What MMF is for
MMF files use SMAF, a format by Yamaha for the sound chips of mobile phones. Samsung and other makers used it for ringtones and alerts on feature phones in the 2000s. Today you need MMF only if you still use, repair or collect such a phone, or if a retro project requires the original format. Smartphones play MP3, M4A and OGG directly, so they do not need it.
What you get
SMAF can hold synthesizer notes or recorded audio. This converter writes recorded audio, using Yamaha's ADPCM coding: 4 bits per sample, in mono, at a low sample rate. It sounds like a phone speaker from that era, a little thin and noisy, which is expected.
| Sample rate | Bitrate | Size per 30 seconds |
|---|---|---|
| 8 kHz | 32 kbps | about 120 KB |
| 11 kHz | 44 kbps | about 165 KB |
| 22 kHz | 88 kbps | about 330 KB |
Getting a good ringtone
- Keep it short. Many old phones limit the size of ringtone files. Cut the part you need with Cut first; 15–30 seconds is typical.
- Make it loud. Small speakers need a strong signal. Use Normalize before you convert OGG to MMF.
- Prefer simple sounds. A clear melody or voice survives 4-bit coding better than a dense mix with heavy bass.
Copying it to the phone
Most of these phones accept ringtones over Bluetooth, a memory card or a USB cable with the maker's PC software. If the phone refuses the file, try 8 kHz and a shorter clip, since some models only support the lowest rates. MMF has no fields for titles or artists, so give the file a clear name before you copy it; the phone usually shows the file name in its ringtone list.
Keep your original OGG file as well. The MMF version is made for one old device, and it is a poor starting point for any later conversion because so much detail is removed. To turn old MMF ringtones back into something modern, see MMF to MP3.