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 The Future of AV Distribution

As audio has moved largely to IP networks, will video distribution soon move in that direction?

Video has been moving to Ethernet over the past decade or so, but at a much slower adoption rate than audio over Ethernet.

AT THE BASE OF any professional audio, video, and lighting system, is the distribu­tion mechanism—how you get your signals from one location to another.

For years, an­alog audio has been carried over balanced audio cable; for analog video, that would be co-ax cable(s) or VGA cable. With the advent of digital video, options expanded to include HDMI and DisplayPort over their own ca­bling types, or SDI delivered over co-ax cable.

On the audio side for professional distri­bution, digital adopted Ethernet’s IP proto­col as the standard, with CobraNet leading the way as the first commercially successful digital distribution system in the 1990s, and Dante by Audinate becoming the standard over the last decade, all using standard low-cost Cat5E or Cat6 networking cable and TCP/IP networking protocols, which elimi­nates the need for point-to-point cabling be­tween specific pairs of sources and receivers, as routing takes place in software, as well as eliminating the need for wiring that’s specif­ic to the needs of audio.

Video has also been moving to Ethernet over the last decade or more, but with much slower adoption than audio over Ethernet.

OVERVIEW

“The big advantage with AV over IP is we can take a signal and put it on a standard IP net­work,” says David Battershell, senior consul­tant with Idibri in Dallas, Texas. “It can utilize a network that already exists, or a new net­work. We can leverage an existing network to distribute your AV to other rooms without running additional cabling.”

Additional advantages include, for larger installations, more flexibility and lower cost of routing signals.

“With Video over IP,” states Chris Ko­pin, VP of technology for Kramer US, “switching also becomes a lot simpler. For traditional video transmission sys­tems such as HDMI or SDI, you needed a fixed-sized hardware-based matrix video switcher to route video signals from a source to a destination. With AV over IP, matrix switching still takes place, but happens through a network switch where the decoders subscribe to the en­coder’s multicast stream. With a prop­erly configured video encoder over an IP network, all decoders automatically have access to all encoders.”

The challenge with putting video on IP networks is bandwidth and latency. “If you want the video to use less of your network­ing bandwidth,” says Battershell, “you need to more highly compress it. However, high compression takes time and introduces latency into your video transmission. The more compression, the more latency.” If you are transmitting your video to another room in your facility, such as a video overflow room, then latency isn’t an issue. But if the video will be seen in the same room as the live action, then it becomes very noticeable.

Another advantage that Kopin points out is simplification in powering the encoders and decoders. Most AV-over-IP endpoints can take advantage of PoE, or Power over Ethernet. PoE hubs provide a small amount of electrical power through the Ethernet ca­ble to the device attached to the other end, eliminating the need for small devices to have their own power supply.

HISTORY

There have been a multitude of AV-over-IP solutions, but many are proprietary to a spe­cific manufacturer. A few, however, strove to become a cross-manufacturer standard, and have had some success.

“Audio Video Bridging (AVB), has been around for over a decade,” says John Linden, co-owner of Provision Audio Video Solutions in Wake Forest, N.C. “It initially had a number of manufacturers creating solutions based on it. However, the larger players on the video side didn’t see an advantage over SDI, and it also required expensive specialized network switches. The big players in video switching, distribution, and displays never really bought in.”

While AVB was taking form, another op­tion popped up: HDBaseT.

“HDBaseT received more traction from the video manufacturing world, it was standardized to a degree and relatively inexpensive. HDBaseT was being built-in to a lot of video switchers, routers, and projectors,” says Linden. “However, it is predominantly point-to-point and does not use standard ethernet switches, so it cannot be used on a network that also car­ries standard computer networking traffic. And while it is intended to be compatible between different manufacturers, if you start mixing too many different brands, problems tend to crop up.”

HDBaseT also supports HDCP (High-bandwidth Digital Content Protection). This is a protocol to protect copyrighted material from being copied. If a signal source (such as a Blu-ray player) is playing material protect­ed with HDCP, it can only be read by devic­es that give a correct “handshake,” assuring that the information is only displayed, not recorded or otherwise captured. So, it can be fed to a video projector, but not a video re­corder or even a display that did not support HDCP. AVB is capable of HDCP, but manufac­turers still didn’t embrace it.

“For a time, we found HDBaseT very help­ful,” says Linden. “We used it a lot for youth spaces. Anywhere you may want to watch the Super Bowl or a movie, HDBT was helpful. It’s the sort of thing that can’t easily be done over an SDI-based system, because of content pro­tection—SDI does not support HDCP.”

Another issue that cropped up with HDBa­seT is the original specification contained five components that needed to be supported: video, audio, control, USB and networking. To make implementations more cost-effec­tive, Linden comments that newer versions of the specification allowed for implementing a subset of these components. However, this caused compatibility issues between compo­nents and made implementation of an HD­BaseT system more problematic.

“We are now seeing growth in the adop­tion of HDBaseT flatten; the number of manufacturers partnering with the HDBT Alliance has shrunk,” Linden says.

MOVING FORWARD

As with any technology, a common, cost-ef­fective, adopted standard would bring AV over IP to a new level of acceptance. This was the case with Dante audio networking—it is now quite common to see new facilities equipped with Dante for audio signal rout­ing. And there are indications this is happen­ing for the video side as well.

SDVoE, or Software Defined Video over Eth­ernet, is working towards standardization of AV over IP,” comments Kopin. Founded in early 2017, SDVoE has numerous companies participating in the process.

“Our six founding members (Aquantia, Christie Digital, NETGEAR, Semtech, Sony, and ZeeVee) were all working with a simi­lar technology to one another, for moving AV without compromise over 10G Ethernet networks,” states Justin Kennington, presi­dent of the SDVoE Alliance. “We recognized together that partnering to try and drive a standardized approach to AV over IP would result in better market adoption and accep­tance than the AV world’s more usual ‘every manufacturer for themselves’ approach. Therefore, we chartered the SDVoE Alliance in late 2016, and built up to a public an­nouncement in 2017.”

Kennington reports that there were over 158 companies shipping SDVoE devices at the end of 2018, and projections from their member companies show that over 150,000 endpoints (an endpoint is an encoder or de­coder) will be delivered in 2019.

With regards to compatibility between manufacturers, Kennington says “interop­erability is guaranteed by use of a common chipset, provided by Semtech and Aquantia, as well as a common software API, which ensures that all SDVoE endpoints report themselves and respond to commands in the same way.”

Additionally, Audinate, the creators of the Dante audio distribution protocol, has announced that video is being added to the Dante system.

“Video is a natural extension from audio,” says Brad Price, senior product marketing manager for Audinate. “Audinate believes that IP connectivity is the path forward for the entire AV universe, regardless of media type. We designed Dante from the start to be vendor-neutral and capable of distributing any time-dependent content.”

To ensure compatibility between vendors, Price says Dante AV is delivered in two inter­locking parts, both of which support HDCP. The first is the Dante AV module, which is a compact hardware component that pro­vides 1 Gbps networking functionality, Dan­te control and Dante audio/video. The Dante AV Module is codec-agnostic, and so can be used by manufacturers who already have a preferred 1 Gbps codec. In this case, care would been to be taken to specify encoders and decoders that use the same codec.

The second is the Dante AV Product Design Suite, which is a set of documents and software that allow a manufacturer to build their own complete encoder/decoder solution using an implementation of the popular JPEG2000 codec. The Dante AV Product Design Suite gives manufacturers a rapid path to finished products that are fully interoperable.

“One big advantage with Dante AV is the seamless integration of Dante audio with video,” Price comments. “We have many manufacturers who use Dante to ‘break out’ audio from video products and send the signals to Dante networks, and Dan­te AV makes that simply a default. Since there are far more Dante-enabled audio products on the market than any other au­dio-over-IP solution (over 1,700), this gives manufacturers and integrators instant ac­cess to a thriving ecosystem from which to assemble systems.”

SUMMARY

Currently, much of AV over IP is manufac­turer specific, and AVB requires specialized hardware switches. If you are interested in an IP solution for your video distribution and choose a proprietary system, you’ll want to pick a company that provides all the func­tionality you need, as mixing and matching pieces from different manufacturers may not be feasible. You also need to understand what other traffic you want to put on the same network. Quality, low-latency video consumes a significant amount of band­width and can impact the performance of other systems and applications residing on the same physical network.

The other decision point is to determine whether AV over IP is really a benefit to your facility.

“In really basic setups, it’ll probably be more expensive,” says Battershell. “When you scale to larger sizes is where the cost sav­ings occurs.”

And innovation is only likely to increase, Battershell adds. “Since AV over IP is using standard IP protocols, the components are being built by the networking world, which is much larger than the AV industry. So, if we can use products delivered by another indus­try, the AV industry can progress faster. It will be able to use hardware that the IT industry is building.”

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