Bulk AMR to M4B Converter Online — Free HD Quality
Drag and drop your multiple AMR files into this free online AMR to M4B converter (.amr 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 AMR 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
AMR vs M4B — File Format Comparison
| Feature | AMR | M4B |
|---|---|---|
| File Extension | .amr | .m4b |
| MIME Type | audio/amr | audio/mp4 |
| Compression Type | Lossy | Lossy |
| Metadata Support | No | Yes |
What Is AMR Format?
Adaptive Multi-Rate — the standard voice codec for GSM and UMTS mobile networks, used in phone call recordings and voice messages; delivers compact files optimised for speech at 8 kHz.
- Compression: Lossy
- Tags & Metadata: Not 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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