AV Technology - May 2008 - (Page B3)

NETWORKED AUDIO Much of the audio equipment used today is digital inside, but the most common way of distributing audio remains as analog signals over pointto-point networks. However, digital offers clear advantages over analog distribution. Multiple audio signals can be sent over a single connection, digital signals are less prone to attenuation and noise, and the degradation and delay that multiple A/D and D/A conversions introduce can be minimized or avoided if the distribution, processing, and mixing of audio signals is performed in the digital domain and conversion only takes place at the edge of the network. For audio signal transport, there are at least four digital audio networking technologies vying for dominance. One of the earliest approaches to digital audio signal transport was developed by Peak Audio (now Cirrus Logic) in the mid-1990s. CobraNet is a combination of software, hardware, and network protocols that allow distribution of many channels of realtime, high-quality digital audio over an Ethernet network. CobraNet is supported for repeater and switched Ethernet variants. On repeater networks, CobraNet eliminates collisions and allows full bandwidth utilization of the network. CobraNet uses standard Ethernet packets and network infrastructure (controllers, hubs, repeaters, switches, cabling, etc.). CobraNet delivers audio in standard Ethernet packets over 100Mbit Fast Ethernet. Switches, hubs, media converters, and other gear that operate in compliance with the IEEE 802.3u specification for Fast Ethernet will A networked audio system is a collection of components designed to accept audio input signals, process these signals, and make them available throughout the system in digital format via some sort of highspeed interconnects. work with CobraNet. According the company, CobraNet devices can coexist on an existing LAN with office PCs as long as it’s a switched network. Dante is a new digital audio networking technology from Audinate that is compatible with standard lnternet Protocols (not just Ethernet) ministic network protocol with high data capacity at mixed sample rates and powerful control functions. EtherSound’s latency is stable and easily calculated: the pointto-point transmission time between an audio input and an audio output in an EtherSound network is six samples (125 microseconds at 48 kHz), independent of the number of channels transmitted. As Ethernet standards evolve, EtherSound is able to keep pace, since the Network and Data Link layers are implemented via FPGA’s (Field Programmable Gate Arrays). EtherSound networks can accommodate more than 60,000 networked audio devices in daisy-chain or star architectures, or a combination of both. All Photo courtesy of L-Acoustics without compromising performance. Sample-accurate synchronization and low latency allows Dante to be used in live audio applications. Audinate’s “Zen” technology builds on and extends “zero configuration” network techniques into the application domain to simplify network set-up. There’s no need to allocate IP addresses, no need to set up and manage DNS or DHCP servers before the network will operate, and equipment in the network becomes aware of the audio capabilities of other nodes in the network. Like CobraNet, Dante allows audio channels to co-exist with other data traffic. EtherSound is an open standard for networking digital audio using off-theshelf Ethernet components. Fully compliant with IEEE 802.3, EtherSound is a deter- daisy-chained devices can send and receive all channels concurrently. A-Net is Aviom’s proprietary audio distribution and networking technology. A-Net is based on the physical layer of Ethernet, so it uses familiar CAT-5e cables and RJ-45 connectors. Unlike Ethernet, however, A-Net is designed specifically for the unique demands of data-intensive streaming audio. Because of this, A-Net claims several benefits over Ethernet-based approaches to distributing audio digitally, including reduced latency, longer cable runs, and improved clock performance, without sample rate converters or restrictions on system layout. To date, there are seven manufacturing partners who offer A-Net compatibility with their products. GUIDE TO NETWORKED AV 3

Table of Contents Feed for the Digital Edition of AV Technology - May 2008

AV Technology - May 2008 Contents Precedent Corporate: How to Qualify an AV Supplier Education: Working Smarter AV Technology's Guide to Networked AV Government: IPv6 — Why You Should Care Calculating ROI on Your Digital Signage Investment Enhancing Audio in the Classroom Minimizing Equipment Theft Smart AV The Tribe Has Spoken AV Enables Interactive Research AV Image Enhancement Product Spotlight Tech Horizons Product Review New Products AV MO

AV Technology - May 2008

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