Opus Audio (.opus)

The OPUS file extension denotes a highly versatile and efficient audio codec format developed by the Xiph.Org Foundation and standardized by the Internet Engineering Task Force (IETF). Primarily designed for internet streaming, Voice over IP (VoIP), video conferencing, and in-game chat, the OPUS format is beneficial for delivering high-quality audio with low latency, making it ideal for real-time interactive communication. The OPUS codec integrates two technologies: SILK, originally developed for Skype, and CELT, a codec from Xiph.Org. By combining these technologies, OPUS can seamlessly switch between or merge them to optimize audio quality and efficiency based on content and network conditions. This adaptability allows OPUS to support a wide range of bit rates from 6 kbps to 510 kbps, making it suitable for various applications, from narrowband speech to full-band stereo music.

A standout feature of the OPUS format is its ability to maintain low latency, which is crucial for real-time audio transmission. The codec achieves an algorithmic delay as low as 26.5 milliseconds, which can be further reduced to 5 milliseconds by trading off some quality or bitrate. This low delay is significantly better than many competing codecs, which often require over 100 milliseconds. Additionally, OPUS is an open and royalty-free format, meaning it is freely available for use and implementation without licensing fees. This has led to its widespread adoption in various platforms and applications, including popular services like Discord, WhatsApp, and the PlayStation 4. The OPUS format is typically encapsulated in the Ogg container but can also be used in other containers like Matroska, WebM, and MPEG-TS, further enhancing its flexibility and compatibility across different systems and devices.