Opus file format
Opus Interactive Audio Codec
Opus is the most efficient general-purpose audio codec, standardised by the IETF in 2012. WhatsApp voice notes, Discord and WebRTC calls use it; it sounds good even at 32 kbps.
| Property | Opus |
|---|---|
| File extensions | .opus |
| MIME type | audio/ogg |
| Introduced | 2012 by IETF (Xiph.Org, Skype, Mozilla) |
| Compression | Lossy |
| Typical bitrate | 24–160 kbps |
| 3-minute song | ≈ 2.9 MB at 128 kbps |
| Tags and cover art | Yes (Vorbis comments) |
| Compatibility | Browsers, Android, WhatsApp, Discord; partial on Apple |
| Best for | Voice notes, podcasts, streaming at low bitrates |
What is an Opus file?
Opus is an open, royalty-free codec standardised by the IETF as RFC 6716 in 2012. It blends speech technology from Skype's SILK with music coding from Xiph's CELT, so it handles both voice and music well. Files are usually stored in the Ogg container with the .opus extension.
Strengths and weaknesses
Opus beats MP3 and AAC at almost every bitrate, especially for speech — voice stays clear at 24–32 kbps. Support outside browsers and Android is patchier: many car stereos and older Apple apps can't play .opus files.
When should you use Opus?
Use Opus for voice recordings, podcasts and streaming. Convert WhatsApp voice notes (.opus) to MP3 to play them anywhere.