audio/opus

Opus audio carried over RTP, as in WebRTC calls. A .opus file is Ogg, and is served as audio/ogg.

Extensions
None. It is not kept in a file of its own.
Header
Content-Type: audio/opus
Registered
Yes, in the IANA media type registry.
References
IANA · RFC 7587

Common audio types

Every media type, in one table