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.
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
Measure True Peak of original file
Calculate gain to reach target True Peak (default -0.1 dB)
Apply linear gain
Linear Gain = Target TP - Original TP
Stage 2: Dynamic Range Compression
Uses FFmpeg's acompressor filter
Moderately compresses dynamic range
Default settings: threshold=-16dB, ratio=2.5:1
Stage 3: LUFS Normalization (2-pass, Linear Gain)
1st pass: Measure compressed audio to obtain optimal parameters
2nd pass: Perform LUFS normalization using linear gain adjustment based on measurements (linear=true mode)
Target LUFS: Default -16.0
No dynamic processing, only linear gain adjustment
Correction Process
If final True Peak exceeds target, automatically applies correction gain
May intentionally lower True Peak for some files to prioritize LUFS target
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
-16 dB (Default): Same as LUFS target. Starts compression at moderate level
-20 dB: Starts at lower level. Overall gentler compression
-12 dB: Only high levels compressed. For peak control
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)
attack (Attack Time): Time from level exceeding threshold until compression starts
Fast (5-10ms): Compresses fast transients too More controlled sound
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
Sample Rate: No restrictions (44.1kHz, 48kHz, 96kHz, 192kHz, etc., all preserved)
Bit Depth: Supports 16-bit, 24-bit, 32-bit float (original depth preserved)
Metadata Processing
Special WAV File Processing
WAV files store metadata using ID3v2.3 tags:
ID3v2.3 tags (UTF-8 support): Can be viewed/edited with Mp3tag and other professional software. Special characters (e.g., BOØWY) are correctly preserved
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
Title
Artist
Album
Album Artist
Composer
Date
Genre
Track Number
Disc Number
Album Art
Technical Specifications
Audio Engine
Processing Engine: FFmpeg + soundfile (Python)
Loudness Measurement: EBU R128 compliant (FFmpeg ebur128 filter)
True Peak Measurement: Accurate measurement with 4x oversampling
Metadata Library: Mutagen (Python)
Processing Precision
Internal Processing: Float64 precision
DC Offset Removal: Performed before writing to improve True Peak measurement accuracy
Bit Depth Preservation: Output maintains same bit depth as input (16/24/32-bit float)
Performance
Parallel Processing: Multi-threaded processing using ThreadPoolExecutor
Default Workers: 4 (configurable in settings)
Memory Usage: Minimized through efficient streaming
Troubleshooting
Configuration File Not Loading
Symptom: YAML file edits not reflected in settings
Solution:
Verify advanced_lufs_unifier.yaml is in same folder as EXE
Check YAML syntax errors (use 2 spaces for indentation)
Verify filename is exactly advanced_lufs_unifier.yaml
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
Cause: Original file may contain corrupted metadata
Solution:
Check original file metadata with Mp3tag
Clean up original file metadata if necessary
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.