New recordings, old phones
M4A is what modern phones record and what iTunes sells. MMF, the extension of Yamaha's SMAF format, is what many feature phones of the 2000s used for ringtones, especially Samsung models with Yamaha sound chips. These phones usually cannot play M4A at all. If you want a familiar song, or a recording of a family member's voice, as the ringtone on an older handset, converting M4A to MMF is the way to do it.
A personal voice ringtone
A short voice memo makes a charming ringtone: a grandchild saying "Grandma, pick up!", a pet, or a family joke. Speech also survives MMF conversion very well, because voices sit in the middle frequencies that old phone speakers reproduce clearly. Record it with the Voice Memos app or any recorder, keep it under 15 seconds, and make it loud: use increase volume or normalize before converting.
What the conversion changes
- The audio becomes mono, even if the M4A is stereo.
- It is encoded as 4-bit Yamaha ADPCM at 22 kHz by default.
- Treble is reduced and a little hiss is added, which is barely audible on a phone speaker.
- Tags and artwork from the M4A are not kept.
| Clip | M4A (AAC) | MMF at 22 kHz | MMF at 8 kHz |
|---|---|---|---|
| 10-second voice memo | about 80 KB | about 110 KB | about 40 KB |
| 30-second song clip | about 960 KB at 256 kbps | about 330 KB | about 120 KB |
Notice that a low-bitrate voice memo can become slightly larger as MMF, because ADPCM is simpler than AAC. For speech, the 8 or 11 kHz setting keeps it small and still clear.
Preparing and transferring
Cut the part you need in Cut audio. For a song, choose a section with a strong melody, since bass is lost on a small speaker. Copy the MMF to the phone's memory card or send it by Bluetooth, then set it as the ringtone in the sound settings. Apple Music downloads are DRM-protected and cannot be converted; your own recordings and iTunes Store purchases work. If the phone refuses the file, it may be too large: shorten it or use a lower sample rate.