MMF File

What are MMF files and how to open them

Are you having problems opening a MMF file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your MMF files.

What is a MMF file?

MMF files have multiple uses, and Yamaha Synthetic-Music Mobile Application Format Audio is one of them. Read more about the other uses further down the page.

Yamaha Synthetic-Music Mobile Application Format Audio

Yamaha Synthetic-Music Mobile Application Format Audio (extension .mmf) is a Yamaha-proprietary audio / multimedia file type designed for use on handheld devices like mobile phones and PDAs. It stores compact music and multimedia content - often ringtones - that combine note sequences, instrument definitions, and sometimes graphics, rather than full recordings. The files are used when devices include a Yamaha SMAF-compatible sound chip, allowing lightweight playback of music using FM synthesis, PCM samples, or a combination thereof.

These files are produced with Yamaha authoring tools such as SMAF Sound Decorator, Wave to SMAF Converter, or SMF-to-SMAF converters, which accept inputs like MIDI (.mid) or WAV (.wav) and output .mmf files formatted for specific sound chip types (for example MA-1, MA-2, MA-3, MA-5, MA-7). The .mmf file is typically loaded into mobile device firmware or system sound banks, where the device's SMAF player reads the file and drives its sound chip to render the content, rather than decoding audio like MP3.

Inside the file, the beginning signature is MMMD in ASCII (hex 4D 4D 4D 44) at offset 0, followed by chunked data sections, one of which is identified by CNTI at offset 8 (bytes 0x434E5449). These segments define content such as instrument parameters, note sequence data, master control information, and audio sample data.

How to open MMF files

Important: Different programs may use files with the MMF file extension for different purposes, so unless you are sure which format your MMF file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested ten different MMF openers which you will find listed below.

Last updated: August 10, 2026

All known file formats using extension .MMF

While Yamaha Synthetic-Music Mobile Application Format Audio is a popular type of MMF-file, we know of 4 different uses of the .MMF file extension. Different software may use files with the same extension for different types of data.

MathMagic Equation File

MathMagic Equation File (extension .MMF) is the native file format used by MathMagic Personal Edition by InfoLogic to store mathematical equations in a way that preserves full editable equation information. It is used when you build or edit a formula using MathMagic, saving all formatting, symbols, color, layout, and metadata so you can reopen and modify it exactly as created. The format allows cross-platform interoperability between Windows, macOS, iOS and Android versions of MathMagic.

This .MMF file is text-based rather than binary, similar in structure to formats like LaTeX or MathML. Equations saved in .MMF retain MathMagic-specific data that controls display style, color, version, and layout. When you export to image or generic math interchange formats, the .MMF data is often embedded as annotations so future editing in MathMagic remains possible.

Internally, .MMF files begin with the ASCII signature "\INFORMATION" at file offset 0. They include identifiable keywords such as CREATOR(MATHMAGIC, VERSION(, COLOR(, TITLE(, DATE(, SETTING, ROOT(, NORMAL TEXT, EXPLAIN(), CONTENT, and MMTIMES. These markers help distinguish the file format and aid software in recognizing that the file truly contains MathMagic equation data rather than some other .mmf-extension format.

MMF opener for Windows

We have identified one MMF opener that is compatible with this specific type of MMF file.

Meal-Master Format Recipe

Meal-Master Format Recipe files (extension .mmf) are plain-text recipe files created by the MealMaster DOS recipe-database program originally from Episoft Systems. They are used to save cooking recipes in a standardized text format so recipes can be archived, shared, searched by title or category, printed or imported by other recipe programs. These files store the recipe title, category list, yield or servings, ingredient list, and preparation instructions. These files are popular among recipe-collectors and hobbyists preserving vintage recipe archives.

Meal-Master recipes are exported by the MealMaster software and then typically read or imported by recipe-management tools, cook-book apps or text editors capable of interpreting its layout. Because .mmf files are plain text, users can view or edit them directly. Many modern recipe-apps support importing .mmf exports to convert them into newer, structured formats. The format supports both one-column and two-column layouts for ingredients, allows section headings within the ingredient list (e.g. for dough versus filling), and separates ingredients from preparation instructions.

File headers begin with a separator line (often five or more hyphens or "MMMMM") containing the phrase "Recipe via Meal-Master (tm)" plus version number. Labeled metadata fields follow such as "Title: …", "Categories: …", and "Yield:" or "Servings: …". Ingredients are listed in fixed -width columns (amount, unit, ingredient description), with continuation lines starting with a hyphen. After a blank line or after the ingredient section end, instructions appear as free-text paragraphs. A line of hyphens or "MMMMM" terminates the recipe.

Microsoft Message File

A Microsoft Message File (extension .MMF) is a data file used by the Windows NT Mail client to store a user's email messages in one file. Each Windows NT Mail user has their own .MMF file (called "Username.mmf" by default) located in the Winnt35 folder. It holds messages in the user's inbox, outbox, and other mail folders in a proprietary collection/database format rather than as separate individual files.

These files are produced automatically by the Windows NT Mail application and are no longer updated or supported by current email clients. To access content in a .MMF file today, users typically import them using Microsoft Exchange Server, which converts the message collection into a format usable by more modern systems.

Each .MMF file is a single container that groups messages together; it does not use the plain-text structures of Internet email standards like EML or MIME. The internal structure is undocumented in public Microsoft Open Specifications, and no reliable header signature for .MMF has been confirmed.

Programs that open these MMF files

We have identified one MMF opener that is compatible with this specific type of MMF file.

Various apps that use files with this extension

These apps are known to open certain types of MMF files. Remember, different programs may use MMF files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about MMF file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.