Increase Video Volume

Phone videos of talks, interviews and school events are often too quiet, and turning the player up to the maximum still is not enough. This tool raises the sound inside the video file itself. It measures the soundtrack first, then either maximises it so the loudest moment just reaches the limit without distortion, normalises it to an even −16 LUFS like podcasts and streaming apps, or changes it by the number of decibels you choose, with a limiter that holds the loudest moments back instead of letting them crackle. The picture is copied untouched. It runs in your browser with the ffmpeg engine (about 30 MB, downloaded once); nothing is uploaded.

How to use this tool

1. Pick how: maximise, normalise loudness, or a fixed change (louder or quieter).
2. For a fixed change, choose the decibels and keep the limiter on when making it louder.
3. Choose one or more videos.
4. Listen to the result and download it; the levels before and after are shown.

Formula

New level (dB) = old level + change; amplitude × 10^(change ÷ 20)

Decibels are logarithmic: +6 dB doubles the amplitude, and about +10 dB sounds twice as loud. "Maximise" uses change = −1 dB − the measured peak, so nothing clips. The limiter lets quieter parts rise by the full amount and smoothly holds anything that would pass about −1.5 dBFS, leaving room for the small overshoot of the sound encoder. Loudness normalising (EBU R128) adjusts the level continuously towards −16 LUFS, which helps when some speakers are much quieter than others.

Example

A lecture recording peaks at −14 dBFS. "Maximise" applies +13 dB (−1 − (−14)), about 4.5 times the amplitude, with no distortion. A fixed +20 dB with the limiter makes the quiet parts louder still, while the loud parts are held at about −1.5 dB instead of clipping.