Video converter

How to use the Video Converter

1. Drop in the clips. A queue can mix formats, for instance a MOV from a phone next to an old AVI.
2. Pick the output in the Convert to menu. For sharing, editing and uploading, MP4 is nearly always the one.
3. Choose High, Balanced or Small file, and open More settings if you want 1080p, 720p or a smaller resolution.
4. Convert, then save each result or the whole batch as a ZIP.

Rewrap when possible, re-encode when needed

Every video file is a wrapper around compressed picture and sound streams. If those streams are already legal in the new wrapper, for example H.264 going from MKV into MP4, they are carried over untouched: no quality loss and a job measured in seconds rather than minutes.

A real encode is needed only if the new wrapper has no room for the source codec or when you ask for a lower resolution. That is when the quality choice matters; smaller clips are never scaled up.

Two engines behind one button

MP4, MOV, WebM and MKV sources go to WebCodecs first, the media encoder and decoder built into current browsers, which can use the graphics chip. Anything else is handled by ffmpeg compiled to WebAssembly, a roughly 31 MB engine fetched once that the browser keeps in its cache.

That ffmpeg build is the single-thread version, so a long 1080p re-encode on it can take several times the running time of the clip. Pure rewraps and sound-only work stay quick either way.

What each target holds

MP4, MOV, MKV and FLV are written as H.264 with AAC sound. WebM gets VP9 and Opus, or VP8 when the browser lacks WebCodecs. AVI uses Xvid-style MPEG-4 with MP3, WMV pairs WMV2 with WMA, MPEG means MPEG-2 with MP2, and OGV means Theora with Vorbis.

Only the first picture track and the first sound track are kept. Subtitle and data tracks are dropped.

Questions