Switching off for good?
As content distribution shifts online via IP networks, is the end nigh for matrix switchers? Steve Montgomery investigates the likely outcomes.
The demise of the video matrix switch in professional AV installations has been predicted. It is expected to be replaced in the future by online content distribution over IP networks. If this is true, the questions facing the industry are when will it occur and how should manufacturers and integrators address the industry in the near term in order to future-proof products and installations?
Nick Mawer, marketing manager at Kramer, believes that: “Eventually we will route all our signals on the network; closed AV systems based on proprietary technologies will vanish. As the AV industry converges to IT we’ll see more manufacturers picking up with this shift and introducing a multitude of AV over IP products and systems. As with every new technology it will have its own adoption rate, like the move from analogue to digital.”
Stijn Ooms, technology director for Crestron EMEA, agrees: “Whilst it is true that the network is playing an increasingly central role in the AV industry, the reality is that matrix switchers will continue to be a valuable asset for some time to come. The main reason for this is that currently-available codecs are not sufficiently efficient to stream effectively without using a great deal of bandwidth. Insufﬁcient bandwidth leads to a myriad of problems for other applications on the network such as email, access to the internet and IP telephony.”
The response from Crestron is a hybrid product. Ooms continues: “The DigitalMedia switcher combines a traditional matrix switcher with streaming capability that can receive streaming signals as well as send them when the application requires it.”
Matrix switchers are the backbone of AV systems. Their function is to route the outputs of computers and other image sources to display devices located within the same room, or across buildings, campuses, and even around the world.
The type of matrix switcher required will depend on the application for which it is intended. To meet an extremely wide range of potential applications, matrix switches are available in several sizes and forms. From small HDMI video switches used to manage multiple sources onto multiple displays, to massive extender-switches capable of delivering many video streams over long distances. Many companies offer modular systems that allow mixing and matching of input and output types, additional components such as back up control cards and redundant power supplies and extended features, including USB interfaces for data transmission to allow the addition of keyboards and mice to the end terminals.
Individual selection of the most appropriate device depends upon its intended use and the features required for the particular installation.
“There is a long list of questions the integrator should address,” says Dave Schorah, WyreStorm product application specialist. “Start with the desired transmission distance and consider how many source and display devices are required, what type of content is to be transmitted, what does the end-user want to do with that transmission and what control features are necessary. That leads on to detailed system
requirements: decision on video resolution, formats, control interface, whether Ethernet needs to be passed, and how remote terminals are to be powered. Only then can the actual device be selected, to meet the expected number of inputs and outputs expected; with allowance, of course, for future expansion.”
Since its introduction in 2011, HDBaseT has had a major effect on the video matrix switch market. It has become the de-facto standard for long distance HD video content distribution when HDMI fails at around 15 metres. HDBaseT devices can transmit video up to 4K UHD resolution (although not at 60Hz, 4:4:4 colour space) and the newly released HDBaseT 2.0 will add additional features to add multipoint and multistream capability as well as USB support for KVM applications.
At the same time, a new version of HDMI is being launched. HDMI 2.0 caters for 4K transmission, multiple video streams and users, and adds extra audio channels and resolution.
However, as Mawer points out: “The HDMI 2.0 spec exists, but display and source manufacturers are not rushing to meet it yet.” David Shamir, Atlona’s senior product manager for IP Audio/Video, points out, along with an interesting twist on HDMI marketing: “Manufacturers have been asked to specify product using the speciﬁcs of the features rather than the HDMI version number.”
The net effect is that matrix switchers are keeping pace with the rapid evolution in display technology, even if their full capabilities are not yet being utilised; a characteristic that will maintain their leading position and longevity in an industry that is constantly being asked to provide the latest-and-greatest products.
Whilst 4K is receiving a lot of attention and many UHD monitors and TV sets are already available, there are relatively few devices that are capable of producing native 4K images.
This will change. “Given how fast prices of screens are falling and the inevitability of the technology as an evolution of HD, 4K screens are certainly a necessity for new installations,” believes James Meredith, WyreStorm NetworkHD and Enado product manager. “Laptops, tablets and even some phones are capable of generating 4K content, so anyone specifying an HD screen now is really not looking very far down the road unless they are happy to scale content down to HD. However, in terms of whether a client or end user is looking for 4K@30Hz or 60Hz, as long as its 4K they don’t really know, or care, about the difference as long if they can perceive improvement over their old HD screen.
“The reality is that even with no noticeable improvement, most users will probably presume they are getting 4K, a problem further compounded by screens offering an HD to 4K upscaling function that might offer slightly higher picture quality that still falls short of true 4K.”
Ooms points to another consideration for mixed resolution systems: “Many devices in use now are referred to as ‘tweeners’: they fall between 1080p resolution and 4K. These native resolutions are far greater than HD distribution systems can handle.
Many organisations still use a 1080p switching environment so a presentation produced at the native high resolution of a laptop, might lose some of the imagery and text impact when it is scaled down to 1080. Also, many industries, such as medical, government and military require the highest resolution possible. Those who have invested in new 4K displays expect 4K resolution, rather than downscaled 1080p.”
Matrix switchers based on HDBaseT distribute uncompressed video and therefore do not suffer image artefacts brought about by compression, nor do they suffer transmission delay or latency from the packetisation process employed in video-over-IP network transmission. The degree of acceptance of compression and delay depends largely on the application. Live content and videoconferencing should not be delayed by ore than two frames, although in large event staging the delay may be nulliﬁ ed by audio delay across a stadium. As long as screens are synchronised, signage and playback of recorded content is not usually important.
Every application can accept an amount of compression: presentations and conference rooms have one level, live events another. Command and control and medical applications cannot tolerate any compression artefacts at all. There are many different and alternative compression schemes although JPEG2000 and H.264 are the two most commonly used in AV network video transmission devices.
JPEG2000 is a wavelet-based technique that tends to make a higher quality image then macro block based compression algorithms. It is typically used in mission critical applications such as military, government, legal or healthcare where the visually lossless nature of the compression ensures the image at one end is the same as at the other. H.264 is efﬁcient and highly selective but is not desirable in applications that require high quality, as it can discard important elements of the image.
According to Paul Harris, ceo of Aurora: “A compression ratio of 8:1 can be used, however quality depends not just on the level but the technique and choice. Many of the higher compression ratio devices will convert 4:4:4 to 4:2:2 making a PC image softer-looking and the colour palette will no longer be correct. Users understand the term ‘lossless compression’, however the issue the industry has is there is no ofﬁcial testing to conﬁrm an industry-standard minimum requirement. Most visually lossless systems are not. JPEG2000 products are typically 9:1 and you can see artefacts with some content.”
The bottom line is that we are all heavy consumers of visual lossy compression. Lossless video is essential for some highly demanding applications but high quality lossy compression is acceptable for most others.
“There are many variables that inﬂuence whether an existing data network can support AV streaming,” explains Shamir. “Network load pattern; how busy the network is, and at what time of the day it gets the busiest. How much bandwidth can be allocated to the AV component; achievable image quality and latency when operating within the allocated bit rate; available bit rate between network switches; trafﬁc forecast and whether the network can sustain that trafﬁc at a sufﬁciently high quality of service (QoS).”
Both technologies have their advantages and position in the market. Harman’s recent acquisition of network AV provider SVSi indicates its commitment to that technology and complements the AMX Enova matrix switch product range. “In the long term the ability to move large amounts of data anywhere is most likely to be based on Ethernet, as network bandwidth increase,” says Brian Davies, European technical director at AMX. “We can already distribute 4K/30Hz over 10Gb ﬁbre networks and with new encoder ﬁrmware that will soon be possible over 1Gb too. As the industry moves upwards to 40Gb and then 100Gb, it will make video distribution even more efﬁcient, reduce latency and enhance picture quality, opening up opportunities even further.”
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