Bulk RMI to M4B Converter Online — Free HD Quality
Drag and drop your multiple RMI files into this free online RMI to M4B converter (.rmi to .m4b), and click the Convert button to bulk convert them to M4B format in HD quality. Use the quality slider to fine-tune your M4B output, then download your converted files one by one or as a single ZIP — your original RMI files are removed from our servers right after.
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PNG, JPG, WebP, GIF, HEIC, RAW, PSD, SVG and more
Max 100MB per file
RMI vs M4B — File Format Comparison
| Feature | RMI | M4B |
|---|---|---|
| File Extension | .rmi | .m4b |
| MIME Type | audio/midi | audio/mp4 |
| Compression Type | Varies | Lossy |
| Metadata Support | Yes | Yes |
What Is RMI Format?
RIFF MIDI — a Windows variant of the MIDI format wrapped in a RIFF container (the same container used by WAV), produced by older Windows Media Player and Cakewalk software.
- Compression: Varies
- Tags & Metadata: Supported
What Is M4B Format?
MPEG-4 Audiobook — AAC audio in an MP4 container with bookmarking support, the standard format for audiobooks on Apple Books, Audible exports, and iPhone podcasts.
- Compression: Lossy
- Tags & Metadata: Supported
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