OPUS to AU converter
A free OPUS to AU converter for Opus Interactive Audio Codec files. Browser-based pairs here usually run in this tab, with no file upload.
Drop your OPUS files here
or browse your device · paste with Ctrl+V
Accepts .opus files. You can queue several files; each is processed one after another on your own device.
Your files never leave this device — there is no upload and no server to delete them from.
- 01
Add your OPUS files
Drop them onto the box above or click to browse. They are read straight from disk — nothing is sent anywhere.
- 02
Check the settings
AU is already selected. Open the gear icon on any row if you want to change quality, dimensions or codec before converting.
- 03
Download your AU
Press convert and wait for the row to finish. Convert several files and you can take them all as a single ZIP.
OPUS
Opus Interactive Audio CodecThe best-performing lossy codec available, and an IETF standard. It handles speech at 24 kbps and full music at 128 kbps equally well, which is why WhatsApp, Discord and every WebRTC call use it.
- Developed by
- IETF / Xiph.Org
- Released
- 2012
- Extension
- .opus
- MIME type
- audio/opus
- Compression
- Lossy
- Specification
- Open
AU
Sun AudioThe Unix system-sound format from Sun Microsystems, usually holding 8-bit mu-law audio. Historically important, practically obsolete.
- Developed by
- Sun Microsystems
- Released
- 1992
- Extension
- .au, .snd
- MIME type
- audio/basic
- Compression
- Lossy or lossless
- OPUS is already lossy, and while AU can be saved either way, this conversion cannot restore discarded details. Saving it lossless here preserves what is already present instead of discarding more.
Questions about converting OPUS to AU
Is this OPUS to AU converter free?
Yes. Converting OPUS to AU here is free, with no account, no watermark and no daily quota. The work runs on your own device, so there is no server cost to pass on to you.
Is my OPUS file uploaded anywhere?
For browser-based pairs, your file is read locally and converted by ffmpeg in this tab. No file payload is uploaded; you may still see analytics and engine downloads in network logs.
Is there a file-size limit for OPUS to AU?
There is no imposed upload cap when it runs in-browser, but each conversion still depends on your device and browser memory. Large videos are the first practical limit, then memory-heavy documents or images.
Does converting OPUS to AU lose quality?
It depends on your selected settings and codec path. Many engines can write either lossy or lossless output for AU, so you can usually increase quality if this file is your final version.
Can I convert several OPUS files to AU at once?
Yes. Drop in several files and each gets its own row; they are processed one after another on your device. You can download them one by one or as one ZIP.
Does OPUS to AU work on a phone, Mac or Chromebook?
Most modern browsers on Windows, macOS, Linux, ChromeOS, Android and iOS work. Very large videos are often more reliable on desktop or a browser with more memory.
Why do some conversions take longer on first run?
The conversion engine has to download first. Small codec bundles are fast, while ffmpeg is commonly 12–30 MB; later conversions of similar type use the cached engine.
I converted a file and the output is blank or unusable. What should I check?
Start over with default settings, then change one option at a time (quality, bitrate, page size, or codec) to isolate what changed behavior. If it keeps failing, retry with a smaller file and confirm the source format matches the pair.
Convert other formats to AU
41 formats can become AU here.
Convert OPUS to other formats
A OPUS file can become any of these.
AU to OPUS
The reverse conversion
OPUS to MP3
OPUS to WAV
OPUS to FLAC
Extract Audio from Video
Pull the soundtrack out of a video as an MP3.…
Compress Audio
Lower the bitrate of audio files to save space.…
Trim Audio
Cut a section out of an audio file.…
Normalise Audio
Even out loudness across files so nothing is jarring…