Free online OPUS to AU converter

OPUS is a modern audio codec and file format commonly used for voice, streaming, and internet audio because it offers high quality at low bitrates. AU is an older audio container format originally used on Unix systems, often associated with simple, uncompressed or lightly compressed audio data. Converting OPUS to AU means changing a compressed, efficient audio file into a more legacy-compatible audio format.

Why convert opus to au

You may need this conversion for compatibility with older software, embedded systems, Unix-based tools, or workflows that specifically require .au files. Since AU is less common today, conversion is usually done to meet a technical requirement rather than for better audio quality.

Best software for opus to au conversion

The best all-around choice is FFmpeg, because it supports both formats, preserves audio quality well, and works on Windows, macOS, and Linux. For a simple graphical option, Audacity can import OPUS and export AU if the needed export settings are available. If you want a fast command-line solution, FFmpeg is usually the most reliable.

How to convert with ffmpeg

Use a command like this:

ffmpeg -i input.opus output.au

This reads the OPUS file and writes it as AU. If the target system requires a specific audio codec or sample rate, you may need to add options such as -ar for sample rate or -ac for channel count.

How to convert with audacity

Open the OPUS file in Audacity, then choose File → Export → Export Audio and select AU as the output format if available. This is useful when you want to inspect or edit the audio before saving it.

Important notes

• OPUS is compressed and efficient; AU may be larger depending on the chosen encoding.
• Some AU variants are limited in codec support, so compatibility can vary by player or system.
• If the destination requires a specific sample rate, convert to that rate during export.
• For batch conversion, FFmpeg is the best choice.

Recommended workflow

For most users, the simplest path is to use FFmpeg for direct conversion. If you need editing or visual inspection first, use Audacity and then export to AU. Always verify the resulting file in the target application to ensure it plays correctly.