Convert Video

Questions

Which conversions are supported?

Between MP4, WebM and MOV, and from any of them to WAV audio. What actually works depends on your browser, because the encoding is done by the browser itself — Chrome and Edge cover the most ground, Safari handles MP4 and MOV well. The tool checks before it starts and says so if a combination is not available rather than failing halfway through.

Can I extract just the audio?

Yes — choose WAV and the picture is discarded, leaving the sound as an uncompressed file any editor or transcription tool will accept. WAV is deliberately large; if you need something small, convert and then compress, or keep the original.

Is anything uploaded?

No. Conversion runs through WebCodecs in your browser. That is the point of doing it this way: converting a large file by uploading it, waiting on a queue and downloading it back is slower than doing it locally, and it puts your footage on a stranger's disk in between.

Why can my browser not open a MOV from my camera?

A .mov file is a container, and what matters is the codec inside it. Browsers handle H.264 and, increasingly, HEVC — but not ProRes, DNxHD or camera-raw formats, which is what professional cameras usually write into a .mov. Those need a real transcode from a desktop tool first.

Does converting lose quality?

Changing container between MP4 and MOV can often be done without touching the video at all. Changing codec — to WebM, for example — means re-encoding, and re-encoding always costs a little. It is generally invisible for one generation, and it accumulates if you convert the same file repeatedly.

The other tools

• Trim Video — Drag the handles to the part you want, preview it, save it. Audio stays in sync.
• Compress Video — Make a file smaller and see exactly what it cost. No size limit, because there is no server.
• Video to MP3 — Pull the audio out of a video and keep it as MP3, WAV or OGG.
• Convert Video — MP4, WebM and MOV in any direction — or pull the audio out as WAV.
• Video Splitter — Cut a long video into Reels or Shorts that start on a shot change instead of every 30 seconds, ranked by picture quality.
• BPM Detector — Find a track’s tempo and the time of every beat, then send the grid to Resolve, Premiere, Final Cut or Audacity as markers.
• Scene Detector — Find every cut in a video and get the shot list with thumbnails, timecodes and quality scores.

import { getFirstEncodableVideoCodec, WebMOutputFormat } from 'mediabunny';

const format = new WebMOutputFormat();
const codec = await getFirstEncodableVideoCodec(format.getSupportedVideoCodecs());
if (!codec) throw new Error('This browser cannot encode WebM video');

Add "convert a video between formats" to my project, running entirely in the browser.

Requirements:
- Use "mediabunny" (WebCodecs). Support MP4, WebM and MOV, plus WAV for audio-only output.
- Check what the browser can actually encode BEFORE starting, with getFirstEncodableVideoCodec on the
  chosen output format. Finding out by failing at 70% of a long encode is the worst possible way to
  learn it. Say which codec will be used when it succeeds.
- A container is not a codec. Read what is inside the file and show it: browsers handle H.264 and
  often HEVC, but never ProRes or camera raw, and a .mov from a professional camera will not open.
  Say that in the error rather than "unsupported file".
- Hide the resolution control for audio-only output — it is meaningless without a picture.
- MP4 to MOV can often be done without touching the video; changing codec cannot.

Reference implementation: https://life2film.com/tools/video-converter/