# Convert AU to Opus

> Convert AU to Opus online for free. Runs entirely in your browser, so your files never leave your device. Fast batch conversion, no sign-up, no watermarks.

URL: https://www.converterrr.com/au-to-opus

- Runs in the browser with FFmpeg (WASM): files are not uploaded, and no credits are used.
- Engines: FFmpeg (WASM) (browser), FFmpeg (cloud).
- API: available. `POST /api/v1/jobs` with `"output_format": "opus"` (paid plans).
- More: [Audio converter](https://www.converterrr.com/audio-converter), [AU converter](https://www.converterrr.com/au-converter).

## How to convert AU to Opus

1. **Add your AU files.** Drag and drop AU files onto the converter, paste them, or click to browse. You can add several at once.
2. **Choose Opus.** Opus is already selected. Open Options if you want to change quality, size or metadata.
3. **Convert.** Click Convert. Your files are converted right in your browser in seconds.
4. **Download your Opus.** Download each Opus file, or everything at once as a ZIP.

## Good to know

- We encode at a high-quality bitrate by default. Pick a specific bitrate or sample rate under Options.
- AU files are typically used for legacy Unix and Java applications, while Opus is best for voice messages, VoIP and efficient music streaming.
- This conversion runs on FFmpeg (WASM), running locally in your browser — nothing is uploaded and it works even on slow connections.

## AU vs Opus

|  | AU | Opus |
| --- | --- | --- |
| Full name | Sun Audio | Opus Audio |
| Type | Audio | Audio |
| Extensions | .au | .opus |
| MIME type | audio/basic | audio/opus |
| Best for | legacy Unix and Java applications | voice messages, VoIP and efficient music streaming |
| Properties | legacy format | lossy compression, open standard |

**AU:** AU is a simple audio format introduced by Sun Microsystems, common on early Unix systems and Java.

**Opus:** Opus is a modern open codec that beats MP3 and AAC at every bitrate and excels at speech. WhatsApp voice notes use it.

The other way around: [convert Opus to AU](https://www.converterrr.com/opus-to-au).

## Related conversions

- [Opus to AU](https://www.converterrr.com/opus-to-au) (in the browser)
- [AU to MP3](https://www.converterrr.com/au-to-mp3) (in the browser)
- [MP3 to Opus](https://www.converterrr.com/mp3-to-opus) (in the browser)
- [AU to WAV](https://www.converterrr.com/au-to-wav) (in the browser)
- [MP4 to Opus](https://www.converterrr.com/mp4-to-opus) (in the browser)
- [AU to M4A](https://www.converterrr.com/au-to-m4a) (in the browser)
- [WAV to Opus](https://www.converterrr.com/wav-to-opus) (in the browser)
- [AU to FLAC](https://www.converterrr.com/au-to-flac) (in the browser)
- [MOV to Opus](https://www.converterrr.com/mov-to-opus) (in the browser)
- [AU to AAC](https://www.converterrr.com/au-to-aac) (in the browser)
- [M4A to Opus](https://www.converterrr.com/m4a-to-opus) (in the browser)
- [AU to OGG](https://www.converterrr.com/au-to-ogg) (in the browser)

## Convert AU to other formats

[AU to MP3](https://www.converterrr.com/au-to-mp3), [AU to WAV](https://www.converterrr.com/au-to-wav), [AU to M4A](https://www.converterrr.com/au-to-m4a), [AU to FLAC](https://www.converterrr.com/au-to-flac), [AU to AAC](https://www.converterrr.com/au-to-aac), [AU to OGG](https://www.converterrr.com/au-to-ogg), [AU to WMA](https://www.converterrr.com/au-to-wma), [AU to AIFF](https://www.converterrr.com/au-to-aiff), [AU to AMR](https://www.converterrr.com/au-to-amr), [AU to M4B](https://www.converterrr.com/au-to-m4b), [AU to AC3](https://www.converterrr.com/au-to-ac3), [AU to MP2](https://www.converterrr.com/au-to-mp2), [AU to WEBA](https://www.converterrr.com/au-to-weba), [AU to OGA](https://www.converterrr.com/au-to-oga), [AU to MKA](https://www.converterrr.com/au-to-mka), [AU to WV](https://www.converterrr.com/au-to-wv), [AU to TTA](https://www.converterrr.com/au-to-tta)

## Convert other formats to Opus

[MP3 to Opus](https://www.converterrr.com/mp3-to-opus), [MP4 to Opus](https://www.converterrr.com/mp4-to-opus), [WAV to Opus](https://www.converterrr.com/wav-to-opus), [MOV to Opus](https://www.converterrr.com/mov-to-opus), [M4A to Opus](https://www.converterrr.com/m4a-to-opus), [WebM to Opus](https://www.converterrr.com/webm-to-opus), [FLAC to Opus](https://www.converterrr.com/flac-to-opus), [MKV to Opus](https://www.converterrr.com/mkv-to-opus), [AAC to Opus](https://www.converterrr.com/aac-to-opus), [AVI to Opus](https://www.converterrr.com/avi-to-opus), [OGG to Opus](https://www.converterrr.com/ogg-to-opus), [WMV to Opus](https://www.converterrr.com/wmv-to-opus), [WMA to Opus](https://www.converterrr.com/wma-to-opus), [M4V to Opus](https://www.converterrr.com/m4v-to-opus), [3GP to Opus](https://www.converterrr.com/3gp-to-opus), [FLV to Opus](https://www.converterrr.com/flv-to-opus), [MPEG to Opus](https://www.converterrr.com/mpeg-to-opus), [AIFF to Opus](https://www.converterrr.com/aiff-to-opus), [AMR to Opus](https://www.converterrr.com/amr-to-opus), [TS to Opus](https://www.converterrr.com/ts-to-opus), [MPG to Opus](https://www.converterrr.com/mpg-to-opus), [M4B to Opus](https://www.converterrr.com/m4b-to-opus), [MTS to Opus](https://www.converterrr.com/mts-to-opus), [VOB to Opus](https://www.converterrr.com/vob-to-opus)

## AU to Opus: frequently asked questions

### How do I convert AU to Opus?

Drop your AU file onto the converter above, make sure Opus is selected, and click Convert. When it's done, download the Opus file — it usually takes a few seconds.

### Is it safe to convert AU to Opus here?

Yes. AU to Opus conversion happens entirely inside your browser using WebAssembly, so your file is never uploaded to any server.

### Is the AU to Opus converter free?

Yes — free with no watermark. Signed-out visitors can convert 25 files a day, and a free account raises that to 250.

### Will converting AU to Opus reduce quality?

Opus is a lossy format, but our defaults are tuned to be visually indistinguishable for most files. You can raise the quality under Options.

### Can I convert multiple AU files at once?

Yes. Add up to 5 files at a time without an account, 10 with a free account and up to 500 on paid plans, then download them individually or as a single ZIP.

### Can I convert Opus back to AU?

Yes — use our Opus to AU converter. Note that converting back and forth between formats can't recover detail lost to lossy compression.