Convert RMI to M4A — Free Online Converter
Convert RIFF MIDI (.rmi) to MPEG-4 Audio (.m4a) online for free. Fast, secure audio conversion with no watermarks or registration....
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How to Convert
Upload your .rmi file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .m4a file when it's ready.
About RMI to M4A Conversion
RMI (RIFF MIDI) is Microsoft's RIFF-wrapped MIDI format, integral to the Windows multimedia architecture from Windows 3.1 through Windows XP. The format was processed by the Windows MIDI mapper (midiOutGetDevCaps, midiOutOpen) and DirectMusic loader, providing MIDI sequencing through the same RIFF infrastructure that handled WAV audio. RMI's DISP chunk could store a display name for Windows Explorer integration, and INFO chunks held attribution metadata.
M4A is the standard audio-only MPEG-4 container, Apple's default music format used by iTunes, Apple Music, iPhone voice memos, and GarageBand exports. Converting RMI to M4A extracts MIDI from the Windows RIFF envelope, synthesizes audio, and packages the result as AAC or ALAC within the M4A container — creating a modern, universally compatible audio file from legacy Windows content.
Why Convert RMI to M4A?
RMI is completely invisible to Apple's ecosystem — Core Audio, AVFoundation, and iTunes cannot parse the RIFF MIDI container. M4A is Apple's native audio format with first-class support across iPhone, iPad, Mac, Apple Watch, Apple TV, and HomePod. Converting RMI to M4A is the most natural path for making Windows MIDI content accessible to Apple users.
M4A with AAC encoding offers excellent audio quality at modest file sizes, supports gapless playback, chapter markers, and artwork embedding, and integrates directly with iTunes for library management. For organizations migrating Windows multimedia assets to Apple-centric infrastructure, M4A is the target format of choice.
Common Use Cases
- Publishing legacy Windows multimedia MIDI compositions in Apple Music-compatible M4A format
- Converting Windows kiosk background music from RMI to M4A for iPad-based digital signage systems
- Migrating Windows CE notification sounds to M4A for iPhone integration via iTunes
- Creating iTunes-compatible music library entries from archived Windows RMI compositions
- Preparing Windows-era educational software soundtracks as M4A for iPad classroom deployment
How It Works
FFmpeg detects the RIFF MIDI container, extracts the enclosed MIDI data, and routes the event stream to a software synthesizer with a loaded SoundFont bank. The synthesizer processes note events with velocity-sensitive amplitude, program changes for instrument selection, and control changes for dynamics and expression. The stereo PCM output is encoded using AAC-LC at the target bitrate and packaged in an M4A container with ftyp (M4A brand), moov (metadata atoms including iTunes tags), and mdat (encoded audio data) boxes.
Quality & Performance
M4A with AAC at 256 kbps delivers transparent audio quality for synthesized MIDI content — encoding artifacts fall below the noise floor of typical SoundFont synthesis. RMI files were designed to be played through the Microsoft GS Wavetable Synth, which uses Roland Sound Canvas-derived samples. A different SoundFont will produce different instrument voicings. For authentic Windows-era character, choose a SoundFont that approximates the Microsoft GS patch set.
Device Compatibility
| Device | RMI | M4A |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Native |
| iPhone/iPad | Partial | Native |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No | No |
Recommended Settings by Platform
Spotify
Resolution: N/A
Bitrate: 320 kbps
OGG Vorbis preferred
Apple Music
Resolution: N/A
Bitrate: 256 kbps
AAC format required
SoundCloud
Resolution: N/A
Bitrate: 128 kbps
Lossless FLAC/WAV for best quality
Podcast
Resolution: N/A
Bitrate: 128 kbps
MP3 mono for spoken word
Tips for Best Results
- 1Use 256 kbps AAC-LC for Apple Music-standard quality — this is the sweet spot for synthesized MIDI audio
- 2Embed album artwork and iTunes metadata in the M4A output for proper display in Apple's Music app and iTunes
- 3Transfer attribution from the RMI's RIFF INFO chunks to M4A metadata atoms for proper copyright preservation
- 4Trim any leading silence from the rendered M4A — MIDI files sometimes have empty measures at the beginning that produce silence
- 5Test the M4A on both iPhone and Mac to verify consistent playback and metadata display before batch converting RMI collections
RMI to M4A bridges Windows RIFF MIDI content into Apple's audio ecosystem. This is the natural conversion for making legacy Windows multimedia MIDI accessible on iPhone, iPad, and Mac.