Bulk OPUS to M4B Converter Online — Free HD Quality
Drag and drop your multiple OPUS files into this 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 — your original OPUS 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
OPUS vs M4B — File Format Comparison
| 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
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