Convert OPUS to M4B
Convert your OPUS audio files to M4B directly in your browser.
How to convert audio in 3 steps
Choose a OPUS audio file.
Click convert to M4B.
Download your M4B audio.
Format descriptions
OPUS — OPUS is a modern, open and royalty-free audio codec. It delivers excellent quality even at low bitrates, making it ideal for streaming, voice and podcasts.
M4B — M4B is the MP4-based container used for audiobooks. It supports chapters and bookmarks, using the AAC codec just like M4A.
Technical comparison: OPUS vs M4B
Technical breakdown of the OPUS and M4B specifications: compression, colour, transparency and animation support.
| Property | Opus | M4B |
|---|---|---|
| Specification | Opus (Opus Interactive Audio Codec) | M4B (MPEG-4 Audiobook Container) |
| Media type | Audio | Audio |
| Compression | Lossy · Opus (RFC 6716) | Lossy · AAC |
| Color space / bit depth | 16-bit, 8-48 kHz | 16-bit up to 48 kHz |
| Transparency | Not applicable | Not applicable |
| Animation | No (static) | No (static) |
| Best for | OPUS is a modern, open and royalty-free audio codec. It delivers excellent quality even at low bitrates, making it ideal for streaming, voice and podcasts. | M4B is the MP4-based container used for audiobooks. It supports chapters and bookmarks, using the AAC codec just like M4A. |
What happens when converting OPUS to M4B?
The OPUS data is decoded inside your browser with WebAssembly and re-encoded to the M4B specification, so no file is ever uploaded to a server. M4B uses lossy compression: the file gets far lighter, but a small amount of fine detail is discarded in the process.
Frequently Asked Questions
What is audio conversion?
Audio conversion changes an audio file from one format to another, for example from OPUS to M4B, while keeping the audio content.
Are my audio files uploaded?
No. This tool processes audio files directly in your browser. Your audio files are never sent to a server.
Which audio formats are supported?
This tool converts OPUS audio files to M4B, all in your browser.
Is it really free and unlimited?
Yes, the tool is completely free and you can convert as many audio files as you want, with no limits.
Does it work on mobile too?
Yes, it works on any modern device, including smartphones, tablets and desktop computers.
Which format will the result be in?
The converted file will always be in M4B format, ready to download and use.
About the audio converter
Convert OPUS to M4B audio online for free. Everything happens in your browser: your files are never uploaded to a server, and you need no downloads or sign-up to get started.
See also:
- Audio Converters
- Compress Audio OnlineCompress MP3, WAV, OGG, M4A, AAC, OGA, FLAC, ALAC, AIFF, OPUS, M4B and AC3 audio files online for free. Reduce the file size of your audio recordings while keeping good quality. Everything happens in your browser: audio files are never uploaded to a server, and you need no downloads or sign-up to get started.
- Convert OPUS to MP3Convert OPUS to MP3 audio online for free. Everything happens in your browser: your files are never uploaded to a server, and you need no downloads or sign-up to get started.
- Convert OPUS to WAVConvert OPUS to WAV audio online for free. Everything happens in your browser: your files are never uploaded to a server, and you need no downloads or sign-up to get started.
- Convert OPUS to OGGConvert OPUS to OGG audio online for free. Everything happens in your browser: your files are never uploaded to a server, and you need no downloads or sign-up to get started.