Opus SW codec RTLAB Ki Eun Seong

What is the Opus Codec? Real-time interactive audio codec Targets interactive audio over the internet Aims to be royalty-free, reference implementation is provided under the 3-clause BSD license Combination of the SILK and CELT codecs IETF standard (RFC 6716)

SILK codec Speech codec, used in Skype Sampling frequency : 8,12,16, 24kHz Bit rate : 6 – 40 kb/s Based on linear prediction (LP), a bit like Speex but much better Not very good on music, good for narrowband and wideband(6 – 32kb/s) Not compatible with the original SILK codec

CELT codec Constrained Energy Lapped Transform Royalty free lossy audio compression format Low algorithmic delay for use in low-latency audio communication Uses modified discrete cosine transform (MDCT) Most efficient on fullband audio (40 kb/s above) Not very good on low bit-rate speech

Architecture of Opus 3 operating modes : SILK- only Hybrid CELT -only

Opus Codec’s Characteristics Sampling rate : 8 – 48kHz Bitrates : 6 – 510 kb/s Mono and stereo support Speech and music support IT JUST WORKS FOR EVERYTHING

Performance

Applications VoIP and video conference Music/video streaming and storage Remote music jamming Wireless speakers/headphones/mic Audio books