Bulk M4B to OPUS Converter Online — Free HD Quality
Drag and drop your multiple M4B files into this 100% free online M4B to OPUS converter (.m4b to .opus), and click the Convert button to bulk convert them to OPUS format in HD quality. Use the quality slider to fine-tune your OPUS output, then download your converted files one by one or as a single ZIP — no signup and no downloads needed, and your original M4B files are removed from our servers right after. Also see:Queue OGA to WAV conversions.
Drop your M4B files here to convert to OPUS, or click to browse
Converts .m4b to OPUS (.opus) in HD quality — bulk, free, no signup
Choose FilesM4B vs OPUS — File Format Comparison
See how M4B and OPUS compare across file extension, MIME type, compression, and feature support. Related:Switch M4B to AMR format.
| Feature | M4B | OPUS |
|---|---|---|
| File Extension | .m4b | .opus |
| MIME Type | audio/mp4 | audio/opus |
| Compression Type | Lossy | Lossy |
| Metadata Support | Yes | Yes |
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. See also:Online M4B to FLAC converter tool.
- Compression: Lossy
- Tags & Metadata: Supported
What Is OPUS Format?
Opus — the IETF standard for internet voice and music streaming; outperforms MP3, AAC, and Vorbis at every bitrate, and is the default codec for WebRTC, Discord, and Spotify Connect.
- Compression: Lossy
- Tags & Metadata: Supported