I want to create some ringtones for my iPhones using Garageband and Audacity program in Mac. The ringtones extension is .m4r and for iPhones, they must be in AAC .m4a format. All we need is to create a 30-40sec audio file in this format and rename it to .m4r and we have ringtones. Garageband has the share button that would convert any mp3 format to m4r and put it in the tones folder for iTunes to transfer to iPhones when synced.
Audacity is a program that also let us to edit a music format and export to m4a (AAC) format using ffmpeg plugin. After the song is exported (less than 40 sec), we can just rename to .m4a to .m4r and put in the phones folder of our choice.