AV over IP: Scalable and flexible
The transportation of AV over IP has become the key issue in the AV world in the past decade. Steve Montgomery examines the effect this has had on the industry.
AV signals are distributed widely in commercial, entertainment, industrial and government buildings and sites, for a wide variety of purposes. For many years the dominant method of connecting source devices to remote displays has been direct connection over dedicated copper or ﬁbre wiring. In due course video matrix switches have been added to enable users to select and control the content viewed on individual displays.
More recently, distribution of AV over IP networks has become more common; as a result of two factors: more efficient and faster compression technology and the wider availability of network bandwidth throughout buildings. Its use is widespread. James Keen, group marketing manager, Tripleplay: “Enterprise video isn’t just about video and live streams, it is about training, messaging, compliance and understanding. It is not simply sending a camera image from one room to the next, the CEO can now address an entire workforce via mobile phones, tablets, virtual desktops, set top boxes and smart TVs all across corporate networks and the internet.”
AV over IP is not a single technology, nor does it provide a single advantage, as Samuel Recine director of sales, Americas & Asia Pacific, Matrox Graphics points out: “AV over IP is a superset of technologies replacing proprietary technologies such as HDBaseT. As well as an inherent ability to connect to legacy equipment or replace it with newer, easier to manage, and easier to modify user interfaces, it makes new applications of AV possible, such as transmission, switching, and management of AV to disparate devices, including wireless products such as phones, tablets, and smart devices.”
The contest between directly connected and networked AV distribution systems is closing. The trade-off between image quality, latency and bandwidth has always been a delicate balance; an improvement in one aspect causes degradation in another. “Every aspect of quality can be matched on IP compared to legacy direct AV connection,” he says. “The bulk of AV applications can be covered by very low bitrate solutions that fit comfortably on existing 1Gb deployed infrastructures. The best new AV over IP products don’t require a chain of additional steps to be able to immediately connect to web delivery and other applications. Modern encoders are highly bandwidth efficient. An H.264 encoder can generate a 4K stream that can be transmitted and switched and displayed with ultra-low latency as an on-premises AV solution at 15Mb to 30Mb per second. Even high quality signal encoders do not introduce large delays. “For more ‘niche’ applications, 30Mb per second streams can offer 4Kp60 4:4:4 with latency of as low as 50ms, glass-to-glass. Solutions at 800Mb to 900Mb per second for 4Kp60 4:4:4 can offer even lower latency in the infrequent application cases where that is required.”
One of the greatest advantages of AV over IP systems is scalability. Rob Carter, Crestron’s technology manager, Digital Media points out that: “A traditional AV matrix is always limited to a certain amount of inputs and outputs, like 64x64 or 128x128. With single gigabit AV over IP the AV system can be as large as the network allows; thousands of endpoints can easily be a part of a virtual matrix.” But he warns: “AV over IP solutions exist that require a 10Gb infrastructure. These solutions are very difﬁ cult to scale and don’t truly offer the advantages of AV over IP. The reason for this is the uplink bandwidth between the network switches will drastically limit the number of endpoints you can route between switches.”
With efficient codecs it is possible to fit 30 streams of 4Kp60 4:4:4, H.264-based video and one 4Kp60 4:4:4 stream of J2K-based video on the 1Gb infrastructure that makes up the vast majority of existing networks. However, as Carter explains: “Latency can be an issue, depending on the application and the technology selected. H.264 solutions give very good image quality at low bandwidths, but at a latency penalty of several hundred milliseconds. This makes it inappropriate for many professional applications where users interact with content using a mouse and keyboard and where two-way communication is desired.”
Ten Gb Ethernet networks are becoming more common. “Research from Netgear shows that 33% of small to medium businesses had already deployed 10G networking at the beginning of 2017, and 75% will have deployed it by end of 2017. The higher capacity network is here, and it is necessary to offer true matrix switch performance over Ethernet” says Justin Kennington, Aptovision. “1Gb networks actually deliver inferior performance. Surprisingly, 1Gb networks for AV also cost more than 10G. It turns out that compressing an 18G HDMI signal down to 1Gb with any quality at all is complex and requires expensive IP and expensive processing chips. The list price of popular 1Gb solutions ranges from USD2,500 to nearly USD4,000 per endpoint. Meanwhile 10Gb products list for around USD1,500 to USD2,000. The saving is hundreds or thousands of dollars per I/O and the 10G system gives higher performance. This is the beneﬁ t of Ethernet.”
The Software-Defined Video Over Ethernet (SDVoE) alliance was unveiled at ISE 2017 by founding members Aptovision, Zeevee, Christie, Netgear, Sony and Aquantia. Its role is to standardise the adoption of Ethernet to transport AV signals in professional AV environments and to create an ecosystem around SDVoE technology allowing software to define AV applications. Through this standardisation, members can take advantage of a hardware and software platform that is flexible, and allows them to collaborate to provide interoperability of individual products and solutions.
AV over IP systems are capable of transporting signals from almost any source, including current HD and 4K streams as well as those complying to common analogue standards of old. Johnson: “AV over IP is highly scalable and flexible. Any quantity and mix of sources and displays can be placed anywhere the network can reach. USB, IR and serial RS-232 control signals. Some systems may not transport HDCP-encrypted signals if they do not have provisions for protecting the content.” HDCP must be considered when specifying a system, as Carter points out: “Sources requiring HDCP2 support are becoming more and more prevalent. Even PC video cards are starting to support HDCP2. It is essential to ensure that a proposed solution supports HDCP2 end-to-end.”
Security of content is an important aspect that Colin Farquhar, CEO of Exterity feels is not taken strongly enough: “Third party content taken from an HDCP-protected source and distributed over an IP-based system must be protected,” he says. “HDCP Pro makes provision for an HDCP- protected HDMI source to be re-encrypted, passed over the network and converted back to HDMI for display, with a limit on the number of end-points that can access simultaneously.”
The question of whether the AV over IP distribution system requires its own network or can piggy-back on an existing in-house data network often arises and there are conflicting thoughts. Kevin Madeja of Snelling Business Systems believes that: “As long as the network is at least 1Gbs and that it can be structured for a separate VLAN for the AV, it is possible to use the existing in-house network given some careful planning. AV over IP does use quite a large chunk of bandwidth and, therefore, needs be considered carefully as to impact on the network and its topology.”
However, Joseph Barbier from DVI Gear disagrees: “Regardless of technology, all high performance AV over IP solutions must be run over a dedicated network in order to provide the required bandwidth and security needed for professional applications. The reason for this is that normal LAN traffic tends to come in bursts and it is not unusual for a port on a network switch to be over-subscribed from time to time. However, AV signals occupy much greater bandwidth that is sustained. This places much greater demand on existing networks, which obliges IT managers to demand isolated networks. Of course these isolated networks can be linked to corporate networks using VLANs, which can be configured to meet bandwidth and security requirements of the local network.”
The technology and the markets it serves are moving rapidly. There is clearly a demand for the delivery of AV over IP, but some doubt and confusion too. One of the greatest factors in the successful deployment of an AV over IP solution is the interaction with the IT infrastructure in a building and the need to provision AV services that meet the corporate and security objectives of the IT department. Madeja sums this up: “The single biggest issue is bridging the knowledge gap between AV professionals and IT professionals. We are dealing with the converging technologies of AV and IT which will result in a few bumps and scrapes along the way. AV professionals need to be much more comfortable and knowledgeable with the IT networks and solutions order to continue to flourish in the future.”
Markus Lubik, senior sales consultant, Fundamental Consulting is in agreement: “There are a lot of considerations but the first and foremost should be ensuring an understanding of networks and how to set them up properly. It is a complex topic that requires a lot of specific knowledge to handle. The vast majority of problems will arise from the network and the way it is configured. Video is not the innovation driver for faster network speeds: the key drivers are WiFi and Cloud/Virtualised Environments. The networks we can build today are fully capable of handling the requirements of the regular customer. Looking at the bigger picture and the shift that has been going on towards IP in the AV world, I think that the level of integration will greatly increase in the near future.”