AV Smarts

An Introduction to AV Over IP

AV over IP promises to take full advantage of the convergence of AV and IT, with the ability to distribute video, audio and control signals over traditional network infrastructure. Here are the features and limitations to consider when designing AV over IP-based systems.

If you've been paying attention to the audiovisual industry for the past couple of years, you've certainly noticed the AV over IP trend. While it may not yet be widespread in higher ed classrooms, it's definitely going to play a big part in the future of AV system design. There are lots of details to pay attention to when designing AV over IP-based systems, but I'll try to give you a big-picture view of the technology.

Existing Designs

These days, when dealing with high-definition resolutions and frame rates, AV system designers typically look to transport video, audio and control signals throughout their classrooms using twisted pair extenders. Many of the popular classroom AV products (like Crestron DigitalMedia and Extron DTP) are based on HDBaseT technology. These are point-to-point systems with transmitters at source devices and receivers at destination devices. Even when you place a switcher between those source and destination devices, you're essentially adding more mid-stream transmitters and receivers into your point-to-point environment. We see larger and larger matrix switchers coming from the manufacturers, but our switching design is still limited to the number of inputs and outputs on those switcher frames. Everyone knows the feeling of needing to add one more device to your AV system, but the switcher doesn't have any available inputs. While limited in some respects, these point-to-point systems offer a bandwidth-controlled environment, high resolutions and frame rates, and very low latency.

AV Over IP

The AV over IP model differs from existing classroom AV designs in that it's essentially a streaming infrastructure. We're all used to video and audio streaming over the network, but AV over IP technology is taking streaming to a different level. Instead of placing HDBaseT transmitters and receivers at all the devices in the room, the AV over IP model calls for an encoder at each source device and a decoder at each destination device. The encoders and decoders are all connected to standard Ethernet switches. As a result, we're no longer limited to a finite number of inputs and outputs, and theoretically we can connect as many encoders and decoders as our network design allows — with the ability to scale up at lower costs. Based on the network configuration, we're also no longer limited to AV signals being confined within the room. The decoders can be controlled to display any stream from any of the encoders.

Bandwidth

AV and IT professionals pay attention to bandwidth restrictions, and the AV over IP trend is certainly in the thick of the bandwidth discussion. While it might sound like an easy solution, you can't just start throwing these high-end AV encoders and decoders on your network and expect flawless results. There are different classes of these encoders and decoders; for instance, SVSI (AMX) offers everything from low-bandwidth H.264 compression that's friendly to your enterprise networks, to higher bandwidth technology like JPEG2000 compression, and beyond. When comparing AV over IP technologies, pay attention to bandwidth requirements and explore the possibility that you'll need to establish a separate, dedicated AV network to keep your network services department happy.

Considerations

As you start to investigate the various AV over IP technology that's being offered, there are quite a few features and limitations that you need to pay attention to. Different manufacturers have different resolution, frame rate and color compression capabilities. Some may boast that they can offer 4K60 4:4:4 video, but then you'll find out that they require a 10 Gb/sec switch, while others claim they can do it over a 1 Gb switch. Even if you're not yet heavy into 4K-resolution sources and display devices in your classrooms, you should certainly be planning the infrastructure to handle it in the future. Achieving 4:4:4 color sampling is the goal, but plenty of manufacturers are using 4:2:0 compression to save on bandwidth.

Latency is a big topic too in the AV over IP world. Encoding and decoding high resolutions and frame rates with limited compression can take some decent processing power, resulting in latency issues. It may not be a concern if you're talking about a simple one-way video and audio stream to an overflow room, but excessive latency is a big deal when talking about encoders and decoders that are in the same room.

Just like in your existing classroom AV systems, HDCP (high-bandwidth digital content protection) is a major consideration when comparing AV over IP devices. Settling on encoders and decoders that don't properly pass current HDCP signals means you're in for a massive headache as source devices continue to migrate to outputting HDCP signals.

Many of these encoders and decoders also offer power over Ethernet (PoE) capabilities, which is a nice feature compared to having to deal with those bulky wall-wart power supplies. Just pay attention to the PoE capabilities of the network switches you're using.

Since higher ed classroom AV designers love to incorporate control systems into their designs, pay attention to the control capabilities of the encoders and decoders that you choose. The majority of them integrate well with IP-based control systems from the major manufacturers like Crestron, Extron or AMX. Maybe even a cloud-based control solution like Utelogy will be a fitting option for your new AV over IP design.

The Future

A few key market indicators came out of the Integrated Systems Europe tradeshow last month that point to a strong future for AV over IP technology. The first major announcement was from Crestron, debuting its DigitalMedia NVX product line. Crestron is claiming that its NVX encoder/decoder can transport 4K60 4:4:4 signal (along with many other features) over standard 1 Gb/sec Ethernet cabling and switches. Crestron certainly isn't the first company to develop this AV over IP technology, but for a company that has made lots of money off its HDBaseT-based point-to-point DigitalMedia line, this is a big tip off that it's embracing AV over IP. Also during the ISE 2017 show, the HDBaseT Alliance announced that by June it will debut an extension to the HDBaseT standard that will allow for HDBaseT over IP.

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