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Networking and third party control by Henry Goodman S ince the advent of digital technologies, the way audio and video is controlled and transported around broadcast facilities has been constantly evolving in the search for greater efficiencies and improved workflows. Today, broadcasters are demanding more and more versatility and integration from their equipment, and in turn, the capabilities now available are leading broadcasters to reassess how they design studio complexes. Sources have long been shared between control rooms by using splitters, distribution amplifiers, tie-lines and miles of cabling. As production requirements have become more demanding, using such methods becomes increasingly impractical. Traditional routers provide a practical method for dealing with larger amounts of sources and destinations, allowing users to change signal flow on the fly, and en-masse without having to hunt around on physical patch-bays, but they do not address the cabling issue and have finite capabilities. The ever increasing requirements of modern broadcasting requires scalable solutions. Traditional routers, distribution amplifiers, format convertors, tie-lines and even physical patch-bays themselves are now being replaced by modern, networked router systems, capable of providing plug and play convenience to scale up when required. I/O modules can be located remotely from the routers, passing large quantities of signals over a fiber or cat5 cable, reducing overall cabling costs and installation / setup times. Networked I/O and routers break the traditional link between control room and studio, allowing for much more flexibility and ease in the planning of studio resource management, and providing a solution capable of meeting whatever the future may require. Using recent UK examples, Salford’s Media City, BBC’s West 1, and Sky’s Harlequin are all designed around a scalable networked router, I/O and mixing console system. Transporting audio, video or any data over a network requires that the data is sent in packets. Rather than sending a constant stream of audio or video data from point A to point B, the stream is chopped up into manageable sized segments and each packaged up with the destination and source address, allowing multiple streams 48 | TV-BAY MAGAZINE of data with differing destinations to be sent out over a single cable. In order for this to work seamlessly, with high quality audio, without buffering or interruptions, it needs to be very quick and network traffic needs to be predictable or managed – this can be a problem across shared use networks. Using an Ethernet infrastructure, communications protocols can be split into three main groups: those that operate on a physical layer, those that operate on a data link (ie. in the frame), and those that operate on the network layer. Layer 1 protocols use Ethernet wiring and signalling components but not the Ethernet frame structure. They are very cost effective and reliable because of this, but commercial ethernet components such as switches, hubs or media converters cannot be used so topology can be limited. Layer 2 protocols encapsulate audio data in standard Ethernet frames and most can make use of standard Ethernet hubs and utilise a variety of topologies i.e. stars, rings, daisy chains etc. Calrec’s Hydra1 is an example of this. Layer 3 protocols encapsulate audio data in standard IP packets rather than MAC frames. This can be less efficient as the segmentation and reassembly is more processor intensive, which may mean fewer channels and higher latency or more expensive hardware. Hydra2 was introduced in 2009 with the launch of the Apollo platform of consoles and is an 8192 x 8192 router which is integral to the console. With Hydra2, you can take a single mic input and send it out to more than 8000 outputs if you want. It’s a TDM-type router, capable of true ‘one to many’ routing, and although it uses the physical layer of Gigabit Ethernet technology (a tried and tested technology with an affordable chip set), the Hydra2 protocol itself is a considerably more efficient system, which is how 512 bidirectional connections can be packed down each link. Networked infrastructures like Hydra2 are cheap, easy to install and very simple to understand in that sharing inputs and outputs across any number of mixing consoles is an easy and natural process. The idea of networking has involved a shift from end to end points to the network itself, where the only