Video Over IP

IPTV, Internet Video, H.264, P2P, Web TV, and Streaming: A Complete Guide to Understanding the Technology

Wes Simpson

• Publisher: Routledge
• Year: 2013
• Print ISBN: 9780240810843
• eBook ISBN: 9781136031052
• Topic: Languages & Linguistics
• Subtopic: Communication Studies
• Index: Languages & Linguistics

Video Over IP gives you everything you need to know to choose from among the many ways of transferring your video over a network. The information is presented in an easy to read format, with comparison charts provided to help you understand the benefits and drawbacks of different technologies for a variety of practical applications. This new edition is expanded to fully cover HD and wireless technologies and new case studies. Whether your background is video, networking, broadcast, or telecommunications, you will benefit from the breadth of coverage that this book provides. Real-life application examples give readers successful examples of a variety of Video over IP networks that are up and running today.

1 Overview of Video Transport

DOI: 10.4324/9780080888170-1

Transporting video signals is a round-the-clock business throughout the world today. Whether for entertainment, education, or personal communication, we now live in a world where we are exposed to video content in many forms. The scale of the technologies and systems that are used to gather and deliver all of this content are amazing. For example, the 2006 FIFA World Cup^™ tournament had a cumulative television audience of over 26 billion viewers during the 30-day tournament. But Internet video is rapidly catching up-a January 17, 2008 press release from comScore reported that Americans watched 9.5 billion Internet videos in November 2007, with the average viewer watching 69 videos at an average length of 2.8 minutes, representing an increase of 29 percent since the beginning of 2007.

As Internet Protocol (IP) technologies for video transport continue to mature, more of the video delivery process will take place over IP networks. This change will ultimately include all phases of video content creation and delivery, beginning at the video camera and ending at a home viewer's video display. As we will see throughout this book, many different areas of the video industry will be affected by IP technology.

In this chapter, we will look at the methods used today for delivering video signals to viewers around the world. Then we'll discuss the main technologies used in telecommunications networks. We will also investigate some of the issues surrounding video transport on the Internet. Finally, we will introduce our Video User Checklist, which will be augmented throughout the book. By the end of this chapter, you should be familiar with the common forms of video transport and the common types of telecom networks.

Defining Iptv

Problems can occur when new terminology is created and not everyone agrees on the meanings. Case in point: the term IPTV. While it is true that all Internet Protocol Television (IPTV) installations send video over IP networks, it is not true that any kind of video sent over an IP network is IPTV. For the latter, the term Internet video is much more descriptive.

IPTV is simply a way to deliver traditional broadcast channels to consumers over an IP network in place of terrestrial broadcast, CATV, and satellite services. Even though IP is used, the public Internet actually doesn't play much of a role. In fact, IPTV services are almost exclusively delivered over private IP networks, such as those being constructed by telephone companies in the United States and elsewhere. At the viewer's home, a set-top box is installed to take the incoming IPTV feed and convert it into standard video signals that can be fed to a consumer television.

Some of the main characteristics of IPTV include:

• Continuous streams of professionally produced content (such as a TV broadcast network feed)
• Hundreds of 24 × 7 channels
• Uniform content format (all channels typically share one compression method and use roughly the same bit rate)
• Delivered over a private network, such as a telco digital subscriber line (DSL)
• Viewed on consumer televisions by way of a set-top box

Internet Video

Internet video is used to supply video content to viewers by way of the public Internet. In a typical Internet video installation, service providers set up a website portal that can be reached by anyone with a standard browser. At this site, a list or index of the various pieces of content will be available. Once the user has selected content, it is delivered from servers to the viewer's PC, where media viewer software can be used or where it can be downloaded to another device.

Some of the main characteristics of Internet Video include:

• Discrete content elements, ranging from clips lasting a handful of seconds to full-length movies
• Millions of content offerings
• Widely varying content formats, including dozens of different types of video compression, rights management technologies, and image resolutions
• Delivered over the public Internet
• Viewed on PCs via software, on portable video players, or on televisions by means of network adapters

Video Transport Technologies

Television was invented for a single purpose: to transport moving pictures from one location to another. The word television comes from the Greek word tele, meaning “distant,” and the Latin verb visio, meaning “to see.” (The word video also comes from this same Latin root.) Hence, television means “seeing at a distance.” Modern video transport technology is all about sending moving images to a viewer who is far away.

Today, users have many options for video transport, which presents a challenge: How does a user select the best way to transport video for each application? Many factors are involved in this choice, so there is no one best answer for all users. Let's begin by looking at the many methods used for transporting video signals today.

Broadcast TV

The first IP networking applications in broadcast TV production were video file storage and retrieval, particularly for supporting digital video-editing stations. From there, it was a small step to supporting live ingest, which is the process of taking live video content into the digital domain for storage in files on hard disks. Then live-toair output over IP networks became feasible. This whole process has been driven in part by the continuing spread of high-performance computer workstations that are able to handle video streams in real time. It is actually simpler to configure these workstations with a high-bandwidth networking card (such as Gigabit Ethernet) than it is to equip each station with a video card and audio input and output cards.

Many people first encountered TV in its original form-as a signal broadcast from a central tower, through the air over a dedicated channel, to a television equipped with an antenna. Let's look at some of the key components of a modern broadcast television system (see Figure 1-1).

Figure 1-1Broadcast Television System Diagram

The master control room (MCR) is the operational hub of a television station, where video content is assembled and made ready for broadcasting to viewers. Video content can come from a variety of sources-a live local source, a broadcast network,¹ a videotape, or from a video server. Table 1-1 gives a small sample of the many functions that a modern television station must perform.

1. Somewhat confusingly, the term network has two different meanings for people with broadcast television or data communications backgrounds. In this book, we will try to use the term broadcast network whenever we are referring to the distributor of programming that operate in many countries, such as the BBC in the UK, ARD in Germany, or CBS in the United States. When we use the term network by itself or with another modifier, we are referring to a data, voice, or other type of telecommunications system.

A studio-to-transmitter link (STL) is used whenever the master control room is separated from the actual transmitter tower. The STL carries the television signal directly to the transmitter, normally over a dedicated facility. Microwave radio can be used where there is a direct line of sight available from the studio to the transmitter. Fiber-optic links are more reliable than microwave radio links, but they require a fiber-optic cable to be connected from the studio to the transmitter. These links can be owned by a local telephone company, some other local utility, a municipality, or even by the television station itself.

At the transmitter, the signal is received from the studio and then placed into a specific channel frequency band. For example, in the United States, Channel 30 occupies the frequencies between 566 and 572 MHz. The modulated signal is amplified to a high power level and fed into the broadcast antenna. The television signal then radiates from the antenna to viewers’ locations.

Table 1-1 Television Station Functions

•	Collect video content from a variety of sources, including broadcast network feeds, advertising agencies, local television studios, and syndicated program distributors.
•	Prepare the video content for broadcast by editing the material to fit into time constraints and adding local programming and advertising.
•	Ensure that the broadcast signal meets all of the performance standards (such as operating frequency and peak radiated power) specified in the station's broadcast license.
•	Make sure there is no “dead air,” i.e., times when nothing is being broadcast.

At each viewer's location, a receiving antenna collects the radiated signal and generates a very tiny output signal. This signal is then demodulated and decoded to recover the video and audio signals. These signals are then amplified many times over until they are powerful enough to drive the television set's display and loudspeakers.

Satellite Television

Satellites orbiting the earth are commonly used to receive signals from one earth location and send them to another. Satellites can also be used to broadcast a collection of television signals directly to viewers’ homes. Both these applications are in widespread use today.

Satellite transmission of television programs has been used since the mid-1960s to send live programming from one continent to another. Broadcast networks began using satellites to send programming to local television stations and cable TV systems in the mid-1970s. It wasn't until the late 1980s that satellite broadcasting to consumers really began, as exemplified by Sky television in the UK in 1989. This market became known as the direct-to-home (DTH) market, since satellite television service providers were transmitting their programs directly to consumers rather than to local television broadcast stations or cable television systems as in the past. This service is also commonly known as direct broadcast satellite (DBS) service. Let's look at the key components of a typical satellite DTH system (Figure 1-2).

Figure 1-2Direct-to-Home (DTH) Satellite Television System Diagram

An uplink facility transmits signals from the ground to a satellite, using a high-power signal and a large-diameter dish. The uplink facility gathers video content from a variety of sources, including local television stations in various cities, specialized programmers (such as movie and sports networks), and many others. Because a single uplink facility can create multiple signals to be sent to one or more satellites (by means of a separate dish for each satellite) for rebroadcast over a large area, one facility can serve an entire continent.

Satellites are positioned above the equator at a height of 22,300 miles, which causes them to orbit the earth once every 24 hours and appear to be stationary above a fixed point on the earth's surface. Each satellite is equipped with multiple transponders, each of which receives a signal transmitted by an uplin...

Table of contents

• Cover Page
• Half Title Page
• Title Page
• Copyright Page
• Dedication
• Contents
• Introduction to the Second Edition
• Introduction
• 1 Overview of Video Transport
• 2 Ip Video Transport Applications
• 3 Video Basics
• 4 Video and Audio Compression
• 5 Ip Networking Basics
• 6 From Video Into IP Packets
• 7 Ip Packet Transport
• 8 Private Video Streaming And Media Players
• 9 Multicasting
• 10 Videoconferencing Over Ip
• 11 Drm, Content Ownership, and Content Security
• 12 Private Networks Secure and Transport
• 13 Iptv—Delivering Television To Consumers
• 14 Video File Transfer, Podcasting, and P2P
• 15 Internet Video
• 16 Network Administration
• appendix1
• appendix2
• Index