Opus is a lossy audio coding format developed by the Xiph.Org Foundation and standardized by the Internet Engineering Task Force, designed to efficiently code speech and general audio in a single format, while remaining low-latency enough for real-time interactive communication and low-complexity enough for low-end ARM3 processors. Opus replaces both Vorbis and Speex for new applications, and several blind listening tests have ranked it higher-quality than any other standard audio format at any given bitrate until transparency is reached, including MP3, AAC, and HE-AAC.
an audio format from Apple that was developed to remove the limitations of AIFF and WAV formats. This is a container that can store sound encoded by various algorithms and track metadata. Its characteristic feature - the format doesn’t have limitations on file size and so this allows one to store infinitely long recordings.