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2 Livewire-WAN Link
Livewire is a professional-grade IP Audio system, used over controlled local area networks. As a modern replacement for older analog or TDM digital systems, it offers very low delay and high audio fidelity. There are a wide range of products made for broadcast studio facilities that take advantage of Livewire: interface nodes for analog and AES3 audio, routers, mixing consoles, dynamics processors, ISDN and POTS telephone interfaces, delay units, satellite encoders and receivers, PC-based delivery systems, and – of course – codecs. Facilities span the gamut from a single interface Node to multi-studio installations with dozens or even hundreds of connected devices.
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Because Livewire is uncompressed, it requires a lot of bandwidth: around 3Mbps for a stereo channel. And because Livewire needs to be very low delay, it cannot tolerate a network with too much latency or jitter. These conditions are easily fulfilled with an inexpensive switched Ether- net LAN. But these conditions don’t generally exist for wide area networks, which use telephone lines and IP routers. The iPort bridges the two environments. It reduces the needed bandwidth and accommodates the delay and jitter caused by WANs. Remember that 3Mbps rate? After MPEG AAC compression, a typical rate would be 140kbps – over 20 times less. Most of the reduction comes from the compression process, but some comes from using larger packets with less header overhead.
If you already have a Livewire-based installation, the iPort is a simple and low-cost way to extend it over a wide-area IP network. Connect the local network to one of the iPort’s jacks, the WAN to the other, make some configuration choices, and you are ready to go. This application nicely illustrates the advantages of IP Audio – were you to do the same thing with traditional
