HDTV (high definition television) is a television display
technology that provides picture quality similar to 35 mm. movies with sound
quality similar to that of today's compact disc. Some television stations have
begun transmitting HDTV broadcasts to users on a limited number of channels.
HDTV generally uses digital rather than analog signal transmission. However, in
Japan, the first analog HDTV program was broadcast on June 3, 1989. The first
image to appear was the Statue of Liberty and the New York Harbor. It required
a 20 Mhzchannel, which is why analog HDTV
broadcasting is not feasible in most countries.
HDTV and standard definition television (SDTV) are the two categories of display
formats for digital television (DTV) transmissions, which are becoming
the standard. HDTV provides a higher quality display with a vertical resolution display from 720p to 1080i.
The p stands forprogressive scanning, which means that
each scan includes every line for a complete picture, and the i stands
for interlaced scanning which means that each scan includes
alternate lines for half a picture. These rates translate into a frame rate of up to 60 frames per second,
twice that of conventional television.
One of HDTV's most prominent features is
its wider aspect ratio (the width to height ratio of the screen) of 16:9, a
development based on research showing that the viewer's experience is enhanced
by screens that are wider. HDTV pixel numbers range from one to two
million, compared to SDTV's range of 300,000 to one million. New television
sets will be either HDTV-capable or SDTV-capable, with receivers that can
convert the signal to their native display format.
In the United States, the FCC has assigned broadcast channels for
DTV transmissions. In SDTV formats, DTV makes it possible to use the designated
channels for multiple signals at current quality levels instead of single
signals at HDTV levels, which would allow more programming with the same bandwidth usage. Commercial and public
broadcast stations are currently deciding exactly how they will implement their
use of HDTV.
HDTV uses the MPEG-2 file format and compression standard.
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