Audio Loudness Batch Normalize

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(Previous attempt: Loudness-Normalization-tauri-app. As the EBU R128 algorithm proved less effective for galgame voice streaming scenarios, I try to directly normalize the loudness of raw galgame audio instead.)

Audio Loudness Batch Normalize is a command-line tool designed for batch processing audio files to achieve consistent loudness levels across multiple files. It utilizes the EBU R128 algorithm for loudness adjustment and offers configurable target loudness values and true peak limiting.

Features

• Batch processing with multi-threading
• Configurable true peak limiting
• Automatic target loudness (LUFS) setting

Installation

Choose one of the following methods:

• Download the latest pre-built binary from Releases.
• Install via cargo-binstall:

  cargo binstall audio-loudness-batch-normalize
  

Usage

loudness-normalize <input_directory> [options]

Options:

<input_directory>                     Input directory for audio files
-o, --output <path>                   Output directory (default: {input_directory}_normalized)
-s, --sample-percentage <float>       Percentage of files to sample (default: 1.00, samples all audio files)
-t, --trim-percentage <float>         Trimming percentage for averaging (default: 0.30, removes the highest 15% and lowest 15%)
    --target-lufs <float>             Target loudness value (LUFS) (default: auto-calculated)
    --true-peak-db <float>            Target true peak (dBTP) (default: -1.5)
-t, --threads <number>                Number of processing threads (default: CPU core count)

Tip

• Only WAV, OGG encoders are supported currently. If the input format is not OGG, the output will be in WAV format and may need to be manually converted.

Theory

1. Search for all audio files in the input directory.
2. Randomly sample all audio files based on sample_percentage to calculate the target loudness (LUFS).
   • If the audio's active duration is too short, the EBU R128 algorithm may return NaN, in which case it will fall back to RMS loudness calculation.
3. Calculate the trimmed mean of audio loudness based on trim_percentage. For example, setting trim_percentage to 0.3 will remove the loudness values in the top 15% and bottom 15% of the samples.
4. Adjust the audio loudness using the target loudness (LUFS) and the EBU R128 algorithm.

Special Thanks

Gemini 2.5 Pro Preview 03-25