.opus File — Opus Audio Codec

Opus is a versatile, open, royalty-free audio codec standardized by the IETF as RFC 6716 in 2012. Developed collaboratively by Xiph.Org and Skype/Microsoft, Opus is unique in combining the best qualities of speech codecs (SILK from Skype) and music codecs (CELT from Xiph.Org) into a single codec that handles everything from voice calls to high-fidelity music. Opus supports bitrates from 6 kbps to 510 kbps, sample rates from 8 to 48 kHz, and up to 255 channels. At virtually every bitrate, Opus outperforms all other codecs — it produces better quality than Vorbis, AAC, and MP3 in comparative listening tests. The codec features extremely low latency (as low as 2.5 ms), making it ideal for real-time communication. Opus is the mandatory audio codec for WebRTC (powering video calls in browsers), the default voice codec in Discord and WhatsApp, used by Wikipedia for audio files, and the recommended codec for streaming in many applications. Its combination of open licensing, superior quality, and versatility has made it the most technically advanced general-purpose audio codec available.