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NETWORK PRIMER V2 CONTENTS Forward 5 Introduction 7 Chapter One: The benefits of networking 11 Chapter Two: Some technical background 19 Chapter Three: Routes to interoperability 23 Chapter Four: Control, sync and metadata over IP 27 4 NETWORK PRIMER V2 NETWORK PRIMER V2 FORWARD This Primer is a new edition that updates field of computer networking technology the original 2013 Calrec Networking might gain a clearer understanding of the Primer to reflect the many changes that subject. have occurred in the world of broadcast networking technology since then — four This Primer aims to explain the increasing years is a long time in this field. use of data and IP-based networking technology in broadcast applications, Nonetheless, our aim is still to explain examines the benefits that this technology the background and technology behind can offer forward-thinking modern data and IP-based networks with broadcasters, and considers where it may specific reference to its application in take the world of broadcast in the future. broadcasting, such that a broadcast engineer with no formal training in the Hebden Bridge, Spring 2017 calrec.com 6 NETWORK PRIMER V2 NETWORK PRIMER V2 INTRODUCTION calrec.com INTRODUCTION The word ‘network’ has a long history; it was first recorded in the mid-sixteenth century, but its roots hint that it may well have been in use much earlier than that. Like much of modern English, it has gone through a variety of ever more abstracted meanings, from a description of a physical object to more figurative, intangible concepts. What began as a way of describing an invention for catching fish was later applied to similarly interconnected physical systems, including those of canals, railways, telephone wires – and eventually computers. By the early 20th century, the word had come to refer to systems of related entities that were no longer physically connected, as with radio and TV transmitters belonging to a single broadcaster, or groups of business colleagues. In the last few years, we’ve had ‘wireless networks’ (which medieval speakers of English might have regarded as an oxymoron) and ‘social networks’ composed of users that ‘connect’ solely via data transmissions over the Internet; itself a network of physically disconnected, but nonetheless linked computers. A similar process of abstraction has been taking place in the world of broadcast technology, transforming the hard-wired, localised studios of the past into more flexible, networked systems. Forty years ago, television studios consisted of cameras and microphones hard-wired into discrete hardware vision mixers, patchbays and audio mixing consoles which routed to specific video tape machines in one location. In such systems, 8 NETWORK PRIMER V2 INTRODUCTION a separate physical connection is required and even to work ‘in’ - virtual broadcast greater flexibility and geographical for each audio channel, whether from a studios, where the control surface is in freedom available to them. microphone, mixing console, or recording one location, the DSP used for the mixing device. in a completely different building, and the In the longer term, the broadcast industry audio inputs and outputs somewhere else will further borrow from the IT industry Modern networked broadcast systems altogether - perhaps even in a different by shifting away from bespoke hardware offer more flexibility; all of the hardware country. towards software processing running on is permanently connected to a data commodity computing platforms. While network, and the precise nature of the As long as they are all connected to the not all broadcast processes will fit this interconnections between the equipment same network, they should be able to model, many will, and in doing so, offer can be redefined and reassigned at any interoperate just as effectively as the days benefits in scalability and economy. time under software control, remotely if when all these components were part required. of a single mixer in a hard-wired studio, As the shift to an IP infrastructure permanently located in one place. continues, we will be encouraged to drop Such ideas are not new, and small- our conventional signal-based approach in scale proprietary networks of this type These more flexible, abstracted favor of a services model, where content, have existed in broadcasting for many implementations of once-tangible, both live and stored, may be discovered years. But the declining complexity hard-wired, and immovable resources, and accessed by anyone in possession and improving cost-to-benefit ratio of offer broadcasters many benefits, as of access rights and an appropriate IP implementing large networked broadcast we shall see. These include the ability to connection, regardless of their location. systems, coupled with the widening move projects swiftly from one studio to capabilities of the technology, has another by reassigning connections, or However, at the time of writing, much tempted more and more of the world’s controlling aspects of the mixing process remains to be done. Standards enabling forward-thinking broadcasters to move to remotely, without having to be in the same practitioners to define and realise all of networked systems. geographical location as the event being these possibilities are still being written mixed. and ratified, and manufacturers are still In the past few years, the spread of IP- developing networking protocols based based IT networking technology across At the same time, we’re getting closer on open standards that will allow their the world has furthered the development to the goal of being able to transmit equipment to interface and work together. of such networks. Increasingly, broadcast broadcast audio, video, sync information, technology manufacturers and standards control data and metadata together over There is no doubt that there are organisations are developing systems that agnostic, scalable IP-based data networks huge opportunities for forward- utilise, at least in part, hardware, standards consisting simply of data cable and IT thinking broadcasters and technology and data transmission protocols originally switches. manufacturers who are prepared to created for the world of IT, rather than embrace and engage with the changes. developing proprietary systems. This promises further advantages which It’s time to look at some of these benefits will transform how audio, video and in more detail. This is bringing costs down further, as control data is encoded, transported and well as adding a more global dimension managed, such as the prospect of being to the capabilities of the networks being able to dispense with separate audio, developed for broadcast. video and data transports, expensive analogue audio and video cabling, and As IP networks make geography and relatively inefficient embedded-audio the physical proximity of resources less video interfaces such as SDI. and less important, the very concept of a studio itself is becoming more abstract. In the medium term, broadcast workflows Already, it is possible to conceive of - will evolve to take advantage of the CALREC Putting Sound in the Picture 9 10 NETWORK PRIMER V2 NETWORK PRIMER V2 CHAPTER ONE: BENEFITS OF NETWORKING calrec.com CHAPTER ONE: BENEFITS OF NETWORKING A networked broadcast studio, of these simultaneously are still under dedicated to a single room again when the editing suite or transmission station development, but progress towards that job is complete. isn’t necessarily more efficient goal is moving fast. than a hard-wired one — indeed Even with patchbays that allow flexible for smaller broadcasters, the You may well ask what difference it makes interconnection between studio and costs associated with setting up a whether audio is being routed around control room, this would be a challenge