Signal management for live venues: The show must go on
Venues of all sizes are embracing technology, and the need to provide a range of content on a range of screens is putting more strain than even on signal management systems. Steve Montgomery looks at your options.
The ever increasing size and number of digital displays, combined with the introduction of ever-higher image resolutions, has greatly increased the complexity of local signal management in public venues; like sports arenas, concert halls and theatres. These complex environments need equally complex systems that are capable of routing a large number of sources to multiple displays and provide comprehensive switching and selection. In some cases there is also a need to mix and manipulate several video streams to provide eye-catching on-screen effects that raise the quality of entertainment and information delivered to the audience.
Large venues can have upward of two to three hundred screens, ranging from small wall-mounted LCD screens to giant LED matrix displays above a central arena or pitch. These are all expected to be managed as a single system with content shared between them with delivered to displays according to their locations.
As a consequence there may be several display formats and content must run equally well on all of them. “In addition to standard displays, there is growing demand for large, dense, high resolution LED displays in non-standard formats,” says Justin Knox, marketing director, RGBlink. “Very large, very fine pitch displays have become extremely common in entertainment applications. Now displays are being integrated into the installation environment – whole walls for example, where video can be displayed wall-to-wall. Video processors have never been more important than they are today and are the vital piece of equipment to deliver today high quality, high performance video to these next generation display environments in what are essentially creative applications.”
Depending on LED wall manufacturer, display aspect ratio and overall size, the video processor must be capable of supporting customised resolutions for both input and output video images. These and many other special requirements are part of the reason why consultants and design engineers choose high-end video processors for the task, albeit at much higher cost than general use video processors or computer-based platforms.
Larger venues often have a wider range of sources and therefore need more complex switching and processing, as Felix Knight, Lightware, explains: “A major difference between venues is that the larger venue will typically have more sources that need to be incorporated into a production or event: multiple camera feeds, live streams, recorded material and so on. This increases the burden on signal routing and switching.” Interoperability between equipment is essential and a device that is difficult or impossible to integrate can present a real problem.
“Larger venues tend to have multiple configurations and the time taken to switch between them needs to be considered,” Knight adds. “In this way, a larger and more capable system can be justified if it reduces switching times between two configurations. Smaller venues do not tend to have such drastically different configurations, and if there are, the cost in time of repurposing the necessary hardware is not so great.”
It is not always the larger venues that have the most demanding requirements, as Knox points out: “There is a large discrepancy in the level of sophistication of equipment used and the need for staff with greater technical skills to operate it at the highest levels.” Larger venues are likely to be able to recruit and deploy dedicated operational support engineers; smaller venues not so. “We have been putting a lot of effort into improving usability and accessibility into equipment designed for smaller spaces, like interactive touch screen control, which has become really important to making those applications workable as the display market increasingly moves to large format LED.”
Reliability of system operation is a massive factor, since the displays are so prominent, and as anyone who has experienced a system failure at a large public gathering can contest; they are highly noticeable by the audience. In extreme cases it can even rule the venue out of action with a potential loss of revenue.
Measures to increase system reliability through component redundancy, backup and replication can be taken to almost any level, but come at a cost; which must be considered at the earliest possible stage in system design. “Reliability and redundancy can have a significant impact on overall project cost. Thoughtful and serious discussion about system up-time requirements versus downtime risks should always take place at the outset of the project planning process,” says Jay Gonzalez, president of Analog Way Americas. “All stakeholders - end user, vendors, consultants and integrators - should join this discussion. Redundancy measures may range from offline product replacement schemes or advance replacements to total redundancy and auto switchover of all devices in the chain. Regardless of what redundancy strategy is selected a thorough discussion about reliability and anticipated up-time operation is always recommended.”
The measures taken and equipment used to ensure the acceptable level of reliability will depend upon the type of video distribution systems in use and will be different for each location. Knox outlines the possible options offered by RGBlink. “Uninterrupted power is always the first level of reliable operation. We offer hotswap and redundant power supply options on many of our products to support those requirements. At the device level, our high level of modularity has been crucial in providing tool-free maintenance and low down time. At the signal level, we can support a wide range of scenarios including signal backup and fail-over, together with seamless preset switching in the event of a lost signal. Additionally with our OpenAPI we support commands over UDP/RS232 that maybe triggered by EMS and BMS systems.”
Mark Stanborough, sales director, EMEA & APAC at Cabletime explains his company’s approach: “The systems have to be designed to be robust and reliable from the start using superior components and designing and building systems that are fit-for-purpose. IP-based systems will usually incorporate a failover stream and if one endpoint or encoder fails, the content can be routed from a different source.”
Data security can be an issue in public venues that are spread over large areas, often with tens of kilometres of wiring and publicly-accessible Wi-Fi networks. Encrypting valuable content provides a counter measure. “IPTV is an integral part of the public presentation solution in many large-scale public environments,” explains James Keen, group marketing manager for Tripleplay. “It provides a high level of core flexibility and security. Encrypted feeds can be delivered to thousands of TV screens, mobile devices or PCs simultaneously across the core IT network, delivering a unique feed to each and every screen and, if required, incorporated into digital signage layouts.” He believes that it is this functionality that: “sets IPTV aside from many of the solutions that are emerging in our market.”
Distribution of AV content over IP network offers some important benefits to installations that are spread over large physical areas. One of the most welcome advantages is that display points can be established wherever a network can be accessed. Knight summarises the benefits: “Whilst AV distribution over IP systems are not yet able to completely replace traditional pro AV systems, they are being considered in a wider range of applications than ever before. There is something of a sweet spot regarding cost and system size. Systems under this size are still most effectively handled by traditional AV systems, whilst systems above it can be handled by AV-over-IP much more efficiently.
“This technology comes with a set of advantages. It enables asymmetrical systems to be established with unequal numbers of inputs and outputs rather than the traditional ‘square’ format. It is scalable and can be built up to user requirements, without them having to invest in a larger matrix than initially needed. It is highly flexible and economic as it uses the standard IP protocol, so it is compatible with a lot of network switchers and existing Cat5 infrastructure.”
However, as he admits, there are disadvantages associated with AV-over-IP distribution technology. “The signal encoding-decoding process adds latency and it is necessary to compress the video to pass it around the limited bandwidth of the network. It may not be simple to incorporate new features, like HDR, into an existing distribution system and at some point the existing IP data network may be insufficient to handle heavy AV-over-IP traffic a separate network may be required. It is important for the IT department to be aware of this and accommodate new devices and technologies that they may need to be working with. AV-over-IP systems can only work well when the AV and the IT departments are coordinated. If they are not, huge network problems can occur.”
Latency can be a drawback in applications that take advantage of advanced real-time video processing. This needs to be carefully considered and the total end-to-end system latency calculated, particularly for broadcast and live events in which lip-sync on stage-to-display stage systems is important and delay easily noticed.
Signal switching is another area that can potentially cause problems. Gonzalez: “In pro-AV, switching is often loosely defined. Our high-end products feature clean and totally seamless transition from one video image to another with no image freezing, de-synchronisation or black frames. Switching very high-resolution images require a tremendous amount of processing resource and high speed number-crunching.”
IP-based systems also bring a new and heightened level of accessibility, as Knox explains: “An interesting point with regard to IP is how it has enabled and extended controllability. While we do all the video processing on our hardware, the ability to control and signal those devices from computers and mobile devices over common IP infrastructure has been a great advantage an innovation. While video transport over IP is all the talk, this ability for controllability via IP is not to be discounted.”
Video processors often provide the bridge between multiple systems or applications, he says. “The ability for up/down cross conversion to suit the various requirements in one box can be instrumental in enabling these scenarios in a world where there are increasing demands for multiple video destinations; whether that is locally, through wider broadcast, streaming or recording.”