Boost a video's audio in your browser — play it loud, export the audio

The two different problems people call "quiet video"

The first is that the audio in the file is genuinely low-level: someone filmed a lecture from the back of the room, or a phone recorded a conversation across a table. The waveform is small, and the fix is to multiply it — which is what this page does, up to five times, with a limiter to keep the peaks honest.

The second is that the file is fine and the playback is quiet: your phone is on 40 %, the app has its own volume slider set low, a Bluetooth speaker is halfway down, or a browser tab is muted. Boosting the file will not help there, and it is worth ruling out first — turn the system volume to maximum and play the video somewhere else before you process anything.

How the boost works here

The video plays from your own disk and its audio is routed through the same chain the rest of this site uses — five-band equalizer, bass shelf, volume, soft limiter — before it reaches your speakers. That means you can push well past 100 % and hear the result in context, with the picture, rather than guessing at a number and exporting blind.

The Movie preset in the equalizer is worth a try on dialogue you cannot follow: a little more weight underneath and a firm +4 dB at 3 kHz, which is where consonants live. Very often speech that seemed too quiet was actually just unclear, and a 3 kHz lift fixes it at a lower volume than brute force would need.

What you can save, and what you cannot

This page can export the boosted audio as a WAV — the full soundtrack, processed exactly as you hear it. That is what you want if you are putting the audio back into a video editor, sending someone a listenable copy of a recording, or salvaging the sound from a clip.

It does not re-encode the video itself. Rewriting an H.264 stream with new audio in a browser tab means either a real-time re-record — which takes as long as the video runs and degrades the picture — or shipping a large video encoder to every visitor. Neither is a good trade, so this page does not pretend to do it.

Nor does the app: Increase Volume is an audio-file processor and exports WAV, the same as this page. To end up with a video file, take the WAV you saved here and mux it back onto the picture — any video editor will do it, and ffmpeg -i clip.mp4 -i boosted.wav -c:v copy -map 0:v -map 1:a out.mp4 does it losslessly, without touching the picture at all.

Which video files work

MP4 and MOV with H.264 video and AAC audio play in every modern browser, which covers essentially everything a phone or camera produces. WebM works in Chrome and Firefox. MKV and AVI usually do not play in browsers at all — if yours does not load, that is a container support issue rather than a problem with your file, and converting it to MP4 first will fix it.

Saving the boosted audio needs one extra thing: your browser has to be able to decode the video's audio track on its own. Most can, for MP4 and MOV. If yours cannot, playback will still be boosted and the page will tell you plainly that the export is unavailable rather than handing you a broken file.

A note on hearing safety

Boosting a quiet video and then forgetting the setting is a genuinely good way to hurt your ears when the next thing you play is at normal level. This is a bigger risk with headphones than with speakers, and a bigger risk with the limiter on, because limited audio sounds less alarming than it is. Drop the volume back to 100 % when you are done.