AI Video Generation Callbacks

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

TIP

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

Callback Request Format

When the task is completed, the system will send a POST request to your callBackUrl in the following format:

Success 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"
  }
}

Failure Callback

{
  "code": 400,
  "msg": "Inappropriate content detected. Please replace the image or video.",
  "data": {
    "task_id": "ee603959-debb-48d1-98c4-a6d1c717eba6",
    "video_id": "",
    "video_url": "",
    "image_url": ""
  }
}

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	Yes	Generated video ID for identification and tracking
data.video_url	string	No	Accessible video URL, valid for 14 days. Empty on failure
data.image_url	string	No	Cover image URL of the generated video. Empty on failure

Status Code Details

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

Common Error Messages

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!"

Callback Reception Examples

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

Node.js

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');
});

Python

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

<?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

1. Use HTTPS: Ensure your callback URL uses HTTPS protocol for secure data transmission
2. Verify Source: Verify the legitimacy of the request source in callback processing
3. Idempotent Processing: The same task_id may receive multiple callbacks, ensure processing logic is idempotent
4. Quick Response: Callback processing should return a 200 status code as quickly as possible to avoid timeout
5. Asynchronous Processing: Complex business logic should be processed asynchronously to avoid blocking callback response
6. Immediate Download: Video URLs are valid for only 14 days, download and save files immediately upon success

:::caution 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:

• 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

• 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.