VoIP II: Controlling the IP environment and its security


In a time in which broadcasters are gradually deploying their systems over IP technology, there are several issues to keep in mind that are important. On the one hand, control: How to handle all the systems involved in a new environment. Secondly, interoperability and interconnectivity, from the exchange of signals between systems to their operation. And, last but not least, security is no longer an isolated system but it is connected to others, including the Internet, and must be properly protected.

By Yeray Alfageme



Unified control of the various systems involved in capture, production and broadcast of content has always been one of the most important issues in the design of audiovisual systems. There is no point in having the best equipment if the machines do not understand each other or we cannot control them as a whole. For this purpose GPIO (General Purpose Input Output) was originally created. It is a very simple but effective system and all broadcast equipment have GPIO inputs and outputs to control their functions. From audio follow video up to control of graphics and content playback, everything can be automated with this simple and versatile system at the same time.

To progress a little more in the control of systems, control ports based on serial protocols, either RS232 or RS422, began to be implemented. Again, if we look at it from today’s perspective, these systems are very simple and require specific wiring to operate, but for a long time, and indeed also today, they have been the basis for the control and automation of entire systems.

With the ambition to unify all these control systems, SWP-08 emerged. It is much more flexible than GPIOs but still requires serial interfaces, as well as specific wiring and connections. Some manufacturers have implemented serial protocols over Ethernet cables, but this is nothing more than using a different cable and connector for the same purpose; they are not IP communications.


The flexibility of IP control

Looking at IP as a purely communications protocol, which in fact it is, its great flexibility and adaptation have been proven thanks to the fact that it does not matter what type of data it conveys. Packages are transported in the same way, whether they contain audio, video, documents or a phone call. The same thing applies to the network.

This is of great help especially when we want to exchange audio and video signals outside the purely broadcast environment. Imagine a current contribution and distribution system that does not support IP protocols. Unthinkable, right? Returning to control protocols, implementing them over IP technology has several advantages.

The same wiring is used; in fact, even the same connectors without the need to add anything extra, both for the transport of the audiovisual signal and for control. A single RJ-45 connector -or fiber depending on bandwidth needs- utilized to connect the equipment via Ethernet to the network, can be used for all purposes. This provides great flexibility in configuration and control of the equipment, automatically achieving great interoperability.

In fact, protocols such as SWP-08 have been updated in order to enable transport through IP technology, thus allowing broadcasters to use IP infrastructure for everything from audio and video to control and all the rest of the necessary operations on the systems.


SDI is rigid, but highly interoperable

The more we immerse ourselves in the IP world, the more we realize that interoperability of equipment is ultimately the key. Something that was not even feasible in SDI environments, all equipment could exchange signals with everything, remains yet a problem to be solved in the IP world.

SDI is rigid, no doubt about it. Specific cabling, only one type of signal -unidirectional- and a long list of drawbacks that were previously assumed to be inherent in systems and that are now questionable in current data environments. In addition, SDI had the need to exchange signals synchronously. Ask the technical heads of mobile units and witness the problems that synchronism signals, clocks and worldclocks always cause each time signals are exchanged between mobile units on a TV Compound. Madness.

In contrast to this, IP is highly flexible, asynchronous, allows multiple formats through the same network, it is bidirectional and data of all kinds can coexist with audio and video signals, as long as all equipment units understand each other. And this last tagline was not necessary in the SDI world, although it is the main headache in IP environments: interoperability once again.



The challenges of interoperability

The great flexibility that IP presents comes with new challenges to solve. For example, a camera with a data interface of up to 25 Gbps can exchange signals bidirectionally, not just send the signal it records; all this through a single physical connection. The use of UDP or TCP over the IP protocol is transparent: the signals arrive from one side to the other and that’s it.

AMWA was created in an attempt to solve these interoperability issues. AMWA is a free community of manufacturers, broadcasters and different industry participants whose greatest achievement is the creation of the NMOS (Networked Media Operation Specifications). NMOS establishes a framework through which all compliant systems can communicate with each other by using IP technology within a media world. No more interoperability problems. Or almost….


The NMOS specifications

I wish NMOS were the solution to all problems, but, as any other environment, NMOS was not born with all the capabilities from the beginning, it has been evolving. IS-04 began by offering registration and discovery functionalities within the network. The equipment items would able to discover each other and to make themselves visible within the network in order to be discovered. This makes things even easier.

IS-05 introduced the concept of interconnectivity. In other words, a microphone and a mixing console, for example, could exchange audio signals and ‘self-configure’ to define the bitrate, sample rate and specifications of the signal to be exchanged. For this purpose the Session Description Protocol is used, as it facilitates this interoperability.

IS-06 provides another leap of abstraction from the network, thus allowing some computers to control others. For example, controlling a matrix from a control surface, having a camera tell a mixer what format to work in and asking for the return PGM signal, or having an audio mixing console configure all the microphones on the network in the same way.

NMOS IS-07 was yet a huge leap forward and had the specification introduced, which included event control and tally. These are two very important aspects in the control of audiovisual systems. And the thing is that ‘when this occurs that happens’ is essential in all productions. For example, nobody can imagine not being able to perform a macro in a video mixing system: this is event control.


And finally, security

The title of this section is neither trivial nor the last thing to consider. Security of our signals was something that ‘almost’ no one had noticed in traditional linear signal environments, SDI, MADI and AES. And it was unthinkable that someone would come and steal your signal. It was only in distribution and contribution environments that a simple layer of security was put in place through BISS encryption. And I still remember the number of encoders and decoders that I have configured with the BISS 12345678 key, but I would rather not say where.

Security was not a problem and here the tense is important, it was not, because now it is. Not only because they can steal and copy our signals that we transmit through an IP network or the Internet -this is obvious- but because they can break into our systems, change them or, even worse, control them for us and we would not even know.

Imagine a situation in which we are in the middle of a production and, without any operator noticing, the signals that are sent and the way the equipment works are controlled by a third party. Scary, right? Well, it is possible, real and it has already happened.

Our IT colleagues are over 30 years ahead of us in this area of security. They are the first ones and the experts to deal with these issues and they know what systems to implement and how to configure them. It is important that we do not include security considerations just as one more layer of the project, but as something to take into account from the project’s outset that has an impact on the design of the final solution. Otherwise it will be too late again.



In this second installment of VoIP we have focused on interoperability and security, two issues that in traditional linear environments were things almost to not take into account, but that in IP environments are essential and necessary to consider right from the start.

Because migrating to IP does not only mean changing the coaxial cable for RJ-45 or fiber, but also changing our mindset and adopting new standards. If we want to make use of the innumerable advantages of the IP environment, we must ensure that we tackle all the challenges and are able to overcome them.

In the last issue we will talk about a practical application and we will see how to implement an IP production environment within a real production experience with the aim of closing this trilogy in the most practical way possible.

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