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Connecting Audio Visual devices via an IP network – the same technology that speeds computer data around an organisation – is flexible, scalable and cheap.audio visual technician in queens ny
“AV over IP offers organisations scalable deployment, because there’s no limit to the number of devices that can be connected, and a centrally controlled and managed installation,” says Ryan McElvaney, networked AV business manager at Exertis. “Other key benefits include sharing content over a distance beyond that supported by conventional AV technologies, lower total cost of ownership using existing network infrastructure that can be managed by the IT department, and better interoperability of devices.”
So where’s the catch? There doesn’t have to be one, but you will need to keep your wits about you – starting with the “B” word.
“Bandwidth is beyond critical,” says Chris F, product marketing manager at Biamp. “It’s fundamental to determine how large the streams are expected to be, and how many simultaneous streams are expected to be transmitted over a particular network link at a time. Best practice would be to work off a ‘worst case scenario’ and build in a decent amount of overhead for the unexpected. And think very carefully about future needs: what’s sufficient today will almost certainly not be five years from now.”
“If the available network bandwidth is restricted, the frame rate and resolution of the video and audio content will trigger compression, which may impact quality and latency,” says Laurent Masia, director for managed switches at Netgear. audio visual technician in queens ny
Latency can be as important as raw quality, Masia adds. “If instant switching, instant scaling and zero-frame latency are a must, it’s important to eliminate any compression trade-off and select 10Gbit AVoIP transport instead. Lifesaving surgery applications can’t stand any latency on the surgeons’ displays, for instance.”
It follows that managing bandwidth is at the core of successfully implementing AV on a corporate network, argues Paul Streffon, customer service and training manager at tvONE.
“Most vendors will indicate the network capacity their products will use, so check equipment spec sheets for typical data rates at different video qualities. There may be several choices, and you must decide what quality fits your needs. AV managers must also consider how many devices will be accessing the network at one time. If you have 20 cameras, will they all be streaming at once or only one or two at a time? Unicast and multicast methods also need to be considered to minimise bandwidth usage.”
Switches and streams
Requirements depend heavily on the type of traffic. “Control and monitoring systems use very little bandwidth, no more than a short, unformatted email per message,” says Jonathan Mangnall, vice-president, sales at Utelogy. “But typical video and audio streams with compression can generate 1Gbps per encoder, at a consistent rate. Most enterprise-level switches handle this traffic with ease so long as the stream is contained within the same switch.”
The quality of switches can be critical. “With a very well-crafted 1Gbit network, you can distribute a decent number of compressed programs,” says Rob Muddiman, EMEA sales director at ZeeVee. “But if you have bottlenecks, or there’s a switch at the core of your network that doesn’t have capacity, then you ruin your ability to do anything. This can derail a 10Gbit AV network project, particularly if capacity isn’t provisioned for core switches in the network.”
“Any single Ethernet switch is generally non-blocking, meaning it can run all its ports at full rate (‘line rate’) without any data loss or collisions, so you don’t have to worry about bandwidth if your system is run by a single switch,” says Justin Kennington, president of the SDVoE Alliance. “When designing with multiple switches, you need to consider how many streams need to pass between switches, and size the connecting data link accordingly. Bandwidth requirement will vary by implementation and data type, but generally it’s a simple calculation of bandwidth per stream times number of streams.”audio visual technician in queens ny
If your network traffic is primarily audio, you may spend less time reaching for the paracetamol.
“Audio-only systems frequently require less bandwidth than is commonly thought,” says Brad Price, senior product manager at Audinate. “A good rule of thumb is that four channels of 48 kHz/24-bit lossless audio require approximately 6Mbits of bandwidth; hence a group of 64 channels requires approximately 100Mbits.
Since nearly all modern networks are using 1Gbit switches, even 64 channels represent only 10 per cent of bandwidth for a given port.
“Video requires quite a bit more bandwidth, and depends on the codec used and resolution required. As a rule of thumb, a 1Gbit network port can typically handle one 4K60 4:4:4 full colour JPEG2000 video stream sent to many endpoints alongside approximately eight channels of lossless audio. Different codecs may yield different results.”
AV and IT management
In principle, one of the prime attractions of networking AV is to get some extra mileage out of your existing IP network by piggy-backing AV on to it. Whether you can do so in practice is less certain, however, and will probably entail some serious head-scratching.
“You can’t leverage your existing network for new AV-over-IP applications because your infrastructure is already oversubscribed,” says Masia. “Even if your AV-over-IP application is restricted to 1Gbit, regular IT traffic will still have to compete with the AV streams, slowing everyone’s browsing, email and data transfers. Likewise, the quality of video streams will suffer if corporate traffic is high. So you’ll always need to build a new infrastructure for AV.”
Kennington is more optimistic. “AV can and often should be combined into existing IT networks, with one important caveat: few existing IT networks are designed to handle AV signals. IT networks are designed on the principle that host devices (PCs, printers, iPhones) rarely need all their available bandwidth. So compromises are made and bottlenecks are intelligently designed into the network to save cost, without significantly impacting performance. AV endpoints are different in that they do require most of the available bandwidth any time they’re operating.”
Any network, new or existing, must therefore be designed or upgraded to account for AV signals. audio visual technician in queens ny
Fitzsimmons also believes that, with care, networked AV can be deployed on to existing networks, although this is certainly more complex than creating a new network.
“You need to consider the correct allocation of devices to appropriate VLANs, and give a great deal of thought to managing multicast traffic,” he says. “Some protocols require the use of technologies such as IGMP Snooping to do that, others can automate that process fully. Getting this stuff wrong will result in severe degradation in the performance of the core systems, the media system or (most likely) both.”audio visual technician in queens ny
Some AV-over-IP implementations, such as AVB/TSN, cater for quality of service, latency and network management through software layers, says Rob Green, senior manager for pro AV and broadcast at Xilinx. “They carry email and other general data alongside the AV traffic but with a lower priority, which means the AV content shouldn’t stutter or stop when, say, someone else on the network downloads a huge file. However, it can be easy to oversubscribe a network, so new equipment will probably be needed anyway to manage bandwidth allocation and synchronisation.”
Over and above the network itself – the Ethernet switches and cables – you will need to connect each AV device to the network. This, at least, is refreshingly straightforward. “The beauty of networked AV is the simplicity of the hardware architecture,” says Kennington. “Every design is basically the same – an encoder at every source, a decoder at every display, and the network in between.”
Encoders take an HDMI signal (the ‘classic’ AV signal) and convert it into packets that are sent across the network. At the other end, decoders convert the packets back into HDMI. All these devices need to be managed with a router, or a switch capable of handling a DHCP server that assigns IP addresses, and a software management platform needs to be running on the network to control which feeds are sent to specific displays.
The commercial AV market has matured over the past 12 months, says Greg Mirsky, product manager for networked AV at Atlona. “Many vendors offer AV-over-IP solutions based on 1Gbit Ethernet, although not all are equal. Network switch manufacturers also offer many professional grade PoE+ switches that can be used for deployments. The key differentiators for customers are usually about specific features that match their use case, quality of technical support, and warranty.”
“Some systems provide a level of interoperability and others none at all,” says Chris Kendell, systems architect at Visavvi. “We’ve seen a plethora of manufacturers trying to bring their own variants to market without any consideration for interoperability or even in some cases integration with control systems.
In general, most integrators and clients prefer to stay with one manufacturer where possible.”
However, some standards are gaining traction. SDVoE (Software Defined Video over Ethernet) is a combined chipset and software hybrid designed to enable zero latency and uncompressed video. Now supported by 45 member companies, SDVoE makes systems more adaptable, says Kennington. “When the end user’s needs change, an SDVoE system can be easily reprogrammed to perform new and different functions. Previously these changes would have required new hardware and installation.”
Audinate’s Dante, the widely-used standard for uncompressed, multichannel audio, has recently been extended to video. “This technology uses high quality compression that’s entirely suitable for the distribution of video to endpoints using the same familiar toolset as Dante audio,” says Price.
Source: AV Magazine – avinteractive.com/features/buying-advice/really-planning-ahead-18-10-2019/
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