Is it free to convert between OPUS and AU?

Yes, Convert999 is 100% free. All conversions happen locally in your browser with no file size limits, no registration, and no watermarks.

.opus

.au

OPUS vs AU

Compare Opus Audio and Sun Audio formats — understand the key differences and when to use each

Format Overview

OPUS

Opus Audio

Opus Audio (.opus) is a audio file format.

.opusaudio

AU

Sun Audio

Sun Audio (.au) is a audio file format.

.auaudio

OPUS vs AU: Feature Comparison

Feature	OPUS	AU
Full Name	Opus Audio	Sun Audio
File Extension	.opus	.au
Category	audio	audio
Free to Convert	✓ Yes	✓ Yes
Browser Support	✓ All Browsers	✓ All Browsers
Convert to Each Other	✓ Yes	✓ Yes

When to Use OPUS vs AU

Use OPUS when you need:

•Files in Opus Audio format for maximum compatibility
•Industry-standard audio format support
•Wide software and platform compatibility

Use AU when you need:

•Files in Sun Audio format for specific workflows
•Optimized audio format features
•Modern format advantages and smaller file sizes

Convert Between Them

OPUS AU AU OPUS

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Frequently Asked Questions

What is the difference between OPUS and AU?

OPUS (Opus Audio) and AU (Sun Audio) are both audio file formats. OPUS files use the .opus extension while AU uses .au. They differ in compression, quality, compatibility, and intended use cases.

Can I convert OPUS to AU for free?

Yes! Convert999 lets you convert OPUS to AU completely free, directly in your browser. No file upload to any server, no registration needed — your files stay private on your device.

Which is better, OPUS or AU?

It depends on your use case. OPUS (Opus Audio) may be better for certain workflows, while AU (Sun Audio) excels in others. Consider factors like file size, quality, software compatibility, and your specific needs.

Is it safe to convert files on Convert999?

Absolutely. Convert999 processes all files 100% locally in your browser. Your files are never uploaded to any server, ensuring complete privacy and security.

OPUS Converter

Convert from OPUS

AU Converter

Convert from AU

File Tools

Compress, resize, merge

Convert to OPUS

All sources → OPUS

Convert to AU

All sources → AU

Format Statistics

Trends & data 2025

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Feature