Upload M4A 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
M4A is a file extension used in compressed MPEG-4 audio files that have a lossy compression algorithm. M4A is pretty much very similar to another popular compressed audio format, but is designed to have better quality in the same or even smaller file size. The M4A format was developed by Apple in 2004 and is based on the QuickTime format. Music available for purchase on iTunes usually uses M4A recordings. Many M4A files are encoded with the Advanced Audio Coding (AAC) lossy codec to reduce file size. Some M4A files may use the Apple Lossless Audio Codec (ALAC) instead. The M4A format provides good compression with high sound quality. Any compatible media player will work to play M4A audio, including Apple iTunes, Windows Media Player, VideoLAN VLC media player, Nullsoft Winamp, Apple QuickTime Player, and others.
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.