Opus files: the best audio codec in use, and the least playable
Why Opus beats everything at low bitrates, where the files come from, and what bitrate to use when converting out. Convert Opus in your browser, no upload.
At a glance
- Type
- Audio
- Compression
- Lossy
- Extensions
- .opus
- MIME type
- audio/opus
- Common codecs
- opus
Opus was standardised in 2012 by the IETF, combining two earlier codecs — SILK for speech and CELT for music — into one that switches between them as the content demands. The result is the best general-purpose audio codec in use: transparent for speech at bitrates where MP3 is obviously struggling, and competitive with AAC on music. It is also royalty-free, which is why it became the default for anything built after it.
Read more
That is where your Opus files come from: WhatsApp and Telegram voice notes, Discord recordings, browser microphone capture, WebRTC calls, and the audio track inside most WebM. Software that records audio today generally records Opus without asking.
Converting out of it is always a downgrade in efficiency, and the practical consequence is about bitrate. A voice note recorded at 24 or 32 kbps in Opus sounds fine; requesting the same bitrate in MP3 would sound poor. Give the MP3 room — 96 or 128 kbps for speech — and accept that the file will be several times larger than the original. That is the price of playing on hardware that has never heard of Opus.
One asymmetry on this site: conversions from Opus work, conversions to Opus do not. The Opus encoder in the WebAssembly ffmpeg build shipped here fails on every input while its decoder is fine, so rather than ship something that breaks, that direction is marked unavailable.
Convert Opus to other formats
FAQ
What bitrate should I use converting Opus to MP3?
Higher than the source. Opus at 32 kbps sounds good; MP3 at 32 kbps does not. Use 96 or 128 kbps for speech so the weaker codec has room to reproduce what Opus captured.
Why is the MP3 several times larger than the Opus?
Because Opus is far more efficient, especially for speech at low bitrates. Matching its quality in MP3 genuinely requires several times the data.
Where do Opus files come from?
WhatsApp and Telegram voice notes, Discord recordings, browser microphone capture, WebRTC calls, and the audio inside most WebM files.
Can I convert something to Opus here?
No. The Opus encoder in the WebAssembly ffmpeg build fails on every input, while the decoder works — so conversions out of Opus are available and conversions into it are marked unavailable rather than shipped broken.
Is Opus better than AAC?
For speech and at low bitrates, clearly. For music at high bitrates they are close. Opus is also royalty-free, which is why new software defaults to it.
Why will my player not open an .opus file?
Because hardware and older software never implemented it. Browsers and modern phones handle it; car stereos, portable players and a lot of desktop audio software do not.