Convert MP3 to Vorbis OGG format using ffmpeg.
<pre lang="bash">
ffmpeg -i input.mp3 -c:a libvorbis -q:a 4 output.ogg
If you want multiple files, use a loop.
<pre lang="bash">
for f in ./*.mp3; do ffmpeg -i "$f" -c:a libvorbis -q:a 4 "${f/%mp3/ogg}"; done