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OPUS at a glance
OPUS
RFC 6716 standardized Opus as an interactive audio codec that can scale across speech and music use cases.
AU at a glance
AU
AU belongs to an earlier multimedia era where workstation and Unix vendors often had their own practical audio defaults.
Format comparison
| Feature | OPUS | AU |
|---|---|---|
| File type | Audio | Audio |
| Extensions |
|
|
| MIME type |
|
|
| Compression / quality | depends | depends |
| File size characteristics | medium | medium |
| Compatibility | broad | broad |
| Editability | limited | limited |
| Created year | 2012 | 1987 |
| Inventor | IETF | Sun Microsystems |
| Status | active | active |
| Primary use cases |
|
|
| Common software |
|
|
| Archival suitability | moderate | moderate |
| Metadata handling | moderate | moderate |
| Delivery profile | strong | strong |
| Workflow fit | delivery | delivery |
| Multitrack support | Not supported | Not supported |
| HDR support | Not supported | Not supported |
| Streaming ready | Supported | Not supported |
When to use each format
When to use OPUS
- capture ingest
- editing and mastering
- streaming or playback delivery
- Excellent flexibility across bitrate and latency targets.
When to use AU
- capture ingest
- editing and mastering
- streaming or playback delivery
- Historically important in Unix/workstation audio.
FAQs
Why convert OPUS to AU?
Choose AU as target when preserving compatibility with older Unix or workstation software, educational assets, or historical multimedia archives.
What changes when converting OPUS to AU?
Convert to AU when preserving compatibility with older Unix or workstation software, educational assets, or historical multimedia archives. In most present-day workflows the practical task is to decode AU content and move it to WAV, AIFF, or a modern compressed format. Use AU only when downstream compatibility makes it necessary.
What should I review after converting OPUS to AU?
After conversion, review these destination checks: Open converted output in legacy Unix tools and verify behavior on real samples; Compare output against the expected depends quality profile; Largely obsolete in mainstream media workflows.
How can I keep quality stable in OPUS to AU conversion?
Run representative samples, keep settings deterministic, and monitor these risks: Usually converted immediately into newer formats; Largely obsolete in mainstream media workflows; Validate destination compatibility before large-batch conversion.