AVI to WEBM

How to do it

1. Download Asteria and open it. It's free and needs no account.
2. Drop your AVI files onto its window, or press ⌘O (Ctrl O on Windows) to choose them. Drop as many as you like.
3. Type webmand pick Convert to WebM. VP9 WebM for the web.
4. The first time, Asteria asks to download FFmpeg, a free add-on from the FFmpeg project, under the GPL-3.0-or-later license. It shows the download size before you say yes, and needs no administrator password.
5. Press ⌘↵ (Ctrl ↵ on Windows) to save. The WEBM files appear next to the originals, which stay exactly as they were.

What it needs

AVI to WEBM uses FFmpeg, a free program for audio and video. Asteria doesn't bundle it. The first time you need it, Asteria offers to download it, checks the download against a pinned checksum, and keeps it in its own folder, where Settings can remove it again. If FFmpeg is already on your computer, Asteria uses that copy.

How it was tested

A real AVI file was converted on macOS on Apple silicon and Linux, and the WEBM that came out was opened and checked with ffprobe to make sure it is what it says it is.