Ever thought that there were too many audio codecs, each with its own special niche? So did we, so we made a new one (1). The difference is that Opus scales from very low bit-rate VoIP to high-fidelity, low delay music transmission. It can be used for anything from making phone calls, to remote jam sessions, to archiving your music collection. It's better at speech than Speex, and better at music than Vorbis and MP3.