Audio Normalizer

Normalize the loudness of audio files in your Anki collection for a more consistent listening experience.

Features

• Normalize new audio: process files that haven’t been normalized yet.
• Normalize all audio: reprocess your collection using your current settings.
• Automatic normalization: optionally normalize new audio before syncing.
• Customizable settings: adjust target loudness, peak level, loudness range, and encoding quality.
• Supported formats: MP3, AAC, OGG, Opus, WAV, and WebM.
• FFmpeg included: no separate installation or PATH configuration required.

Compatibility

Anki Desktop on Windows 64-bit.

How to Use

Open Tools → Audio Normalizer and choose an action:

• Normalize New Audio: normalize audio that has not already been processed.
• Normalize All Audio Collection: normalize all supported audio files, including previously processed files.
• Normalize New Audio Before Sync: enable or disable automatic normalization before syncing.
• Rebuild Audio Index: mark the current audio files as already processed without modifying them. Use this when you want future runs to process only newly added audio.

Configuration

Go to Tools → Add-ons → Audio Normalizer → Config to edit the settings in JSON format.

| target_lufs | Target loudness in LUFS. Less negative values produce louder audio: -14 is louder than -17.

| true_peak | True-peak ceiling in dBTP used during normalization. A value such as -2 leaves headroom. Lossy encoding can affect the final peak level.

| lra | Target loudness range in LU. Lower values aim for more uniform loudness; higher values allow more variation.

| mp3_quality | MP3 variable-bitrate quality, from 0 (highest quality, larger files) to 9 (lowest quality, smaller files).

| ogg_quality | OGG Vorbis quality, from -1 to 10. Higher values produce better quality and larger files.

| opus_bitrate | Opus bitrate, also used for WebM audio. For example, "32k" means 32 kbps.

| aac_bitrate | AAC bitrate. Higher values generally improve quality and increase file size.

| normalize_before_sync | Set to true to normalize new audio automatically before syncing, or false to process audio manually.

Example Configuration

{ "target_lufs": -17, "true_peak": -2, "lra": 7, "mp3_quality": 7, "ogg_quality": 2, "opus_bitrate": "32k", "aac_bitrate": "96k", "normalize_before_sync": false }

Keep bitrate values in quotation marks, such as "32k", and use lowercase true or false.

Changes apply the next time audio is processed. To apply new settings to previously normalized files, select Tools → Audio Normalizer → Normalize All Audio Collection.

Important Notes

• Normalization replaces the original audio files. Back up your collection’s media before processing.
• Re-encoding lossy formats may reduce audio quality, especially when repeated.
• Normalization adjusts loudness; it does not remove noise or repair distorted recordings.
• Automatic normalization may delay syncing while new audio files are processed.

FFmpeg

This add-on uses FFmpeg. The Windows package includes the executable, corresponding source code, build instructions, and license notices.