Basic Standards for Audio Coding (2/3)

Basic Standards for Audio Coding

Real-time speech transmission supported by IP resources requires a dedicated coding
system. The International Telecommunication Union (ITU) has developed a set of coding
schemes suitable for the different network bandwidths. These coding schemes - named
codecs (coder-decoder) - are part of the H.323 protocol family and use different converting
and reconverting algorithms to transform signals from one form into the other one. Different
degrees of compression are available to provide different levels of speech quality.
Redundancy information can be added to the original signal to facilitate decoding and
provide a certain amount of protection against transmission errors.

Coding techniques reduce the original signal data rate for efficient transmission without an
audible decrease in speech quality. This is achieved by the use of highly-sophisticated
algorithms - including predictive techniques - and adaptating those techniques to the specific
characteristic of the human voice.