MIDI(SMF) and MP3 format for PC are common and used on the Internet throghout the world. For Ringtone, however, MFi(DOCOMO) and SMAF(VODAFONE) based formats are common. They are similar to MIDI but not the same. Furthermore, they are programmed to make small files. The difference of format styles between Ringtone's and PC's is to make Ringtone file sizes as small as possible. Of course, the purpose is to download files at high speed.

Ringtone files are based on MIDI(SMF). MFi and SMAF format are popular, and they are worked out to make data file size small. For example, when making a sound in SMF format, it required 2 kinds of data which "makes" sounds and "stop" sounds. This system is called "Note On/ Note Off Message". However, as common mechanism for both MFi and SMAF, they don't contain a program to stop sounds. Since Ringtone data contains how long every note lasts, it's needless to have "Note Off Message". Addition to that, we can select parts to be repeated (though it's not sure if there has been a precedent for this system...). This function is also for cutting down duplicated data and making file size small.