YouTube Volume Normalizer by むらひと

YouTube Volume Normalizer

Say goodbye to constantly adjusting your volume. This audio engine unifies YouTube audio to a broadcast standard (-14 LUFS) and delivers high-fidelity sound compensation based on human hearing characteristics.

YouTube videos are often a mix of "too quiet" and "suddenly loud." This add-on automatically adjusts all content to meet professional broadcast standards. Additionally, it features a Dynamic EQ based on the ISO 226:2023 standard, ensuring that bass and treble remain rich and clear even when listening at low volumes.

🎵 Key Features

• Universal Consistency: Works seamlessly with Standard Videos, Shorts, Live Streams, and Embedded videos.
• Hybrid Processing Engine: Automatically switches between "Static Normalization" (using video metadata) and "Active AGC" (real-time measurement) to minimize audio degradation.
• Psychoacoustic Compensation (Dynamic EQ): Automatically boosts bass and treble frequencies when the volume is lowered, maintaining a balanced sound profile based on human hearing.
• Safety First: Built-in "Lookahead Limiter" prevents sudden loud peaks, and "Dynamic Range Control" reduces listening fatigue.

🛠️ Detailed Features

1. Smart Loudness Normalization

The engine instantly analyzes the video's volume metadata to calculate the perfect gain required to hit the -14 LUFS target. If metadata is unavailable (e.g., during Live streams), a high-precision loudness meter measures audio in real-time and adjusts the volume using a natural curve.

• Native Compatibility: Optimized to avoid conflicts with YouTube's built-in "Stable Volume" feature.
• Optimized for Shorts: Pre-reads metadata for seamless volume transitions when swiping through YouTube Shorts.

2. ISO 226:2023 Dynamic EQ

The human ear naturally loses sensitivity to bass and treble at lower volumes (Equal-loudness contours). This add-on applies a real-time equalizer based on the ISO 226:2023 standard relative to your current playback volume.
* The Effect: Enjoy punchy bass and crisp highs even when watching late at night with the volume turned down.

3. Advanced Signal Processing (DSP)

Brings professional-grade audio processing directly to your browser.
* Lookahead Limiter: Monitors audio 15ms in advance to detect and prevent clipping distortion and sudden loud bursts.
* Dynamic Range Control (DRC): Compresses the dynamic range of videos with extreme volume fluctuations (High LRA) for a more consistent listening experience.
* Momentary Smoothing: Smooths out rapid gain changes to prevent unnatural "pumping" artifacts.

4. Advanced Settings & UI

A status indicator is added to the video player, allowing you to check the current input level and applied gain at a glance. Clicking it opens a detailed menu where you can customize:

• Max Gain Limit: Set a ceiling for amplification to prevent boosting background noise.
• LRA Algorithm: Choose between Adaptive (CPU optimized) or Fixed calculation modes.
• Calibration: One-click calibration to set the reference level for loudness compensation to match your specific listening environment.

📊 Technical Specifications

For audiophiles and engineers:

• Loudness Standard: ITU-R BS.1770-4
• Loudness Range (LRA): EBU Tech 3342:2020
• Hearing Compensation: ISO 226:2023 (Equal-loudness contours)
• Processing Engine: Low-latency, high-precision processing via AudioWorklet (Web Audio API)
• Sample Rate: Automatic support for 48kHz / 44.1kHz

🔒 Privacy & Permissions

This add-on uses only the minimum permissions necessary for its functionality.

• Hosts: youtube.com, googlevideo.com (Required for audio analysis and control).
• Data Privacy: No watch history or personal data is collected or transmitted. All audio processing is performed locally