Upload AAC file from your device memory or cloud or via URL
Once uploading is complete, press the convert button
Wait until the end of the conversion and download new M4R file
AAC was originally created as a successor to MP3 with improved audio coding quality. Also AAC is a multi-channel audio coding algorithm that supports streaming. To date, the AAC format has not yet reached mass distribution on audio media, but in a number of parameters it surpasses all types of audio compression existing today. This means you can have files that take up less space but still have the same audio quality as other popular compressed audio formats. The format itself is proprietary and requires the purchase of a license for commercial use. AAC is the preferred audio file format for iTunes and Apple Music, but ACC files can be played on Android and Windows computers. Files encoded with AAC can have the extensions .m4a and .mp4. These formats act as containers for packaging audio streams.
M4A is an audio file compressed using MPEG-4 technology, which has a lossy compression algorithm. The M4R file contains the ringtone in the M4A MPEG-4 file format, which uses the default audio format to store the song in the iPhone. The M4R format, like M4A, is designed to download audio to Apple devices through iTunes. Such a file can be created by converting other formats or uploading it from the official iTunes store. You don't have to look for converters or special programs, you can make m4r from m4a using standard tools of any operating system by changing the last letter of the extension manually. But for this to work like an iPhone ringtone, remember that it can only be created from songs purchased from the iTunes music store.