Opus Audio Codec
Opus is a versatile open-source audio codec that excels at every bitrate from voice calls to high-fidelity music. It combines the best of SILK (voice) and CELT (music) codecs, and it outperforms MP3, AAC, and Vorbis in listening tests at equivalent bitrates.
MIME Type
audio/opus
Type
Binary
Compression
Lossy
Advantages
- + Best-in-class quality at every bitrate (voice through high-fidelity)
- + Open source and royalty-free (RFC 6716)
- + Ultra-low latency (as low as 2.5 ms) for real-time communication
- + Mandatory in WebRTC — universal browser support
Disadvantages
- − Less hardware support than MP3 on older dedicated players
- − OGG/Opus files are not universally supported by car stereos
- − Relatively new — some legacy tools may not recognize it
When to Use .OPUS
Use Opus for VoIP, streaming, podcasts, and any application needing the best quality-per-bit across voice and music.
Technical Details
Opus dynamically switches between SILK mode (for voice at low bitrates) and CELT mode (for music at higher bitrates) or uses a hybrid of both. It supports 6 kbps to 510 kbps, frame sizes from 2.5 ms to 120 ms.
History
Opus was developed by the IETF, Xiph.Org, Mozilla, and Skype/Microsoft, and standardized as RFC 6716 in 2012. It is mandatory in WebRTC and has been adopted by WhatsApp, Discord, YouTube, and Spotify.