Bulk OPUS to M4B Converter Online — Free HD Quality
Drag and drop your multiple OPUS files into this 100% free online OPUS to M4B converter (.opus 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 — no signup and no downloads needed, and your original OPUS files are removed from our servers right after. Also see:Switch WAV to FLAC format.
Drop your OPUS files here to convert to M4B, or click to browse
Converts .opus to M4B (.m4b) in HD quality — bulk, free, no signup
Choose FilesOPUS vs M4B — File Format Comparison
See how OPUS and M4B compare across file extension, MIME type, compression, and feature support. Related:Handle many AAC to OGA at once.
| Feature | OPUS | M4B |
|---|---|---|
| File Extension | .opus | .m4b |
| MIME Type | audio/opus | audio/mp4 |
| Compression Type | Lossy | Lossy |
| Metadata Support | Yes | Yes |
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
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