Opus Audio Codec Format

Opus is a totally open, royalty-free, highly versatile audio codec developed by the Xiph.Org Foundation in collaboration with the IETF (Internet Engineering Task Force). Standardized as RFC 6716 in September 2012, Opus combines the SILK speech codec (from Skype) and CELT music codec (from Xiph) into a single unified codec, surpassing the quality of all predecessors including MP3, AAC, and Vorbis. Key features: wide bitrate range from 6 kbps to 510 kbps, maintaining usable quality even at extremely low bitrates for speech and near-transparent quality at moderate bitrates for music. Full-band audio from narrowband (8 kHz) to fullband (48 kHz) sampling rates in a single codec, adapting to different content types. Music and speech modes with automatic or manual selection, using SILK for speech-optimized encoding and CELT for music-optimized encoding, with hybrid mode for the best of both. Low algorithmic delay as low as 5 ms for real-time communication including VoIP, video conferencing, and live streaming, far better than competing codecs. Dynamic bitrate adaptation enabling seamless quality adjustment during streaming without re-initialization. Packet loss concealment (PLC) and forward error correction (FEC) for robust performance over unreliable networks. Surround sound support including mono, stereo, and multichannel (up to 255 channels). In-band DTX (Discontinuous Transmission) for silence suppression to save bandwidth. Bandwidth-efficient and redundancy modes for network resilience. Standardized and royalty-free under BSD license, with no licensing fees or patent concerns. Supported by WebRTC for browser-based real-time communication, WebM, Ogg Opus, and MPEG-TS containers. Used by Discord, WhatsApp, YouTube, Zoom, and virtually all modern VoIP and streaming platforms.