What is Opus?
Opus is a modern lossy audio codec designed to handle everything from speech and real-time communication to high-quality music.
Opus technical specifications
| Property | Opus | What that means |
|---|---|---|
| Bitrate | 6–510 kbps | One codec spans narrowband speech through high-quality stereo music. |
| Effective sample rates | 8, 12, 16, 24 or 48 kHz | Opus is fundamentally bandwidth-oriented and internally works up to 48 kHz. |
| Audio bandwidth | Up to 20 kHz | Fullband Opus intentionally does not code ultrasonic content above about 20 kHz. |
| Channels | Mono/stereo per elementary stream; up to 255 channels with Opus multistream mappings | Normal music and calls use one or two channels; multichannel Opus is possible. |
| Frame duration | 2.5–60 ms in standard Opus operation | Short frames help real-time voice and low-latency applications. |
| PCM bit depth | Not a preserved codec property | Opus encodes audio perceptually rather than storing PCM words at a fixed bit depth. |
Why Opus is unusual
Opus was designed to cover a very wide range of bitrates and audio types. It can switch efficiently between speech-oriented and music-oriented coding behaviour and is well suited to low-latency communication.
Where Opus is used
- Voice and video calls
- WebRTC and browser communication
- Streaming and web audio
- Discord-like real-time applications
- Music playback at efficient bitrates
Opus vs Ogg
Opus is the codec. Ogg is a container format that can carry Opus audio. An .opus file commonly uses an Ogg-based container structure specifically for Opus.
Opus vs AAC and MP3
MP3 remains strongest for legacy compatibility. AAC is deeply established in MP4, Apple and many streaming workflows. Opus is especially strong for real-time communication and efficient low-to-medium bitrate audio.
See Opus vs AAC for a direct comparison.
Common confusion
Opus describes the audio encoding. Ogg describes a container family that can carry Opus and other codecs.
An Ogg file may contain Vorbis, Opus or another compatible stream.