What is OPUS?

OPUS is a versatile audio codec that combines the best of SILK (for speech) and CELT (for music) to deliver excellent quality at any bitrate from 6 kbit/s to 510 kbit/s. It's designed for real-time applications like VoIP, video conferencing, and streaming, with extremely low latency (as low as 5ms). OPUS outperforms MP3, AAC, and Vorbis at equivalent bitrates.

OPUS is royalty-free and open standard (RFC 6716), making it ideal for modern web applications. Used by Discord, WhatsApp, YouTube, Spotify, and countless other platforms. It handles network packet loss gracefully and adapts bitrates dynamically for optimal quality under varying network conditions.

Did you know? OPUS provides better quality than MP3 at half the bitrate!

History

Opus was developed by the IETF (Internet Engineering Task Force) to create a universal audio codec for internet communications, combining the strengths of existing speech and music codecs.

Key Milestones

  • 2010: SILK and CELT codecs merged
  • 2012: OPUS approved as RFC 6716
  • 2013: Chrome/Firefox add native support
  • 2017: YouTube uses Opus for all videos
  • 2020: Spotify switches to Opus
  • Present: Industry standard for streaming

Key Features

Core Capabilities

  • Versatile: Speech and music optimized
  • Low Latency: 5-60ms configurable delay
  • Adaptive Bitrate: 6-510 kbit/s range
  • Packet Loss Resilience: Robust streaming
  • Wide Bandwidth: Narrowband to fullband
  • Royalty-Free: No licensing fees

Common Use Cases

VoIP

Voice calls, conferencing

Streaming

YouTube, Spotify, podcasts

Gaming

Discord, in-game voice chat

Web Audio

HTML5 audio, WebRTC

Advantages

  • Best quality-to-bitrate ratio
  • Ultra-low latency
  • Royalty-free and open source
  • Handles speech and music perfectly
  • Excellent packet loss resilience
  • Dynamic bitrate adaptation
  • Wide platform support

Disadvantages

  • Limited hardware device support
  • Not supported on older systems
  • Smaller file ecosystem than MP3
  • May need fallback formats
  • Newer than established formats

Technical Information

Format Specifications

Specification Details
File Extension .opus
MIME Type audio/opus
Format Type Lossy audio codec
Bitrate 6-510 kbit/s variable
Sample Rate 8-48 kHz
Latency 5-60 ms
Container Ogg, WebM, Matroska
Standard RFC 6716 (IETF)

Common Tools

  • Players: VLC, foobar2000, mpv
  • Encoders: opusenc, FFmpeg
  • Browsers: Chrome, Firefox, Edge (native)
  • Platforms: Discord, YouTube, Spotify, WhatsApp