Loudness Normalizer by Jason

Keeps the volume consistent across everything you play in Firefox. Quiet videos get a boost, loud ones get turned down, and a limiter stops anything from clipping.

Loudness is measured the way broadcasters do it (ITU-R BS.1770 / EBU R128, in LUFS) over the whole video, so the gain settles to one steady level per video. Quiet scenes stay quiet and loud scenes stay loud; it does not pump or breathe.

Settings (click the toolbar icon)
- Target loudness, default −16 LUFS
- Maximum boost, default 12 dB
- On/off switch
- Live readout of the source loudness and the gain being applied

Lightweight
Nothing runs until something audible plays. When everything is paused the audio processing is suspended. Muted autoplay in feeds is ignored.

Limitations
- DRM-protected media (Netflix, Spotify, Disney+) cannot be processed.
- Cross-origin media served without CORS is left alone, since Web Audio would silence it. YouTube, Twitch, Reddit and X work.
- Players inside shadow DOM are not detected.

No data is collected and no network requests are made.