 format. The content is uncompressed and the inter- face becomes a convenient physical point to connect to a transmission or recording channel. The commonly used reference in broadcasting and similar applica- tions is AES/EBU. The original standard, AES3-1985 has been modi- fied and updated over the years. Current network design and operations practice revolves around specification of the number of PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS channels and bitrate required through the transmission channel. Typically this is simply stated as AES/EBU two or four channels, and 384- or 768-Kb bandwidth. Five-channel surround sound is be- coming more widely used, and practice has become a matter of specifying the source as five-channel surround sound and the amount of bandwidth desired. Summarizing, audio content is created using digital technology that is standardized around interface, bitrate, quantizing depth, and coding practices. Network facilities capable of supporting audio content transport is a matter of understanding the capabilities and limitations of the chosen standard and matching the nature and characteristics of content package to the requirements placed on the network transmis- sion channel. From a network design and operations perspective, we care about the payload bitrate and interface. For example, if the audio source side of an interface is said to be compliant with AES/EBU, then the network equipment receiving the payload must also be compliant with the same standard. The signal or audio information is un-com- pressed. If compression is to be used, then the compression equipment between the audio source equipment and network equipment must be compliant with the AES/EBU interface on the source side, matching Internet and/or Telecom interface on the network side. The Audio Engineering Society (www.aes.org) is the source of AES/ EBU standards. The Moving Picture Experts Group (MPEG) is the source of MP3, a compression standard (www.chiariglione.org/ mpeg/standards.htm). Another i