SVOPC (Sinusoidal Voice Over Packet Coder) is a compression method for audio which is used by

VOIP Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet t ...

applications. It is a

lossy In information technology, lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content. These techniques are used to reduce data size ...

speech compression codec designed specifically towards communication channels suffering from

packet loss Packet loss occurs when one or more packets of data travelling across a computer network fail to reach their destination. Packet loss is either caused by errors in data transmission, typically across wireless networks, or network congestion.Kur ...

. It uses more bandwidth than best bandwidth-optimised codecs, but it is

resistant instead.

Skype Limited Skype Technologies S.A.R.L (also known as Skype Software S.A.R.L, Skype Communications S.A.R.L, Skype Inc., and Skype Limited) is a Luxembourgish telecommunications company headquartered in Luxembourg City, Luxembourg, whose chief business is th ...

developed a codec called 'SVOPC' for Skype. It was first used in Skype 3.2 beta 53, released on March 28, 2007.Skype Community (2008-07-29
Current codec uses
(Internet Archive)Skype Journal (2007-03-28

Retrieved 2009-09-01Lee S. Dryburgh (2008-02-06

eComm Media, Inc. Retrieved 2009-09-01Michael Stanford (2009-01-13
Skype’s new super-wideband codec (SILK)
Wirevolution, Retrieved 2009-09-01 Starting with Skype 4.0, SVOPC is replaced by

SILK Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the coc ...

Technical information

Operation is quasi-harmonic modelling of the linear prediction residual. The codec uses a 16 kHz sample rate and allows for 8 kHz of audio bandwidth. SVOPC provides synthesized speech of good subjective quality at around 20 kbit/s. Because the compression relies on

floating point In computing, floating-point arithmetic (FP) is arithmetic that represents real numbers approximately, using an integer with a fixed precision, called the significand, scaled by an integer exponent of a fixed base. For example, 12.345 can be ...

mathematics it can be inefficient when it's running in an

embedded system An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' as ...

as this will likely not offer the same kind of floating point capabilities as, say, a PC. The new codec

has been designed with this in mind.

References

Sources

* Dryburghon, L.
"Interview with Jonathan Christensen, General Manager of Skype, about SVOPC Audio"
* Lindblom, J.
"Sinusoidal Voice Over Packet Coder Tailored for the Frame-Erasure Channel"
* Stanford, M.
"Skype’s new super-wideband codec"
Skype Audio codecs Speech codecs {{multimedia-software-stub

Technical information

See also

References

Sources