Video streaming is ready for take off
Could the growing use of network video distribution be the factor that finally delivers widespread 4K adoption in the proAV world? Steve Montgomery investigates.
Whilst those of us in the AV industry are conversant with the differences between the various HD and UHD resolutions and frame rates, it may not be so apparent to end users. However, thanks to high volumes of consumer advertising the general awareness of domestic 4K TV displays is increasing; with people at least understanding that it is a better solution than high definition TV; a product that has been around for several years. That awareness is flowing through to end users in corporate and commercial video systems.
4K displays are being installed widely in corporate meeting rooms for collaboration applications, allowing multiple on-screen windows to be worked on simultaneously. In the retail environment, digital signage shown on 4K screens allows multiple zones of information to be displayed on a single panel. Other applications, including medical, finance and control rooms require the highest level of image detail and the use of 4K screens facilitates that. However UHD screens command a premium price and user focus is often on whether a solution is good enough for what they need, whether it will meet their operational requirements and, of course, the total cost.
End users are also fully aware that standards and technology change rapidly, become out of date quickly and need to be updated or replaced. “Ultra HD 4K sources are becoming prevalent in the marketplace but users are more concerned about future-proofing their video distribution technology than on what their current sources can provide,” says Helen Badger, director of marketing EMEA, Harman. “This means that as manufacturers, we need to understand the direction of the technology as well as its current capabilities. The range of Ultra HD devices on the market continues to grow but as a manufacturer of infrastructure technology, our focus has to be on the technology to come as well as the technology that is already available.
“A trend in the ProAV sector has been a move towards network distribution of video. The only viable solution to transmitting 4K content over longer distances is by means of a network. Once a video signal is passed through a 4K encoder, it becomes network data rather than a video stream. As long as the network infrastructure has sufficient bandwidth and is capable of managing the network traffic, this data can be switched and routed in the same way as any other data on the network. This brings a level of flexibility that we are not always used to in the AV world.”
This is something that Rob Carter, technology manager at Crestron, endorses: “The network video market is going to take off in the next few years; it's poised for significant growth. Some of this will be about a new way to tackle an old problem, but I think we'll start to see new use cases crop up as people start to take advantage of the flexibility network video brings to the table.”
One of the reasons for this is that alternative transmission methods that are capable of sending video over distances of 100 metres or so, don’t offer the flexibility and convenience of network systems. “HDBaseT isn't going anywhere; although it will always be great for in-room point-to-point and simple switching applications. We're still fully invested in HDBaseT and are actively working on the next round of products but it cannot offer a solution for wider distribution.”
The HDMI standard is also being upgraded and HDMI 2.1 has been announced, although not yet adopted by equipment and cable manufacturers. When it matures, signals of 48Gb/s speeds will be handled, sufficient for up to 8K signals. However the transmission distance is limited to 2 metres, which is adequate to interface between devices, but not for general longer-distance transmission.
Some companies, specifically those in the IPTV domain have been producing network-based distribution systems for some time. “Our IPTV systems are AV-over-IP solutions and have been around for 12 years,” points out Mark Stanborough, sales manager EMEA & APAC, Cabletime. “Because they use standard IP networks, video can be distributed anywhere the network reaches and to any number of points. This is the case with a major commercial corporation that operates 5000 end points in 130 offices around the world; all managed from a single server at head office. The buzz about AV-over-IP today is largely generated by companies that have traditionally offered matrix-based systems and have now moved into the AV-over-IP area and launched new ranges of products.”
As good as it sounds, AV-over-IP cannot solve everyone’s needs all the time and trade-offs have to be made, particularly in unicast systems in which individuals need to access dedicated streams of content. Limited network bandwidth is the main restriction; a problem exacerbated by the demand for higher video resolution. “Efficient use of available bandwidth is the key element to transmitting video at high resolutions, frame-rates and colour depths,” says Badger. “An uncompressed 4K60 video feed requires a bandwidth of a little under 18Gb/s which means we have to apply compression to make this manageable. In the case of networked systems, today, this means bringing the bandwidth down to well under 1Gb/s. Thankfully, the latest compression technology allows us to reduce the bandwidth to a manageable level without visually compromising the video quality. Image quality versus bandwidth is an important balance to maintain however, as poorly compressed or over-compressed video would mean negating the use of a high quality source in the first place.”
Crestron’s DigitalMedia NVX Series combines compression and scaling to reduce the bandwidth requirement for a video stream to 1Gb/s, whilst incorporating security procedures. “They are designed to move 4K60 4:4:4 or HDR content over gigabit networks with no latency,” says Carter. “And since sensitive data is on the network, it's critical that content is secure. We've baked in technologies like Network Access Control, AES encryption and Active Directory integration to ensure the device, the content, and the network is protected. And every control interface into NVX is authenticated and encrypted.”
Compressing a video signal will inevitably introduce artefacts. All compression algorithms can be defeated, however the state-of-the art today is such that for these codecs artefacts are only visible when the content is created to include unnatural images patterns which are never encountered in real life images. The latest generations of codecs are able to produce compressed video which is visually lossless, in which users will not be able to detect any image artefacts.
However latency is another issue. The process of compressing an image takes time and delays a picture stream. “With AV-over-IP there is always a trade off between image quality, latency and bandwidth required. Best image quality, means high bandwidth, whereas compression of any type will add latency and affect picture quality,” says Rob Muddiman, sales director EMEA, ZeeVee. “It is definitely possible to add compressed 4K traffic of any standard to an existing IP network, leveraging the infrastructure that is in place. One way to do this is using highly compressed solutions based around H.264/H.265, however this will reduce image quality and add significant latency. JPEG2000 compression offers a compromise with low latency, but needs higher bandwidth, so users would probably be advised to put it on a dedicated network, or at least VLAN.”
Compressing video streams to low bandwidth is necessary primarily because existing IP networks cannot handle large bandwidths. This is set to improve. “The AV signal distribution market is at a crossroad and a significant disruption is about to occur in this industry, believes Kamran Ahmed, VP and GM, AptoVision products at Semtech: “This disruption is caused by the simple fact that for the first time in the history of AV, mainstream networking technologies have more bandwidth than is required for uncompressed video; both for the incumbent 1080P video format and for the latest 4K video format. Previous generations of networking technologies at up to 1Gb/s were insufficient to support the bandwidths required for HD distribution. With 10G networking, 1080p or 4K is not an issue.
“We have reached a tipping point where going forward, available bandwidth on networking switches will always be higher than that required for the video standard of the day. 25G, 40G and 100G network equipment already exists. This is a significant trend which will change AV signal distribution as we know it today. The days of custom AV switches are numbered since the research and development required to develop such systems is immense and these systems do not benefit from the same economies of scale as IP equipment does. Moreover, the industry will jump on the ability to remove the redundant cabling and other infrastructure required for custom AV networks, and will merge the two networks into one.”
Despite the enormous opportunities open to manufacturers and integrators, there is considerable confusion. As summed up by Muddiman: “In the AV-over-IP market today there are so many different products targeted at many different needs that is confusing to the end user. Education has to be provided by the industry to the end user as AV-over-IP will raise its market share year on year. We all agree that AV-over-IP is the future of AV signal distribution. On the audio side of things there is a well-accepted Dante standard today while AES67 is gaining more and more exposure. One day we might see a similar consolidation on the video side; but not in the short term.”
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