AI Video Extension Callbacks

When you submit a video extension task to the Runway API, you can set a callback address through the callBackUrl parameter. After the task is completed, the system will automatically push the results to your specified address.

Callback Mechanism Overview

The callback mechanism eliminates the need to poll the API for task status. The system proactively pushes task completion results to your server.

Callback Timing

The system sends callback notifications in the following situations:

Video extension task successfully completed

Video extension task failed

Errors occurred during task processing

Callback Method

HTTP Method: POST

Content Type: application/json

Timeout: 15 seconds

Callback Request Format

After task completion, the system will send a POST request to your callBackUrl in the following format:

Success Callback

Failure Callback

{
  "code": 200,
  "msg": "All generated successfully.",
  "data": {
    "image_url": "https://file.com/m/xxxxxxxx.png",
    "task_id": "ee603959-debb-48d1-98c4-a6d1c717eba6",
    "video_id": "485da89c-7fca-4340-8c04-101025b2ae71",
    "video_url": "https://file.com/k/xxxxxxx.mp4"
  }
}

Status Code Description

Parameter Description

Parameter	Type	Required	Description
`code`	integer	Yes	Callback status code indicating task processing result
`msg`	string	Yes	Status message providing detailed status description
`data.task_id`	string	Yes	Task ID, consistent with the taskId returned when you submitted the task
`data.video_id`	string	No	Video unique identifier (returned only on success)
`data.video_url`	string	No	Accessible video URL, valid for 14 days (returned only on success)
`data.image_url`	string	No	Cover image URL of the generated video (returned only on success)

Status Code Details

Status Code	Description
200	Success - Request has been processed successfully
400	Client Error - Request parameters are incorrect or content is inappropriate
500	Server Error - An unexpected error occurred while processing the request

Common Error Messages

When code is 400, possible error messages include:

Get image info failed

Inappropriate content detected. Please replace the image or video

Incorrect image format

Please try again later. You can upgrade to Standard membership to start generating now

Reached the limit for concurrent generations

Unsupported width or height. Please adjust the size and try again

Upload failed due to network reasons, please re-enter

Your prompt was caught by our AI moderator. Please adjust it and try again!

Your prompt/negative prompt cannot exceed 2048 characters. Please check if your input is too long

Your video creation prompt contains NSFW content, which isn't allowed under our policy. Kindly revise your prompt and generate again

Callback Reception Examples

Here are example codes for receiving callbacks in popular programming languages:

Node.js

Python

PHP

Best Practices

Callback URL Configuration Recommendations

Use HTTPS: Ensure callback URL uses HTTPS protocol for secure data transmission

Verify Source: Verify the legitimacy of the request source in callback processing

Idempotent Processing: The same task_id may receive multiple callbacks, ensure processing logic is idempotent

Quick Response: Callback processing should return 200 status code promptly to avoid timeout

Asynchronous Processing: Complex business logic should be processed asynchronously to avoid blocking callback response

Timely Download: Video URLs are valid for only 14 days, please download and save promptly

Extension Management: Properly manage extended video files and cover images

Important Reminders

Callback URL must be publicly accessible

Server must respond within 15 seconds, otherwise it will be considered timeout

After 3 consecutive retry failures, the system will stop sending callbacks

Video URLs are valid for only 14 days, please download and save to your storage system promptly

Ensure the stability of callback processing logic to avoid callback failures due to exceptions

Properly handle content moderation errors to ensure input content complies with platform policies

Extended videos are usually longer than original videos

Pay attention to concurrent generation limits to avoid submitting too many tasks simultaneously

Troubleshooting

If you don't receive callback notifications, please check the following:

Network Connection Issues

Server Response Issues

Content Format Issues

Video Processing Issues

Content Moderation Issues

Concurrency Limit Issues

Extension Quality Issues

Extension-Specific Considerations

AI Video Extension Features

AI video extension functionality continues generation based on existing videos with the following characteristics:

Duration Increase: Extended videos will be longer than original videos

Style Continuation: The system tries to maintain the visual style and motion patterns of the original video

Smooth Transition: Extended portions will naturally connect with the original video

Quality Preservation: Extended video quality should be comparable to the original video

Motion Coherence: Object movement and scene changes will maintain logical coherence

URL Validity: Generated video URLs are valid for only 14 days

Alternative Approach

If you cannot use the callback mechanism, you can also use polling:

Poll Query Results

Use the Get AI Video Details interface to periodically query task status, recommended every 30 seconds.

AI Video Extension Callbacks

Callback Mechanism Overview#

Callback Timing#

Callback Method#

Callback Request Format#

Status Code Description#

Parameter Description#

Status Code Details#

Common Error Messages#

Callback Reception Examples#

Best Practices#

Troubleshooting#

Extension-Specific Considerations#

Alternative Approach#

Callback Mechanism Overview

Callback Timing

Callback Method

Callback Request Format

Status Code Description

Parameter Description

Status Code Details

Common Error Messages

Callback Reception Examples

Best Practices

Troubleshooting

Extension-Specific Considerations

Alternative Approach