Digital Video Surveillance and Security - Anthony C. Caputo

Digital Video Surveillance and Security (eBook)

Anthony C. Caputo (Autor)

eBook Download: PDF | EPUB

2014 | 2. Auflage
440 Seiten
Elsevier Science (Verlag)
978-0-12-420043-2 (ISBN)

The use of digital surveillance technology is rapidly growing as it becomes significantly cheaper for live and remote monitoring. The second edition of Digital Video Surveillance and Security provides the most current and complete reference for security professionals and consultants as they plan, design, and implement surveillance systems to secure their places of business.

By providing the necessary explanations of terms, concepts, and technological capabilities, this revised edition addresses the newest technologies and solutions available on the market today. With clear descriptions and detailed illustrations, Digital Video Surveillance and Security is the only book that shows the need for an overall understanding of the digital video surveillance (DVS) ecosystem.

Highly visual with easy-to-read diagrams, schematics, tables, troubleshooting charts, and graphs
Includes design and implementation case studies and best practices
Uses vendor-neutral comparisons of the latest camera equipment and recording options

The use of digital surveillance technology is rapidly growing as it becomes significantly cheaper for live and remote monitoring. The second edition of Digital Video Surveillance and Security provides the most current and complete reference for security professionals and consultants as they plan, design, and implement surveillance systems to secure their places of business. By providing the necessary explanations of terms, concepts, and technological capabilities, this revised edition addresses the newest technologies and solutions available on the market today. With clear descriptions and detailed illustrations, Digital Video Surveillance and Security is the only book that shows the need for an overall understanding of the digital video surveillance (DVS) ecosystem. Highly visual with easy-to-read diagrams, schematics, tables, troubleshooting charts, and graphs Includes design and implementation case studies and best practices Uses vendor-neutral comparisons of the latest camera equipment and recording options

Digital Video Overview

Abstract

This chapter explains the difference between NTSC and PAL closed-circuit television (CCTV) technology and digital video surveillance, including how the traditional analog waveforms are encoded for digital transmissions over an IP network. The various digital resolutions for display and recording are explained, and the required architecture to support high definition for surveillance is discussed.

Keywords

NTSCPALmegapixelencodingdecodinginterlacingprogressive scanpixelsMPEG-4H.264MJPEGmacroblocksbandwidthstorage

The difference between digital video and standard analog video is the method of delivery. Digital video follows the laws of all digital technology, breaking down video imagery into a binary data stream composed of ones and zeros delivered as low-voltage electronic pulses over copper wire or light pulses over fiber optics. Anything that requires digital churning of bits (binary digits) uses a microprocessor and stores information in binary “on” and “off” (ones and zeros).

Digital video is not necessarily better than the traditional analog signal, but it is far more consistent in its delivery and transmission and, with the right digital compression, takes far less bandwidth. Analog video is a waveform, which inherently can be corrupted and/or changed by environmental, atmospheric, or technological interference. In fact, because any waveform is allowable and inconsistent, there can be difficulty differentiating noise and distortion from the core analog signal. People who still used the old “rabbit ears” antennas in the days of analog television often experienced this interference. Digital video, however, is a mathematical absolute, using more effective compression techniques to deliver more data, including parameters for redundancy, retries, and quality. Digital video is also somewhat universal, thanks to the proliferation of the Internet. Unlike analog video, which has several standards, with two predominant international ones (NTSC and PAL), and limited radio frequency (RF) spectrum for delivery, digital video is limited only by bandwidth.

In Japan, 20 MHz of RF bandwidth is used for analog television. That’s over three times that of the United States, and that bigger RF pipe provides Japanese broadcasters with the means of delivering HDTV over their traditional analog channels of video communication. The United States is limited to only 6 MHz in an RF spectrum crowded by a multitude of applications. The United States needed to turn to digital technology in order to fit more data within that same bandwidth (10 digital channels fit into the same bandwidth as a single analog channel); hence the need to switch to digital technology for HDTV video transmissions (see Figure 2.1). However, digital transmissions are not limited exclusively to video or even a single stream of video. As mentioned in the previous chapter, the convergence of all things digital can create a multimedia interface not unlike the Internet but now delivered through television. Based on a study by the Television Bureau of Advertising (tvb.org), there are over 115 million U.S. households with television sets (representing 98% of the U.S. population), whereas only 64% of U.S. households own computers and use the Internet, and within that group, only 42% use broadband (the rest are still on 56K narrowband dial-up). Digital television can provide the advantages of the network’s power to the 34% of Americans who do not have the means of accessing online information and can deliver broadband connectivity to the 58% still struggling with a POTS dial-up connection. To paraphrase John Barrett, director of research at Park Associates, a research firm for digital living, in an Information Week interview, “without access to the Internet, you are economically disadvantaged.”

FIGURE 2.1Digital vs. analog transmission.

Analog to Digital

It’s easy to understand the profound change in the way we communicate when we observe how video transmissions have changed within the last decade. Prior to the digital network (and the Internet), video delivery and communications were limited to the same standards developed almost a century ago, using the Federal Communications Commission (FCC) regulated RF analog signal to secure and protect transmissions from being hijacked or corrupted before they made it to your television. This same signal was encapsulated using magnetic tape for videocassette recorders and later was digitized for DVD. However, video wasn’t the first analog medium that made the leap into digital delivery media. Music was originally released as record albums—the same method of delivery invented by Thomas Edison in 1877. In 1911 the original recorded cylinders were replaced with recorded discs (thanks to Columbia Record’s Victrolas). It wasn’t until much later in the 20th century that those vinyl record discs had any competition—first from eight-track tapes in the 1970s and then later, in the 1980s, from cassette tapes. Although the compact disc (CD) player was introduced in 1982, the theory behind it can be traced back to British engineer Alec Reeves, who patented pulse code wave modulation (PCM) in 1943. PCM is the digital representation of an analog signal and is used today in converting any waveform, including video, into mathematical data.

The quality difference between a cassette tape and a CD is the same as between a videocassette tape and a DVD. Simply put, when we digitize the analog signal, the process also includes filters and quantification to produce the best possible delivery (see Figure 2.2). Although the music industry first introduced the digital alternative to a long-antiquated analog system, the benefits included far more than performance quality. Disc players, whether they are CD players or DVD players, have fewer moving parts as well as digital printed integrated circuit boards, which have a longer lifespan than analog circuits and components.

FIGURE 2.2A diagram illustrating interlacing.

Analog vs. Digital

The image on any monitor or screen, whether the traditional analog cathode ray tube (CRT) television or computer monitor, is the accumulation of rectangular dots called pixels, a term that stands for picture elements. All images, video or static, are measured in pixels. In the analog world, each of these pixels is composed of three color dots of red, green, and blue (RGB). The naked eye blends these three color dots into a single color on the phosphor CRT screen. The phosphor emits light in direct proportion to the intensity of the electron beam hitting the screen. Analog television screens have a color depth of about 256 levels for each of the three colored layers, so each analog pixel has a spectral range of about 16.8 million colors (16,777,216). The same holds true for liquid crystal display (LCD) monitors, only the result is achieved differently. The LCD monitor is a thin, flat display of liquid crystals sandwiched between two pieces of polarized glass called the substrate. A small fluorescent bulb (the backlight) illuminates the first substrate, and when the electric current from a thin-film transistor activates the crystals to align at various levels of light and color, it passes through the second substrate, creating what you see on the screen.

While the CRT monitor projects the RGB dots using phosphor, the LCD monitor still needs those same three degrees of colored dots to create its own pixel. Ideally, these three dots or layers would be in exactly the same spot, but they’re close enough and overlayed at varying percentages to fool the naked eye into seeing 16.8 million different colors. The printed color page, under magnification, also shows a similar methodology using the four-color process of cyan, magenta, yellow, and black (CMYK). These four simple CMYK colors, used in varying percentages, can simulate to a close proximity (enough for the naked human eye) the same 16.8 million different colors.

Worldwide Video Standards

There are three major worldwide analog television standards. These are the American National Television Systems Committee (NTSC) color television system, the European Phase Alternation Line Rate (PAL) system, and the French-Former Soviet Union Sequential Couleur avec Memoire (SECAM) system.

WHY 29.97 FRAMES PER SECOND?

Believe it or not, television began in black and white with 525 lines scanned in one-thirtieth of a second. This produced a line scan rate of 15,750 Hz (525 × 30), but with the invention of color television, room was needed for the new RGB signals. So the 15,750 Hz became 15,734 Hz, changing the 30 frames per second to 29.97 frames per second (15,734 / 525).

Table 2.1

Worldwide Television...

Erscheint lt. Verlag	18.3.2014
Sprache	englisch
Themenwelt	Mathematik / Informatik ► Informatik
	Recht / Steuern ► Strafrecht ► Kriminologie
	Sozialwissenschaften
	Technik ► Bauwesen
	Technik ► Elektrotechnik / Energietechnik
	Technik ► Nachrichtentechnik
ISBN-10	0-12-420043-5 / 0124200435
ISBN-13	978-0-12-420043-2 / 9780124200432

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