normalize

Normalize audio levels to consistent loudness using industry-standard EBU R128 loudness normalization.

Overview

The normalize command ensures consistent audio levels across your files using professional loudness standards. Unlike simple peak normalization, it uses the EBU R128 loudness normalization (loudnorm) filter which measures perceived loudness and adjusts audio to match professional broadcast and streaming standards.

Key Features:

• EBU R128 loudness normalization (LUFS-based)
• Peak normalization option
• Industry-standard target levels for broadcast, streaming, and podcasts
• True peak limiting to prevent clipping
• Batch processing for consistent album or podcast volumes

Common Use Cases:

• Normalizing podcast episodes for consistent volume
• Preparing audio for streaming platforms (Spotify, YouTube, Apple Music)
• Broadcast audio preparation (TV, radio)
• Album mastering for consistent track volumes
• Fixing quiet or loud recordings

Usage

Options

Basic Options

Normalization Settings

Flag Details

--target - Target Loudness

Set the target loudness level in LUFS (Loudness Units relative to Full Scale).

Industry Standards:

-16 LUFS - EBU R128 Broadcast Standard (Default)

• European broadcast standard
• TV and radio broadcasting
• General streaming (Amazon Music, Deezer)
• Balanced loudness for most content

-23 LUFS - ATSC A/85 Streaming Standard

• Spotify loudness normalization
• YouTube audio leveling
• Apple Music normalization
• Most streaming platforms

-14 LUFS - Podcast Standard

• Podcast industry recommendation
• Spoken word content
• Audiobook standard
• Clear and present voice

-9 to -11 LUFS - Mastering Reference

• Loud commercial sound
• Club/dance music
• Maximum impact (aggressive)
• Used for competitive loudness

Recommendations by Content:

--max-level - True Peak Limiting

Set the maximum true peak level in dB to prevent clipping during playback.

Common Values:

-1.5 dB (Default)

• Safe for most use cases
• Prevents inter-sample peaks
• Broadcast-safe

-1.0 dB

• Slightly more headroom
• Professional mastering
• Hi-fi playback systems

-2.0 dB

• Very conservative
• Streaming services
• Guaranteed no clipping

-3.0 dB

• Maximum safety
• Podcast distribution
• Legacy playback systems

True Peak vs Sample Peak:

• Sample Peak: Measures individual samples
• True Peak: Measures actual analog waveform between samples
• True peak limiting prevents distortion on consumer devices

--method - Normalization Method

Choose between loudness-based and peak-based normalization.

loudnorm (EBU R128) - Recommended

• Measures perceived loudness
• Industry standard for broadcast and streaming
• More consistent perceived volume
• Adjusts dynamics intelligently
• Use for: All professional content, streaming, broadcast

peak (Peak Normalization)

• Normalizes to maximum sample peak
• Simple but less sophisticated
• Can make quiet content sound louder without improving clarity
• Use for: Quick fixes, legacy workflows

Examples

Normalize for Streaming Platforms

Normalize Podcast Episode

Batch Normalize Album Tracks

Normalize with Format Conversion

Simple Peak Normalization

Common Workflows

Podcast Production

# Normalize episode to podcast standard
mediaproc audio normalize episode.mp3 -t -16

# Process entire season
mediaproc audio normalize season-01/*.mp3 -t -16 -o normalized/

# Extra safe for all platforms
mediaproc audio normalize episode.mp3 -t -16 -l -2.0

Music Mastering

# Streaming-ready master
mediaproc audio normalize master.wav -t -14 --format flac

# Loud master for clubs
mediaproc audio normalize master.wav -t -9 -l -1.0

# Consistent album volume
for file in *.flac; do
  mediaproc audio normalize "$file" -t -14 -o masters/
done

Broadcast Preparation

# EBU R128 broadcast standard
mediaproc audio normalize program.wav -t -23 -l -1.0

# Radio-ready file
mediaproc audio normalize ad.mp3 -t -16 -m loudnorm

Video Audio Preparation

# YouTube audio normalization
mediaproc audio extract video.mp4 -f wav
mediaproc audio normalize video-audio.wav -t -13

# Consistent volume for playlist
mediaproc audio normalize clips/*.mp3 -t -16 -o ready/

Understanding Loudness

What is LUFS?

LUFS (Loudness Units relative to Full Scale) is an international standard for measuring perceived loudness:

• Based on human hearing perception
• Accounts for frequency sensitivity
• More accurate than simple dB peak measurements
• Industry standard for broadcast and streaming

Integrated Loudness:

Measures the average loudness of the entire file, weighted by time and frequency.

Momentary Loudness:

Short-term loudness (400ms windows) to prevent sudden loud peaks.

True Peak:

The actual maximum level of the analog waveform, including inter-sample peaks that can cause clipping on playback devices.

Platform-Specific Guidelines

Spotify:

• Target: -14 LUFS integrated
• True Peak: -2 dB
• If louder than -14, Spotify will turn it down
• If quieter than -14, Spotify will turn it up

YouTube:

• Target: -13 to -15 LUFS
• True Peak: -1 dB
• Applies normalization automatically

Apple Music / iTunes:

• Target: -16 LUFS (Sound Check enabled)
• True Peak: -1 dB
• Sound Check is optional for users

Amazon Music:

• Target: -14 to -16 LUFS
• True Peak: -2 dB

Podcast Platforms:

• Target: -16 to -19 LUFS
• True Peak: -1 to -2 dB
• Consistency matters more than absolute level

Quality Considerations

Dynamic Range:

Loudness normalization preserves dynamic range better than simple compression:

• Quiet parts stay relatively quiet
• Loud parts stay relatively loud
• Overall perceived loudness is consistent

Two-Pass vs One-Pass:

EBU R128 loudnorm uses two-pass processing:

1. First pass: Analyze loudness
2. Second pass: Apply correction

This ensures accurate loudness measurement and adjustment.

Format Preservation:

By default, normalization preserves the input format. Use --format to convert while normalizing.

Performance Tips

Preview Analysis:

See what changes will be made without processing:

mediaproc audio normalize audio.mp3 --dry-run -v

Verbose Output:

Monitor loudness measurements:

mediaproc audio normalize audio.mp3 -v

Batch Processing:

Process directories efficiently:

# Process all MP3s in a folder
mediaproc audio normalize *.mp3 -t -16 -o normalized/

Related Commands

• convert - Convert normalized audio to other formats
• merge - Merge with automatic normalization option
• trim - Trim and then normalize

Learn More

• EBU R128 Loudness Standard
• Loudness Normalization Explained
• FFmpeg Loudnorm Filter
• Streaming Loudness Standards