M4R file format
Apple QuickTime Player
This format is used in smartphones of the iPhone series. Mainly this format is an AAC and M4A file. Not all audio files of the iTunes store can be converted to M4R. When syncing with an iPhone and a computer, these files are automatically moved to the phone. These files can be purchased or downloaded from iTunes. Moreover, audio files of other formats can be converted to M4R format. This format ensures possible best ringtone for iPhone.
M4R differs from MP3 because of compression. This format is a type of MPEG-4 standard under the ISO-IEC standard 14495-3. Despite auditory masking, a lossy compression of this format is similar to AAC and MP3 files. It helps to shrink the audio by removing the data and audio, which can not be sensed by the human ear. Meaning M4R can produce high-end audio file without acquiring large space. Users can use any of their desired audio as their choice (like ringtone or alert tone).