Audio Separation Callbacks

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

app.use(express.json());

app.post('/vocal-separation-callback', (req, res) => {
  const { code, msg, data } = req.body;
  
  console.log('Received vocal separation callback:', {
    taskId: data.task_id,
    status: code,
    message: msg
  });
  
  if (code === 200) {
    // Task completed successfully
    console.log('Vocal separation completed');
    const vocalInfo = data.vocal_removal_info;
    
    if (vocalInfo) {
      console.log('Separation results:');
      console.log(`  Original audio: ${vocalInfo.origin_url}`);
      
      // Handle different separation types
      if (vocalInfo.instrumental_url) {
        // separate_vocal type
        console.log(`  Instrumental only: ${vocalInfo.instrumental_url}`);
        console.log(`  Vocals only: ${vocalInfo.vocal_url}`);
      } else {
        // split_stem type
        console.log(`  Vocals: ${vocalInfo.vocal_url}`);
        console.log(`  Backing vocals: ${vocalInfo.backing_vocals_url}`);
        console.log(`  Drums: ${vocalInfo.drums_url}`);
        console.log(`  Bass: ${vocalInfo.bass_url}`);
        console.log(`  Guitar: ${vocalInfo.guitar_url}`);
        console.log(`  Keyboard: ${vocalInfo.keyboard_url}`);
        console.log(`  Percussion: ${vocalInfo.percussion_url}`);
        console.log(`  Strings: ${vocalInfo.strings_url}`);
        console.log(`  Synthesizer: ${vocalInfo.synth_url}`);
        console.log(`  Effects: ${vocalInfo.fx_url}`);
        console.log(`  Brass: ${vocalInfo.brass_url}`);
        console.log(`  Woodwinds: ${vocalInfo.woodwinds_url}`);
      }
      
      // Download separated audio files
      const https = require('https');
      const fs = require('fs');
      
      const downloadFile = (url, filename) => {
        if (!url) return;
        
        const file = fs.createWriteStream(filename);
        https.get(url, (response) => {
          response.pipe(file);
          file.on('finish', () => {
            file.close();
            console.log(`Saved: ${filename}`);
          });
        }).on('error', (err) => {
          console.error(`Download failed ${filename}:`, err.message);
        });
      };
      
      // Download all available audio files
      Object.keys(vocalInfo).forEach(key => {
        if (vocalInfo[key] && key.endsWith('_url')) {
          const filename = `${data.task_id}_${key.replace('_url', '')}.mp3`;
          downloadFile(vocalInfo[key], filename);
        }
      });
    }
    
  } else {
    // Task failed
    console.log('Vocal separation failed:', msg);
    
    // Handle failure cases...
    if (code === 400) {
      console.log('Parameter error or unsupported audio 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');
});