Ffmpeg/Cheatsheet
Converting from m4a to ogg
Converting a bunch of file from .m4a to .ogg under ksh or bash. After the work has been completed delet the orignial. File deletion can be commented out if required.
for file in *m4a; do [[ -f ${file%.m4a}.ogg ]] || ffmpeg -i "${file}" -acodec libvorbis "${file%.m4a}.ogg"; ## [[ $? -eq 0 ]] && rm "${file}" done