AI Video Generation Callbacks
When video generation is complete, the system will send a POST request to the provided callback URL to notify the result
When you submit a video generation task to the Runway API, you can use the callBackUrl parameter to set a callback URL. The system will automatically push the results to your specified address when the task is completed.
Callback Mechanism Overview
The callback mechanism eliminates the need to poll the API for task status. The system will proactively push task completion results to your server.
Callback Timing
The system will send callback notifications in the following situations:
AI video generation task completed successfully
AI video generation task failed
Errors occurred during task processing
Callback Method
HTTP Method : POST
Content Type : application/json
Timeout Setting : 15 seconds
When the task is completed, 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" : {
"task_id" : "ee603959-debb-48d1-98c4-a6d1c717eba6" ,
"video_id" : "485da89c-7fca-4340-8c04-101025b2ae71" ,
"video_url" : "https://file.com/k/xxxxxxx.mp4" ,
"image_url" : "https://file.com/m/xxxxxxxx.png"
}
}
Status Code Description
Callback status code indicating task processing result: Status Code Description 200 Success - Video generation completed successfully 400 Client Error - Inappropriate content, format error, quota limit, or other client-side issues 500 Server Error - Internal server error during video generation
Status message providing detailed status description. Common error messages include:
“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.”
“Your prompt was caught by our AI moderator. Please adjust it and try again!”
Task ID, consistent with the taskId returned when you submitted the task
Generated video ID for identification and tracking
Accessible video URL, valid for 14 days . Empty on failure.
Cover image URL of the generated video. Empty on failure.
Callback Reception Examples
Here are example codes for receiving callbacks in popular programming languages:
const express = require ( 'express' );
const fs = require ( 'fs' );
const https = require ( 'https' );
const path = require ( 'path' );
const app = express ();
app . use ( express . json ());
app . post ( '/runway-video-callback' , ( req , res ) => {
const { code , msg , data } = req . body ;
console . log ( 'Received Runway video generation callback:' , {
taskId: data . task_id ,
videoId: data . video_id ,
status: code ,
message: msg
});
if ( code === 200 ) {
// Task completed successfully
console . log ( 'Runway video generation completed successfully' );
const { task_id , video_id , video_url , image_url } = data ;
console . log ( `Video URL: ${ video_url } ` );
console . log ( `Cover Image URL: ${ image_url } ` );
console . log ( 'Note: Video URL is valid for 14 days' );
// Download video file
if ( video_url ) {
downloadFile ( video_url , `runway_video_ ${ task_id } .mp4` )
. then (() => console . log ( 'Video downloaded successfully' ))
. catch ( err => console . error ( 'Video download failed:' , err ));
}
// Download cover image
if ( image_url ) {
downloadFile ( image_url , `runway_cover_ ${ task_id } .png` )
. then (() => console . log ( 'Cover image downloaded successfully' ))
. catch ( err => console . error ( 'Cover image download failed:' , err ));
}
} else {
// Task failed
console . log ( 'Runway video generation failed:' , msg );
// Handle specific error types
if ( code === 400 ) {
console . log ( 'Client error - check content, format, or quota' );
} else if ( code === 500 ) {
console . log ( 'Server error - retry may be needed' );
}
}
// Return 200 status code to confirm callback received
res . status ( 200 ). json ({ status: 'received' });
});
// Helper function to download files
function downloadFile ( url , filename ) {
return new Promise (( resolve , reject ) => {
const file = fs . createWriteStream ( filename );
https . get ( url , ( response ) => {
if ( response . statusCode === 200 ) {
response . pipe ( file );
file . on ( 'finish' , () => {
file . close ();
resolve ();
});
} else {
reject ( new Error ( `HTTP ${ response . statusCode } ` ));
}
}). on ( 'error' , reject );
});
}
app . listen ( 3000 , () => {
console . log ( 'Callback server running on port 3000' );
});
from flask import Flask, request, jsonify
import requests
import os
app = Flask( __name__ )
@app.route ( '/runway-video-callback' , methods = [ 'POST' ])
def handle_callback ():
data = request.json
code = data.get( 'code' )
msg = data.get( 'msg' )
callback_data = data.get( 'data' , {})
task_id = callback_data.get( 'task_id' )
video_id = callback_data.get( 'video_id' )
video_url = callback_data.get( 'video_url' )
image_url = callback_data.get( 'image_url' )
print ( f "Received Runway video generation callback:" )
print ( f "Task ID: { task_id } , Video ID: { video_id } " )
print ( f "Status: { code } , Message: { msg } " )
if code == 200 :
# Task completed successfully
print ( "Runway video generation completed successfully" )
print ( f "Video URL: { video_url } " )
print ( f "Cover Image URL: { image_url } " )
print ( "Note: Video URL is valid for 14 days" )
# Download video file
if video_url:
try :
video_filename = f "runway_video_ { task_id } .mp4"
download_file(video_url, video_filename)
print ( f "Video downloaded as { video_filename } " )
except Exception as e:
print ( f "Video download failed: { e } " )
# Download cover image
if image_url:
try :
image_filename = f "runway_cover_ { task_id } .png"
download_file(image_url, image_filename)
print ( f "Cover image downloaded as { image_filename } " )
except Exception as e:
print ( f "Cover image download failed: { e } " )
else :
# Task failed
print ( f "Runway video generation failed: { msg } " )
# Handle specific error types
if code == 400 :
print ( "Client error - check content, format, or quota" )
elif code == 500 :
print ( "Server error - retry may be needed" )
# Return 200 status code to confirm callback received
return jsonify({ 'status' : 'received' }), 200
def download_file ( url , filename ):
"""Download file from URL and save locally"""
response = requests.get(url, stream = True )
response.raise_for_status()
os.makedirs( 'downloads' , exist_ok = True )
filepath = os.path.join( 'downloads' , filename)
with open (filepath, 'wb' ) as f:
for chunk in response.iter_content( chunk_size = 8192 ):
f.write(chunk)
if __name__ == '__main__' :
app.run( host = '0.0.0.0' , port = 3000 )
<? php
header ( 'Content-Type: application/json' );
// Get POST data
$input = file_get_contents ( 'php://input' );
$data = json_decode ( $input , true );
$code = $data [ 'code' ] ?? null ;
$msg = $data [ 'msg' ] ?? '' ;
$callbackData = $data [ 'data' ] ?? [];
$taskId = $callbackData [ 'task_id' ] ?? '' ;
$videoId = $callbackData [ 'video_id' ] ?? '' ;
$videoUrl = $callbackData [ 'video_url' ] ?? '' ;
$imageUrl = $callbackData [ 'image_url' ] ?? '' ;
error_log ( "Received Runway video generation callback:" );
error_log ( "Task ID: $taskId , Video ID: $videoId " );
error_log ( "Status: $code , Message: $msg " );
if ( $code === 200 ) {
// Task completed successfully
error_log ( "Runway video generation completed successfully" );
error_log ( "Video URL: $videoUrl " );
error_log ( "Cover Image URL: $imageUrl " );
error_log ( "Note: Video URL is valid for 14 days" );
// Download video file
if ( ! empty ( $videoUrl )) {
try {
$videoFilename = "runway_video_{ $taskId }.mp4" ;
downloadFile ( $videoUrl , $videoFilename );
error_log ( "Video downloaded as $videoFilename " );
} catch ( Exception $e ) {
error_log ( "Video download failed: " . $e -> getMessage ());
}
}
// Download cover image
if ( ! empty ( $imageUrl )) {
try {
$imageFilename = "runway_cover_{ $taskId }.png" ;
downloadFile ( $imageUrl , $imageFilename );
error_log ( "Cover image downloaded as $imageFilename " );
} catch ( Exception $e ) {
error_log ( "Cover image download failed: " . $e -> getMessage ());
}
}
} else {
// Task failed
error_log ( "Runway video generation failed: $msg " );
// Handle specific error types
if ( $code === 400 ) {
error_log ( "Client error - check content, format, or quota" );
} elseif ( $code === 500 ) {
error_log ( "Server error - retry may be needed" );
}
}
// Return 200 status code to confirm callback received
http_response_code ( 200 );
echo json_encode ([ 'status' => 'received' ]);
function downloadFile ( $url , $filename ) {
$downloadDir = 'downloads' ;
if ( ! is_dir ( $downloadDir )) {
mkdir ( $downloadDir , 0755 , true );
}
$filepath = $downloadDir . '/' . $filename ;
$fileContent = file_get_contents ( $url );
if ( $fileContent === false ) {
throw new Exception ( "Failed to download file from URL" );
}
$result = file_put_contents ( $filepath , $fileContent );
if ( $result === false ) {
throw new Exception ( "Failed to save file locally" );
}
}
?>
Best Practices
Callback URL Configuration Recommendations
Use HTTPS : Ensure your 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 a 200 status code as quickly as possible to avoid timeout
Asynchronous Processing : Complex business logic should be processed asynchronously to avoid blocking callback response
Immediate Download : Video URLs are valid for only 14 days, download and save files immediately upon success
Important Reminders
Callback URL must be a publicly accessible address
Server must respond within 15 seconds, otherwise it will be considered a timeout
If 3 consecutive retries fail, the system will stop sending callbacks
Video URLs expire after 14 days - download immediately upon receiving callback
Please ensure the stability of callback processing logic to avoid callback failures due to exceptions
Handle both video_url and image_url fields for complete media management
Pay attention to error messages for specific failure reasons (content moderation, format issues, quotas)
Troubleshooting
If you do not receive callback notifications, please check the following:
Network Connection Issues
Confirm that the callback URL is accessible from the public network
Check firewall settings to ensure inbound requests are not blocked
Verify that domain name resolution is correct
Ensure the server returns HTTP 200 status code within 15 seconds
Check server logs for error messages
Verify that the interface path and HTTP method are correct
Confirm that the received POST request body is in JSON format
Check that Content-Type is application/json
Verify that JSON parsing is correct
Confirm that video URLs are accessible
Check video download permissions and network connections
Verify video save paths and permissions
Note the 14-day URL expiration - implement immediate download logic
Handle both video and cover image downloads
Content Moderation Issues
Review error messages for content policy violations
Adjust prompts if flagged by AI moderator
Ensure uploaded images/videos meet content guidelines
Check for inappropriate content detection messages
Alternative Solution
If you cannot use the callback mechanism, you can also use polling:
Poll Query Results Use the get AI video details endpoint to regularly query task status. We recommend querying every 30 seconds.
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