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Unit 5: Video

are placed so close together that the human senses perceive them as a continuous flow. Analogue notes
data, such as video recorded on tape, is transmitted as electronic signals of varying frequency or
amplitude that are added to carrier waves of a given frequency. To make that information usable
on a computer or a modern media player, analogue-to-digital conversion translates an analogue
signal to a series of zeroes and ones, which represent, respectively, “negative” and “positive,”
“off” and “on,” or “low” and “high.” The opposite action, digital-to-analogue conversion, recreates
the analogue signal for playback.
Digital video offers a number of advantages over analogue video, including:

1. Ease of sharing and storage.
2. No degradation of data quality when copied.
3. Easy and inexpensive copying.
4. The capacity for multicasting.

Digital video technology can also incorporate analytical software for intelligent video, which
enables capabilities such as video search, object tracking and intrusion detection.

5.5 Digital video standards—atsC, DvB, isDB

5.5.1 advanced television systems Committee (atsC)
The ATSC coexists with the more widely used DVB standards, and ISDB being implemented in
Japan. The system includes the capability to carry PAL- and SECAM-format video (576 displayable
lines, 50 fields per second) along with NTSC (480 displayable lines, 60 fields per second) and film
(24 frames per second). Broadcasters, who use ATSC and must retain an analogue signal, have to
broadcast on two separate channels, as the ATSC system requires use of an entire 6 MHz channel.
The system has been criticized as being complicated and expensive to implement and use. Many
aspects of ATSC are patented, including the AC-3 audio coding, and the VSB modulation. The
standards ATSC depends on are often ambiguous, one example would be the EIA-708 standard
for closed captioning.

5.5.2 Digital video Broadcasting (DvB)
Digital Video Broadcasting (DVB) is a suite of internationally accepted open standards for DTV.
The DVB standards are maintained by the DVB Project, an international industry consortium with
more than 270 members, and they are published by a Joint Technical Committee (JTC) of European
Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical
Standardization (CENELEC) and European Broadcasting Union (EBU). The interaction of the DVB
sub-standards is described in the DVB Cookbook. Many aspects of DVB are patented, including
elements of the MPEG video coding and audio coding.
Services using DVB standards are available on every continent with more than 600 million DVB
receivers deployed. The DVB worldwide section offers country-by-country news stories and an
overview of where DVB technology has been deployed.
History

From the very earliest days of television, right up until the 1990s, all television broadcasts were
made using analogue television and it had not been thought feasible to introduce a digital system
due to the complexity of the processing required. However, with the advance of digital processing
techniques and the advances made in integrated circuit technology, the possibility of using digital
techniques for television broadcasting became a real possibility.
As a result, over the course of 1991, various organisations discussed how to move forwards with
the idea and how to form a pan-European platform that would enable considerable economies
of scale to be achieved.

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