SECTION 2 |
7
AUDIO TRANSPORT VIA MPEG OR OPTIONAL APTX® ENHANCED
2
Audio Transport via MPEG or
Optional aptX® Enhanced
Livewire is a professional-grade IP Audio system, used over controlled local area networks. It is a modern
replacement for older analog or TDM digital systems. 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 xNode to multi-studio
installations with dozens or even hundreds of connected devices.
If you already have a Livewire-based installation, the Zephyr iPort PLUS 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 equipment, you’d have a rack full of codec boxes, expensive router
interface cards, and a plethora of cables.
If you don’t already have a Livewire installation, no problem. You can use an xNode audio interface or two (avail-
able from The Telos Alliance), and still benefit from the Zephyr iPort PLUS’s simplicity and low cost.
Because Livewire is uncompressed, it requires a lot of bandwidth - up to 5 Mbps 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 a switched Ethernet LAN, but they don’t generally exist for wide area networks.
Zephyr iPort PLUS bridges the two environments. It reduces the needed bandwidth and accommodates the delay
and jitter caused by WANs. Remember that 5 Mbps data rate? After MPEG AAC compression, a typical rate might
be 256 kbps – about 20 times less. Most of the reduction comes from the compression process, but some comes
from using larger packets with comparatively less header overhead. Zephyr iPort PLUS uses state-of-the-art MPEG
codec technology to conserve network bandwidth, while preserving excellent audio quality.
