When you submit a task to the WAV Format Conversion 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.

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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.

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Callback Timing

The system will send callback notifications in the following situations:
  • WAV format conversion task completed successfully
  • WAV format conversion task failed
  • Errors occurred during task processing

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Callback Method

  • HTTP Method: POST
  • Content Type: application/json
  • Timeout Setting: 15 seconds
  • Retry Mechanism: Retry 3 times after failure, with intervals of 1 minute, 5 minutes, and 15 minutes respectively

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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": "success",
  "data": {
    "audio_wav_url": "https://example.com/s/04e6****e727.wav",
    "task_id": "988e****c8d3"
  }
}

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Status Code Description

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code
integer
required
Callback status code indicating task processing result:
Status CodeDescription
200Success - WAV format conversion completed
400Bad Request - Parameter error, unsupported source audio file format, etc.
451Download Failed - Unable to download source audio file
500Server Error - Please try again later
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msg
string
required
Status message providing detailed status description
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data.task_id
string
required
Task ID, consistent with the taskId returned when you submitted the task
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data.audio_wav_url
string
Converted WAV audio file download URL, returned on success

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Callback Reception Examples

Here are example codes for receiving callbacks in popular programming languages: 
const express = require('express');
const app = express();

app.use(express.json());

app.post('/wav-conversion-callback', (req, res) => {
  const { code, msg, data } = req.body;
  
  console.log('Received WAV format conversion callback:', {
    taskId: data.task_id,
    status: code,
    message: msg
  });
  
  if (code === 200) {
    // Task completed successfully
    console.log('WAV format conversion completed');
    console.log(`WAV file URL: ${data.audio_wav_url}`);
    
    // Download WAV file
    if (data.audio_wav_url) {
      const https = require('https');
      const fs = require('fs');
      
      const filename = `wav_${data.task_id}.wav`;
      const file = fs.createWriteStream(filename);
      
      https.get(data.audio_wav_url, (response) => {
        response.pipe(file);
        file.on('finish', () => {
          file.close();
          console.log(`WAV file saved as ${filename}`);
        });
      }).on('error', (err) => {
        console.error('WAV file download failed:', err.message);
      });
    }
    
  } else {
    // Task failed
    console.log('WAV format conversion failed:', msg);
    
    // Handle failure cases...
    if (code === 400) {
      console.log('Parameter error or unsupported source file format');
    } else if (code === 451) {
      console.log('Source audio 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');
});

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Best Practices

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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 taskId 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. File Processing: WAV file download and processing should be done in asynchronous tasks to avoid blocking callback response

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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 WAV file URLs may have time limits, recommend downloading and saving promptly
  • WAV files are typically larger than MP3 files, pay attention to storage space and download time
  • Ensure sufficient disk space to save WAV files

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Troubleshooting

If you do not receive callback notifications, please check the following:

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Alternative Solution

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

Poll Query Results

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