English, recommended no more than 500 characters for Chinese. Maximum prompt length: 10000 tokens

Details:

The prompt must state the extension intent, e.g., "Extend @video1 backward, the character walks out of the frame"
You can use natural language to specify the purpose of each material, e.g., "extend @video1 forward following the style of @image1"
The model will automatically understand the correspondence between material numbers and their intended uses

Example:

"Extend @video1 backward: the character walks out of the frame, the camera slowly pulls back to reveal the empty street"

video_urls

string<uri>[]

required

Input video URL array, required; 1–10 videos

Requirement: At least 1 video required — the video to extend. The first video is the video being extended; additional videos serve as references.

Role description:

Media Type	Role	Typical Usage
Video	`reference_video`	The video to extend (first video), camera movement or motion reference (additional videos)

Video requirements:

Supported formats: .mp4, .mov
Resolution: 480p, 720p, 1080p, 4K
Duration per video: 2 ~ 30 seconds, max 10 videos, total duration of all videos ≤ 30 seconds
Aspect ratio (width/height): 0.4 ~ 2.5
Width/height pixels: 300 ~ 6000 px
Frame pixels (width × height): 409,600 ~ 8,295,044 (e.g., 640×640 ~ 3326×2494)
Max size per video: 200MB
Frame rate: 24 ~ 60 FPS
Total request body size must not exceed 64MB, do not use Base64 encoding
Specific codec, resolution, and other media validity checks are performed by the upstream model
Using video references will increase costs (input video duration is counted in billing)
Video URLs must be directly accessible by the server

Required array length: 1 - 10 elements

Example:

["https://example.com/original.mp4"]

image_urls

string<uri>[]

Reference image URL array, optional; 1–30 images when provided

Requirement: video_urls is required for this model; images are optional supplementary references.

Role description:

Media Type	Role	Typical Usage
Image	`reference_image`	Style reference, product image, scene reference (specified via prompt)

Image requirements:

Supported formats: .jpeg, .png, .webp
Aspect ratio (width/height): 0.4 ~ 2.5
Width/height pixels: 300 ~ 6000 px
Max size per image: 30MB
Total request body size must not exceed 64MB, do not use Base64 encoding
Image URLs must be directly accessible by the server

Required array length: 1 - 30 elements

Example:

[
  "https://example.com/ref1.jpg",
  "https://example.com/ref2.jpg"
]

audio_urls

string<uri>[]

Reference audio URL array, optional; 1–10 clips when provided

Requirement: video_urls is required for this model; audio clips are optional supplementary references.

Role description:

Media Type	Role	Typical Usage
Audio	`reference_audio`	Background music, sound effects, voice/dialogue reference

Audio requirements:

Supported formats: .wav, .mp3
Duration per clip: 2 ~ 30 seconds, max 10 clips, total duration of all audio ≤ 30 seconds
Max size per clip: 15MB
Total request body size must not exceed 64MB, do not use Base64 encoding
Audio URLs must be directly accessible by the server

Required array length: 1 - 10 elements

Example:

["https://example.com/bgm.mp3"]

duration

integer

default:5

Output video duration (seconds), defaults to 5 seconds

Details:

Supports any integer value between 4–30 seconds
-1: automatic duration, settled by actual output length
Duration directly affects billing

Example:

12

quality

enum<string>

default:720p

Video resolution, defaults to 720p

Options:

480p: Lower clarity, lower cost
720p: Standard clarity, this is the default

Available options:

480p,

720p

Example:

"720p"

aspect_ratio

enum<string>

default:adaptive

Video aspect ratio, defaults to adaptive

Options:

adaptive: the output ratio follows the first input video, the only value this model accepts
Fixed ratios such as 16:9 or 9:16 are rejected

Available options:

adaptive

Example:

"adaptive"

generate_audio

boolean

default:true

Whether to generate synchronized audio, defaults to true

Options:

true: Video includes synchronized audio at no additional charge
false: Output silent video

Example:

true

content_filter

boolean

default:true

Content filter, enabled by default true

Options:

true: Standard content safety check, this is the default
false: Relaxes content restrictions, billed at +10% (1.1x). Illegal and prohibited content is always enforced regardless of this setting

Example:

true

output_format

enum<string>

default:mp4

Output container format, defaults to mp4

Options:

mp4: H.264 encoding with the best compatibility and standard color precision, this is the default
mov: H.264 + yuv444p chroma sampling + PCM audio for higher color fidelity, recommended for color grading, keying and compositing workflows. Browser inline playback may not support it; download and play with VLC / mpv / ffplay. No extra charge

Available options:

mp4,

mov

Example:

"mp4"

callback_url

string<uri>

HTTPS callback URL for task completion

Callback timing:

Triggered when the task is completed, failed, or cancelled
Sent after billing confirmation is complete

Security restrictions:

Only HTTPS protocol is supported
Callbacks to private IP addresses are prohibited (127.0.0.1, 10.x.x.x, 172.16-31.x.x, 192.168.x.x, etc.)
URL length must not exceed 2048 characters

Callback mechanism:

Timeout: 10 seconds
Up to 3 retries after failure (at 1/2/4 seconds after failure respectively)
Callback response body format is consistent with the task query endpoint response format
A 2xx status code is considered successful; other status codes trigger retries

Example:

"https://your-domain.com/webhooks/video-task-completed"

Response

Video generation task created successfully

created

integer

Task creation timestamp

Example:

1761313744

string

Task ID

Example:

"task-unified-1774857405-abc123"

model

string

Actual model name used

Example:

"seedance-2.5-video-extend"

object

enum<string>

Specific type of the task

Available options:

video.generation.task

progress

integer

Task progress percentage (0-100)

Required range: 0 <= x <= 100

Example:

0

status

enum<string>

Task status

Available options:

pending,

processing,

completed,

failed

Example:

"pending"

task_info

object

Video task details

Show child attributes

type

enum<string>

Output type of the task

Available options:

text,

image,

audio,

video

Example:

"video"

usage

object

Usage and billing information

Show child attributes

Image Series

Video Series

Audio Series

Text Series

Account Management

Task Management

File Management

Seedance 2.5 Video Extend

Authorizations

Body

Response