Transitioning From Analog To Digital Broadcast Transmission Part II
Although many people might think that HDTV and digital video are the same thing, they actually began as separate technologies, before they merged to form the basis of today’s video revolution.
HDTV, also known as high-definition television, emerged in the early 1980s as an experimental Japanese analog system developed by Japan’s public TV network, NHK, which began research and development for this technology as far back as 1963. It offered near-theater-quality pictures and a surround sound, but it required too much bandwidth to be transmitted on standard TV channels. NHK marketed its analog HDTV worldwide under the names Hi-Vision and MUSE (Multiple Sub-Nyquist Sampling Encoding), but it never spread commercially beyond Japan.
The FCC rejected NHK’s analog HDTV for use in the United States, because it required 9 MHz of broadcast bandwidth, which was 1.5 times that of the standard U.S. television channels. In addition, the FCC felt political pressure to nurture a homegrown advanced-TV system, hoping to stem Japan’s dominance of the video-hardware industry. As Canada’s FCC equivalent, the CRTC, nearly always followed the technical standards adopted in the United States by the FCC, Canada again followed the lead of the United States for digital television.
In 1982, the Advanced Television Systems Committee (ATSC), was formed by several industry and professional associations which included the National Association of Broadcasters, the National Cable Television Association, and the Society of Motion Picture and Television Engineers, among others. The committee’s name was based on the old NTSC acronym, and this group would spearhead private-sector efforts to create a new way to produce, send, and receive TV signals. In 1987, the FCC formed the Advisory Committee on Advanced Television Service to oversee the government’s side of advancing TV technology. Initially, it rejected several proposals for enhanced analog TV systems, because none of them provided enough improvement over traditional NTSC signals within the bandwidth of a standard TV channel.
As analog video uses a continuous, variable electrical signal, the new solution would be digital. In contrast, digital video uses a sequence of discrete binary digits or 1s and 0s following the basis of computing technology. These digits would form the pixels (picture elements), that combine to produce final picture you see on screen. Digital video images weren’t intrinsically superior to analog video images, but they provided an opportunity to move beyond the NTSC’s primitive color encoding. They could be copied and retransmitted with no degradation in image quality, and more importantly, these digital signals could be compressed by replacing redundant information with mathematical algorithms.
In the late 1980s and early 1990s, digital video surfaced on two fronts. The first came on the professional end with lightweight chip-based cameras and tape-less editing systems, which eventually revolutionized video production that makes today’s nonstop news channels and reality shows more feasible. The second front came in the mid-1990s with the proliferation of the world wide web gave rise to various new compressed video formats from the likes of Apple, RealNetworks, and Microsoft among others by bringing small-screen-size video clips to computer desktops around the world. As broadband connections were not not readily available at the consumer level back then, image compression was standard in every online-video.
Digital video compression wouldn’t end these these proprietary systems, as other digital video standards are available for license to the industry as a whole. The most prominent of these is the MPEG series of specifications that is named for the Moving Picture Experts Group, the international consortium that originally worked out both audio and video compression standards. The audio-compression format known popularly as MP3 is a subset of the group’s earliest video format, MPEG-1. The group’s MPEG-2 video standard has become a basic part of digital TV standards in the United States. Thanks to digital compression, high-definition signals could at last fit into standard broadcast TV channels, with room for one or two standard-definition signals as well.
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