Convert MP4 to WebM
basic conversion
// what it does
Transcodes into the open WebM container. The bare first form lets ffmpeg pick WebM's default encoders (libvpx-vp9 for video, Opus for audio), while the second form explicitly uses libsvtav1 — the fast SVT-AV1 encoder — at -crf 30 with Opus audio for better compression than VP9. Reach for this when you need a royalty-free format for web <video> or want AV1's efficiency without a multi-hour encode.
// shell
$ ffmpeg -i input.mp4 output.webm$ ffmpeg -i input.mp4 -c:v libsvtav1 -crf 30 -c:a libopus output.webm// gotcha
WebM only accepts VP8/VP9/AV1 video and Vorbis/Opus audio, so it will reject H.264/AAC; also the default libvpx-vp9 path in the first command is notoriously slow, which is exactly why the SVT-AV1 variant exists.