FFmpeg - Encode Vorbis

ffmpeg -i <input.file> -a:c libvorbis -qscale:a 3 <output.file>

"libvorbis" - Usable range ≥ 96 Kbps. Recommended range ≥ 192 Kbps.
-qscale:a – audio quality. Range is -1.0 to 10.0, where 10.0 is highest quality. Default is -q:a 3 with a target of ​112kbps. The formula 16×(q+4) is used below 4, 32×q is used below 8, and 64×(q-4) otherwise. Examples: 112=16×(3+4), 160=32×5, 192=32×6, 384=64×(10-4).
Reference: [FFmpeg Guidelines for high quality lossy audio encoding]
Reference: [FFmpeg: A Brief Theora and Vorbis Encoding Guide]