Music Extension Callbacks

When you submit a task to the Music Extension API, you can use the callBackUrl parameter to set a callback URL. When 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 will proactively push task completion results to your server.

Callback Timing

The system will send callback notifications in the following situations:

Music extension task completed successfully
Music extension 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:

{
  "code": 200,
  "msg": "All generated successfully.",
  "data": {
    "callbackType": "complete",
    "task_id": "2fac****9f72",
    "data": [
      {
        "id": "8551****662c",
        "audio_url": "https://example.cn/****.mp3",
        "source_audio_url": "https://example.cn/****.mp3",
        "stream_audio_url": "https://example.cn/****",
        "source_stream_audio_url": "https://example.cn/****",
        "image_url": "https://example.cn/****.jpeg",
        "source_image_url": "https://example.cn/****.jpeg",
        "prompt": "[Verse] Night city lights shining bright",
        "model_name": "chirp-v3-5",
        "title": "Iron Man",
        "tags": "electrifying, rock",
        "createTime": "2025-01-01 00:00:00",
        "duration": 228.28
      }
    ]
  }
}

Status Code Description

code

integer

required

Callback status code indicating task processing result:

Status Code	Description
200	Success - Music extension completed
400	Bad Request - Parameter error, content violation, etc.
451	Download Failed - Unable to download related files
500	Server Error - Please try again later

msg

string

required

Status message providing detailed status description

data.callbackType

string

required

Callback type indicating the current callback stage:

text: Text generation completed
first: First music track completed
complete: All music tracks completed
error: Task failed

data.task_id

string

required

Task ID, consistent with the taskId returned when you submitted the task

data.data

array

Music extension result information, returned on success

data.data[].id

string

Music unique identifier

data.data[].audio_url

string

Extended audio file URL

data.data[].source_audio_url

string

Original audio file URL

data.data[].stream_audio_url

string

Streaming audio URL

data.data[].source_stream_audio_url

string

Original streaming audio URL

data.data[].image_url

string

Cover image URL

data.data[].source_image_url

string

Original cover image URL

data.data[].prompt

string

Generation prompt/lyrics

data.data[].model_name

string

Model name used

data.data[].title

string

Music title

data.data[].tags

string

Music tags

data.data[].createTime

string

Creation time

data.data[].duration

number

Audio duration (seconds)

Callback Reception Examples

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

Node.js
Python
PHP

const express = require('express');
const app = express();

app.use(express.json());

app.post('/extend-music-callback', (req, res) => {
  const { code, msg, data } = req.body;
  
  console.log('Received music extension callback:', {
    taskId: data.task_id,
    callbackType: data.callbackType,
    status: code,
    message: msg
  });
  
  if (code === 200) {
    // Task completed successfully
    console.log('Music extension completed');
    const musicData = data.data || [];
    
    console.log(`Extended ${musicData.length} music tracks:`);
    musicData.forEach((music, index) => {
      console.log(`Music ${index + 1}:`);
      console.log(`  Title: ${music.title}`);
      console.log(`  Duration: ${music.duration} seconds`);
      console.log(`  Audio URL: ${music.audio_url}`);
      console.log(`  Cover URL: ${music.image_url}`);
    });
    
    // Process extended music
    // Can download audio files, save locally, etc.
    
  } else {
    // Task failed
    console.log('Music extension failed:', msg);
    
    // Handle failure cases...
    if (code === 400) {
      console.log('Parameter error or content violation');
    } else if (code === 451) {
      console.log('File download failed');
    } else if (code === 500) {
      console.log('Server internal error');
    }
  }
  
  // Return 200 status code to confirm callback received
  res.status(200).json({ status: 'received' });
});

app.listen(3000, () => {
  console.log('Callback server running on port 3000');
});

from flask import Flask, request, jsonify
import requests

app = Flask(__name__)

@app.route('/extend-music-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')
    callback_type = callback_data.get('callbackType')
    music_data = callback_data.get('data', [])
    
    print(f"Received music extension callback: {task_id}, type: {callback_type}, status: {code}, message: {msg}")
    
    if code == 200:
        # Task completed successfully
        print("Music extension completed")
        
        print(f"Extended {len(music_data)} music tracks:")
        for i, music in enumerate(music_data):
            print(f"Music {i + 1}:")
            print(f"  Title: {music.get('title')}")
            print(f"  Duration: {music.get('duration')} seconds")
            print(f"  Audio URL: {music.get('audio_url')}")
            print(f"  Cover URL: {music.get('image_url')}")
            
            # Download audio file example
            try:
                audio_url = music.get('audio_url')
                if audio_url:
                    response = requests.get(audio_url)
                    if response.status_code == 200:
                        filename = f"extended_music_{task_id}_{i + 1}.mp3"
                        with open(filename, "wb") as f:
                            f.write(response.content)
                        print(f"Audio saved as {filename}")
            except Exception as e:
                print(f"Audio download failed: {e}")
                
    else:
        # Task failed
        print(f"Music extension failed: {msg}")
        
        # Handle failure cases...
        if code == 400:
            print("Parameter error or content violation")
        elif code == 451:
            print("File download failed")
        elif code == 500:
            print("Server internal error")
    
    # Return 200 status code to confirm callback received
    return jsonify({'status': 'received'}), 200

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'] ?? '';
$callbackType = $callbackData['callbackType'] ?? '';
$musicData = $callbackData['data'] ?? [];

error_log("Received music extension callback: $taskId, type: $callbackType, status: $code, message: $msg");

if ($code === 200) {
    // Task completed successfully
    error_log("Music extension completed");
    
    error_log("Extended " . count($musicData) . " music tracks:");
    foreach ($musicData as $index => $music) {
        error_log("Music " . ($index + 1) . ":");
        error_log("  Title: " . ($music['title'] ?? ''));
        error_log("  Duration: " . ($music['duration'] ?? 0) . " seconds");
        error_log("  Audio URL: " . ($music['audio_url'] ?? ''));
        error_log("  Cover URL: " . ($music['image_url'] ?? ''));
        
        // Download audio file example
        try {
            $audioUrl = $music['audio_url'] ?? '';
            if ($audioUrl) {
                $audioContent = file_get_contents($audioUrl);
                if ($audioContent !== false) {
                    $filename = "extended_music_{$taskId}_" . ($index + 1) . ".mp3";
                    file_put_contents($filename, $audioContent);
                    error_log("Audio saved as $filename");
                }
            }
        } catch (Exception $e) {
            error_log("Audio download failed: " . $e->getMessage());
        }
    }
    
} else {
    // Task failed
    error_log("Music extension failed: $msg");
    
    // Handle failure cases...
    if ($code === 400) {
        error_log("Parameter error or content violation");
    } elseif ($code === 451) {
        error_log("File download failed");
    } elseif ($code === 500) {
        error_log("Server internal error");
    }
}

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

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 taskId 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
Audio Processing: Audio download and processing should be done in asynchronous tasks to avoid blocking callback response

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
Please ensure the stability of callback processing logic to avoid callback failures due to exceptions
Generated audio URLs may have time limits, recommend downloading and saving promptly
Pay attention to content policy compliance to avoid generation failures due to policy violations

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

Server Response Issues

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

Content Format Issues

Confirm that the received POST request body is in JSON format
Check that Content-Type is application/json
Verify that JSON parsing is correct

Audio Processing Issues

Confirm that audio URLs are accessible
Check audio download permissions and network connections
Verify audio save paths and permissions
Note whether audio content complies with content policies

Alternative Solution

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

Poll Query Results

Use the get music generation details endpoint to regularly query task status. We recommend querying every 30 seconds.

Generate Music

Generate Lyrics

WAV Conversion

Vocal Removal

Music Video Generation

Account Management

File Upload API

Music Extension Callbacks

Callback Mechanism Overview

Callback Timing

Callback Method

Callback Request Format

Status Code Description

Callback Reception Examples

Best Practices

Callback URL Configuration Recommendations

Important Reminders

Troubleshooting

Alternative Solution

Poll Query Results

Generate Music

Generate Lyrics

WAV Conversion

Vocal Removal

Music Video Generation

Account Management

File Upload API

​Callback Mechanism Overview

​Callback Timing

​Callback Method

​Callback Request Format

​Status Code Description

​Callback Reception Examples

​Best Practices

​Callback URL Configuration Recommendations

​Important Reminders

​Troubleshooting

​Alternative Solution

Poll Query Results

Callback Mechanism Overview

Callback Timing

Callback Method

Callback Request Format

Status Code Description

Callback Reception Examples

Best Practices

Callback URL Configuration Recommendations

Important Reminders

Troubleshooting

Alternative Solution