This paper discusses the voice quality of Opus, IETF driven open source voice and audio codec. Opus is a newly developed hybrid codec based on SILK and CELT codec technologies. Opus construction is described shortly in this paper and more importantly its optimal operating points are found out based on the listening test results. Voice quality was evaluated with two subjective listening tests. Industry standard voice codecs: 3GPP AMR and AMR-WB, and ITU-T G.718B, G.722.1C and G.719 as well as direct signals were used as voice quality references.
Bibliographic reference. Rämö, Anssi / Toukomaa, Henri (2011): "Voice quality characterization of IETF opus codec", In INTERSPEECH-2011, 2541-2544.