Advanced LUFS Unifier

Version 1.0 | December 2025

Advanced LUFS Unifier is a professional audio processing tool that unifies audio volume and performs high-quality mastering. It achieves excellent results through a 3-stage process combining True Peak control, dynamics compression, and LUFS normalization.

Table of Contents

Key Features

Audio Processing

Metadata & Quality Preservation

Performance

System Requirements

Required

Important: FFmpeg must be set in system PATH. Verify that ffmpeg -version works in Command Prompt.

Usage

Basic Usage

  1. Drag and drop audio files onto advanced_lufs_unifier.exe
  2. Processing starts automatically
  3. After processing, a compressed subfolder is created in the same directory as input files, and output files with _compressed suffix are saved there
Using Shortcuts: You can create a shortcut of the EXE file and place it on the desktop - it will work the same way.

Output File Names and Location

Input File Output File
C:\Music\01 Sunset Heart.wav C:\Music\compressed\01 Sunset Heart_compressed.wav
D:\Audio\song.flac D:\Audio\compressed\song_compressed.flac
E:\Files\track.m4a E:\Files\compressed\track_compressed.m4a
Note: The compressed folder is created automatically if it doesn't exist.

Processing Flow

Advanced LUFS Unifier processes audio in 3 stages:

Stage 1: Linear Gain Adjustment

Linear Gain = Target TP - Original TP

Stage 2: Dynamic Range Compression

Stage 3: LUFS Normalization (2-pass, Linear Gain)

Correction Process

Configuration File

All parameters can be adjusted in the advanced_lufs_unifier.yaml file.

Default Configuration

target:
  true_peak: -0.1      # Target True Peak (dB)
  lufs: -16.0          # Target LUFS

processing:
  max_workers: 4       # Number of parallel workers (adjust based on CPU cores)

compressor:
  threshold: -16       # Compressor threshold (dB)
  ratio: 2.5          # Compression ratio
  attack: 20          # Attack time (ms)
  release: 250        # Release time (ms)
  knee: 2             # Knee value (dB)
  detection: rms      # Detection method (rms/peak)

loudnorm:
  lra: 11             # Target loudness range (reference value)
  linear: true        # Linear mode (true=linear gain only)

Compressor Settings Details

The compressor is the key parameter for adjusting dynamic range (LRA).

1. ratio (Compression Ratio) - Greatest Impact on LRA Change

Value Effect LRA Change (Estimated) Use Case
1.0 No compression ~0 When you want to fully preserve dynamics
1.5 Light compression -0.5 to -1.0 Classical music, acoustic
2.5 (Default) Moderate compression -1.3 to -1.8 Balanced, general-purpose setting
4.0 Strong compression -2.0 to -3.0 Pop music, streaming
10.0+ Limiter-like compression -3.0+ Maximum loudness, loudness-focused

2. threshold (Threshold) - At What Level Compression Starts

Tip: Lowering threshold means more audio gets compressed, resulting in gentler overall compression. Raising it means only peaks get strongly compressed.

3. attack / release (Response Speed)

4. Other Parameters

Configuration Examples

Example 1: Classical Music (Dynamics Priority)

target:
  true_peak: -0.5
  lufs: -18.0        # Conservative loudness

compressor:
  threshold: -18
  ratio: 1.5         # Light compression
  attack: 50         # Slow response
  release: 500       # Smooth release
  knee: 4            # Smooth compression onset
  detection: rms

Example 2: Streaming (Loudness Priority, -14 LUFS)

target:
  true_peak: -1.0
  lufs: -14.0        # Streaming standard

compressor:
  threshold: -14
  ratio: 4.0         # Strong compression
  attack: 10         # Fast response
  release: 200
  knee: 2
  detection: rms

Example 3: Podcast (Speech Clarity)

target:
  true_peak: -1.0
  lufs: -16.0

compressor:
  threshold: -18
  ratio: 3.0
  attack: 5          # Very fast response
  release: 150
  knee: 1
  detection: rms

Example 4: Preserve Dynamics (Minimal Compression)

target:
  true_peak: -0.1
  lufs: -16.0

compressor:
  threshold: -16
  ratio: 1.0         # Compression disabled
  attack: 20
  release: 250
  knee: 2
  detection: rms
Note: LRA (Loudness Range) change is primarily determined by ratio and threshold. Actual LRA change varies depending on the original track's dynamic characteristics.

Supported Formats

Format Extension Metadata Cover Art Notes
WAV .wav ID3v2.3 ○ Full Windows Japanese support
FLAC .flac Vorbis Comment ○ Lossless compression
ALAC .m4a iTunes metadata ○ Apple Lossless (lossless compression)

Sample Rate & Bit Depth

Metadata Processing

Special WAV File Processing

WAV files store metadata using ID3v2.3 tags:

ID3v2.3 tags can be viewed and edited with music software such as Mp3tag, foobar2000, and iTunes. UTF-8 encoding ensures correct preservation of artist names with special characters.

Preserved Metadata

Technical Specifications

Audio Engine

Processing Precision

Performance

Troubleshooting

Configuration File Not Loading

Symptom: YAML file edits not reflected in settings
Solution:

True Peak Lower Than Target

Symptom: Some files have True Peak at -2.0 dB or lower than target
Cause: This is normal behavior. True Peak is intentionally lowered to achieve LUFS target
Solution: If you want to prioritize True Peak control over LUFS target, adjust LUFS value in YAML file

Japanese Filenames Garbled

Solution:

Metadata Lost

Cause: Original file may contain corrupted metadata
Solution:

License

This tool is free for both personal and commercial use.

Credits

Created with Claude (Anthropic) - 2025

Support: If you encounter issues or have feature requests, try customizing the YAML file. For more detailed technical information, refer to the official FFmpeg and Mutagen documentation.