Practical IP and Telecom for Broadcast Engineering and Operations

Fred Huffman

• Publisher: Routledge
• Year: 2013
• ISBN:
  9781136037214
• Edition: 1
• Topic: Langues et linguistique
• Subtopic: Études sur la communication

What you need to know to survive, long term.Interests between broadcasters and telecom people are blurring. Technical operations and design engineers in one field are increasingly required to deal with practices and techniques in the other. The problem is expectations and terminology differences aren't recognized until it's too late.Take "Quality of Service." The telecom people specify a percentage of the time that the service is guaranteed to be available. The down time may be very, very small. But, if it occurs during a high-priced commercial in the Super Bowl, it is very, very serious for the broadcaster. Practical IP and Telecom for Broadcast Engineering and Operations teaches the technology and how to structure it and make sure the finances work in your favor.Learn how to: * Define communications circuit, equipment, facilities and services used in broadcast engineering and operations.
* Evaluate suppliers as well as their products and services.
* Prepare technical specifications and requests for bids, proposals required in competitive procurement actions.
* Conduct communications operational effectiveness and cost audits.
* Prepare communications cost management strategies and plans.
* Plan and execute capital projects.
* Survive Long-TermCritical for engineers, technicians, and managers engaged in designing, installing, testing, and maintaining equipment and network services for program content, training material, or audio/video conferencing. Valuable knowledge for planning, design, integration and operation of communications equipment, facilities and services used in broadcast operations, training and conferencing applications.Fred Huffman is a systems engineer with Athens Olympic Broadcasting, the Host Broadcaster for the 2004 Games. He has more than 35 years experience in technical and management roles in broadcasting and telecommunications fields. This work is largely a reflection of that experience, captured in a way that introduces the reader to technical aspects of IP, ATM and classical telecom, along with business essentials such as contracts, tariffs, project planning, budgeting and long range planning.

1

Basic Fundamentals, Definitions, and Key Terms

Picture a group of 104 people in a room at a conference. The make up of the group is about 51% telecom heads, 45% transmission equipment manufacturers, and 5% broadcasters. The broadcasters finished their once a year presentations, yet another attempt to tell the telecom people that their network performance is and has been unsatisfactory, again (!), for the past year. One more time they didn’t get it. A broadcaster cites a 3-hour service interruption and states emphatically and profoundly that they couldn’t even get a telephone call acknowledging the outage until an hour after service was restored. The amount of time, energy, and passion put into attempts to gain a common understanding of service-outage would amaze and amuse even the most disinterested casual observer.

What’s the problem? In a nutshell, and no pun intended, the group is suffering from a communications problem. Actually, that’s not the problem. It’s a symptom of more deep-seated malfunction in the practice of human behavior. Any reasonably objective and not necessarily disinterested observer would see there are several issues in the situation described. At the top of the list of issues is this simple fact: these good people weren’t listening to each other. Therefore, they couldn’t possibly absorb what was being said on the other side and had no chance at reaching a common understanding of and resolution of their age-old common problem(s). Well, maybe they tried, but it was an unsuccessful, feeble attempt at best, to define and reach a common understanding of the term outage. Far too often lack of progress in such encounters is simply because the participants use words and phrases that have different meanings to each other, or they use different words and phrases to mean the same thing and don’t realize it.

This chapter begins to solve problems and challenges dealing with Internet and Telecom facilities, networks, and services such as those mentioned previously. It introduces key concepts, defines basic terms, and suggests a process that will enable the reader to organize and successfully manage an organization’s assets and expenditures for communications equipment and services. It covers the following major topics:

• Definition of content and content transport
• The program content food chain
• The migration from analog to digital content transport
• Description of the functions of a network interface device
• Commonly misused and misunderstood acronyms and terms
• A survey of current and applicable standards

From the perspective of dealing with communications network subject matter, you will find it advantageous to limit what you say or write, and be precise and clear about it. The most critical parts of your work with internal information technology (IT)/Telecom experts and third-party suppliers can be found in a few topics, such as bitrate, interface, class of service, and network performance. If you don’t understand it and can’t communicate it, you risk being misunderstood or, worse yet, mislead or taken advantage of. On the other hand, if you understand and can explain it, you can question and make sure your suppliers and colleagues understand. They might not agree, but that’s another story.

The material in this chapter lays a foundation for the remainder of the book. The three models, mentioned in the introduction—Program Content Food Chain, Network Interface Device (NID), and End-to-End Service—are defined and explained. All are current and relatively undated. However, it would be unrealistic not to expect features and functions of the NID and end-to-end service model to evolve over time. The food chain model should be stable and useful for a long time.

Content and Content Transport Defined

Content, in simple terms, is information in the form of audio, video, still and moving images. Information from transducers, which monitor anything from pressure in a pipe to earthquake vibrations displayed on a Richter scale, could be deemed content. Content is sometimes confused with media. In the event confusion occurs, sort it out by thinking of the paper cup and string model. The sound traveling from one cup to the other is content and the string between the two serves as media. Think of the cups as the interface between the content and the media.

Audio and video signals begin life in analog form. Audio is aperiodic, unstructured, and reflective of the dynamic, random nature of sound. Once converted to digital, it takes on a rigid, blocky, periodic structure. Video is different. It is highly structured, reflecting the nature and character of a scan mechanism. The scanning mechanism supports organization of a frame of information coming from a relatively large group of individual sensors, mechanically and electrically sectioned to capture small parts or areas of a scene. With some amplification and care, the image(s) can convince humans that they can see something in the way of a reasonable and acceptable representation—analog of the real scene.

Digitized audio and video content become an object in computer lingo, capable of being automated and manipulated in many ways not remotely possible in analog form. Content in bits, bytes, cells, or packets can be encapsulated in containers and interfaced to digital transport media. Clocking, synchronization, and timing become critical parameters and characteristics that must be constantly attended to.

Content transport means to move the content from one point to another or from a single location or source to multiple locations. Content can be transported live, or in real time, and used immediately or stored for further editing and packaging before being staged for the ultimate purpose.

An often-used metaphor has digitized content in liquid form that is carried in a digital pipe. Supposedly, the content flows through the pipe like water. Not exactly an ideal description, but close. Maybe a more appropriate metaphor would use marbles instead of water. Imagine replacing marbles with watermelons. Both have unique characteristics, are quite different in size, and respond differently to the relatively fixed and rigid characteristics of any particular transport media type. With a little more imagination, it is easy to see that both should be packed and protected differently for the trip. Packing marbles with material normally used to protect watermelons may turn the marbles into small pieces of glass by the end of the journey. On the other hand, packing watermelons in material suitable for transporting marbles may make watermelons unaffordable at the point of sale.

In summary, and to be practical, content is valuable property as long as it gets to the point of a transaction. Someone has to want it, and order it. Once that’s done, it must be delivered. Content transport simply delivers the valuable property. Somewhere in the process, money or other good and valuable property passes in the opposite direction.

The Program Content Food Chain

The program content food chain envisions three distinct stages: creation, distribution, and delivery. Each stage is unique. Designing and building networks to transport the content within and between each of the stages must address the unique nature and quality characteristics of digitized content. For reasons presented later, the nature of the content is quite different in each of the three stages. It’s not a “one size fits all” world anymore. The days of one analog program on one analog transmission channel are numbered.

The program content food chain model illustrates the flow of content from start to finish. The path of travel for content was initially, and still is in large part, made up of analog vehicles. Moving content in this kind of environment is very limited, and subject to noise, distortion, and deterioration found in passive conductor and radio wave transmission facilities. Initially and for many years, the life cycle of content was very short. Essentially limited to real-time or live sessions only, the invention of recording and playback schemes enabled multiple use of content. This basic capability enabled non–real-time content transport by physically moving the media it was stored on. For the purposes of this book, we will focus on network media, not storage.

Gradually, content production equipment and systems have migrated from analog to digital technology, driven in large part by less expensive electronic components developed for the computer and telecom industries. In fact complete, all digital, end-to-end paths are possible with cable modems, terrestrial, and satellite transmission facilities.

Figure 1-1 is an illustration of the three stages of the life cycle of program content. It also shows the relative quality of each stage and paves the way for later explanations of how picture quality and sound fidelity can be matched to transmission bandwidth and cost of transporting content throughout the process of creating, distributing, and delivering content.

Figure 1-1 Program Content Food Chain

The first stage in the chain is content creation. In this stage, raw audio and/or video is captured, or created. Still images or scenes can be captured on film, printed on paper or, if captured with a digital camera, transferred to a computer system and ultimately added into a program or a piece of motion picture entertainment. Titles and other graphics can be created on computer systems and included in the final package.

In terms of picture quality and sound fidelity, this is as good as it gets—“the best.” Compression and decompression may or may not be used in content creation. Contribution quality is a term that’s been used for many years and is likely to remain a well-understood metric long into the future.

Content distribution is an intermediate state. In the past, and still to a great degree, distribution of content is understood to encompass all processes between creation of the content and use by the viewer. This is quite sufficient for analog content, but is unsatisfactory for digitized content. Digitized content enables multiple versions and repurposing master material across multiple applications. It can also be packaged to fit the myriad of delivery vehicles, all digital, that currently exist and are likely to continue to evolve into the foreseeable future.

Much like physical goods distribution, the transport process requires multiple vehicles and transfer points depending on volume. It’s likely the content may be handed off in compressed form. If it’s not handed off in compressed form, the first step after hand-off is probably compression. At this point, the content is either stored or transmitted. Sometimes both happen. It’s almost certainly subject to degradation because of the effects of lossy compression.

Distribution quality as a term has been around for many years as well, and has been used to characterize quality in what is defined in the food chain model as two separate and entirely different stages.

Content delivery is the third and final stage in the food chain model. This is the point where content is handed off to the end user or target audience. It’s almost guaranteed to be in compressed form and must be decompressed before being used. This is true for live, real-time transport or in a file transfer or non-real time. This is the point where it’s decompressed the last time before it’s used or transmitted to the viewer or target audience, thus the label transmission quality.

Why the food chain model? It is important to recognize some basics. First, program content will have experienced compression-decompression at least once, perhaps several times as it moves through the food chain. Second, the compression process is at best a mix of lossless and lossy, or more likely, all lossy. Lossy compression simply means information bits are thrown away in the compression process, and unrecoverable in the decompression process. For example, a given group of bits making up all the bytes in a television (TV) frame won’t be the same when it’s decompressed. Lossless compression on the other hand is a controlled and intentional process. It ensures bit-for-bit replication of the original source material, each and every time the compression and decompression process takes place.

Picture quality and sound fidelity of the delivered content are directly related to, and dependent on, the bit rate or payload of the compressed signal. Higher bit rate payloads result from less compression and its effect on picture quality and sound fidelity.

Another consideration is amount of detail in the source material. For example, digitized source material can be achieved with ITU-R BT601, and contains far more detail than the same material after it has been encoded for National Television Systems Committee (NTSC), Phase Alternate Line (PAL), or Sequentiel Couleur Avec Memorie (SECAM) transmission. These processes include filtering to limit the amount...