How to batch-convert a folder of videos — ffmpeg shell loops

Not one file but fifty: convert every MP4 in a folder to WebM, or pull an MP3 out of each one.

for f in *.mp4; do ffmpeg -i "$f" -c:v libvpx-vp9 -b:v 2M -c:a libopus "${f%.mp4}.webm"; done
for f in *.mp4; do ffmpeg -i "$f" -vn -c:a libmp3lame -q:a 2 "${f%.mp4}.mp3"; done

FFmpeg Cheatsheet one-page card — 28 commands that actually work — The full one-page card — FFmpeg Cheatsheet. Get the complete cheatsheet on GitHub