> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apikley.ru/llms.txt
> Use this file to discover all available pages before exploring further.

# Runway api extend ai video callbacks

# AI Video Extension Callbacks

> The system calls this callback to notify results when video extension is completed

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

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

### 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:

<CodeGroup>
  ```json Success Callback theme={null} theme={null}
  {
    "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"
    }
  }
  ```

  ```json Failure Callback theme={null} theme={null}
  {
    "code": 400,
    "msg": "Get image info failed.",
    "data": {
      "task_id": "ee603959-debb-48d1-98c4-a6d1c717eba6"
    }
  }
  ```
</CodeGroup>

## Status Code Description

<ParamField path="code" type="integer" required>
  Callback status code indicating task processing result:

  | 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    |
</ParamField>

<ParamField path="msg" type="string" required>
  Status message providing detailed status description. 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
</ParamField>

<ParamField path="data.task_id" type="string" required>
  Task ID, consistent with the taskId returned when you submitted the task
</ParamField>

<ParamField path="data.video_id" type="string">
  Video unique identifier (returned only on success)
</ParamField>

<ParamField path="data.video_url" type="string">
  Accessible video URL, valid for 14 days (returned only on success)
</ParamField>

<ParamField path="data.image_url" type="string">
  Cover image URL of the generated video (returned only on success)
</ParamField>

## Callback Reception Examples

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

<Tabs>
  <Tab title="Node.js">
    ```javascript theme={null} theme={null}
    const express = require('express');
    const fs = require('fs');
    const https = require('https');
    const app = express();

    app.use(express.json());

    app.post('/runway-extend-callback', (req, res) => {
      const { code, msg, data } = req.body;
      
      console.log('Received Runway video extension callback:', {
        taskId: data.task_id,
        status: code,
        message: msg
      });
      
      if (code === 200) {
        // Video extension successful
        const { task_id, video_id, video_url, image_url } = data;
        
        console.log('Video extension successful!');
        console.log(`Task ID: ${task_id}`);
        console.log(`Video ID: ${video_id}`);
        console.log(`Video URL: ${video_url}`);
        console.log(`Cover URL: ${image_url}`);
        
        // Download video file
        if (video_url) {
          downloadFile(video_url, `runway_extend_${task_id}.mp4`)
            .then(() => console.log('Video download successful'))
            .catch(err => console.error('Video download failed:', err));
        }
        
        // Download cover image
        if (image_url) {
          downloadFile(image_url, `runway_extend_cover_${task_id}.png`)
            .then(() => console.log('Cover download successful'))
            .catch(err => console.error('Cover download failed:', err));
        }
        
      } else {
        // Video extension failed
        console.log('Runway video extension failed:', msg);
        
        // Handle specific error types
        if (code === 400) {
          console.log('Client error - Check input parameters and content');
        } else if (code === 500) {
          console.log('Server error - Please try again later');
        }
      }
      
      // Return 200 status code to confirm callback received
      res.status(200).json({ code: 200, msg: 'success' });
    });

    // Helper function: Download file
    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');
    });
    ```
  </Tab>

  <Tab title="Python">
    ```python theme={null} theme={null}
    from flask import Flask, request, jsonify
    import requests
    import os

    app = Flask(__name__)

    @app.route('/runway-extend-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')
        
        print(f"Received Runway video extension callback:")
        print(f"Task ID: {task_id}")
        print(f"Status: {code}, Message: {msg}")
        
        if code == 200:
            # Video extension successful
            video_id = callback_data.get('video_id')
            video_url = callback_data.get('video_url')
            image_url = callback_data.get('image_url')
            
            print("Video extension successful!")
            print(f"Video ID: {video_id}")
            print(f"Video URL: {video_url}")
            print(f"Cover URL: {image_url}")
            
            # Download video file
            if video_url:
                try:
                    video_filename = f"runway_extend_{task_id}.mp4"
                    download_file(video_url, video_filename)
                    print("Video download successful")
                except Exception as e:
                    print(f"Video download failed: {e}")
            
            # Download cover image
            if image_url:
                try:
                    image_filename = f"runway_extend_cover_{task_id}.png"
                    download_file(image_url, image_filename)
                    print("Cover download successful")
                except Exception as e:
                    print(f"Cover download failed: {e}")
                    
        else:
            # Video extension failed
            print(f"Runway video extension failed: {msg}")
            
            # Handle specific error types
            if code == 400:
                print("Client error - Check input parameters and content")
                if 'Inappropriate content' in msg:
                    print("Content moderation failed - Please replace image or video")
                elif 'Incorrect image format' in msg:
                    print("Format error - Please check image format")
                elif 'concurrent generations' in msg:
                    print("Concurrency limit - Please wait or upgrade membership")
                elif 'NSFW content' in msg:
                    print("Content violation - Please modify prompt")
            elif code == 500:
                print("Server error - Please try again later")
        
        # Return 200 status code to confirm callback received
        return jsonify({'code': 200, 'msg': 'success'}), 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)
    ```
  </Tab>

  <Tab title="PHP">
    ```php theme={null} theme={null}
    <?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'] ?? '';

    error_log("Received Runway video extension callback:");
    error_log("Task ID: $taskId");
    error_log("Status: $code, Message: $msg");

    if ($code === 200) {
        // Video extension successful
        $videoId = $callbackData['video_id'] ?? '';
        $videoUrl = $callbackData['video_url'] ?? '';
        $imageUrl = $callbackData['image_url'] ?? '';
        
        error_log("Video extension successful!");
        error_log("Video ID: $videoId");
        error_log("Video URL: $videoUrl");
        error_log("Cover URL: $imageUrl");
        
        // Download video file
        if (!empty($videoUrl)) {
            try {
                $videoFilename = "runway_extend_{$taskId}.mp4";
                downloadFile($videoUrl, $videoFilename);
                error_log("Video download successful");
            } catch (Exception $e) {
                error_log("Video download failed: " . $e->getMessage());
            }
        }
        
        // Download cover image
        if (!empty($imageUrl)) {
            try {
                $imageFilename = "runway_extend_cover_{$taskId}.png";
                downloadFile($imageUrl, $imageFilename);
                error_log("Cover download successful");
            } catch (Exception $e) {
                error_log("Cover download failed: " . $e->getMessage());
            }
        }
        
    } else {
        // Video extension failed
        error_log("Runway video extension failed: $msg");
        
        // Handle specific error types
        if ($code === 400) {
            error_log("Client error - Check input parameters and content");
            if (strpos($msg, 'Inappropriate content') !== false) {
                error_log("Content moderation failed - Please replace image or video");
            } elseif (strpos($msg, 'Incorrect image format') !== false) {
                error_log("Format error - Please check image format");
            } elseif (strpos($msg, 'concurrent generations') !== false) {
                error_log("Concurrency limit - Please wait or upgrade membership");
            } elseif (strpos($msg, 'NSFW content') !== false) {
                error_log("Content violation - Please modify prompt");
            }
        } elseif ($code === 500) {
            error_log("Server error - Please try again later");
        }
    }

    // Return 200 status code to confirm callback received
    http_response_code(200);
    echo json_encode(['code' => 200, 'msg' => 'success']);

    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");
        }
    }
    ?>
    ```
  </Tab>
</Tabs>

## Best Practices

<Tip>
  ### Callback URL Configuration Recommendations

  1. **Use HTTPS**: Ensure 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 200 status code promptly to avoid timeout
  5. **Asynchronous Processing**: Complex business logic should be processed asynchronously to avoid blocking callback response
  6. **Timely Download**: Video URLs are valid for only 14 days, please download and save promptly
  7. **Extension Management**: Properly manage extended video files and cover images
</Tip>

<Warning>
  ### 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
</Warning>

## Troubleshooting

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

<AccordionGroup>
  <Accordion title="Network Connection Issues">
    * Confirm that the callback URL is accessible from the public internet
    * Check firewall settings to ensure inbound requests are not blocked
    * Verify domain name resolution is correct
  </Accordion>

  <Accordion title="Server Response Issues">
    * Ensure server returns HTTP 200 status code within 15 seconds
    * Check server logs for error messages
    * Verify interface path and HTTP method are correct
  </Accordion>

  <Accordion title="Content Format Issues">
    * Confirm that the received POST request body is in JSON format
    * Check if Content-Type is application/json
    * Verify JSON parsing is correct
  </Accordion>

  <Accordion title="Video Processing Issues">
    * Confirm that video URL is accessible
    * Check video download permissions and network connection
    * Verify video save path and permissions
    * Note the 14-day validity period limitation of video URLs
    * Backup videos to long-term storage system promptly
  </Accordion>

  <Accordion title="Content Moderation Issues">
    * Review content moderation error messages
    * Ensure input images or videos do not contain inappropriate content
    * Check if prompts comply with platform policies
    * Avoid using NSFW-related descriptive words
    * Ensure image format is correct and dimensions are appropriate
  </Accordion>

  <Accordion title="Concurrency Limit Issues">
    * Monitor current concurrent task count
    * Implement appropriate task queue mechanism
    * Consider upgrading to Standard membership for higher concurrency limits
    * Reasonably schedule task submission times
  </Accordion>

  <Accordion title="Extension Quality Issues">
    * Check coherence of extended videos
    * Verify if video duration meets expectations
    * Evaluate quality and style consistency of extended portions
    * Ensure extended videos transition naturally
  </Accordion>
</AccordionGroup>

## Extension-Specific Considerations

<Note>
  ### AI Video Extension Features

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

  1. **Duration Increase**: Extended videos will be longer than original videos
  2. **Style Continuation**: The system tries to maintain the visual style and motion patterns of the original video
  3. **Smooth Transition**: Extended portions will naturally connect with the original video
  4. **Quality Preservation**: Extended video quality should be comparable to the original video
  5. **Motion Coherence**: Object movement and scene changes will maintain logical coherence
  6. **URL Validity**: Generated video URLs are valid for only 14 days
</Note>

## Alternative Approach

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

<Card title="Poll Query Results" icon="radar" href="/runway-api/get-ai-video-details">
  Use the Get AI Video Details interface to periodically query task status, recommended every 30 seconds.
</Card>

***

> To find navigation and other pages in this documentation, fetch the llms.txt file at: [https://docs.apikley.ru/llms.txt](https://docs.apikley.ru/llms.txt)

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