Standard Opus Audio MIME Type for HTTP

This article explains the standard MIME type used for streaming and transferring Opus audio files over HTTP. It details the official media types defined by the Internet Engineering Task Force (IETF) for different container formats and provides practical configuration examples for web servers to ensure proper browser playback.

The standard MIME type for the Opus audio format when served over HTTP depends on the container file format used to package the audio. Because Opus is a codec, it must be wrapped in a container to be transmitted as a file.

The Primary Standard: Ogg Container

Most standalone Opus files, which typically use the .opus extension, are encapsulated in an Ogg container. According to RFC 7845, the official and most compatible MIME type for Ogg-encapsulated Opus audio over HTTP is:

To explicitly specify the codec to modern web browsers and media players, the standard media type string is:

The WebM Container

When Opus audio is encapsulated in a WebM container (frequently used for HTML5 audio and video streaming), the correct MIME type is:

The Raw Opus MIME Type

RFC 7587 defines the media type audio/opus, but this is officially designated for raw RTP (Real-time Transport Protocol) streams rather than HTTP file storage and playback. While some modern web applications and servers accept audio/opus for files ending in .opus, using audio/ogg ensures the broadest compatibility across legacy and modern web browsers.

Web Server Configuration

To ensure browsers correctly stream and play .opus files instead of attempting to download them as raw binary data, web servers must be configured to map the file extension to the correct MIME type.

For Apache servers, add the following directive to your configuration or .htaccess file:

AddType audio/ogg .opus

For Nginx servers, include this mapping within your mime.types file:

audio/ogg opus;