Video distribution: Getting the message out12 December 2012
Ask most people which are the internet’s ‘killer apps’ and the response would probably be Google, Facebook, Twitter – and YouTube. Over 800 million unique users visit YouTube each month and watch over 4 billion hours of video. Seventy-two hours of video are uploaded to the site every minute. In 2011, YouTube had more than one trillion views, or around 140 views for every person on Earth.
But supposing what you want to do isn’t to share with 800 million random viewers the allegedly funny footage of your friend falling over drunk or the purportedly cute sequence of your new baby’s first steps? Supposing that what you want is to share the highest possible quality video in real time with 500 people – a chairman’s presentation of the company’s financial performance, for example?
“The main challenge is dealing with distance,” says Nick Mawer, marketing manager at Kramer Electronics UK. “There are a number of possible approaches depending on the quality which the customer requires and whether communication needs to be immediate. Distance limitations can be overcome with fibre optic cables but they are still relatively expensive. Other approaches might be streaming via IP, or updating digital signage players.”
“The biggest challenge is successfully distributing a high-resolution signal throughout an existing infrastructure without introducing any signal latency or compression, while still complying with the HDCP requirements,” adds Mark Ridgwell, advanced technical support engineer at Crestron. “A Crestron DigitalMedia system can do all this and much more.” He notes that the Crestron DigitalMedia system can transmit a full 1080p Deep Colour signal up to 100m when using a copper infrastructure, 300m when using a multi-mode fibre infrastructure or up to 12km when using a single-mode infrastructure.
“If the main focus of a signal distribution system is indeed replicating excellent quality video throughout the installation, then an emphasis should be placed on understanding just how a solution treats the original video file or source,” notes Rob Muddiman, international sales director, Magenta Research. “Is the solution compressing video? Re-encoding it? At Magenta, we have built a reputation on both reliability and replication quality. With our MultiView (for video over UTP) and Voyager (for video over fibre) product lines, video is neither compressed nor re-encoded: the original file is merely replicated, using proprietary technologies, pixel for pixel at every endpoint.”
“Distance is definitely a limiting factor for most signal distribution options,” he continues. “Magenta has overcome these limitations on both the UTP and fibre fronts, with available solutions that can travel over 600m on UTP with no repeaters and 30km via fibre.”
Inevitably, the challenges faced in getting high-quality video out – and the solutions available for those challenges – depend on each organisation’s unique characteristics: is the requirement to distribute the video within a building, within a closely located group of buildings – or further afield?
Each installation’s clients will also have a view of what exactly represents ‘high-quality’ video – and this again determines the possible approaches. Beyond this, as Mike Cuckow, who is sales director EMEA/Asia-Pacific at Cabletime, points out, the requirement is no longer just to get the video onto screens in various rooms.
“It is important to remember the growing trend for distributing video onto handheld and portable devices, such as smartphones and tablets,” he says. “If a message from the chairman is to be seen by the maximum number of people, then all endpoints from large high-quality TV screens in a reception area through to small smartphones must be taken into consideration as part of the distribution mix.”
“The advantage of switchers is that you can take a video source and display it natively without any compression, encoding or decoding,” points out Philip Dodds, business development director, Vision2 Group, AMX. “Switching is appropriate when video isn’t compressed and you have limited sources and limited outputs across an infrastructure that doesn’t require long cable runs. If cable distance is an issue, then fibre transmission could be used in conjunction with this technology. This solution is more applicable in confined corporate areas or residential solutions.”
“With IP,” he continues, “the advantages are that everybody gets the opportunity to receive the same quality of video image; it’s easy to scale in terms of simultaneous streams and users; the same corporate infrastructure can deliver video as well as other applications; there are no delivery distance issues; you can deliver to various decoder devices; you can deliver to the internet; and the video can be recorded and stored easily.”
Implicitly, there is a trade-off between optimum quality on the one hand, and other – perhaps more pragmatic – issues, such as scalability and cost, on the other. And when it comes to considerations of scale, some of the potential issues border on the esoteric.
“Scale can be an issue within the world of digital video distribution, due to the constraints placed upon signals that have to comply with HDCP regulations,” notes Mark Ridgwell. “In order for a signal to be authorised, a key has to be passed from the source to the sink. HDCP limits devices to a maximum number of 128 keys. However, source devices very rarely contain this many – nor is the amount they can provide advertised. This would mean that, if a source can only provide five keys, you would only be able to distribute the signal to four displays – the fifth being taken up by the matrix switch. This is not a problem when using a Crestron DigitalMedia system to distribute the signals. Because Crestron as a manufacturer is licensed to support the full 128 keys, we only require one authentication key from a source device. As all compliant devices must have at least one key, a DigitalMedia system can distribute to 128 sink devices.”
As IP matures, its advantages are unquestionably growing – and of these, flexibility and scalability are perhaps the most compelling. Even here, though, there are issues once the scale of video distribution takes an organisation into an area beyond its LAN infrastructure that it can’t control – the public internet.
“While IP/video codecs offer long-haul – worldwide – connection, there are often compromises,” says Muddiman. “These can come in the form of reduced frame-rate, video image compression, compression/decompression delays, frame dropping, or a combination of any of those.
“In any case,” he continues, “once the IP/video stream is converted back to a native video format – VGA, HDMI, DVI and so on – the single best way to manage that in a single facility or campus is to do as little as possible to the signal. Magenta’s video transport solutions offer just that – transport. With as little added image degradation, manipulation, delay or modification as possible – ‘pixel-perfect’ is always the order of the day.”
“IP internet is a good way of distributing video,” notes Mawer, “but if you want high-quality video on a large screen, there are better ways to do it – by using uncompressed digital video over fibre.”
Kramer has recently introduced the KDS-MP1, a LAN-based digital signage media player for video distribution via the web. For real-time video transmission over IP, the company has launched the KDS-EN1, an H.264-based video encoder.
IP: pros and cons
But IP is, it seems, becoming increasingly prevalent. Colin Farquhar, CEO of Exterity, is clear about its advantages when compared with traditional video distribution. “Image quality is less subject to degradation,” he says. “It can leverage the existing network and the infrastructure of IT support. It’s highly scalable; the user interface is more easily customisable; it is standards-based; access control and security are easy, and more fine-grained than is possible with traditional video distribution paradigms; and it offers a higher degree of investment protection.
“With IPTV,” continues Farquhar, “the length of a cable run has much less influence than is the case with coaxial cable, making it possible to span an entire campus, a metropolitan area, or even, with special software or hardware, a wide area network. With an analogue system, this is economically impractical for all but the largest corporations.”
“I wouldn’t say IP is the default yet,” notes Cuckow, “but it is quickly getting to that point. We are still seeing a split between structured wiring and dataLAN delivery but what is important is real-time delivery, and customers are looking for systems that offer no delays regardless of what cabling is being used.”
Inevitably, not everything about IP is positive. Noting that wireless technologies keep improving, but are not yet reliable enough or far-reaching enough to be considered practical for commercial signal distribution applications, Muddiman explains IP’s potential downside.
“While IP-based distribution has grown more popular, such solutions can easily strain existing infrastructure – and, of course, network cabinets are required every 100m,” he says. “For large applications especially, the best scenario is to position players/sources in a centralised cabinet. Players located at a screen only add remote spots that can fail, which can easily turn into a maintenance nightmare. A centralised cabinet simplifies any required maintenance and it can be done out of view. These are just some of the reasons why widespread signal distribution applications should rely on dedicated structured cabling as an infrastructure.”
Bandwidth: getting scarcer?
Therein lies a not-insignificant issue. Proponents of using the existing IT infrastructure to deliver bandwidth point out the virtues of leveraging the existing investment in cabling and expertise. Opponents – or at least, those who are less enthused – point out that video is a huge consumer of bandwidth that can potentially interfere with more mission-critical business applications.
Farquhar is realistic. “In most cases, using IPTV means the quality of the video will be maintained throughout the transmission,” he says. “However, some organisations may have applications that require a great deal of bandwidth – such as document imaging – meaning there is less free bandwidth available to ensure the quality remains consistent. In these cases, it may be necessary to implement one of a number of Quality of Service (QoS) techniques to prioritise these critical business applications and make sure that video usage doesn’t impact their performance, or to guarantee the performance of important video feeds, such as an ‘all hands’ executive briefing.”
And as Muddiman points out: “Magenta’s switching and extension products don’t need QoS metrics because each link is a point-to-point connection, with well-defined determinism designed into the transport protocol.”
“It all depends on the way that the video is being distributed and the quality of the original content,” adds Cuckow. “Users of MediaStar Digital Media Solutions are guaranteed an excellent quality of service provided the cabling has been selected and installed suitably, and the quality of the content was high.”
Competing for bandwidth is likely to become an even thornier issue as video resolution increases. At IBC, there was much talk of 4K resolution.
“Higher resolutions generally mean higher bit-rates and therefore subsequently more network bandwidth,” notes Dodds. “That means that newer and better compression codecs are required to reduce bit-rates, video packet delivery and provide more effective use of network bandwidth. However, higher resolutions also generally mean more processing is required at the decoder endpoint.”
HEVC: the answer to a prayer?
However, that potential issue may already be approaching a solution. Along with discussion of 4K resolution, IBC also saw numerous companies talking about HEVC/H.265 (see boxout).
A near-term rush to HEVC/H.265 seems unlikely, however, as Dodds points out: “H.264 is a useful codec to take video and compress it to allow better quality at lower bit-rates, but most TV broadcasts are still being delivered in standard MPEG-2 transport streams – although HD may be delivered as H.264, but it is usually in an MPEG-2 wrapper,” he says. “As such, it’s probably not accurate to say that H.264 is the default codec, given how widespread the use of MPEG-2 is.
“That said,” he continues, “any improvements in new, more efficient codecs is welcome as long as they are industry standard and the endpoints have the capability to display the video.”
At the end of the day, the potential strategies for distributing video within an organisation are numerous, and each has its advantages and disadvantages. The reach and scalability of the deployment is likely to be a key determining factor – with broader reach often (although not necessarily) involving some compromise in video quality. Cost, of course, will also be an issue – but the superficially lower-cost option may not find universal approval from those tasked with managing an organisation’s information infrastructure. As ever in the AV world, a finely judged balancing act based on an understanding of the needs of all the stakeholders is the way forward.
And that chairman’s address to his 500 employees? Yes – the chances are, it will end up on YouTube.