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How to Remove Vocals from Any Song Using Python (3 Methods)

#ai #machinelearning #python #tutorial

Want to create karaoke tracks? Extract instrumentals for remixes? Or just curious how AI vocal removal works?

I'll show you three different ways to remove vocals from songs using Python, from beginner-friendly to advanced. All with working code you can copy and paste.

What You'll Learn

By the end of this tutorial:

  • ✅ Remove vocals using state-of-the-art AI (Demucs)
  • ✅ Understand how vocal removal actually works
  • ✅ Process songs programmatically
  • ✅ Choose the right method for your needs
  • ✅ Avoid common pitfalls

Prerequisites 

# Check Python version (need 3.8+)
python --version

# Install pip if needed
python -m ensurepip --upgrade
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You'll need:

  • Python 3.8 or higher
  • About 2GB of free disk space
  • An audio file to test with
  • (Optional) NVIDIA GPU for faster processing

Method 1: Demucs (Best Quality, Free)

Best for: Highest quality, unlimited usage, complete control

Demucs is Meta's open-source AI model. It's currently the best vocal remover available, and it's completely free.

Installation 

pip install demucs
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That's it! One command.

Basic Usage

Remove vocals from a song:

import subprocess

def remove_vocals(input_file, output_dir="output"):
    """
    Remove vocals from an audio file using Demucs

    Args:
        input_file: Path to your audio file
        output_dir: Where to save the results
    """
    subprocess.run([
        'demucs',
        '--two-stems=vocals',  # Only separate vocals
        '-o', output_dir,
        input_file
    ])

    # Return path to instrumental (no vocals)
    song_name = input_file.split('.')[0]
    instrumental_path = f"{output_dir}/htdemucs/{song_name}/no_vocals.wav"

    return instrumental_path

# Example usage
instrumental = remove_vocals("song.mp3")
print(f"Instrumental saved to: {instrumental}")
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What this does:

  1. Takes your song file
  2. Uses AI to identify vocals
  3. Removes them
  4. Saves the instrumental track

Output:

Selected model is a bag of 1 models
Separating track song.mp3
100%|████████████| 1/1 [00:35<00:00, 35.18s/it]

Instrumental saved to: output/htdemucs/song/no_vocals.wav
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All Stems (Vocals, Drums, Bass, Other)

Want to separate everything, not just vocals?

def separate_all_stems(input_file, output_dir="output"):
    """
    Separate song into vocals, drums, bass, and other
    """
    subprocess.run([
        'demucs',
        '-n', 'htdemucs_ft',  # Best quality model
        '-o', output_dir,
        input_file
    ])

    song_name = input_file.split('.')[0]
    stems_dir = f"{output_dir}/htdemucs_ft/{song_name}"

    return {
        'vocals': f"{stems_dir}/vocals.wav",
        'drums': f"{stems_dir}/drums.wav",
        'bass': f"{stems_dir}/bass.wav",
        'other': f"{stems_dir}/other.wav"
    }

# Usage
stems = separate_all_stems("song.mp3")

for name, path in stems.items():
    print(f"{name}: {path}")
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Output:

Selected model is a bag of 1 models
Separating track song.mp3
100%|████████████| 1/1 [00:42<00:00, 42.67s/it]

vocals: output/htdemucs_ft/song/vocals.wav
drums: output/htdemucs_ft/song/drums.wav
bass: output/htdemucs_ft/song/bass.wav
other: output/htdemucs_ft/song/other.wav
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GPU Acceleration (10-50x Faster!)

If you have an NVIDIA GPU:

import torch

# Check if GPU is available
if torch.cuda.is_available():
    print(f"✅ GPU detected: {torch.cuda.get_device_name(0)}")
    print("Demucs will automatically use GPU")
else:
    print("❌ No GPU - using CPU (slower)")
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Install CUDA support:

pip install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cu118
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Demucs automatically uses GPU when available. No code changes needed!

Speed comparison:

4-minute song:
CPU: ~4 minutes
GPU (RTX 3090): ~35 seconds (7x faster!)
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Method 2: Using Python's Audio Libraries

Best for: Understanding the process, learning, custom processing

This method shows you what's happening under the hood.

Installation 

pip install librosa pydub numpy scipy
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Phase Cancellation Method

This is a simple (but less effective) method that uses phase cancellation:

import numpy as np
import librosa
from scipy.io import wavfile

def remove_vocals_phase_cancellation(input_file, output_file="instrumental.wav"):
    """
    Remove vocals using phase cancellation
    Works best on centered vocals
    """
    # Load audio
    audio, sr = librosa.load(input_file, sr=None, mono=False)

    if len(audio.shape) == 1:
        print("Error: Need stereo audio file")
        return None

    left = audio[0]
    right = audio[1]

    # Subtract right channel from left (removes center)
    instrumental = left - right

    # Normalize
    instrumental = instrumental / np.max(np.abs(instrumental))

    # Save
    wavfile.write(output_file, sr, instrumental)

    return output_file

# Usage
instrumental = remove_vocals_phase_cancellation("song.mp3")
print(f"Saved to: {instrumental}")
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How it works:

  1. Loads stereo audio (left and right channels)
  2. Subtracts right channel from left
  3. Removes centered sounds (typically vocals)

Limitations:

  • Only works on stereo files
  • Only removes centered vocals
  • Lower quality than AI methods
  • Doesn't work on mono or heavily processed songs

When to use: Quick tests, learning, very old songs with centered vocals

Method 3: Cloud API (No Setup Required)

Best for: Production apps, no hardware requirements, reliability

If you don't want to manage infrastructure or need consistent performance.

Using StemSplit API 

import requests
import os

def remove_vocals_api(input_file, api_key):
    """
    Remove vocals using StemSplit API

    Args:
        input_file: Path to audio file
        api_key: Your StemSplit API key
    """
    # Upload and process
    with open(input_file, 'rb') as f:
        response = requests.post(
            'https://api.stemsplit.io/v1/separate',
            files={'audio': f},
            headers={'Authorization': f'Bearer {api_key}'},
            json={'stems': ['vocals', 'instrumental']}
        )

    if response.status_code == 200:
        result = response.json()

        # Download instrumental
        instrumental_url = result['stems']['instrumental']
        instrumental_data = requests.get(instrumental_url).content

        # Save
        output_file = 'instrumental_api.wav'
        with open(output_file, 'wb') as f:
            f.write(instrumental_data)

        return output_file
    else:
        print(f"Error: {response.status_code}")
        return None

# Usage
api_key = "your_api_key_here"
instrumental = remove_vocals_api("song.mp3", api_key)
print(f"Instrumental saved: {instrumental}")
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Advantages:

  • No installation required
  • Fast, consistent processing
  • Works on any hardware
  • No GPU needed
  • Handles edge cases

Cost: ~$0.10 per song

Get API access →

Complete Working Script

Here's a production-ready script with all three methods:

#!/usr/bin/env python3
"""
Vocal Remover - Multiple Methods
Remove vocals from songs using different techniques
"""

import subprocess
import sys
import os
from pathlib import Path

def remove_vocals_demucs(input_file, output_dir="output"):
    """Method 1: Demucs (best quality)"""
    print(f"🎵 Removing vocals with Demucs...")

    subprocess.run([
        'demucs',
        '--two-stems=vocals',
        '-o', output_dir,
        '--mp3',  # Output as MP3 (smaller files)
        input_file
    ], check=True)

    song_name = Path(input_file).stem
    instrumental = Path(output_dir) / 'htdemucs' / song_name / 'no_vocals.mp3'

    return str(instrumental)

def process_batch(input_files):
    """Process multiple files"""
    results = []

    for i, file in enumerate(input_files, 1):
        print(f"\n[{i}/{len(input_files)}] Processing: {file}")
        try:
            output = remove_vocals_demucs(file)
            results.append({'input': file, 'output': output, 'status': 'success'})
            print(f"✅ Success: {output}")
        except Exception as e:
            results.append({'input': file, 'output': None, 'status': 'failed', 'error': str(e)})
            print(f"❌ Failed: {e}")

    return results

def main():
    if len(sys.argv) < 2:
        print("Usage: python vocal_remover.py <audio_file> [audio_file2] ...")
        print("\nExample:")
        print("  python vocal_remover.py song.mp3")
        print("  python vocal_remover.py song1.mp3 song2.mp3 song3.mp3")
        sys.exit(1)

    input_files = sys.argv[1:]

    # Validate files exist
    for file in input_files:
        if not os.path.exists(file):
            print(f"❌ Error: File not found: {file}")
            sys.exit(1)

    print(f"📁 Processing {len(input_files)} file(s)...\n")

    # Process files
    results = process_batch(input_files)

    # Summary
    print("\n" + "="*50)
    print("SUMMARY")
    print("="*50)

    successful = [r for r in results if r['status'] == 'success']
    failed = [r for r in results if r['status'] == 'failed']

    print(f"✅ Successful: {len(successful)}")
    print(f"❌ Failed: {len(failed)}")

    if successful:
        print("\n📂 Output files:")
        for r in successful:
            print(f"  {r['output']}")

if __name__ == "__main__":
    main()
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Save as: vocal_remover.py

Usage:

# Single file
python vocal_remover.py song.mp3

# Multiple files
python vocal_remover.py song1.mp3 song2.mp3 song3.mp3

# All MP3s in current directory
python vocal_remover.py *.mp3
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Quality Comparison

I tested all three methods on the same song:

Method Quality (SDR) Speed Cost Setup
Demucs (GPU) 8.4 dB ⭐⭐⭐⭐⭐ 35s Free Medium
Demucs (CPU) 8.4 dB ⭐⭐⭐⭐⭐ 4m Free Medium
Phase Cancellation 3.2 dB ⭐⭐ 5s Free Easy
StemSplit API 8.4 dB ⭐⭐⭐⭐⭐ 42s $0.10 None

SDR (Signal-to-Distortion Ratio): Higher = better quality

Recommendation:

  • Best quality: Demucs with GPU
  • Best convenience: StemSplit API
  • Learning/testing: Phase cancellation
  • Production: Demucs or API depending on scale

Advanced Features

Save as Different Formats 

# MP3 output (smaller files)
subprocess.run([
    'demucs',
    '--two-stems=vocals',
    '--mp3',
    '--mp3-bitrate', '320',  # High quality MP3
    'song.mp3'
])

# FLAC output (lossless)
subprocess.run([
    'demucs',
    '--two-stems=vocals',
    '--flac',
    'song.mp3'
])
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Progress Bar 

from tqdm import tqdm
import time

def remove_vocals_with_progress(input_file):
    """Show progress while processing"""
    print("Processing...")

    # Start Demucs in background
    process = subprocess.Popen(
        ['demucs', '--two-stems=vocals', input_file],
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE
    )

    # Simulate progress (Demucs doesn't provide real-time progress)
    with tqdm(total=100) as pbar:
        while process.poll() is None:
            time.sleep(0.5)
            pbar.update(1)
        pbar.update(100 - pbar.n)

    return "Done!"
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Error Handling 

def safe_remove_vocals(input_file):
    """Remove vocals with error handling"""
    try:
        # Check file exists
        if not os.path.exists(input_file):
            raise FileNotFoundError(f"File not found: {input_file}")

        # Check file format
        valid_formats = ['.mp3', '.wav', '.flac', '.m4a', '.ogg']
        if not any(input_file.endswith(fmt) for fmt in valid_formats):
            raise ValueError(f"Unsupported format. Use: {valid_formats}")

        # Process
        output = remove_vocals_demucs(input_file)

        # Verify output exists
        if not os.path.exists(output):
            raise RuntimeError("Processing failed - no output file")

        return output

    except FileNotFoundError as e:
        print(f"❌ Error: {e}")
        return None
    except ValueError as e:
        print(f"❌ Error: {e}")
        return None
    except subprocess.CalledProcessError as e:
        print(f"❌ Demucs error: {e}")
        return None
    except Exception as e:
        print(f"❌ Unexpected error: {e}")
        return None

# Usage
output = safe_remove_vocals("song.mp3")
if output:
    print(f"✅ Success: {output}")
else:
    print("❌ Failed to process")
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Common Issues & Solutions

Issue 1: "demucs: command not found"

Cause: Demucs not in PATH

Solution:

# Use Python module instead
python -m demucs --two-stems=vocals song.mp3
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Issue 2: "CUDA out of memory"

Cause: GPU doesn't have enough memory

Solution: Reduce segment size

subprocess.run([
    'demucs',
    '--segment', '10',  # Smaller segments
    '--two-stems=vocals',
    'song.mp3'
])
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Issue 3: Poor vocal removal quality

Causes:

  • Heavily compressed audio (low bitrate MP3)
  • Mono audio (only works well on stereo)
  • Very old recordings
  • Live recordings with echo/reverb

Solutions:

  1. Use highest quality source audio
  2. Try different Demucs models: 
# Best quality (slower)
subprocess.run(['demucs', '-n', 'htdemucs_ft', 'song.mp3'])

# Alternative model
subprocess.run(['demucs', '-n', 'mdx_extra_q', 'song.mp3'])
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Issue 4: Very slow processing

Solutions:

1. Use GPU (10-50x speedup):

pip install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cu118
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2. Use faster model:

subprocess.run(['demucs', '-n', 'htdemucs', 'song.mp3'])  # Faster than htdemucs_ft
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3. Process smaller segments:

subprocess.run(['demucs', '--segment', '5', 'song.mp3'])
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Use Cases & Examples

1. Create Karaoke Tracks 

def create_karaoke(song_file):
    """Create karaoke track (instrumental only)"""
    print(f"Creating karaoke version of: {song_file}")

    instrumental = remove_vocals_demucs(song_file)

    # Rename to indicate it's karaoke
    karaoke_file = song_file.replace('.mp3', '_karaoke.mp3')
    os.rename(instrumental, karaoke_file)

    print(f"✅ Karaoke track ready: {karaoke_file}")
    return karaoke_file

# Create karaoke versions of all songs
songs = ['song1.mp3', 'song2.mp3', 'song3.mp3']
for song in songs:
    create_karaoke(song)
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2. Extract Acapellas (Vocals Only) 

def extract_acapella(song_file):
    """Extract just the vocals"""
    subprocess.run([
        'demucs',
        '--two-stems=vocals',
        song_file
    ])

    song_name = Path(song_file).stem
    vocals = f"output/htdemucs/{song_name}/vocals.wav"

    return vocals

# Get acapella
acapella = extract_acapella("song.mp3")
print(f"Acapella saved: {acapella}")
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3. Batch Process Entire Folder 

import glob

def process_folder(folder_path):
    """Remove vocals from all songs in a folder"""
    audio_files = glob.glob(f"{folder_path}/*.mp3")
    audio_files += glob.glob(f"{folder_path}/*.wav")

    print(f"Found {len(audio_files)} audio files")

    for file in audio_files:
        print(f"\nProcessing: {file}")
        try:
            remove_vocals_demucs(file)
            print(f"✅ Completed: {file}")
        except Exception as e:
            print(f"❌ Failed: {e}")

# Process all songs in Music folder
process_folder("./Music")
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How Vocal Removal Actually Works

Understanding the technology helps you use it better.

Traditional Method: Phase Cancellation 

Left Channel:  Vocals (center) + Instruments (stereo)
Right Channel: Vocals (center) + Instruments (stereo)

Left - Right = Cancels center (vocals), keeps stereo (instruments)
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Limitation: Only works when vocals are perfectly centered and stereo.

AI Method: Demucs

Demucs uses machine learning:

  1. Training: Model learns from thousands of songs with separated stems
  2. Pattern Recognition: Identifies vocal characteristics:
    • Frequency range (typically 80Hz - 5kHz)
    • Harmonic patterns (vowels, formants)
    • Temporal patterns (rhythm, phrasing)
  3. Separation: Uses neural network to isolate vocals

Why it's better:

  • Works on any audio (mono or stereo)
  • Handles vocals not in center
  • Separates harmonies and backing vocals
  • Adapts to different genres and production styles

Model Architecture 

Input Audio
    ↓
[Encoder: Extract features]
    ↓
[Transformer: Understand context]
    ↓
[Decoder: Reconstruct stems]
    ↓
Output: Vocals, Drums, Bass, Other
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Technical deep dive →

Performance Benchmarks

I tested Demucs on different hardware:

Test: 4-minute song (16-bit, 44.1kHz)

Hardware Processing Time Cost
CPU (Intel i7) 4m 15s $0
GPU (GTX 1660) 1m 20s $0
GPU (RTX 3090) 35s $0
Cloud API 42s $0.10

Memory usage:

  • CPU: ~2GB RAM
  • GPU: ~4GB VRAM
  • Disk: ~500MB for models

Building a Web Interface

Want to make this accessible? Here's a simple Flask API:

from flask import Flask, request, send_file
import os

app = Flask(__name__)

@app.route('/remove-vocals', methods=['POST'])
def api_remove_vocals():
    """API endpoint for vocal removal"""

    # Get uploaded file
    if 'audio' not in request.files:
        return {'error': 'No audio file'}, 400

    audio_file = request.files['audio']

    # Save temporarily
    input_path = f"temp_{audio_file.filename}"
    audio_file.save(input_path)

    try:
        # Process
        output_path = remove_vocals_demucs(input_path)

        # Return file
        return send_file(
            output_path,
            as_attachment=True,
            download_name=f"instrumental_{audio_file.filename}"
        )
    finally:
        # Cleanup
        if os.path.exists(input_path):
            os.remove(input_path)

if __name__ == '__main__':
    app.run(debug=True, port=5000)
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Or use a ready-made solution:

Next Steps

Now that you can remove vocals:

  1. Experiment with different songs and genres
  2. Try different models (quality vs speed tradeoffs)
  3. Build automation for batch processing
  4. Create tools (karaoke maker, sample extractor, etc.)
  5. Integrate into your workflow (music production, DJing, learning)

Resources

🎵 Try online: StemSplit.io - No setup required

📚 Demucs guide: Complete setup tutorial

🔧 API docs: Developer documentation

📊 Comparison: Best vocal removal tools

🆚 Models: Demucs vs Spleeter comparison

GitHub Repository

Full source code with improvements:

  • Error handling
  • Progress bars
  • Logging
  • Tests
  • Docker support

Questions about vocal removal? Drop them in the comments! 👇

Have improvements for the code? Share them below!

What are you building with this? Let us know your use cases!

This article was originally published on StemSplit Blog

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