The short answer
- Opus is an open, royalty-free audio codec for speech and music that uses Ogg encapsulation in .opus files, with lossy encoding that cannot preserve all source information.
- Use an application that explicitly supports Ogg Opus. On Windows or Mac, open the file from the application's file menu; on a phone, use the file's Open with action to select a compatible audio app. Available applications and versions determine playback support. The official opus-tools package provides command-line encoding, inspection and decoding tools.
- Treat unfamiliar OPUS files with caution and keep reading software updated. RFC 7845 describes memory and resource risks when parsing malicious input, including forged comment lengths. The official opusfile 0.12 notes include fixes for a buffering stack overflow and a possible division by zero. The medium risk rating reflects these implementation risks.
OPUS files: opening, playback and conversion
RFC 6716 defines the Opus codec; RFC 7845 defines its Ogg encapsulation. An Ogg Opus stream contains a required identification header, a metadata comment header and audio packets arranged in Ogg pages.
To make an MP3, choose a converter that explicitly accepts Ogg Opus input and produces MP3 output. Official opus-tools provides Opus decoding, but that alone does not establish MP3 output support. Opus is lossy: decoding to a lossless format cannot recover discarded information, and another lossy encode may add degradation. These quality consequences follow from the codec's quantization.
How to open it
Use an application that explicitly supports Ogg Opus. On Windows or Mac, open the file from the application's file menu; on a phone, use the file's Open with action to select a compatible audio app. Available applications and versions determine playback support. The official opus-tools package provides command-line encoding, inspection and decoding tools.
Use an application that explicitly supports Ogg Opus. On Windows or Mac, open the file from the application's file menu; on a phone, use the file's Open with action to select a compatible audio app. Available applications and versions determine playback support. The official opus-tools package provides command-line encoding, inspection and decoding tools.
To make an MP3, choose a converter that explicitly accepts Ogg Opus input and produces MP3 output. Official opus-tools provides Opus decoding, but that alone does not establish MP3 output support. Opus is lossy: decoding to a lossless format cannot recover discarded information, and another lossy encode may add degradation. These quality consequences follow from the codec's quantization.
File safety
Treat unfamiliar OPUS files with caution and keep reading software updated. RFC 7845 describes memory and resource risks when parsing malicious input, including forged comment lengths. The official opusfile 0.12 notes include fixes for a buffering stack overflow and a possible division by zero. The medium risk rating reflects these implementation risks.
An unknown sender, a name ending in two extensions, or contents that do not match the extension — check before you open it.
Converting it
To make an MP3, choose a converter that explicitly accepts Ogg Opus input and produces MP3 output. Official opus-tools provides Opus decoding, but that alone does not establish MP3 output support. Opus is lossy: decoding to a lossless format cannot recover discarded information, and another lossy encode may add degradation. These quality consequences follow from the codec's quantization.
Convert a copy, never the original, then compare quality, metadata, and layout against what you started with.
Common questions
What is an Opus audio file?
A .opus file contains Opus audio in an Ogg container. Opus is an open, royalty-free, lossy codec designed for speech and music.
How do I open an OPUS file on Windows?
Choose an installed application whose documentation explicitly lists Ogg Opus support, then use its Open command to select the file. The .opus extension alone does not guarantee support in your default player.
How do I open an OPUS file on Mac?
Open an application that explicitly supports Ogg Opus and select the file through its file menu. Check the application's version and supported formats if playback fails.
How do I open an OPUS file on a phone?
Use the file's Open with action and select an audio app that explicitly supports Ogg Opus. If no compatible app is available, you need one or a converted copy in a supported format.
Why will my OPUS file not open?
First confirm that the application and version support Ogg Opus. If they do, use the inspection tools in official opus-tools to investigate the file. An opening failure alone does not establish that the file is corrupt.
What is the difference between Opus and Ogg?
They describe different layers: Opus is the audio codec, while Ogg is the container used by .opus files. For Ogg Opus audio, check for support for that combination; Ogg support alone does not establish Opus support.
How can I convert OPUS to MP3?
Use a converter that explicitly supports Ogg Opus input and MP3 output. MP3 conversion adds another lossy encoding step and may further reduce quality; keep the original OPUS file.
Does converting OPUS to WAV restore audio quality?
No. Decoding Opus into lossless WAV audio cannot reconstruct information discarded during Opus encoding. A lossless destination does not make the source recording lossless.
Are OPUS files safe to open?
There is no absolute guarantee. Malicious files can target container or codec parsers. Use updated reading software and consider the source of the file; official opusfile release notes document past security-related fixes.
What MIME type should an OPUS file use?
RFC 7845 recommends audio/ogg for .opus files. The more explicit declaration audio/ogg; codecs=opus identifies the codec as well.
Does an OpusHead marker prove an OPUS file is valid?
No. OpusHead starts the codec identification header packet inside Ogg; it is not the file's starting byte sequence. Finding it alone proves neither full structural validity nor safety.
Related formats
Sources
RFC 7845: Ogg Encapsulation for the Opus Audio Codec · IETF / RFC Editor，标准规范
RFC 6716: Definition of the Opus Audio Codec · IETF / RFC Editor，编解码器规范
Opus Interactive Audio Codec · Opus 项目官方网站
Opus Downloads · Opus 项目官方工具与发布记录