Files
WebM or MP4: which you get and why
Browsers do not all record to the same format, and you do not get to choose. Which you get depends entirely on the browser.
What each browser produces
Anything built on Chromium hands you a WebM file, as does Firefox — VP9 or VP8 pictures paired with Opus sound. Safari breaks from that and writes MP4 instead, carrying H.264 video and AAC audio.
WebM
Smaller files at the same quality, royalty-free, and plays in every modern browser. Some desktop players and older editing software refuse it.
MP4
Larger for the same quality, but plays in essentially everything: phones, TVs, editors, messaging apps.
Which to want
For sharing a link or uploading to a video platform, WebM is fine and smaller. For sending to someone who will open it in whatever their computer defaults to, convert to MP4 first.
Read next
- How to convert a WebM recording to MP4
Three ways to convert a screen recording to MP4, including one that does not re-encode.
- The recording will not play
What to do when a downloaded recording refuses to open, or shows the wrong length.
- How long can a browser screen recording be?
There is no time limit, but there is a practical one — and it is about memory.