The full form of MMF is Synthetic Music Mobile Application File

Synthetic-music mobile application format, abbreviated SMAF, is a music data format specified by Yamaha for portable electronic devices, such as cell phones and PDAs. The file extension for SMAF is .MMF and is common as ringtones for mobile phones with one of five sound chips.

SMAF resembles MIDI, but also supports graphics and PCM sound playback. Its MIDI playback is produced via FM synthesis or PCM sample-based synthesis, where instrument data (parameters and/or PCM samples) is stored within the .MMF file itself, similar to module files. This enables users to create custom instruments, which will sound exactly the same on devices with the same chip.

The feature set used in SMAF files usually orients itself at the chips produced by Yamaha for playback

The full form of MMF is Microsoft Media Foundation

Media Foundation (MF) is a COM-based multimedia framework pipeline and infrastructure platform for digital media in Windows Vista, Windows 7, Windows 8, Windows 8.1 and Windows 10. It is the intended replacement for Microsoft DirectShow, Windows Media SDK, DirectX Media Objects (DMOs) and all other so-called “legacy” multimedia APIs such as Audio Compression Manager (ACM) and Video for Windows (VfW). The existing DirectShow technology is intended to be replaced by Media Foundation step-by-step, starting with a few features. For some time there will be a co-existence of Media Foundation and DirectShow. Media Foundation will not be available for previous Windows versions, including Windows XP.

Microsoft Media Foundation enables the development of applications and components for using digital media on Windows Vista and later.

Media Foundation is the next generation multimedia platform for Windows that enables developers, consumers, and content providers to embrace the new wave of premium content with enhanced robustness, unparalleled quality, and seamless interoperability.