OPUS is an audio file that is encoded using the Ogg Opus format (lossy coding). It was created for online audio streaming, that is, in order to transmit sound through a global network. The format is being developed by the Internet Engineering Task Force (IETF) and Xiph.Org communities. Applies SILK codecs when used in Skype and CELT (from Xiph.Org), provides support for variable bitrate. Most often, the OPUS codec is used for video conferencing, game chats, VoIP telephony. OPUS is a free audio codec that has international standard status (IETF RFC 6716). Its main advantages are a low coding delay (from 2.5 to 60 ms) and its significant speed, an increased degree of compression of audio data with high-quality sound, as well as support for multi-channel audio (within 255 channels). In 2011, J. Skeglund of Google conducted two series of tests, during which OPUS coding and decoding were compared, taking into account the assessments of experts and ordinary listeners. Studies have shown that OPUS provides stereo music with the same quality as MP3 and better quality than G.719 64 kbps. OPUS offers great streaming capabilities with dynamic tweaking and very low latency. This is always high sound quality and excellent data compression. Full support for OPUS is provided by Mozilla applications. He is the key Skype audio codec.
WMA is a widespread licensed audio stream compression format. Created in 1999 by Signal Processing Group, a member of the IT giant Microsoft. Initially, this company created WMA as a competitor to the popular MP3 format. The name WMA is an abbreviation for Windows Media Audio. Among the advantages of this format is the support of almost all Windows systems and devices, as well as the similarity in characteristics and quality with MP3 files. It is believed that a compressed WMA audio file with a bit rate of 160 kbit / s is fully consistent with the quality of an MP3 file with a bit rate of 256 kbit / s. Today, even Apple devices support the WMA format.