Audio format
The OPUS format
OPUS is the most efficient audio codec in common use, especially for speech. The IETF standardised Opus in 2012; WhatsApp voice notes, Discord and most video calls use it.
When to use OPUS
Use Opus for speech and streaming where small size matters more than compatibility.
It is best for voice notes, calls and streaming at low bitrates, and it opens on browsers, Android and chat apps; many media players, editors and forms can’t open .opus files.
How to open it: Chrome, Firefox, VLC and Android play Opus; iPhones play it in some apps only.
| Full name | Opus |
|---|---|
| Extensions | .opus |
| MIME type | audio/ogg; codecs=opus |
| Introduced | 2012 |
| Compression | Lossy |
| Typical quality | 24–128 kbps |
| Support | Patchy support |
| Typical size | A minute of voice note is often under 200 KB |
Good at
- Sounds good at tiny bitrates
- Excellent for speech
- Very low delay
Not so good at
- Exported voice notes won’t open in plenty of apps
- Always 48 kHz internally
The common mistake
WhatsApp voice notes exported from a phone are Opus files, sometimes named .ogg, which many players and transcription services refuse.
Questions
What is an OPUS file?
OPUS (Opus) is the most efficient audio codec in common use, especially for speech. The IETF standardised Opus in 2012; WhatsApp voice notes, Discord and most video calls use it.
How do I open an OPUS file?
Chrome, Firefox, VLC and Android play Opus; iPhones play it in some apps only.
How do I convert OPUS to another format?
Pick the target on this page, or open the Audio Converter, drop the OPUS file and choose a format. It converts in your browser, so nothing is uploaded.