To Centralise or Not to Centralise?

To centralise or not to centralise? When purchasing an automation system, that is the question. For broadcasters in the Middle East matching rapid growth to scalable, future-proof technology is a key to the successful development of the station. Richard Thomas, software development director at automation specialist Abit, compares centralised and distributed automation architectures to see how closely both models match the needs of growing broadcasters in the region

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By  David Ingham Published  August 9, 2006

|~|Screenshot_HR-L.gif|~|Centralised automation architecture has evolved with new processors, memory expansion and availability of a wide range of interface cards.|~|The majority of broadcast automation suppliers now base their product on a distributed architecture using networked PC/Workstation architectures. However, following ongoing advances in technology in recent years, the centralised architecture has a number of advantages over a distributed model so why do many broadcasters continue to choose the 'old fashioned' approach? The answer is that traditionally centralised architectures have been perceived as the more costly option. In actual fact, these days, because the cost of general processing power has reduced significantly, if you consider both operational and support fees in addition to the tighter level of integration that can be achieved through the adoption of centralised architectures then this often is not the case. So if the cost of a centralised system is comparable with a distributed system what exactly are the differences and advantages of each type of architecture? The Distributed Architecture Originally based on PCs running DOS and linked together using Novell networking techniques the distributed architecture provided a range of broadcast automation functions. The architecture has closely followed the PC, LAN and Windows revolution resulting in its present configuration which incorporates a range of software applications installed on a network of PCs running standard versions of Windows or more recently Linux. Each PC can either be assigned a particular operation such as ingest, scheduling or playout for example, or a small group of channels depending on the overall system design including different software modules on each PC. In the distributed approach, system resilience is provided by moving functional and broadcast responsibility from one personal computer (PC) to one of the other computers on the network in the event of a problem. This can be carried out either operationally, by cross coupling arbitration signals between computers or by the generation of health messages on the LAN. Changeover is carried out either manually or by a software control algorithm. Centralised Architecture Centralised automation architecture on the other hand, has evolved following the growth of newer and faster processors, memory expansion and the availability of a wide range of interface cards while using established real time operating systems (RTOS) such as VxWorks and OS9. Its approach comprises powerful CPU processor boards linked by an internal bus providing high bandwidth and guaranteed low latency for inter-processor communication supported by the development of a wide range of utilities that have in-turn led to a reduction in necessary, manual operational activities in the broadcast environment. The integrated broadcast automation software runs on the master control processor while additional CPU boards act as communication servers controlling the peripheral equipment such as VTR, mixers and routers. The software application modules run on a RTOS maintaining low level synchronisation of logical tasks and communication. Redundant operation is provided by linking two systems together in a one-for-one architecture, the first system acting as the on-line automation system and the second system acting as the stand-by system. Both run identical software and mirrored databases installed in each system, including media location pointers, meta-data and flow-control state transition information. In the event of a failure of the on-line system or by a single-operator command a hardware arbitration mechanism passes control to the stand-by system. Advantages Any broadcast environment, whether it is in the Middle East or elsewhere in the world tends to be made up of a range of equipment including both legacy based hardware and software driven equipment taking advantage of the latest IT developments. This challenges the automation system as the different characteristics of each piece of equipment have to be catered for within the automation system in addition to the overall organisation workflow requirement. It is the responsibility of the automation system to control all of the elements in the broadcast environment. Both centralised and distributed architectures can be made to fit into the workflow and service integration requirement of the broadcaster needing varying degrees of customisation however, a centralised approach provides a point of reference to analyse easily how all elements are reacting and interacting. The centralised architecture allows a single channel to be broadcast on multiple channels allowing last minute changes to be reflected across the broadcast spectrum while taking into account varying factors for each stream such as commercial regulations, time zone differences, transmission path timing characteristics, opt-out scheduling and control signals for use in interactive services. This is particularly suited to the Middle East marketplace where satellite is an important carrier and allows the channel to expand its broadcasting in the EMEA region while ensuring compliance with cross-border agreements. The tightly coupled control algorithms allow seamless inclusion of branding and commercial placement in accordance with the primary schedule or under the control of the production staff, up to the time of transmission efficiently and safely. The architecture provides a central control reference to ensure that all facets of a multi-channel environment are synchronised. The control reference must not only use a recognised time source to synchronise events but also have the ability to react to the characteristics of each individual device attached. The control reference is a combination of the RTOS and tightly coupled low level software logic on the processor card to ensure that the commands are received at all of the active devices in the broadcast chain simultaneously ensuring frame accuracy. The combination of high bandwidth and guaranteed low latency within the centralised architecture ensures that frame accuracy is provided consistently and independent of any changes in the broadcast environment characteristics. The centralisation of all system resources such as recording, playout and duplication along with the immediate availability of associated meta-data and state information allows a high level of automation to be achieved in a multi-channel broadcast environment. In the future, the viewer will set the agenda and request media from the broadcaster which will act as a giant media server. Servers and data centres are currently going through a process of aggregating multiple servers onto single centralised servers to simplify management and improve security to accommodate this move. The centralised automation system is well positioned to service the existing business model providing scheduled playout and the future business model by becoming a gateway to the media server. In an industry that is moving at an increasingly fast pace let's keep the viewer's perspective front of mind. Minor timing differences in the digital domain are obvious to the viewer making frame accuracy one of the biggest challenges to the automation supplier when integrating a mixture of real-time linear and non-linear elements in the broadcast chain. The viewer requires a seamless linear experience with the option to interact on occasions, and that requires true integration. Should this not be provided they will turn to a different channel or even drift away from television altogether if they are not provided with both the content and quality of service they demand. The centralised approach provides a scalable automation solution that meets this fundamental requirement and provides a stepping stone to future advances in broadcasting.||**||

3552 days ago

Great and very comprehensive analysis. Here on the you can read a very good example of why a centralized databank is not a universal solution not just for technical, but primarily for legal or political reasons. It also gives you examples of solutions for highly secure distributed systems. Hope you enjoy the reading!

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